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Loneliness and psychotic experiences in a general population sample
SCHRES-08672; No of Pages 5 Schizophrenia Research xxx (xxxx) xxx
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Loneliness and psychotic experiences in a general population sample Zui Narita a,b, Andrew Stickley c, Jordan DeVylder d,e,⁎ a
Department of Psychiatry and Behavioral Sciences, The Johns Hopkins University School of Medicine, 733 N Broadway, Baltimore, MD 21205, United States Department of Mental Health, Johns Hopkins Bloomberg School of Public Health, 615 N Wolfe St, Baltimore, MD 21205, United States c Department of Preventive Intervention for Psychiatric Disorders, National Institute of Mental Health, National Center of Neurology and Psychiatry, 4-1-1 Ogawahigashicho, Kodaira, Tokyo 1878553, Japan d Graduate School of Social Service, Fordham University, 113 W 60th St, New York, NY 10023, United States e Institute of Comparative Culture, Sophia University, 7-1 Kioicho, Chiyoda-ku, Tokyo 102-8554, Japan b
a r t i c l e
i n f o
Article history: Received 17 October 2019 Received in revised form 28 December 2019 Accepted 19 January 2020 Available online xxxx Keywords: Loneliness Psychosis Schizophrenia Schizoaffective disorder Epidemiology
a b s t r a c t Increased loneliness has been associated with common mental disorders including psychotic disorders. However, as yet, little information is available on the association between loneliness and the occurrence of psychotic experiences (PEs), especially when adjusted for confounding factors. To address this deficit, the current study examined the relationship between PEs and loneliness in a general population sample in the United States (N = 974). We fitted three regression models to examine the associations between loneliness and PEs, using hierarchical adjustments for sociodemographic factors, adverse childhood experiences, and common mental disorders. Even at the highest level of adjustment, loneliness was significantly associated with increased odds for any PEs (OR = 1.25, 95% CI = 1.13–1.39). The same applied to the association between loneliness and delusional mood (OR = 1.29, 95% CI = 1.15–1.44). For delusion of reference and persecution, delusions of control, and hallucinations, there were no significant associations when adjusted for sociodemographic factors, adverse childhood experiences, and common mental disorders. These results suggest that increased loneliness is associated with PEs, particularly delusional mood. Future studies should employ longitudinal data and biological measures to examine potential causal relationships and underlying mechanisms. © 2020 Elsevier B.V. All rights reserved.
1. Introduction Individuals with subthreshold psychotic experience (PE) report hallucination-like or delusion-like symptoms that are analogous to psychosis. These symptoms are of lesser intensity, persistence, or impairment than those of schizophrenia spectrum and other psychotic disorders (Linscott and van Os, 2013). A recent meta-analysis showed that the lifetime prevalence of PEs is 7.2% among the general population (Linscott and van Os, 2013). PEs are used to examine potential etiological factors for psychosis, and are clinically important as risk factors for suicidal behavior (Bromet et al., 2017; DeVylder et al., 2015; Kelleher et al., 2013; Yates et al., 2019), psychiatric comorbidities (DeVylder et al., 2014a; Kelleher et al., 2012; McGrath et al., 2016), and functional impairment (DeVylder and Kelleher, 2016; Kelleher et al., 2015; Navarro-Mateu et al., 2017; Oh et al., 2018). PEs are also associated with a greater need for psychiatric intervention (DeVylder et al., 2014b; Murphy et al., 2012).
⁎ Corresponding author at: Graduate School of Social Service, Fordham University, 113 W 60th St, 7th floor, New York, NY 10023, United States. E-mail addresses: [email protected] (Z. Narita), [email protected] (J. DeVylder).
