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The relationship between psychotic-like experiences and sleep disturbances in adolescents
Sleep Medicine 13 (2012) 1021–1027
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Original Article
The relationship between psychotic-like experiences and sleep disturbances in adolescents Yu Jin Lee a, Seong-Jin Cho a, In Hee Cho a, Joon Hwan Jang b, Seog Ju Kim c,⇑ a
Department of Psychiatry, Gachon University of Medicine and Science, Incheon, Republic of Korea Department of Psychiatry, Seoul National University College of Medicine, Seoul, Republic of Korea c Department of Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea b
a r t i c l e
i n f o
Article history: Received 14 January 2012 Received in revised form 31 May 2012 Accepted 1 June 2012 Available online 25 July 2012 Keywords: Psychosis Adolescent Insomnia Sleepiness
a b s t r a c t Objective: We investigated the relationships between sleep disturbances and psychotic-like experiences (PLEs) among adolescents. Methods: A total of 8530 students (grades 7–11) were recruited in the Republic of Korea, and 7172 students who completed all of the relevant questionnaires participated in the current study. The survey included the Eppendorf Schizophrenia Inventory (ESI), the Youth Psychosis At Risk Questionnaire (YPARQ), the Beck Depression Inventory (BDI), the Epworth Sleepiness Scale and questionnaires about sleep disturbances (insomnia, cataplexy and snoring). Results: Subjects with insomnia, excessive daytime somnolence (EDS), or probable cataplexy had higher ESI and Y-PARQ scores after controlling for age, sex and BDI scores (all p < 0.001). Insomnia (OR = 4.40), EDS (OR = 3.84) and probable cataplexy (OR = 2.97) predicted clinical high risk of psychosis. Insomnia, EDS and probable cataplexy remained as significant predictors of clinical high risk for psychosis, even after controlling for depressive symptoms or when analyses were confined to non-depressive adolescents. Conclusions: Insomnia and EDS were found to predict PLEs in adolescents, independent of depression. Our findings suggest that adolescents complaining of insomnia or sleepiness may require further assessment regarding potential risk of psychosis. Ó 2012 Elsevier B.V. All rights reserved.
1. Introduction Since untreated psychosis induces unnecessary suffering and typically has poor outcomes [1,2], early intervention has been emphasized as a strategy to attenuate or avert the full-blown psychosis [3]. For successful intervention, identification of subjects at potential high risk for subsequent psychosis is important. As psychotic-like experiences (PLEs) or sub-threshold psychotic symptoms have been suggested to be good clinical predictors for psychosis [4,5], subjects with such symptoms may be considered as clinical high risk group for subsequent psychosis. The identification of signs or symptoms associated with PLEs is also warranted. Sleep disturbance is closely associated with psychosis, and insomnia is one of the most frequent presenting complaints in psychotic disorders [6]. In addition, PLEs have been frequently reported in narcolepsy, a sleep disorder characterized by sleepiness, cataplexy, hypnagogic hallucination and sleep paralysis [7]. ⇑ Corresponding author. Address: Department of Medicine, Seoul National University College of Medicine, 28, Yeongeon-dong, Jongno-gu, Seoul 110-799, Republic of Korea. Tel.: +82 2 740 8418; fax: +82 2 744 7241. E-mail address: [email protected] (S.J. Kim). 1389-9457/$ - see front matter Ó 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.sleep.2012.06.002
Furthermore, sleep disturbance is a common prodromal feature of schizophrenia preceding first psychotic episodes or psychotic relapse [8–10]. However, since sleep disturbance has been regarded as a non-specific symptom, it is often overlooked in studies investigating PLEs or risk for psychosis. The relationships between sleep disturbances and PLEs or psychosis may vary depending on age. Adolescence is an especially important period for both sleep and the advent of psychosis. Sleep plays an important role in the reparative and integrative processes of the adolescent brain. In addition, many psychotic disorders onset during late adolescence to young adulthood. One study reported that sleep continuity was more impaired in adolescents with schizophrenia than those with major depression [11], which was opposite to the usual findings in adults. Although both sleep and psychosis are key adolescent mental health issues, few studies have addressed the relationships between these two problems in adolescents. Oshima et al. [12] administered surveys including 4 questions about PLE and 2 questions related to sleep to 341 Japanese high school students and found that short sleep duration was associated with PLEs. Ruhrmann et al. [13] reported that the sleep disturbance item on the Scale of Prodromal Symptoms was a predictor of transition to
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psychosis in an 18-month follow-up study of 245 adolescents and young adults in putatively prodromal states. Although prior studies addressed non-specific sleep disturbances, it remains unclear which specific sleep disturbance (e.g., excessive daytime sleepiness, insomnia or cataplexy) is related to PLEs or clinical high risk of psychosis. In particular, there have been no studies investigating the relationships between excessive daytime somnolence (EDS) and PLEs, even in adults. In addition, the relationships between sleep disturbance and PLEs has never been confirmed in a large community-based sample of adolescents, although such sample enables obtaining a wide range in PLEs and avoiding the complicating issues of selection bias or medication effects in clinical samples. The aims of the current study were to examine the relationships between specific sleep disturbances (insomnia, EDS, snoring and cataplexy) and PLEs in a large community-based Korean adolescent sample. We hypothesized that adolescents with specific sleep disturbances (especially insomnia and EDS) would have higher incidences of PLEs than those without sleep disturbances, and that the presence of such sleep disturbances would independently predict clinical high risk of psychosis among adolescents. 2. Method 2.1. Subjects We recruited subjects from schools in three different areas of South Korea by sending documents to schools requesting participation. All of the schools that agreed to participate, 18 high schools and 5 middle schools, were selected as subject schools. Six were boys’ schools, eight were girls’ schools, and nine were coeducational. All students in the selected grades (8530 students, 3431 males, 5099 females, 16.73 ± 1.09 years old, grades 7–11) were requested to complete the questionnaires. A total of 182 students (2.13%) did not complete the questionnaires (103 males, 79 females, mean age: 16.75 ± 1.10 years) and were excluded. Among the subjects who completed the self-report questionnaires, 1176 students (14.09%; males 620, females 556, mean age: 16.56 ± 1.16 years) were excluded from the analysis because their frankness (FR) scores were 0 or 1 on the Eppendorf Schizophrenia Inventory (ESI), which contains 5 FR (frankness) items assessing tendency to provide socially desirable answers. Low FR score means the reluctance to admit to have socially undesirable character. The remaining 7172 students (84.08%; males 2708, females 4464, mean age: 16.75 ± 1.08 years) participated in the current study. The 7172 participants were older (t = 4.95, p < 0.001) and female predominant (v2 = 113.8, p < 0.001) compared to the excluded 1358 candidates. The study protocol was approved by the Institutional Review Board of Gachon University of Medicine and Science. 2.2. Questionnaires The level of PLEs was assessed primarily by the ESI [14]. The ESI is a self-report questionnaire designed to assess the subjective experiences of subjects at risk for psychosis and schizophrenic patients. The ESI consists of 40 items, of which 34 assess four domains of PLEs: (1) attention and speech impairment (AS), (2) auditory uncertainty (AU), (3) deviant perception (DP) and (4) ideas of reference (IR). The ESI also contains 5 FR (frankness) items assessing tendency to provide socially desirable answers and 1 item assessing survey motivation. Low FR score means the reluctance to admit to have socially undesirable character. When FR score was 0 or 1, the ESI data is regarded unreliable and excluded from data analysis. The 24-item Youth Psychosis At Risk
Questionnaire (Y-PARQ) was also used to identify subjects at high risk for psychosis [15]. Y-PARQ is more focused on adolescents and early prodromal symptoms than ESI, while ESI can provide symptom nature by dividing sub-domains and enhance validity by excluding unreliable data. The agreement between results from Y-PARQ and those from ESI would be more confirmatory, since they are complementary for each other. Accordingly, clinical high risk groups for psychosis were defined by two different criteria: (1) those whose ESI scores were P29 or (2) those whose Y-PARQ scores were P12. Each high risk group was analyzed separately. When adolescents were classified as having clinical high risk, results were notified to their parents. Further psychiatric evaluation was recommended to parents of adolescents at high risk of psychosis. The Beck Depression Inventory (BDI) was administered to assess depressive symptoms [16]. As sleep disturbances were assessed separately in the current study, the sleep item of the BDI was excluded. Participants were coded into participants with probable depression or non-depressive participants according to BDI cutoff score P10. The presence of insomnia in study participants was assessed through self-reported questionnaire regarding experiences over the previous month in terms of (1) difficulty initiating sleep, (2) difficulty maintaining sleep, and (3) early awakening and difficulty resuming sleep. In line with the diagnostic criteria outlined in International Classification of Diseases-10 (ICD-10), participants experiencing at least one of the three types of insomnia (initial, maintenance and terminal) P3/week were classified as having significant insomnia. A 7-item modified version of the Epworth Sleepiness Scale (ESS) was used to measure subjective daytime sleepiness. Because individuals under 20 years of age cannot hold drivers’ licenses in Korea, the last item of the ESS, which addresses driving, was omitted [17]. ESS scores P9 were determined to represent excessive daytime somnolence (EDS). Cataplexy was assessed by the following question; ‘‘How frequently have you experienced episodes of sudden muscle weakness (e.g., knee buckling, jaw opening, neck flopping, or postural collapse) when you are having fun, excited, angry or laughing?’’ Participants who reported cataplexy over once a week were considered to have probable cataplexy [18]. In addition, those who napped P30 min/day were considered to demonstrate significant napping [19]. Those who reported snoring P3 night/week were considered to demonstrate significant snoring [20]. 2.3. Statistical analysis Group differences in the PLEs were explored using ANCOVA (covariates: age and sex). To examine the predictive role of sleep disturbances for clinical high risk of psychosis, data were analyzed using multiple logistic regression analysis adjusted for age and sex. Relationships between other continuous variables were assessed using Pearson’s correlation coefficients. Between-group comparisons of categorical data were performed using the chi-square test. Statistical significance was defined at an alpha of <0.05 (twotailed), and SPSS Ver. 15.0 (SPSS Inc., Chicago, IL, USA) was used for all computations. 3. Results 3.1. Demographic data Summary statistics for the demographic characteristics and questionnaire data of 7172 participants are presented in Table 1. Females (16.68 ± 1.11 years) were younger than males
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depression after controlling for age and sex (3.11 ± 3.28 versus 5.96 ± 4.25, F = 1054.00, p < 0.001).