There is some indication that individuals with PEs may experience increased loneliness (Morgan et al., 2012; Stain et al., 2012). This may be because they have impaired social functioning, limited social networks, and poor social support (Norman et al., 2005). Loneliness may be a cause, consequence, or reciprocally related to psychosis, and studying PEs allows us to understand the role of loneliness prior to the onset of a full diagnosable disorder, particularly when adjusting for related social exposures. A recent meta-analytic review showed a positive relationship between loneliness and psychotic disorders (Michalska da Rocha et al., 2018). However, the heterogeneity of the included studies was high (I2 = 97.6%), and most of them adjusted for only a limited number of confounding factors (Michalska da Rocha et al., 2018). Similarly, in terms of PEs, besides a comparative lack of research on the association with loneliness, there is also little evidence about the role of various factors in this association. For example, adverse childhood experiences and common mental disorders may potentially confound the association between loneliness and PEs (McGrath et al., 2016; Shevlin et al., 2015; Meltzer et al., 2013; Nicolaisen and Thorsen, 2014), and hence, should be adjusted for when examining this relationship. In this study, we examined the association between loneliness and PEs among a general population sample using data from Baltimore and New York City. We hypothesized that perceived
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Please cite this article as: Z. Narita, A. Stickley and J. DeVylder, Loneliness and psychotic experiences in a general population sample, Schizophrenia Research, https://doi.org/10.1016/j.schres.2020.01.018
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loneliness would be related to PEs, and that this association would be robust to adjustment for sociodemographic factors, adverse childhood experiences, and common mental disorders.
other), income (b$20,000, $20,000–59,999, and $60,000 or higher), nativity (US born and foreign born), and marital status (unmarried and married).
2. Methods
2.2.4. Adverse childhood experiences In order to evaluate adverse childhood experiences, participants were asked 10 questions about their first 18 years of life with ‘yes’ or ‘no’ answer options (see Supplementary material). Each item was loaded onto a composite score (range = 0–10) with higher scores indicating an increased number of adverse experiences.
2.1. Sample The Survey of Police-Public Encounters II is a cross-sectional survey administered among a general population sample in the United States (DeVylder et al., 2018). The survey was conducted in March 2017 with Qualtrics, an online survey software. Adults aged 18 or above in Baltimore or New York City were eligible to participate in the study. A quota sampling method was used to recruit samples that were demographically matched to the city from which they were recruited (± 10% of US census distributions on age, race/ethnicity, and gender). Participants were sampled through Qualtrics Panels, a database comprising several million residents who previously consented to be contacted for the purpose of research. Location was self-reported and verified using longitude and latitude coordinates. A monetary incentive, at rates defined by Qualtrics, was provided to individuals who completed the survey. The current study was approved by the sponsoring university's Institutional Review Board. Of the 1221 individuals who participated in the survey, 221 were excluded due to inappropriate responses or dropout prior to completion. Moreover, 26 participants who reported a diagnosis of schizophrenia were excluded as the current study intended to examine psychotic symptoms falling below the clinical threshold. Thus, data from 974 participants were analyzed (79.8% of the eligible sample). 2.2. Measures 2.2.1. PEs PEs were evaluated by the psychosis screen module of the World Health Organization Composite International Diagnostic Interview (WHO-CIDI), a validated scale for the screening of psychotic symptoms (Kessler and Ustün, 2004). Thus, subjects were asked the following questions with ‘yes’ or ‘no’ answer options: During the last 12 months, have you experienced (1) ‘A feeling something strange and unexplainable was going on that other people would find hard to believe?’ (delusional mood), (2) ‘A feeling that people were too interested in you or there was a plot to harm you?’ (delusions of reference and persecution), (3) ‘A feeling that your thoughts were being directly interfered [with] or controlled by another person, or your mind was being taken over by strange forces?’ (delusions of control), (4) ‘An experience of seeing visions or hearing voices that others could not see or hear when you were not half asleep, dreaming or under the influence of alcohol or drugs?’ (hallucinations). Reporting at least one of these symptoms was coded as a positive endorsement of PEs. 2.2.2. Loneliness The Three-Item Loneliness Scale, which was derived from the RUCLA Loneliness Scale (Hughes et al., 2004), was used to evaluate loneliness. It uses a three-point Likert scale (1 = hardly ever, 2 = some of the time, 3 = often) that asks ‘How often do you feel that you lack companionship?’, ‘How often do you feel left out?’, and ‘How often do you feel isolated from others?’ Composite scores were calculated (range = 3–9). Previous research has suggested that the scale has an acceptable level of internal consistency (Cronbach's alpha = 0.72) (Hughes et al., 2004), while in the current study it was good (Cronbach's alpha = 0.84). 2.2.3. Sociodemographic factors Demographic characteristics that may confound the relationship between PEs and loneliness were included as covariates. The current study included the following variables: age, sex (male and female), sexual orientation (heterosexual/straight and other), race (White, Black, and
2.2.5. Common mental disorders Participants were asked the question, ‘Have you ever been diagnosed with a mental illness?’. A ‘yes’ response was classified as having a common mental disorder. 2.3. Statistical analyses Statistical analyses were conducted using Stata 15 (Stata Corp LP, College station, Texas). To examine differences in the baseline characteristics between subjects who reported PEs and those who did not, Chi-square or Fisher's exact tests were used to compare categorical variables, while independent-sample t-tests or Wilcoxon rank sum tests were used for continuous variables. Multivariable logistic regression analysis was performed to assess the association between the Three-Item Loneliness composite score and PEs (delusional mood, delusions of reference and persecution, delusions of control, hallucinations, and any PEs). We fitted three regression models. Model 1 evaluated the crude association without adjusting for covariates. Model 2 adjusted for age and sex. Model 3 adjusted for all variables in Model 2, sexual orientation, race, income, nativity, marital status, adverse childhood experiences, and common mental disorders. The results are presented as odds ratios (OR) with 95% confidence intervals (CI). Mean centering was performed for continuous variables (Iacobucci et al., 2017). Bias-corrected and accelerated bootstrap CIs were used to obtain an accurate estimation of the association between each variable and PEs (Lumley et al., 2002). In executing bootstrap CIs, the size of the bootstrap sample was set at 1000 with 95% CIs. 3. Results The demographic characteristics of the sample are shown in Table 1. A total of 195 individuals reported at least one PE (delusional mood: 147; delusion of reference and persecution: 79; delusion of control: 48; hallucination: 41, respectively). When stratifying by the presence or absence of PEs, significant differences were found in terms of age, race, income, and marital status. Adverse childhood experiences and common mental disorders were also linked to PEs. Significantly higher loneliness composite scores were found in participants with PEs compared to those without PEs. The results of the multivariable logistic regression analyses are shown in Table 2. The OR for any PEs was attenuated across the models but was statistically significant in all of them: Model 1–3 (OR = 1.42, 95% CI = 1.30–1.55; OR = 1.37, 95% CI = 1.25–1.50; and OR = 1.25, 95% CI = 1.13–1.39). The same applied to the association between loneliness and delusional mood (OR = 1.45, 95% CI = 1.32–1.59; OR = 1.41, 95% CI = 1.28–1.56; and OR = 1.29, 95% CI = 1.15–1.44, see Supplementary Tables 1–3). For delusion of reference and persecution, delusions of control, and hallucinations, the ORs were attenuated as the models were built and became non-significant in Model 3 (see Supplementary Tables 1–3). Finally, given the conceptually complex role of common mental disorders in the context of the association between loneliness and PEs, we ran a sensitivity analysis with the exclusion of the adjustment for the common mental disorders variable, but found that this had minimal effect on our results (data available on request).