Table 1 Characteristics of study participants (n = 7172). Mean ± SD (n, %) Age
16.75 ± 1.08
Sex Male Female
2708 (37.76%) 4464 (60.87%)
Psychotic-like experiences ESI AS AU DP IR ESI score Clinical high risk group (ESI score P 29)
3.96 ± 3.51 1.86 ± 2.42 1.65 ± 2.47 2.73 ± 2.95 10.19 ± 9.88 401 (5.59%)
Y-PARQ Y-PARQ score Clinical high risk group (Y-PARQ score P 12)
4.46 ± 4.03 442 (6.16%)
Depression BDI score Subjects with depressive symptoms (BDI score P 10) Non-depressive participants (BDI score 6 9)
10.31 ± 6.69 3395 (47.34%) 3777 (52.66%)
Sleep disturbances Insomnia (P3 night/week) Subjects with initial insomnia Subjects with maintenance insomnia Subjects with terminal insomnia Subjects with any insomnia
465 (6.48%) 319 (4.45%) 97 (1.35%) 695 (9.69%)
Sleepiness ESS score Subjects with EDS (ESS score P 9) Subjects with significant napping (P30 min/day)
7.32 ± 3.09 1577 (21.99%) 1653 (23.05%)
Other sleep problems Subjects with probable cataplexy (P1/week) Subjects with significant snoring (P3 night/week)
410 (5.72%) 367 (5.12%)
Abbreviations: ESI: Eppendorf Schizophrenia Inventory, AS: attention and speech impairment, AU: auditory uncertainty, DP: deviant perception, IR: ideas of reference, Y-PARQ: Youth Psychosis At Risk Questionnaire, BDI: Beck’s Depression Inventory, EDS: excessive daytime somnolence.
(16.87 ± 1.02 years) (t = 7.36, p < 0.001). Age was found to be positively correlated with BDI score (r = 0.04, p < 0.001). Subjects who exhibited EDS or significant napping were older than those who did (t = 2.81, p = 0.005; t = 19.24, p < 0.001, respectively). Females had higher BDI scores (t = 8.43, p < 0.001) but lower ESI (t = 5.64, p < 0.001) or Y-PARQ score (t = 2.67, p < 0.001) than males. While EDS was more common in females (v2 = 5.66, p < 0.001), significant napping was more common in males (v2 = 72.15, p < 0.001). Probable cataplexy was more common in females (v2 = 13.34, p < 0.001). Among subjects with EDS (n = 1577), those with significant snoring showed higher ESS scores than those without significant snoring. (t = 2.5, p = 0.01).
3.2. Depression and PLEs BDI scores were found to be positively correlated with ESI scores (r = 0.56, p < 0.001). All four domains of PLEs were correlated with BDI scores (AS: r = 0.52, p < 0.001, AU: r = 0.45, p < 0.001, DP: r = 0.45, p < 0.001, IR: r = 0.52, p < 0.001). Y-PARQ score was also positively correlated with BDI scores (r = 0.48, p < 0.001). Non-depressive participants (BDI score 69) demonstrated lower ESI scores than those with probable depression (BDI score P10) after controlling for age and sex (6.49 ± 6.24 versus 14.30 ± 11.43, F = 1386.93, p < 0.001). Non-depressive participants also had lower Y-PARQ scores than those with probable
3.3. Relationships between sleep disturbances and PLEs Comparisons between subjects with and without sleep disturbances were conducted by ANCOVA after controlling for age, sex and BDI score (Table 2). Subjects with insomnia were found to have much higher scores on all PLE domains of ESI (i.e., AS, AU, DP and IR) than those without insomnia (all p < 0.001). All PLE domains of ESI were also much higher in subjects with EDS (all p < 0.001) and in subjects with probable cataplexy (all p < 0.001). Subjects who exhibited significant napping had higher scores only in the AS (F = 4.09, p = 0.043) and IR (F = 3.96, p = 0.043) domains. Higher Y-PARQ were also found in subjects with all type of insomnia (all p < 0.001), EDS (p < 0.001), probable cataplexy (p < 0.001) or significant napping (p < 0.01). Controlling for age, gender and BDI score, total ESI score was predicted by the presence of insomnia (b = 2.72, p < 0.001), EDS (b = 2.72, p < 0.001), significant napping (b = 0.47, p = 0.046) and probable cataplexy (b = 3.32, p < 0.001). Y-PARQ score was also predicted by the presence of insomnia (b = 0.99, p < 0.001), EDS (b = 0.77, p < 0.001), significant napping (b = 0.47, p < 0.01) and probable cataplexy (b = 0.95, p < 0.001) after controlling for age, gender and BDI score. In multiple logistic regression analysis adjusted for age and sex (Table 3), the presences of insomnia (OR [odds ratio] = 4.40), EDS (OR = 3.84), significant napping (OR = 1.56), probable cataplexy (OR = 2.97) and significant snoring (OR = 1.55) predicted clinical high risk group on ESI. After additional controlling for BDI scores, significant napping or snoring could no longer predict the clinical high risk group on ESI. The presences of insomnia (OR = 3.77), EDS (OR = 3.67), significant napping (OR = 1.68) and probable cataplexy (OR = 2.42) also predicted the clinical high risk group on YPARQ. Unlike ESI, significant snoring did not predict the clinical high risk group on Y-PARQ. After additional controlling for BDI scores, the presence of insomnia (OR = 1.79), EDS (OR = 2.12), or probable cataplexy (OR = 1.79) still predicted the clinical high risk group on ESI. The presence of insomnia (OR = 1.67), EDS (OR = 1.76), significant napping (OR = 1.28) or probable cataplexy (OR = 1.64) remained to predict the clinical high risk group on Y-PARQ after additional controlling for BDI scores. After additional controlling for BDI scores, significant napping or snoring could no longer predict the clinical high risk group on ESI, while the predictors for the clinical high risk group on Y-PARQ were not changed. 3.4. Association between sleep disturbances and PLEs within nondepressive participants As both sleep disturbances and PLEs were closely related to depression, we conducted additional analysis for non-depressive participants whose BDI scores were 69. Within non-depressive participants, subjects with insomnia (F = 27.09, p < 0.001), EDS (F = 93.70, p < 0.001), significant napping (F = 9.63, p = 0.002) or probable cataplexy (F = 78.78, p < 0.001) showed significantly higher ESI scores after controlling for age and sex (Table 4). Within non-depressive participants, subjects with any insomnia (F = 7.30, p < 0.01), sleep onset insomnia (F = 10.23, p < 0.001), terminal insomnia (F = 10.06, p < 0.001), EDS (F = 38.16, p < 0.001), significant napping (F = 19.03, p < 0.001) or probable cataplexy (F = 19.65, p < 0.001) showed significantly higher Y-PARQ scores after controlling for age and sex. There were no significant differences in Y-PARQ score between subjects with and without maintenance insomnia (F = 2.83, p = 0.09).
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Table 2 Relationships between psychotic-like experiences and sleep disturbances in all study participants (n = 7172) after controlling for age, gender and BDI score (by ANCOVA). ESI
Y-PARQ
AS
AU
DP
IR
Total
Subjects with any insomnia (n = 695) Subjects without any insomnia (n = 6477) F
5.88 ± 4.62 3.75 ± 3.31 26.21***
3.17 ± 3.38 1.72 ± 2.25 42.97***
3.06 ± 3.78 1.49 ± 2.23 55.48***
4.61 ± 3.99 2.53 ± 2.74 67.14***
16.73 ± 14.02 9.49 ± 9.05 66.86***
6.76 ± 4.80 4.21 ± 3.86 46.72***
Subjects with sleep onset insomnia (n = 465) Subjects without sleep onset insomnia (n = 6707) F
5.93 ± 4.74 3.82 ± 3.37 5.76*
3.26 ± 3.52 1.76 ± 2.29 19.98***
3.18 ± 3.92 1.54 ± 2.30 29.83***
4.77 ± 4.19 2.59 ± 2.79 35.27***
17.13 ± 14.60 9.71 ± 9.28 28.97***
7.03 ± 4.90 4.28 ± 3.90 29.13***
Subjects with maintenance insomnia (n = 319) Subjects without maintenance insomnia (n = 6853) F
5.97 ± 4.82 3.86 ± 3.41 17.18***
3.24 ± 3.37 1.79 ± 2.34 26.64***
3.04 ± 3.82 1.58 ± 2.37 23.40***
4.68 ± 4.03 2.64 ± 2.85 35.72***
16.94 ± 14.35 9.88 ± 9.51 36.00***
7.06 ± 5.16 4.33 ± 3.93 38.06***
Subjects with terminal insomnia (n = 97) Subjects without terminal insomnia (n = 7075) F
7.45 ± 5.80 3.91 ± 3.45 21.58***
4.77 ± 4.43 1.82 ± 2.35 60.04***
4.90 ± 5.17 1.60 ± 2.38 80.97***
6.48 ± 4.99 2.68 ± 2.87 62.76***
23.61 ± 18.65 10.01 ± 9.58 74.90***
8.89 ± 6.27 4.39 ± 3.96 39.13***
Subjects with EDS (n = 1577) Subjects without EDS (n = 5595) F
5.55 ± 4.32 3.51 ± 3.11 153.57***
2.65 ± 2.97 1.64 ± 2.19 210.60***
2.49 ± 3.14 1.41 ± 2.18 58.50***
3.95 ± 3.62 2.38 ± 2.63 102.14***
14.64 ± 12.39 8.94 ± 8.64 133.58***
5.87 ± 4.06 4.06 ± 3.76 55.98***
Subjects with significant napping (n = 1653) Subjects without significant napping (n = 5519) F
4.52 ± 3.88 3.79 ± 3.38 4.09*
2.12 ± 2.65 1.78 ± 2.34 0.20
1.98 ± 2.84 1.54 ± 2.33 3.73
3.14 ± 3.27 2.60 ± 2.83 3.96*
11.77 ± 11.11 9.72 ± 9.43 3.99*
5.05 ± 4.42 4.28 ± 3.89 7.27**
Subjects with probable cataplexy (n = 410) Subjects without probable cataplexy (n = 6762) F
7.22 ± 5.08 3.76 ± 3.29 1373.84***
4.00 ± 3.57 1.73 ± 2.27 152.62***
4.00 ± 4.10 1.50 ± 2.25 197.35***
5.62 ± 4.32 2.55 ± 2.75 185.29***
20.85 ± 15.10 9.54 ± 9.08 256.23***
7.80 ± 4.77 4.25 ± 3.89 107.81***
Subjects with significant snoring (n = 367) Subjects without significant snoring (n = 6805) F
4.83 ± 3.95 3.91 ± 3.48 0.25
2.42 ± 2.85 1.83 ± 2.39 1.16
2.21 ± 3.16 1.61 ± 2.42 0.69
3.14 ± 3.23 2.71 ± 2.93 1.66
12.59 ± 11.71 10.06 ± 9.76 0.09
5.04 ± 4.00 4.42 ± 4.03 0.83
Abbreviations: ESI: Eppendorf Schizophrenia Inventory, Y-PARQ: Youth Psychosis At Risk Questionnaire, AS: attention and speech impairment, AU: auditory uncertainty, DP: deviant perception, IR: ideas of reference, BDI: Beck’s Depression Inventory, EDS: excessive daytime somnolence. * <0.05. ** <0.01. *** <0.001.
In multiple logistic regression analysis adjusted for age and sex, the presences of insomnia (OR = 4.10), EDS (OR = 3.52), significant napping (OR = 1.56) or probable cataplexy (OR = 3.57) significantly predicted the clinical high risk group on ESI among non-depressive participants (Table 5). The presences of sleep onset insomnia (OR = 3.56), maintenance insomnia (OR = 3.35), terminal insomnia (OR = 11.90), EDS (OR = 2.28), napping (OR = 2.00) or probable cataplexy (OR = 1.96) significantly predicted the clinical high risk group on Y-PARQ. While maintenance insomnia did not significantly predict the clinical high risk group on ESI, insomnia in total did not significantly predict the clinical high risk group on Y-PARQ.
4. Discussion In the current study, PLEs during adolescence were strongly associated with diverse sleep disturbances such as insomnia, daytime sleepiness and cataplexy. These associations were consistent on two different scales used to assess PLEs (i.e., ESI and Y-PARQ). In addition, the association between sleep disturbances and PLEs was independent of depressive symptoms. The present study is the first to report a relationship between specific sleep disturbances and PLEs in a large sample of community-dwelling adolescents. We found that adolescent insomnia was a predictor of PLEs. All three types of insomnia (sleep onset, maintenance and terminal insomnia) predicted clinical high risk of psychosis. Our findings might be partially consistent with a prior study reporting an association between short sleep duration and PLEs during adolescence [12], although short sleep duration does not necessarily indicate the presence of insomnia. To the best of our knowledge, the present study is the first to suggest EDS as a potential risk factor of psychosis among
adolescents. EDS in psychotic disorders has usually been regarded as a secondary phenomenon, since the most commonly suggested causes of somnolence are adverse effects of antipsychotics. However, we detected a strong and independent association between EDS and PLEs in a community-based sample of adolescents. Therefore, we suggest that EDS is intrinsically related to PLEs, at least during adolescence. Insufficient sleep or sleepiness in adolescents is related to cognitive/perceptual disturbances [20]. Cognitive/perceptual PLEs (i.e., AS, AU and DP) may be induced by these effects. In the present study, the PLE regarding thought content (i.e., IR) was also associated with adolescent sleep disturbance. This finding is consistent with those of prior studies reporting that insomnia predicts new inception or persistence of paranoia [21,22] and that persecutory delusions in psychotic patients are lessened by the treatment of insomnia [23]. It is intriguing that both insomnia and EDS were associated with PLEs in adolescents. Insomnia is caused by nocturnal hyper-arousal, while EDS is caused by daytime hypo-arousal. The current findings suggest that the PLEs of adolescents may be more closely associated with dys-regulation of arousal rather than persistent hyper- or hypo-arousal. Although hyper-arousal related to insomnia can reduce EDS, the insufficient sleep by insomnia can produce EDS. EDS can be found more easily in the insomnia due to environmental factors or circadian dys-regulation, rather than in the insomnia due to depression or psychophysiological factors. Interestingly, adolescence is a stage showing the rapid circadian change and the peak delay in the sleep-wake cycles. Usually, circadian rhythm easily becomes unstable during adolescence [24]. The causal direction between sleep disturbances and PLEs remains unclear. Sleep disturbances may simply be a consequence of anxiety provoked by PLEs. On the other hand, sleep disturbances may induce PLEs in adolescents, as sleep deprivation has long been
4.45–10.89 2.54–3.77 1.35–2.08 2.13–2.75 0.93–2.01 6.96 3.10 1.68 2.42 1.37 0.23 0.10 0.11 0.07 0.20 1.94 1.13 0.52 0.88 0.31 72.42*** 125.33*** 22.21*** 184.49*** 2.54
*
2.16 1.35 0.44 1.07 0.44 91.77*** 164.98*** 15.01*** 278.97*** 5.15* 31 (7.73%) 197 (49.13%) 128 (31.92%) 109 (27.18%) 32 (7.98%) 66 (0.97%) 1380 (20.38%) 1525 (22.52%) 301 (4.45%) 335 (4.95%)
Abbreviations: ESI: Eppendorf Schizophrenia Inventory, Y-PARQ: Youth Psychosis At Risk Questionnaire, EDS: excessive daytime somnolence. <0.05. ⁄⁄ <0.01. *** <0.001.
29 (6.56%) 194 (43.89%) 141 (31.90%) 96 (21.72%) 31 (7.01%) 68 (1.01%) 1383 (20.55%) 1572 (23.36%) 314 (4.67%) 336 (4.99%) 5.56–13.45 3.13–4.72 1.24–1.95 2.58–3.32 1.06–2.27 8.65 3.84 1.56 2.97 1.55
4.40 4.16 4.11 0.12 0.14 0.16 1.48 1.43 1.41 116 (28.93%) 80 (19.95%) 56 (13.97%)
Any insomnia Sleep onset insomnia Maintenance insomnia Terminal insomnia EDS Significant napping Probable cataplexy Significant snoring
579 (8.55%) 385 (5.69%) 263 (3.88%)
155.73*** 110.11*** 80.11***
0.23 0.11 0.11 0.06 0.19
115 (26.02%) 80 (18.10%) 62 (14.03%) 3.49–5.56 3.19–5.43 3.01–5.59
580 (8.62%) 385 (5.72%) 257 (3.82%)
High risk group (n = 442) Group by Y-PARQ
Low risk group (n = 6730)
95% C.I. OR SE Beta Wald High risk group (n = 401) Low risk group (n = 6771)
Group by ESI
Table 3 Prediction of clinical high risk of psychosis by sleep disturbances in all study participants (n = 7172) after controlling for age and gender (by multiple logistic regression) .
Wald
128.38*** 93.61*** 89.10***
1.33 1.30 1.43
Beta
SE
0.12 0.13 0.15
OR
3.77 3.67 4.18
95% C.I.