Please cite this article as: Z. Narita, A. Stickley and J. DeVylder, Loneliness and psychotic experiences in a general population sample, Schizophrenia Research, https://doi.org/10.1016/j.schres.2020.01.018
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Table 1 Overall demographic characteristics of the sample and by PEs. Variables
Overall n = 974
PEs n = 195
No PE n = 779
p value
Age (years) Sex Male Female Sexual orientation Heterosexual/straight Other Race White Black Other Income b$20,000 $20,000-59,999 $60,000 or higher Nativity US born Foreign born Marital status Single Married Adverse childhood experiences Common mental disorders Three-Item Loneliness composite score
39.8 ± 15.1
32.6 ± 11.2
41.6 ± 15.4
p b 0.001 p = 0.12
382 (39.2) 592 (60.8)
86 (44.1) 109 (55.9)
296 (38.0) 483 (62.0)
883 (90.7) 91 (9.3)
171 (87.7) 24 (12.3)
712 (91.4) 67 (8.6)
435 (44.7) 401 (41.2) 138 (14.2)
64 (32.8) 103 (52.8) 28 (14.4)
371 (47.6) 298 (38.3) 110 (14.1)
196 (20.1) 400 (41.0) 378 (38.8)
50 (25.6) 84 (43.1) 61 (31.3)
146 (18.7) 316 (40.6) 317 (40.7)
859 (88.2) 115 (11.8)
170 (87.2) 25 (12.8)
689 (88.5) 90 (11.6)
627 (64.4) 347 (35.6) 1.8 ± 2.4 183 (18.8) 5.3 ± 1.9
141 (72.3) 54 (27.7) 3.5 ± 2.9 73 (37.4) 6.3 ± 1.8
486 (62.4) 293 (37.6) 1.4 ± 2.0 110 (14.1) 5.1 ± 1.8
p = 0.11 p b 0.001
p = 0.02
p = 0.62
p = 0.01
p = 0.006 p b 0.001 p b 0.001
Data are Mean ± SD or n (%). PE: psychotic experience, SD: standard deviation.
4. Discussion 4.1. Main findings In the current study, loneliness was positively correlated with PEs, when adjusted for sociodemographic factors, adverse childhood experiences, and common mental disorders. A similar strength of association was found between loneliness and delusional mood. On the other hand, non-significant associations were observed for delusion of reference and persecution, delusion of control, and hallucination when adjusted for these potential confounders. These results replicate those of previous studies that reported a positive correlation between loneliness and PEs (Meltzer et al., 2013; Michalska da Rocha et al., 2018; Riggio and Kwong, 2009). However, these studies showed the relationship adjusting for only a limited number of confounding factors (Meltzer et al., 2013; Michalska da Rocha et al., 2018). To the best of our knowledge, this study is the first to show the correlation between loneliness and PEs, after controlling for adverse childhood experiences and common mental disorders, as well as sociodemographic factors. A previous study suggested that loneliness can impact negatively on self-esteem (Michalska da Rocha et al., 2018). This might be important as poor self-esteem may result in maladaptive cognition about oneself and others, which may lead to the development of psychosis, especially delusions (Freeman et al., 2005; Kinderman and Bentall, 1996). Also, social deafferentation, in which may induce brain reorganization may result from a lack of social inputs and in turn lead to psychotic symptoms (Hoffman, 2007; Narita et al., 2019), provides a potential mechanism linking loneliness to delusional thoughts. While the positive correlation between loneliness and delusional mood in this study seems reasonable, it is difficult to determine the reason for the non-significant results for delusion of reference and persecution, delusion of control, and hallucinations. At a biological level, loneliness may induce a rise in cortisol (Adam et al., 2006), higher circulating cortisol levels (Cole et al., 2015; Doane and Adam, 2010), and reduced sensitivity of the glucocorticoid receptor (Cole, 2008; Cole et al., 2007), suggesting the activation of the hypothalamic-pituitary-adrenal axis. This mechanism may contribute to increased dopamine release in the striatum, which has been linked to PEs in biologically vulnerable individuals (Mizrahi et al.,
2012). Further studies should examine the occurrence and role of loneliness across the psychosis continuum to further elucidate this relation and the factors that might underlie it. 4.2. Implications A previous study reported that patients' subjective recovery from psychosis was significantly associated with decreased loneliness (Roe et al., 2011). While increased loneliness may play a role in the maintenance of psychosis, decreased loneliness may ameliorate PEs (Michalska da Rocha et al., 2018). The same could apply to the highrisk state of psychosis, which has been shown to benefit from evidence-based interventions such as cognitive behavioral therapy (Cacioppo et al., 