2.99–4.74 2.82–4.78 3.10–5.62
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noted to produce temporary PLEs or psychotic exacerbation [25– 27]. In another way, specific sleep architecture, which is related to sleep disturbances, may be a trait marker for PLEs, as decreased slow wave sleep has been reported as a trait marker for schizophrenia [28,29].Neurotransmitter changes in psychosis may also be related to sleep disturbances. Dopaminergic over-activity underlying positive psychotic symptoms may induce insomnia [30], although it cannot explain the association between EDS and PLEs noted in the current study. As found by previous studies [17,31], both insomnia and EDS during adolescence were closely related to depressive symptoms. PLEs are also related to depression. However, we found that insomnia or EDS during adolescence are independently associated with PLEs after adjusting for depressive symptoms. Furthermore, insomnia (especially sleep onset and terminal insomnia) or EDS predicted the clinical high risk of psychosis even among nondepressive participants. Riemann et al. [11] reported that the most pronounced impairment of sleep continuity was found in schizophrenic adolescents rather than in adolescents with major depression. The association between quality of life and sleep quality in schizophrenic adolescents was also reported to be independent of depression [32]. Another study reported that insomnia was more common in patients with psychotic depression than in patients with non-psychotic depression [33]. These previous findings agree, in part, with our finding of an independent association between sleep disturbances and PLEs. An association between probable cataplexy and PLEs was found in the present study. Cataplexy is one of the key symptoms of narcolepsy, a sleep disorder that usually develops during adolescence. Patients with narcolepsy frequently have hypnagogic/hypnapompic hallucinations and sleep paralysis, which can be confused with psychotic experiences [34]. PLEs in unrecognized narcolepsy were previously reported [7]. However, as the prevalence of probable cataplexy in the current study was much higher than the reported prevalence of narcolepsy [35], it also seems plausible that true psychotic symptoms may be confused with cataplexy-like symptoms in adolescents. Therefore, narcolepsy may be regarded as a differential diagnosis for adolescent psychosis, while psychosis may be regarded as a differential diagnosis for adolescent narcolepsy. Our findings that adolescent sleep disturbances entailed high risk of psychosis may hold important clinical meaning. In a longitudinal study of adolescents with prodromal symptoms, adolescents with sleep disturbances were reported to be more vulnerable to subsequent development of psychosis [13]. Therefore, special programs providing timely surveillance for early psychosis may be warranted for adolescents with sleep disturbances. In addition, prodromal psychosis should be one of the differential diagnoses for adolescents complaining of insomnia or EDS in sleep clinics. Despite the strengths of a large sample size and use of detailed questionnaires, the present study has several limitations. One is that since we relied solely on self-report measures, differential diagnoses of PLEs were not confirmed. PLEs may manifest in various psychiatric disorders including prodromal psychosis, full-blown schizophrenia, bipolar disorder and psychotic depression. Moreover, they can occur during adolescence even in the absence of psychosis. Additionally, as only symptomatic insomnia was dealt with in the current study, comorbid insomnia could not be differentiated from primary insomnia. Future study investigating comorbid psychiatric disorders, sleep disorders, drug abuse, general medical condition and hypnotic medication would be necessary. There was also no information regarding school performance in the current study, although low school performance of adolescents could be related to sleep disturbance or PLEs. In addition, polysomnographic study was not conducted for participants, although it would be a crucial tool to investigate the sleep architecture of adolescents with PLEs and to
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Table 4 Relationships between psychotic-like experiences and sleep disturbances in non-depressive participantsa (n = 3777) after controlling for age and gender (by ANCOVA). ESI
Y-PARQ
AS
AU
DP
IR
Total
Subjects with any insomnia (n = 181) Subjects without any insomnia (n = 3596) F
3.35 ± 2.91 2.70 ± 2.49 12.54***
1.53 ± 2.18 1.10 ± 1.59 13.55***
1.33 ± 2.27 0.91 ± 1.50 12.82***
2.56 ± 2.81 1.67 ± 1.91 36.47***
8.76 ± 8.68 6.38 ± 6.08 27.09***
3.73 ± 3.12 3.08 ± 3.29 7.30**
Subjects with sleep onset insomnia (n = 111) Subjects without sleep onset insomnia (n = 3666) F
3.39 ± 3.07 2.71 ± 2.49 8.31**
1.50 ± 2.28 1.11 ± 1.61 6.84**
1.51 ± 2.62 0.92 ± 1.50 16.48***
2.61 ± 3.10 1.68 ± 1.92 24.63***
9.01 ± 9.69 6.42 ± 6.10 19.69***
4.07 ± 3.47 3.08 ± 3.27 10.23***
Subjects with maintenance insomnia (n = 81) Subjects without maintenance insomnia (n = 3696) F
3.30 ± 2.98 2.72 ± 2.50 5.13*
1.70 ± 2.39 1.11 ± 1.61 12.27***
1.28 ± 2.43 0.93 ± 1.53 4.79*
2.72 ± 3.08 1.69 ± 1.94 22.64***
9.00 ± 9.59 6.44 ± 6.14 15.12***
3.67 ± 3.09 3.09 ± 3.28 2.83
Subjects with terminal insomnia (n = 20) Subjects without terminal insomnia (n = 3757) F
4.40 ± 4.21 2.72 ± 2.50 9.96**
2.70 ± 4.23 1.11 ± 1.61 20.63***
2.85 ± 4.56 0.92 ± 1.52 32.23***
4.00 ± 5.00 1.70 ± 1.94 28.10***
13.95 ± 17.02 6.45 ± 6.12 30.96***
5.35 ± 4.92 3.10 ± 3.27 10.06**
Subjects with EDS (n = 566) Subjects without EDS (n = 3211) F
3.28 ± 2.96 2.58 ± 2.40 78.56***
1.57 ± 2.15 1.04 ± 1.51 51.08***
1.36 ± 2.02 0.86 ± 1.44 51.73***
2.28 ± 2.38 1.61 ± 1.87 57.57***
8.78 ± 7.96 6.09 ± 5.80 93.70***
3.88 ± 4.05 2.97 ± 3.11 38.16***
Subjects with significant napping (n = 733) Subjects without significant napping (n = 3044) F
3.05 ± 2.66 2.66 ± 2.47 6.25*
1.26 ± 1.81 1.08 ± 1.58 1.89
1.12 ± 1.81 0.89 ± 1.78 7.87**
1.95 ± 2.22 1.65 ± 1.90 10.66**
7.39 ± 6.28 6.28 ± 6.05 9.63**
3.66 ± 4.34 2.97 ± 2.96 19.03***
Subjects with probable cataplexy (n = 108) Subjects without probable cataplexy (n = 3669) F
4.13 ± 3.35 2.69 ± 2.47 38.00***
2.37 ± 2.61 1.08 ± 1.58 70.13***
1.97 ± 2.72 0.90 ± 1.49 52.93***
3.10 ± 3.19 1.67 ± 1.91 57.78***
11.57 ± 9.56 6.34 ± 6.04 79.78***
4.44 ± 3.79 3.07 ± 3.26 19.65***
Subjects with significant snoring (n = 144) Subjects without significant snoring (n = 3633) F
3.68 ± 2.94 2.69 ± 2.49 15.26***
1.49 ± 1.81 1.10 ± 1.62 5.24*
1.26 ± 1.81 0.92 ± 1.54 4.26*
1.95 ± 2.04 1.70 ± 1.97 1.49
8.38 ± 7.05 6.42 ± 6.20 9.44**
3.44 ± 2.84 3.09 ± 3.30 0.58
Abbreviations: ESI: Eppendorf Schizophrenia Inventory, Y-PARQ: Youth Psychosis At Risk Questionnaire, AS: attention and speech impairment, AU: auditory uncertainty, DP: deviant perception, IR: ideas of reference, BDI: Beck’s Depression Inventory, EDS: excessive daytime somnolence. * <0.05. ** <0.01. *** <0.001. a BDI score 69.
Table 5 Prediction of clinical high risk of psychosis by sleep disturbances in non-depressive participantsa (n = 3777) after controlling for age and gender (by multiple logistic regression). Group by ESI Low risk group (n = 3740) Any insomnia Sleep onset insomnia Maintenance insomnia Terminal insomnia EDS Significant napping Probable cataplexy Significant snoring
Wald
Beta
SE
OR
95% C.I.
Group by Y-PARQ Low risk group (n = 3713)
High risk group (n = 37)
Wald
Beta
SE
OR
95% C.I.
High risk group (n = 64)
175 (4.68%) 106 (2.83%)
6 (16.22%) 5 (13.51%)
9.66** 12.04**
1.41 1.71
0.45 0.49
4.10 5.54
1.68–10.00 2.11–14.56
175 (4.71%) 105 (2.83%)
6 (9.38%) 6 (9.38%)
2.95 8.24**
0.75 1.27
0.44 0.44
2.12 3.56
0.82–1.30 1.50–8.49
79 (2.11%)
5 (13.51%)
2.05
1.06
0.74
2.88
0.68–12.25
77 (2.07%)
4 (6.25%)
5.14*
1.21
0.53
3.35
1.18–9.51
17 (0.45%)
3 (8.11%)
21.90***
3.10
0.66
22.13
6.05–80.95
17 (0.46%)
3 (4.69%)
14.45***
552 (14.76%) 724 (19.36%)
14 (37.84%) 9 (24.32%)
***
13.49 0.84
1.26 0.12
0.34 0.40
3.52 1.12
1.80–6.88 0.52–2.44
548 (14.76%) 711 (19.15%)
18 (28.13%) 22 (34.38%)
99 (2.65%)
9 (24.32%)
40.43***
1.27
0.20
3.57
2.41–5.28
102 (2.75%)
143 (3.82%)
1 (2.70%)
0.23
0.49
1.02
0.62
0.08–4.55
175 (4.71%)
2.48
0.65
11.90
**
3.32–42.68
8.51 6.13*
0.83 0.69
0.28 0.28
2.28 2.00
1.31–3.97 1.16–3.45
6 (9.38%)
9.61**
0.69
0.22
1.99
1.29–3.07
6 (9.38%)
0.34
0.42
0.73
0.66
0.16–2.72
Abbreviations: ESI: Eppendorf Schizophrenia Inventory, Y-PARQ: Youth Psychosis At Risk Questionnaire, EDS: excessive daytime somnolence. <0.05. ** <0.01. *** <0.001. a BDI score 69. *
objectively assess the sleep-related breathing problem including snoring. Another limitation may be the cross-sectional nature of the study. A longitudinal study would shed light on the causal pathway linking sleep disturbances and PLEs. Furthermore, follow-up studies to detect later development of full-blown psychosis may be needed, especially for adolescents at clinical high risk.
In conclusion, we found that insomnia, EDS and probable cataplexy during adolescence are associated with PLEs, independent of depression. Our results suggest that adolescents with those with insomnia (especially sleep onset and terminal insomnia) or EDS might be at higher risk of developing psychosis than adolescents who do not exhibit these symptoms. Clinical attention and early
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screening programs to detect developing psychosis may be warranted for adolescents with sleep disturbances. Conflict of interest The ICMJE Uniform Disclosure Form for Potential Conflicts of Interest associated with this article can be viewed by clicking on the following link: http://dx.doi.org/10.1016/j.sleep.2012.06.002. Acknowledgment This study was supported by a grant of the Korea Healthcare Technology R&D Project, Ministry for Health, Welfare & Family Affairs, Republic of Korea (A090059).
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Sleep Medicine journal homepage: www.elsevier.com/locate/sleep
Original Article
The relationship between psychotic-like experiences and sleep disturbances in adolescents Yu Jin Lee a, Seong-Jin Cho a, In Hee Cho a, Joon Hwan Jang b, Seog Ju Kim c,⇑ a
Department of Psychiatry, Gachon University of Medicine and Science, Incheon, Republic of Korea Department of Psychiatry, Seoul National University College of Medicine, Seoul, Republic of Korea c Department of Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea b
a r t i c l e
i n f o
Article history: Received 14 January 2012 Received in revised form 31 May 2012 Accepted 1 June 2012 Available online 25 July 2012 Keywords: Psychosis Adolescent Insomnia Sleepiness
a b s t r a c t Objective: We investigated the relationships between sleep disturbances and psychotic-like experiences (PLEs) among adolescents. Methods: A total of 8530 students (grades 7–11) were recruited in the Republic of Korea, and 7172 students who completed all of the relevant questionnaires participated in the current study. The survey included the Eppendorf Schizophrenia Inventory (ESI), the Youth Psychosis At Risk Questionnaire (YPARQ), the Beck Depression Inventory (BDI), the Epworth Sleepiness Scale and questionnaires about sleep disturbances (insomnia, cataplexy and snoring). Results: Subjects with insomnia, excessive daytime somnolence (EDS), or probable cataplexy had higher ESI and Y-PARQ scores after controlling for age, sex and BDI scores (all p < 0.001). Insomnia (OR = 4.40), EDS (OR = 3.84) and probable cataplexy (OR = 2.97) predicted clinical high risk of psychosis. Insomnia, EDS and probable cataplexy remained as significant predictors of clinical high risk for psychosis, even after controlling for depressive symptoms or when analyses were confined to non-depressive adolescents. Conclusions: Insomnia and EDS were found to predict PLEs in adolescents, independent of depression. Our findings suggest that adolescents complaining of insomnia or sleepiness may require further assessment regarding potential risk of psychosis. Ó 2012 Elsevier B.V. All rights reserved.
1. Introduction Since untreated psychosis induces unnecessary suffering and typically has poor outcomes [1,2], early intervention has been emphasized as a strategy to attenuate or avert the full-blown psychosis [3]. For successful intervention, identification of subjects at potential high risk for subsequent psychosis is important. As psychotic-like experiences (PLEs) or sub-threshold psychotic symptoms have been suggested to be good clinical predictors for psychosis [4,5], subjects with such symptoms may be considered as clinical high risk group for subsequent psychosis. The identification of signs or symptoms associated with PLEs is also warranted. Sleep disturbance is closely associated with psychosis, and insomnia is one of the most frequent presenting complaints in psychotic disorders [6]. In addition, PLEs have been frequently reported in narcolepsy, a sleep disorder characterized by sleepiness, cataplexy, hypnagogic hallucination and sleep paralysis [7]. ⇑ Corresponding author. Address: Department of Medicine, Seoul National University College of Medicine, 28, Yeongeon-dong, Jongno-gu, Seoul 110-799, Republic of Korea. Tel.: +82 2 740 8418; fax: +82 2 744 7241. E-mail address: [email protected] (S.J. Kim). 1389-9457/$ - see front matter Ó 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.sleep.2012.06.002
Furthermore, sleep disturbance is a common prodromal feature of schizophrenia preceding first psychotic episodes or psychotic relapse [8–10]. However, since sleep disturbance has been regarded as a non-specific symptom, it is often overlooked in studies investigating PLEs or risk for psychosis. The relationships between sleep disturbances and PLEs or psychosis may vary depending on age. Adolescence is an especially important period for both sleep and the advent of psychosis. Sleep plays an important role in the reparative and integrative processes of the adolescent brain. In addition, many psychotic disorders onset during late adolescence to young adulthood. One study reported that sleep continuity was more impaired in adolescents with schizophrenia than those with major depression [11], which was opposite to the usual findings in adults. Although both sleep and psychosis are key adolescent mental health issues, few studies have addressed the relationships between these two problems in adolescents. Oshima et al. [12] administered surveys including 4 questions about PLE and 2 questions related to sleep to 341 Japanese high school students and found that short sleep duration was associated with PLEs. Ruhrmann et al. [13] reported that the sleep disturbance item on the Scale of Prodromal Symptoms was a predictor of transition to
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psychosis in an 18-month follow-up study of 245 adolescents and young adults in putatively prodromal states. Although prior studies addressed non-specific sleep disturbances, it remains unclear which specific sleep disturbance (e.g., excessive daytime sleepiness, insomnia or cataplexy) is related to PLEs or clinical high risk of psychosis. In particular, there have been no studies investigating the relationships between excessive daytime somnolence (EDS) and PLEs, even in adults. In addition, the relationships between sleep disturbance and PLEs has never been confirmed in a large community-based sample of adolescents, although such sample enables obtaining a wide range in PLEs and avoiding the complicating issues of selection bias or medication effects in clinical samples. The aims of the current study were to examine the relationships between specific sleep disturbances (insomnia, EDS, snoring and cataplexy) and PLEs in a large community-based Korean adolescent sample. We hypothesized that adolescents with specific sleep disturbances (especially insomnia and EDS) would have higher incidences of PLEs than those without sleep disturbances, and that the presence of such sleep disturbances would independently predict clinical high risk of psychosis among adolescents. 2. Method 2.1. Subjects We recruited subjects from schools in three different areas of South Korea by sending documents to schools requesting participation. All of the schools that agreed to participate, 18 high schools and 5 middle schools, were selected as subject schools. Six were boys’ schools, eight were girls’ schools, and nine were coeducational. All students in the selected grades (8530 students, 3431 males, 5099 females, 16.73 ± 1.09 years old, grades 7–11) were requested to complete the questionnaires. A total of 182 students (2.13%) did not complete the questionnaires (103 males, 79 females, mean age: 16.75 ± 1.10 years) and were excluded. Among the subjects who completed the self-report questionnaires, 1176 students (14.09%; males 620, females 556, mean age: 16.56 ± 1.16 years) were excluded from the analysis because their frankness (FR) scores were 0 or 1 on the Eppendorf Schizophrenia Inventory (ESI), which contains 5 FR (frankness) items assessing tendency to provide socially desirable answers. Low FR score means the reluctance to admit to have socially undesirable character. The remaining 7172 students (84.08%; males 2708, females 4464, mean age: 16.75 ± 1.08 years) participated in the current study. The 7172 participants were older (t = 4.95, p < 0.001) and female predominant (v2 = 113.8, p < 0.001) compared to the excluded 1358 candidates. The study protocol was approved by the Institutional Review Board of Gachon University of Medicine and Science. 2.2. Questionnaires The level of PLEs was assessed primarily by the ESI [14]. The ESI is a self-report questionnaire designed to assess the subjective experiences of subjects at risk for psychosis and schizophrenic patients. The ESI consists of 40 items, of which 34 assess four domains of PLEs: (1) attention and speech impairment (AS), (2) auditory uncertainty (AU), (3) deviant perception (DP) and (4) ideas of reference (IR). The ESI also contains 5 FR (frankness) items assessing tendency to provide socially desirable answers and 1 item assessing survey motivation. Low FR score means the reluctance to admit to have socially undesirable character. When FR score was 0 or 1, the ESI data is regarded unreliable and excluded from data analysis. The 24-item Youth Psychosis At Risk
Questionnaire (Y-PARQ) was also used to identify subjects at high risk for psychosis [15]. Y-PARQ is more focused on adolescents and early prodromal symptoms than ESI, while ESI can provide symptom nature by dividing sub-domains and enhance validity by excluding unreliable data. The agreement between results from Y-PARQ and those from ESI would be more confirmatory, since they are complementary for each other. Accordingly, clinical high risk groups for psychosis were defined by two different criteria: (1) those whose ESI scores were P29 or (2) those whose Y-PARQ scores were P12. Each high risk group was analyzed separately. When adolescents were classified as having clinical high risk, results were notified to their parents. Further psychiatric evaluation was recommended to parents of adolescents at high risk of psychosis. The Beck Depression Inventory (BDI) was administered to assess depressive symptoms [16]. As sleep disturbances were assessed separately in the current study, the sleep item of the BDI was excluded. Participants were coded into participants with probable depression or non-depressive participants according to BDI cutoff score P10. The presence of insomnia in study participants was assessed through self-reported questionnaire regarding experiences over the previous month in terms of (1) difficulty initiating sleep, (2) difficulty maintaining sleep, and (3) early awakening and difficulty resuming sleep. In line with the diagnostic criteria outlined in International Classification of Diseases-10 (ICD-10), participants experiencing at least one of the three types of insomnia (initial, maintenance and terminal) P3/week were classified as having significant insomnia. A 7-item modified version of the Epworth Sleepiness Scale (ESS) was used to measure subjective daytime sleepiness. Because individuals under 20 years of age cannot hold drivers’ licenses in Korea, the last item of the ESS, which addresses driving, was omitted [17]. ESS scores P9 were determined to represent excessive daytime somnolence (EDS). Cataplexy was assessed by the following question; ‘‘How frequently have you experienced episodes of sudden muscle weakness (e.g., knee buckling, jaw opening, neck flopping, or postural collapse) when you are having fun, excited, angry or laughing?’’ Participants who reported cataplexy over once a week were considered to have probable cataplexy [18]. In addition, those who napped P30 min/day were considered to demonstrate significant napping [19]. Those who reported snoring P3 night/week were considered to demonstrate significant snoring [20]. 2.3. Statistical analysis Group differences in the PLEs were explored using ANCOVA (covariates: age and sex). To examine the predictive role of sleep disturbances for clinical high risk of psychosis, data were analyzed using multiple logistic regression analysis adjusted for age and sex. Relationships between other continuous variables were assessed using Pearson’s correlation coefficients. Between-group comparisons of categorical data were performed using the chi-square test. Statistical significance was defined at an alpha of <0.05 (twotailed), and SPSS Ver. 15.0 (SPSS Inc., Chicago, IL, USA) was used for all computations. 3. Results 3.1. Demographic data Summary statistics for the demographic characteristics and questionnaire data of 7172 participants are presented in Table 1. Females (16.68 ± 1.11 years) were younger than males
Y.J. Lee et al. / Sleep Medicine 13 (2012) 1021–1027
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depression after controlling for age and sex (3.11 ± 3.28 versus 5.96 ± 4.25, F = 1054.00, p < 0.001).