2015; Fusar-Poli et al., 2013). Cognitive behavioral therapy and social skills training have been shown to improve social functioning among people with psychosis (Granholm et al., 2009), and may serve to address the potential worsening or maintenance of psychotic experiences within the context of loneliness. Further, non-clinical general population samples, including many or possibly most individuals experiencing PEs, may benefit from general wellness interventions (Davidson and McEwen, 2012) that do not require the specific identification and pathologization of a psychosis-risk state. As PEs may lead to future psychotic disorder and other detrimental outcomes such as suicidal behavior (Bromet et al., 2017; DeVylder et al., 2015; Kelleher et al., 2013; Yates et al., 2019), the findings obtained in the current study may also be of clinical relevance for the prevention of these outcomes. 4.3. Limitations Several limitations should be acknowledged in the present study. First, the analyses were based on data from a cross-sectional survey, and hence, did not allow us to determine the direction of the observed associations and also limited causal inference. Second, no biological data were analyzed to determine potential mechanisms that mediate the potential role of loneliness in the etiology of PEs. Third, the assessment of common mental disorder was not validated by a face-to-face diagnosis by a clinician. We also had no information about whether the mental health conditions were current or not, and no information
Please cite this article as: Z. Narita, A. Stickley and J. DeVylder, Loneliness and psychotic experiences in a general population sample, Schizophrenia Research, https://doi.org/10.1016/j.schres.2020.01.018
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Table 2 The association between loneliness and any PEs evaluated by multivariable logistic regression. Variables
Three-Item Loneliness composite score Age Sex Male Female Sexual orientation Heterosexual/straight Other Race White Black Other Income b$20,000 $20,000-59,999 $60,000 or higher Nativity US born Foreign born Marital status Single Married Adverse childhood experiences Common mental disorders
Model 1
Model 2
Model 3
OR of any PEs [95% CI]
OR of any PEs [95% CI]
OR of any PEs [95% CI]
1.42⁎⁎⁎ [1.30–1.55]
1.37⁎⁎⁎ [1.25–1.50] 0.96⁎⁎⁎
1.25⁎⁎⁎ [1.13–1.39] 0.96⁎⁎⁎
[0.95–0.97]
[0.95–0.98]
1.00 0.68⁎ [0.48–0.96]
1.00 0.58⁎⁎ [0.39–0.86] 1.00 0.88 [0.45–1.71] 1.00 1.31 [0.85–2.02] 0.98 [0.54–1.79] 1.00 0.96 [0.59–1.57] 1.05 [0.61–1.81] 1.00 1.33 [0.77–2.30] 1.00 0.91 [0.59–1.41] 1.30⁎⁎⁎ [1.20–1.40] 2.14⁎⁎⁎ [1.36–3.35]
Model 1: unadjusted. Model 2: adjusted for age and sex. Model 3: adjusted for all variables in Model 2, race, income, nativity, marital status, adverse childhood experiences, and common mental disorders. PE: psychotic experience; OR: odds ratio. ⁎ p b 0.05. ⁎⁎ p b 0.01. ⁎⁎⁎ p b 0.001.
about specific diagnoses. Notably, excluding this item from the analysis had minimal effect on results. Also, the assessment of loneliness may not directly reflect objective isolation, which is a distinct construct from subjective loneliness (Hughes et al., 2004). The focus of the present study was to evaluate how participants perceive isolation, rather than on objective indicators of isolation, and the Three-Item Loneliness Scale has a high validity in that respect (Hughes et al., 2004). Finally, we used data from an online survey that are geographically limited. The relatively high prevalence of PEs in this study suggests that the analyzed sample might not be fully representative of the general population. Future studies should confirm and expand upon our findings using longitudinal data, biological mechanisms, and using samples that are representative of the general population. Funding This study was funded by an intramural research grant from the School of Social Work, University of Maryland (DeVylder). Contributors ZN conducted the statistical analyses, reviewed the literature, and wrote the first and subsequent drafts of the manuscript. JD developed the study concept and hypothesis, managed data collection, contributed to the interpretation of the results, and assisted in writing the manuscript. AS contributed toward the interpretation of results, revised drafts
of the manuscript, and provided feedback. All authors contributed to and have approved the final manuscript. Declaration of competing interest The authors declare no conflict of interest in the current study. Acknowledgements Not applicable.