Table 1 Characteristics of study participants (n = 7172). Mean ± SD (n, %) Age
16.75 ± 1.08
Sex Male Female
2708 (37.76%) 4464 (60.87%)
Psychotic-like experiences ESI AS AU DP IR ESI score Clinical high risk group (ESI score P 29)
3.96 ± 3.51 1.86 ± 2.42 1.65 ± 2.47 2.73 ± 2.95 10.19 ± 9.88 401 (5.59%)
Y-PARQ Y-PARQ score Clinical high risk group (Y-PARQ score P 12)
4.46 ± 4.03 442 (6.16%)
Depression BDI score Subjects with depressive symptoms (BDI score P 10) Non-depressive participants (BDI score 6 9)
10.31 ± 6.69 3395 (47.34%) 3777 (52.66%)
Sleep disturbances Insomnia (P3 night/week) Subjects with initial insomnia Subjects with maintenance insomnia Subjects with terminal insomnia Subjects with any insomnia
465 (6.48%) 319 (4.45%) 97 (1.35%) 695 (9.69%)
Sleepiness ESS score Subjects with EDS (ESS score P 9) Subjects with significant napping (P30 min/day)
7.32 ± 3.09 1577 (21.99%) 1653 (23.05%)
Other sleep problems Subjects with probable cataplexy (P1/week) Subjects with significant snoring (P3 night/week)
410 (5.72%) 367 (5.12%)
Abbreviations: ESI: Eppendorf Schizophrenia Inventory, AS: attention and speech impairment, AU: auditory uncertainty, DP: deviant perception, IR: ideas of reference, Y-PARQ: Youth Psychosis At Risk Questionnaire, BDI: Beck’s Depression Inventory, EDS: excessive daytime somnolence.
(16.87 ± 1.02 years) (t = 7.36, p < 0.001). Age was found to be positively correlated with BDI score (r = 0.04, p < 0.001). Subjects who exhibited EDS or significant napping were older than those who did (t = 2.81, p = 0.005; t = 19.24, p < 0.001, respectively). Females had higher BDI scores (t = 8.43, p < 0.001) but lower ESI (t = 5.64, p < 0.001) or Y-PARQ score (t = 2.67, p < 0.001) than males. While EDS was more common in females (v2 = 5.66, p < 0.001), significant napping was more common in males (v2 = 72.15, p < 0.001). Probable cataplexy was more common in females (v2 = 13.34, p < 0.001). Among subjects with EDS (n = 1577), those with significant snoring showed higher ESS scores than those without significant snoring. (t = 2.5, p = 0.01).
3.2. Depression and PLEs BDI scores were found to be positively correlated with ESI scores (r = 0.56, p < 0.001). All four domains of PLEs were correlated with BDI scores (AS: r = 0.52, p < 0.001, AU: r = 0.45, p < 0.001, DP: r = 0.45, p < 0.001, IR: r = 0.52, p < 0.001). Y-PARQ score was also positively correlated with BDI scores (r = 0.48, p < 0.001). Non-depressive participants (BDI score 69) demonstrated lower ESI scores than those with probable depression (BDI score P10) after controlling for age and sex (6.49 ± 6.24 versus 14.30 ± 11.43, F = 1386.93, p < 0.001). Non-depressive participants also had lower Y-PARQ scores than those with probable
3.3. Relationships between sleep disturbances and PLEs Comparisons between subjects with and without sleep disturbances were conducted by ANCOVA after controlling for age, sex and BDI score (Table 2). Subjects with insomnia were found to have much higher scores on all PLE domains of ESI (i.e., AS, AU, DP and IR) than those without insomnia (all p < 0.001). All PLE domains of ESI were also much higher in subjects with EDS (all p < 0.001) and in subjects with probable cataplexy (all p < 0.001). Subjects who exhibited significant napping had higher scores only in the AS (F = 4.09, p = 0.043) and IR (F = 3.96, p = 0.043) domains. Higher Y-PARQ were also found in subjects with all type of insomnia (all p < 0.001), EDS (p < 0.001), probable cataplexy (p < 0.001) or significant napping (p < 0.01). Controlling for age, gender and BDI score, total ESI score was predicted by the presence of insomnia (b = 2.72, p < 0.001), EDS (b = 2.72, p < 0.001), significant napping (b = 0.47, p = 0.046) and probable cataplexy (b = 3.32, p < 0.001). Y-PARQ score was also predicted by the presence of insomnia (b = 0.99, p < 0.001), EDS (b = 0.77, p < 0.001), significant napping (b = 0.47, p < 0.01) and probable cataplexy (b = 0.95, p < 0.001) after controlling for age, gender and BDI score. In multiple logistic regression analysis adjusted for age and sex (Table 3), the presences of insomnia (OR [odds ratio] = 4.40), EDS (OR = 3.84), significant napping (OR = 1.56), probable cataplexy (OR = 2.97) and significant snoring (OR = 1.55) predicted clinical high risk group on ESI. After additional controlling for BDI scores, significant napping or snoring could no longer predict the clinical high risk group on ESI. The presences of insomnia (OR = 3.77), EDS (OR = 3.67), significant napping (OR = 1.68) and probable cataplexy (OR = 2.42) also predicted the clinical high risk group on YPARQ. Unlike ESI, significant snoring did not predict the clinical high risk group on Y-PARQ. After additional controlling for BDI scores, the presence of insomnia (OR = 1.79), EDS (OR = 2.12), or probable cataplexy (OR = 1.79) still predicted the clinical high risk group on ESI. The presence of insomnia (OR = 1.67), EDS (OR = 1.76), significant napping (OR = 1.28) or probable cataplexy (OR = 1.64) remained to predict the clinical high risk group on Y-PARQ after additional controlling for BDI scores. After additional controlling for BDI scores, significant napping or snoring could no longer predict the clinical high risk group on ESI, while the predictors for the clinical high risk group on Y-PARQ were not changed. 3.4. Association between sleep disturbances and PLEs within nondepressive participants As both sleep disturbances and PLEs were closely related to depression, we conducted additional analysis for non-depressive participants whose BDI scores were 69. Within non-depressive participants, subjects with insomnia (F = 27.09, p < 0.001), EDS (F = 93.70, p < 0.001), significant napping (F = 9.63, p = 0.002) or probable cataplexy (F = 78.78, p < 0.001) showed significantly higher ESI scores after controlling for age and sex (Table 4). Within non-depressive participants, subjects with any insomnia (F = 7.30, p < 0.01), sleep onset insomnia (F = 10.23, p < 0.001), terminal insomnia (F = 10.06, p < 0.001), EDS (F = 38.16, p < 0.001), significant napping (F = 19.03, p < 0.001) or probable cataplexy (F = 19.65, p < 0.001) showed significantly higher Y-PARQ scores after controlling for age and sex. There were no significant differences in Y-PARQ score between subjects with and without maintenance insomnia (F = 2.83, p = 0.09).
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Table 2 Relationships between psychotic-like experiences and sleep disturbances in all study participants (n = 7172) after controlling for age, gender and BDI score (by ANCOVA). ESI
Y-PARQ
AS
AU
DP
IR
Total
Subjects with any insomnia (n = 695) Subjects without any insomnia (n = 6477) F
5.88 ± 4.62 3.75 ± 3.31 26.21***
3.17 ± 3.38 1.72 ± 2.25 42.97***
3.06 ± 3.78 1.49 ± 2.23 55.48***
4.61 ± 3.99 2.53 ± 2.74 67.14***
16.73 ± 14.02 9.49 ± 9.05 66.86***
6.76 ± 4.80 4.21 ± 3.86 46.72***
Subjects with sleep onset insomnia (n = 465) Subjects without sleep onset insomnia (n = 6707) F
5.93 ± 4.74 3.82 ± 3.37 5.76*
3.26 ± 3.52 1.76 ± 2.29 19.98***
3.18 ± 3.92 1.54 ± 2.30 29.83***
4.77 ± 4.19 2.59 ± 2.79 35.27***
17.13 ± 14.60 9.71 ± 9.28 28.97***
7.03 ± 4.90 4.28 ± 3.90 29.13***
Subjects with maintenance insomnia (n = 319) Subjects without maintenance insomnia (n = 6853) F
5.97 ± 4.82 3.86 ± 3.41 17.18***
3.24 ± 3.37 1.79 ± 2.34 26.64***
3.04 ± 3.82 1.58 ± 2.37 23.40***
4.68 ± 4.03 2.64 ± 2.85 35.72***
16.94 ± 14.35 9.88 ± 9.51 36.00***
7.06 ± 5.16 4.33 ± 3.93 38.06***
Subjects with terminal insomnia (n = 97) Subjects without terminal insomnia (n = 7075) F
7.45 ± 5.80 3.91 ± 3.45 21.58***
4.77 ± 4.43 1.82 ± 2.35 60.04***
4.90 ± 5.17 1.60 ± 2.38 80.97***
6.48 ± 4.99 2.68 ± 2.87 62.76***
23.61 ± 18.65 10.01 ± 9.58 74.90***
8.89 ± 6.27 4.39 ± 3.96 39.13***
Subjects with EDS (n = 1577) Subjects without EDS (n = 5595) F
5.55 ± 4.32 3.51 ± 3.11 153.57***
2.65 ± 2.97 1.64 ± 2.19 210.60***
2.49 ± 3.14 1.41 ± 2.18 58.50***
3.95 ± 3.62 2.38 ± 2.63 102.14***
14.64 ± 12.39 8.94 ± 8.64 133.58***
5.87 ± 4.06 4.06 ± 3.76 55.98***
Subjects with significant napping (n = 1653) Subjects without significant napping (n = 5519) F
4.52 ± 3.88 3.79 ± 3.38 4.09*
2.12 ± 2.65 1.78 ± 2.34 0.20
1.98 ± 2.84 1.54 ± 2.33 3.73
3.14 ± 3.27 2.60 ± 2.83 3.96*
11.77 ± 11.11 9.72 ± 9.43 3.99*
5.05 ± 4.42 4.28 ± 3.89 7.27**
Subjects with probable cataplexy (n = 410) Subjects without probable cataplexy (n = 6762) F
7.22 ± 5.08 3.76 ± 3.29 1373.84***
4.00 ± 3.57 1.73 ± 2.27 152.62***
4.00 ± 4.10 1.50 ± 2.25 197.35***
5.62 ± 4.32 2.55 ± 2.75 185.29***
20.85 ± 15.10 9.54 ± 9.08 256.23***
7.80 ± 4.77 4.25 ± 3.89 107.81***
Subjects with significant snoring (n = 367) Subjects without significant snoring (n = 6805) F
4.83 ± 3.95 3.91 ± 3.48 0.25
2.42 ± 2.85 1.83 ± 2.39 1.16
2.21 ± 3.16 1.61 ± 2.42 0.69
3.14 ± 3.23 2.71 ± 2.93 1.66
12.59 ± 11.71 10.06 ± 9.76 0.09
5.04 ± 4.00 4.42 ± 4.03 0.83
Abbreviations: ESI: Eppendorf Schizophrenia Inventory, Y-PARQ: Youth Psychosis At Risk Questionnaire, AS: attention and speech impairment, AU: auditory uncertainty, DP: deviant perception, IR: ideas of reference, BDI: Beck’s Depression Inventory, EDS: excessive daytime somnolence. * <0.05. ** <0.01. *** <0.001.
In multiple logistic regression analysis adjusted for age and sex, the presences of insomnia (OR = 4.10), EDS (OR = 3.52), significant napping (OR = 1.56) or probable cataplexy (OR = 3.57) significantly predicted the clinical high risk group on ESI among non-depressive participants (Table 5). The presences of sleep onset insomnia (OR = 3.56), maintenance insomnia (OR = 3.35), terminal insomnia (OR = 11.90), EDS (OR = 2.28), napping (OR = 2.00) or probable cataplexy (OR = 1.96) significantly predicted the clinical high risk group on Y-PARQ. While maintenance insomnia did not significantly predict the clinical high risk group on ESI, insomnia in total did not significantly predict the clinical high risk group on Y-PARQ.
4. Discussion In the current study, PLEs during adolescence were strongly associated with diverse sleep disturbances such as insomnia, daytime sleepiness and cataplexy. These associations were consistent on two different scales used to assess PLEs (i.e., ESI and Y-PARQ). In addition, the association between sleep disturbances and PLEs was independent of depressive symptoms. The present study is the first to report a relationship between specific sleep disturbances and PLEs in a large sample of community-dwelling adolescents. We found that adolescent insomnia was a predictor of PLEs. All three types of insomnia (sleep onset, maintenance and terminal insomnia) predicted clinical high risk of psychosis. Our findings might be partially consistent with a prior study reporting an association between short sleep duration and PLEs during adolescence [12], although short sleep duration does not necessarily indicate the presence of insomnia. To the best of our knowledge, the present study is the first to suggest EDS as a potential risk factor of psychosis among
adolescents. EDS in psychotic disorders has usually been regarded as a secondary phenomenon, since the most commonly suggested causes of somnolence are adverse effects of antipsychotics. However, we detected a strong and independent association between EDS and PLEs in a community-based sample of adolescents. Therefore, we suggest that EDS is intrinsically related to PLEs, at least during adolescence. Insufficient sleep or sleepiness in adolescents is related to cognitive/perceptual disturbances [20]. Cognitive/perceptual PLEs (i.e., AS, AU and DP) may be induced by these effects. In the present study, the PLE regarding thought content (i.e., IR) was also associated with adolescent sleep disturbance. This finding is consistent with those of prior studies reporting that insomnia predicts new inception or persistence of paranoia [21,22] and that persecutory delusions in psychotic patients are lessened by the treatment of insomnia [23]. It is intriguing that both insomnia and EDS were associated with PLEs in adolescents. Insomnia is caused by nocturnal hyper-arousal, while EDS is caused by daytime hypo-arousal. The current findings suggest that the PLEs of adolescents may be more closely associated with dys-regulation of arousal rather than persistent hyper- or hypo-arousal. Although hyper-arousal related to insomnia can reduce EDS, the insufficient sleep by insomnia can produce EDS. EDS can be found more easily in the insomnia due to environmental factors or circadian dys-regulation, rather than in the insomnia due to depression or psychophysiological factors. Interestingly, adolescence is a stage showing the rapid circadian change and the peak delay in the sleep-wake cycles. Usually, circadian rhythm easily becomes unstable during adolescence [24]. The causal direction between sleep disturbances and PLEs remains unclear. Sleep disturbances may simply be a consequence of anxiety provoked by PLEs. On the other hand, sleep disturbances may induce PLEs in adolescents, as sleep deprivation has long been
4.45–10.89 2.54–3.77 1.35–2.08 2.13–2.75 0.93–2.01 6.96 3.10 1.68 2.42 1.37 0.23 0.10 0.11 0.07 0.20 1.94 1.13 0.52 0.88 0.31 72.42*** 125.33*** 22.21*** 184.49*** 2.54
*
2.16 1.35 0.44 1.07 0.44 91.77*** 164.98*** 15.01*** 278.97*** 5.15* 31 (7.73%) 197 (49.13%) 128 (31.92%) 109 (27.18%) 32 (7.98%) 66 (0.97%) 1380 (20.38%) 1525 (22.52%) 301 (4.45%) 335 (4.95%)
Abbreviations: ESI: Eppendorf Schizophrenia Inventory, Y-PARQ: Youth Psychosis At Risk Questionnaire, EDS: excessive daytime somnolence. <0.05. ⁄⁄ <0.01. *** <0.001.
29 (6.56%) 194 (43.89%) 141 (31.90%) 96 (21.72%) 31 (7.01%) 68 (1.01%) 1383 (20.55%) 1572 (23.36%) 314 (4.67%) 336 (4.99%) 5.56–13.45 3.13–4.72 1.24–1.95 2.58–3.32 1.06–2.27 8.65 3.84 1.56 2.97 1.55
4.40 4.16 4.11 0.12 0.14 0.16 1.48 1.43 1.41 116 (28.93%) 80 (19.95%) 56 (13.97%)
Any insomnia Sleep onset insomnia Maintenance insomnia Terminal insomnia EDS Significant napping Probable cataplexy Significant snoring
579 (8.55%) 385 (5.69%) 263 (3.88%)
155.73*** 110.11*** 80.11***
0.23 0.11 0.11 0.06 0.19
115 (26.02%) 80 (18.10%) 62 (14.03%) 3.49–5.56 3.19–5.43 3.01–5.59
580 (8.62%) 385 (5.72%) 257 (3.82%)
High risk group (n = 442) Group by Y-PARQ
Low risk group (n = 6730)
95% C.I. OR SE Beta Wald High risk group (n = 401) Low risk group (n = 6771)
Group by ESI
Table 3 Prediction of clinical high risk of psychosis by sleep disturbances in all study participants (n = 7172) after controlling for age and gender (by multiple logistic regression) .
Wald
128.38*** 93.61*** 89.10***
1.33 1.30 1.43
Beta
SE
0.12 0.13 0.15
OR
3.77 3.67 4.18
95% C.I.