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Schizophrenia Research journal homepage: www.elsevier.com/locate/schres
Loneliness and psychotic experiences in a general population sample Zui Narita a,b, Andrew Stickley c, Jordan DeVylder d,e,⁎ a
Department of Psychiatry and Behavioral Sciences, The Johns Hopkins University School of Medicine, 733 N Broadway, Baltimore, MD 21205, United States Department of Mental Health, Johns Hopkins Bloomberg School of Public Health, 615 N Wolfe St, Baltimore, MD 21205, United States c Department of Preventive Intervention for Psychiatric Disorders, National Institute of Mental Health, National Center of Neurology and Psychiatry, 4-1-1 Ogawahigashicho, Kodaira, Tokyo 1878553, Japan d Graduate School of Social Service, Fordham University, 113 W 60th St, New York, NY 10023, United States e Institute of Comparative Culture, Sophia University, 7-1 Kioicho, Chiyoda-ku, Tokyo 102-8554, Japan b
a r t i c l e
i n f o
Article history: Received 17 October 2019 Received in revised form 28 December 2019 Accepted 19 January 2020 Available online xxxx Keywords: Loneliness Psychosis Schizophrenia Schizoaffective disorder Epidemiology
a b s t r a c t Increased loneliness has been associated with common mental disorders including psychotic disorders. However, as yet, little information is available on the association between loneliness and the occurrence of psychotic experiences (PEs), especially when adjusted for confounding factors. To address this deficit, the current study examined the relationship between PEs and loneliness in a general population sample in the United States (N = 974). We fitted three regression models to examine the associations between loneliness and PEs, using hierarchical adjustments for sociodemographic factors, adverse childhood experiences, and common mental disorders. Even at the highest level of adjustment, loneliness was significantly associated with increased odds for any PEs (OR = 1.25, 95% CI = 1.13–1.39). The same applied to the association between loneliness and delusional mood (OR = 1.29, 95% CI = 1.15–1.44). For delusion of reference and persecution, delusions of control, and hallucinations, there were no significant associations when adjusted for sociodemographic factors, adverse childhood experiences, and common mental disorders. These results suggest that increased loneliness is associated with PEs, particularly delusional mood. Future studies should employ longitudinal data and biological measures to examine potential causal relationships and underlying mechanisms. © 2020 Elsevier B.V. All rights reserved.
1. Introduction Individuals with subthreshold psychotic experience (PE) report hallucination-like or delusion-like symptoms that are analogous to psychosis. These symptoms are of lesser intensity, persistence, or impairment than those of schizophrenia spectrum and other psychotic disorders (Linscott and van Os, 2013). A recent meta-analysis showed that the lifetime prevalence of PEs is 7.2% among the general population (Linscott and van Os, 2013). PEs are used to examine potential etiological factors for psychosis, and are clinically important as risk factors for suicidal behavior (Bromet et al., 2017; DeVylder et al., 2015; Kelleher et al., 2013; Yates et al., 2019), psychiatric comorbidities (DeVylder et al., 2014a; Kelleher et al., 2012; McGrath et al., 2016), and functional impairment (DeVylder and Kelleher, 2016; Kelleher et al., 2015; Navarro-Mateu et al., 2017; Oh et al., 2018). PEs are also associated with a greater need for psychiatric intervention (DeVylder et al., 2014b; Murphy et al., 2012).
⁎ Corresponding author at: Graduate School of Social Service, Fordham University, 113 W 60th St, 7th floor, New York, NY 10023, United States. E-mail addresses: [email protected] (Z. Narita), [email protected] (J. DeVylder).