2.99–4.74 2.82–4.78 3.10–5.62
Y.J. Lee et al. / Sleep Medicine 13 (2012) 1021–1027
1025
noted to produce temporary PLEs or psychotic exacerbation [25– 27]. In another way, specific sleep architecture, which is related to sleep disturbances, may be a trait marker for PLEs, as decreased slow wave sleep has been reported as a trait marker for schizophrenia [28,29].Neurotransmitter changes in psychosis may also be related to sleep disturbances. Dopaminergic over-activity underlying positive psychotic symptoms may induce insomnia [30], although it cannot explain the association between EDS and PLEs noted in the current study. As found by previous studies [17,31], both insomnia and EDS during adolescence were closely related to depressive symptoms. PLEs are also related to depression. However, we found that insomnia or EDS during adolescence are independently associated with PLEs after adjusting for depressive symptoms. Furthermore, insomnia (especially sleep onset and terminal insomnia) or EDS predicted the clinical high risk of psychosis even among nondepressive participants. Riemann et al. [11] reported that the most pronounced impairment of sleep continuity was found in schizophrenic adolescents rather than in adolescents with major depression. The association between quality of life and sleep quality in schizophrenic adolescents was also reported to be independent of depression [32]. Another study reported that insomnia was more common in patients with psychotic depression than in patients with non-psychotic depression [33]. These previous findings agree, in part, with our finding of an independent association between sleep disturbances and PLEs. An association between probable cataplexy and PLEs was found in the present study. Cataplexy is one of the key symptoms of narcolepsy, a sleep disorder that usually develops during adolescence. Patients with narcolepsy frequently have hypnagogic/hypnapompic hallucinations and sleep paralysis, which can be confused with psychotic experiences [34]. PLEs in unrecognized narcolepsy were previously reported [7]. However, as the prevalence of probable cataplexy in the current study was much higher than the reported prevalence of narcolepsy [35], it also seems plausible that true psychotic symptoms may be confused with cataplexy-like symptoms in adolescents. Therefore, narcolepsy may be regarded as a differential diagnosis for adolescent psychosis, while psychosis may be regarded as a differential diagnosis for adolescent narcolepsy. Our findings that adolescent sleep disturbances entailed high risk of psychosis may hold important clinical meaning. In a longitudinal study of adolescents with prodromal symptoms, adolescents with sleep disturbances were reported to be more vulnerable to subsequent development of psychosis [13]. Therefore, special programs providing timely surveillance for early psychosis may be warranted for adolescents with sleep disturbances. In addition, prodromal psychosis should be one of the differential diagnoses for adolescents complaining of insomnia or EDS in sleep clinics. Despite the strengths of a large sample size and use of detailed questionnaires, the present study has several limitations. One is that since we relied solely on self-report measures, differential diagnoses of PLEs were not confirmed. PLEs may manifest in various psychiatric disorders including prodromal psychosis, full-blown schizophrenia, bipolar disorder and psychotic depression. Moreover, they can occur during adolescence even in the absence of psychosis. Additionally, as only symptomatic insomnia was dealt with in the current study, comorbid insomnia could not be differentiated from primary insomnia. Future study investigating comorbid psychiatric disorders, sleep disorders, drug abuse, general medical condition and hypnotic medication would be necessary. There was also no information regarding school performance in the current study, although low school performance of adolescents could be related to sleep disturbance or PLEs. In addition, polysomnographic study was not conducted for participants, although it would be a crucial tool to investigate the sleep architecture of adolescents with PLEs and to
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Y.J. Lee et al. / Sleep Medicine 13 (2012) 1021–1027
Table 4 Relationships between psychotic-like experiences and sleep disturbances in non-depressive participantsa (n = 3777) after controlling for age and gender (by ANCOVA). ESI
Y-PARQ
AS
AU
DP
IR
Total
Subjects with any insomnia (n = 181) Subjects without any insomnia (n = 3596) F
3.35 ± 2.91 2.70 ± 2.49 12.54***
1.53 ± 2.18 1.10 ± 1.59 13.55***
1.33 ± 2.27 0.91 ± 1.50 12.82***
2.56 ± 2.81 1.67 ± 1.91 36.47***
8.76 ± 8.68 6.38 ± 6.08 27.09***
3.73 ± 3.12 3.08 ± 3.29 7.30**
Subjects with sleep onset insomnia (n = 111) Subjects without sleep onset insomnia (n = 3666) F
3.39 ± 3.07 2.71 ± 2.49 8.31**
1.50 ± 2.28 1.11 ± 1.61 6.84**
1.51 ± 2.62 0.92 ± 1.50 16.48***
2.61 ± 3.10 1.68 ± 1.92 24.63***
9.01 ± 9.69 6.42 ± 6.10 19.69***
4.07 ± 3.47 3.08 ± 3.27 10.23***
Subjects with maintenance insomnia (n = 81) Subjects without maintenance insomnia (n = 3696) F
3.30 ± 2.98 2.72 ± 2.50 5.13*
1.70 ± 2.39 1.11 ± 1.61 12.27***
1.28 ± 2.43 0.93 ± 1.53 4.79*
2.72 ± 3.08 1.69 ± 1.94 22.64***
9.00 ± 9.59 6.44 ± 6.14 15.12***
3.67 ± 3.09 3.09 ± 3.28 2.83
Subjects with terminal insomnia (n = 20) Subjects without terminal insomnia (n = 3757) F
4.40 ± 4.21 2.72 ± 2.50 9.96**
2.70 ± 4.23 1.11 ± 1.61 20.63***
2.85 ± 4.56 0.92 ± 1.52 32.23***
4.00 ± 5.00 1.70 ± 1.94 28.10***
13.95 ± 17.02 6.45 ± 6.12 30.96***
5.35 ± 4.92 3.10 ± 3.27 10.06**
Subjects with EDS (n = 566) Subjects without EDS (n = 3211) F
3.28 ± 2.96 2.58 ± 2.40 78.56***
1.57 ± 2.15 1.04 ± 1.51 51.08***
1.36 ± 2.02 0.86 ± 1.44 51.73***
2.28 ± 2.38 1.61 ± 1.87 57.57***
8.78 ± 7.96 6.09 ± 5.80 93.70***
3.88 ± 4.05 2.97 ± 3.11 38.16***
Subjects with significant napping (n = 733) Subjects without significant napping (n = 3044) F
3.05 ± 2.66 2.66 ± 2.47 6.25*
1.26 ± 1.81 1.08 ± 1.58 1.89
1.12 ± 1.81 0.89 ± 1.78 7.87**
1.95 ± 2.22 1.65 ± 1.90 10.66**
7.39 ± 6.28 6.28 ± 6.05 9.63**
3.66 ± 4.34 2.97 ± 2.96 19.03***
Subjects with probable cataplexy (n = 108) Subjects without probable cataplexy (n = 3669) F
4.13 ± 3.35 2.69 ± 2.47 38.00***
2.37 ± 2.61 1.08 ± 1.58 70.13***
1.97 ± 2.72 0.90 ± 1.49 52.93***
3.10 ± 3.19 1.67 ± 1.91 57.78***
11.57 ± 9.56 6.34 ± 6.04 79.78***
4.44 ± 3.79 3.07 ± 3.26 19.65***
Subjects with significant snoring (n = 144) Subjects without significant snoring (n = 3633) F
3.68 ± 2.94 2.69 ± 2.49 15.26***
1.49 ± 1.81 1.10 ± 1.62 5.24*
1.26 ± 1.81 0.92 ± 1.54 4.26*
1.95 ± 2.04 1.70 ± 1.97 1.49
8.38 ± 7.05 6.42 ± 6.20 9.44**
3.44 ± 2.84 3.09 ± 3.30 0.58
Abbreviations: ESI: Eppendorf Schizophrenia Inventory, Y-PARQ: Youth Psychosis At Risk Questionnaire, AS: attention and speech impairment, AU: auditory uncertainty, DP: deviant perception, IR: ideas of reference, BDI: Beck’s Depression Inventory, EDS: excessive daytime somnolence. * <0.05. ** <0.01. *** <0.001. a BDI score 69.
Table 5 Prediction of clinical high risk of psychosis by sleep disturbances in non-depressive participantsa (n = 3777) after controlling for age and gender (by multiple logistic regression). Group by ESI Low risk group (n = 3740) Any insomnia Sleep onset insomnia Maintenance insomnia Terminal insomnia EDS Significant napping Probable cataplexy Significant snoring
Wald
Beta
SE
OR
95% C.I.
Group by Y-PARQ Low risk group (n = 3713)
High risk group (n = 37)
Wald
Beta
SE
OR
95% C.I.
High risk group (n = 64)
175 (4.68%) 106 (2.83%)
6 (16.22%) 5 (13.51%)
9.66** 12.04**
1.41 1.71
0.45 0.49
4.10 5.54
1.68–10.00 2.11–14.56
175 (4.71%) 105 (2.83%)
6 (9.38%) 6 (9.38%)
2.95 8.24**
0.75 1.27
0.44 0.44
2.12 3.56
0.82–1.30 1.50–8.49
79 (2.11%)
5 (13.51%)
2.05
1.06
0.74
2.88
0.68–12.25
77 (2.07%)
4 (6.25%)
5.14*
1.21
0.53
3.35
1.18–9.51
17 (0.45%)
3 (8.11%)
21.90***
3.10
0.66
22.13
6.05–80.95
17 (0.46%)
3 (4.69%)
14.45***
552 (14.76%) 724 (19.36%)
14 (37.84%) 9 (24.32%)
***
13.49 0.84
1.26 0.12
0.34 0.40
3.52 1.12
1.80–6.88 0.52–2.44
548 (14.76%) 711 (19.15%)
18 (28.13%) 22 (34.38%)
99 (2.65%)
9 (24.32%)
40.43***
1.27
0.20
3.57
2.41–5.28
102 (2.75%)
143 (3.82%)
1 (2.70%)
0.23
0.49
1.02
0.62
0.08–4.55
175 (4.71%)
2.48
0.65
11.90
**
3.32–42.68
8.51 6.13*
0.83 0.69
0.28 0.28
2.28 2.00
1.31–3.97 1.16–3.45
6 (9.38%)
9.61**
0.69
0.22
1.99
1.29–3.07
6 (9.38%)
0.34
0.42
0.73
0.66
0.16–2.72
Abbreviations: ESI: Eppendorf Schizophrenia Inventory, Y-PARQ: Youth Psychosis At Risk Questionnaire, EDS: excessive daytime somnolence. <0.05. ** <0.01. *** <0.001. a BDI score 69. *
objectively assess the sleep-related breathing problem including snoring. Another limitation may be the cross-sectional nature of the study. A longitudinal study would shed light on the causal pathway linking sleep disturbances and PLEs. Furthermore, follow-up studies to detect later development of full-blown psychosis may be needed, especially for adolescents at clinical high risk.
In conclusion, we found that insomnia, EDS and probable cataplexy during adolescence are associated with PLEs, independent of depression. Our results suggest that adolescents with those with insomnia (especially sleep onset and terminal insomnia) or EDS might be at higher risk of developing psychosis than adolescents who do not exhibit these symptoms. Clinical attention and early
Y.J. Lee et al. / Sleep Medicine 13 (2012) 1021–1027
screening programs to detect developing psychosis may be warranted for adolescents with sleep disturbances. Conflict of interest The ICMJE Uniform Disclosure Form for Potential Conflicts of Interest associated with this article can be viewed by clicking on the following link: http://dx.doi.org/10.1016/j.sleep.2012.06.002. Acknowledgment This study was supported by a grant of the Korea Healthcare Technology R&D Project, Ministry for Health, Welfare & Family Affairs, Republic of Korea (A090059).
[14] [15] [16] [17] [18]
[19]
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