There is some indication that individuals with PEs may experience increased loneliness (Morgan et al., 2012; Stain et al., 2012). This may be because they have impaired social functioning, limited social networks, and poor social support (Norman et al., 2005). Loneliness may be a cause, consequence, or reciprocally related to psychosis, and studying PEs allows us to understand the role of loneliness prior to the onset of a full diagnosable disorder, particularly when adjusting for related social exposures. A recent meta-analytic review showed a positive relationship between loneliness and psychotic disorders (Michalska da Rocha et al., 2018). However, the heterogeneity of the included studies was high (I2 = 97.6%), and most of them adjusted for only a limited number of confounding factors (Michalska da Rocha et al., 2018). Similarly, in terms of PEs, besides a comparative lack of research on the association with loneliness, there is also little evidence about the role of various factors in this association. For example, adverse childhood experiences and common mental disorders may potentially confound the association between loneliness and PEs (McGrath et al., 2016; Shevlin et al., 2015; Meltzer et al., 2013; Nicolaisen and Thorsen, 2014), and hence, should be adjusted for when examining this relationship. In this study, we examined the association between loneliness and PEs among a general population sample using data from Baltimore and New York City. We hypothesized that perceived
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Please cite this article as: Z. Narita, A. Stickley and J. DeVylder, Loneliness and psychotic experiences in a general population sample, Schizophrenia Research, https://doi.org/10.1016/j.schres.2020.01.018
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loneliness would be related to PEs, and that this association would be robust to adjustment for sociodemographic factors, adverse childhood experiences, and common mental disorders.
other), income (b$20,000, $20,000–59,999, and $60,000 or higher), nativity (US born and foreign born), and marital status (unmarried and married).
2. Methods
2.2.4. Adverse childhood experiences In order to evaluate adverse childhood experiences, participants were asked 10 questions about their first 18 years of life with ‘yes’ or ‘no’ answer options (see Supplementary material). Each item was loaded onto a composite score (range = 0–10) with higher scores indicating an increased number of adverse experiences.
2.1. Sample The Survey of Police-Public Encounters II is a cross-sectional survey administered among a general population sample in the United States (DeVylder et al., 2018). The survey was conducted in March 2017 with Qualtrics, an online survey software. Adults aged 18 or above in Baltimore or New York City were eligible to participate in the study. A quota sampling method was used to recruit samples that were demographically matched to the city from which they were recruited (± 10% of US census distributions on age, race/ethnicity, and gender). Participants were sampled through Qualtrics Panels, a database comprising several million residents who previously consented to be contacted for the purpose of research. Location was self-reported and verified using longitude and latitude coordinates. A monetary incentive, at rates defined by Qualtrics, was provided to individuals who completed the survey. The current study was approved by the sponsoring university's Institutional Review Board. Of the 1221 individuals who participated in the survey, 221 were excluded due to inappropriate responses or dropout prior to completion. Moreover, 26 participants who reported a diagnosis of schizophrenia were excluded as the current study intended to examine psychotic symptoms falling below the clinical threshold. Thus, data from 974 participants were analyzed (79.8% of the eligible sample). 2.2. Measures 2.2.1. PEs PEs were evaluated by the psychosis screen module of the World Health Organization Composite International Diagnostic Interview (WHO-CIDI), a validated scale for the screening of psychotic symptoms (Kessler and Ustün, 2004). Thus, subjects were asked the following questions with ‘yes’ or ‘no’ answer options: During the last 12 months, have you experienced (1) ‘A feeling something strange and unexplainable was going on that other people would find hard to believe?’ (delusional mood), (2) ‘A feeling that people were too interested in you or there was a plot to harm you?’ (delusions of reference and persecution), (3) ‘A feeling that your thoughts were being directly interfered [with] or controlled by another person, or your mind was being taken over by strange forces?’ (delusions of control), (4) ‘An experience of seeing visions or hearing voices that others could not see or hear when you were not half asleep, dreaming or under the influence of alcohol or drugs?’ (hallucinations). Reporting at least one of these symptoms was coded as a positive endorsement of PEs. 2.2.2. Loneliness The Three-Item Loneliness Scale, which was derived from the RUCLA Loneliness Scale (Hughes et al., 2004), was used to evaluate loneliness. It uses a three-point Likert scale (1 = hardly ever, 2 = some of the time, 3 = often) that asks ‘How often do you feel that you lack companionship?’, ‘How often do you feel left out?’, and ‘How often do you feel isolated from others?’ Composite scores were calculated (range = 3–9). Previous research has suggested that the scale has an acceptable level of internal consistency (Cronbach's alpha = 0.72) (Hughes et al., 2004), while in the current study it was good (Cronbach's alpha = 0.84). 2.2.3. Sociodemographic factors Demographic characteristics that may confound the relationship between PEs and loneliness were included as covariates. The current study included the following variables: age, sex (male and female), sexual orientation (heterosexual/straight and other), race (White, Black, and
2.2.5. Common mental disorders Participants were asked the question, ‘Have you ever been diagnosed with a mental illness?’. A ‘yes’ response was classified as having a common mental disorder. 2.3. Statistical analyses Statistical analyses were conducted using Stata 15 (Stata Corp LP, College station, Texas). To examine differences in the baseline characteristics between subjects who reported PEs and those who did not, Chi-square or Fisher's exact tests were used to compare categorical variables, while independent-sample t-tests or Wilcoxon rank sum tests were used for continuous variables. Multivariable logistic regression analysis was performed to assess the association between the Three-Item Loneliness composite score and PEs (delusional mood, delusions of reference and persecution, delusions of control, hallucinations, and any PEs). We fitted three regression models. Model 1 evaluated the crude association without adjusting for covariates. Model 2 adjusted for age and sex. Model 3 adjusted for all variables in Model 2, sexual orientation, race, income, nativity, marital status, adverse childhood experiences, and common mental disorders. The results are presented as odds ratios (OR) with 95% confidence intervals (CI). Mean centering was performed for continuous variables (Iacobucci et al., 2017). Bias-corrected and accelerated bootstrap CIs were used to obtain an accurate estimation of the association between each variable and PEs (Lumley et al., 2002). In executing bootstrap CIs, the size of the bootstrap sample was set at 1000 with 95% CIs. 3. Results The demographic characteristics of the sample are shown in Table 1. A total of 195 individuals reported at least one PE (delusional mood: 147; delusion of reference and persecution: 79; delusion of control: 48; hallucination: 41, respectively). When stratifying by the presence or absence of PEs, significant differences were found in terms of age, race, income, and marital status. Adverse childhood experiences and common mental disorders were also linked to PEs. Significantly higher loneliness composite scores were found in participants with PEs compared to those without PEs. The results of the multivariable logistic regression analyses are shown in Table 2. The OR for any PEs was attenuated across the models but was statistically significant in all of them: Model 1–3 (OR = 1.42, 95% CI = 1.30–1.55; OR = 1.37, 95% CI = 1.25–1.50; and OR = 1.25, 95% CI = 1.13–1.39). The same applied to the association between loneliness and delusional mood (OR = 1.45, 95% CI = 1.32–1.59; OR = 1.41, 95% CI = 1.28–1.56; and OR = 1.29, 95% CI = 1.15–1.44, see Supplementary Tables 1–3). For delusion of reference and persecution, delusions of control, and hallucinations, the ORs were attenuated as the models were built and became non-significant in Model 3 (see Supplementary Tables 1–3). Finally, given the conceptually complex role of common mental disorders in the context of the association between loneliness and PEs, we ran a sensitivity analysis with the exclusion of the adjustment for the common mental disorders variable, but found that this had minimal effect on our results (data available on request).
Please cite this article as: Z. Narita, A. Stickley and J. DeVylder, Loneliness and psychotic experiences in a general population sample, Schizophrenia Research, https://doi.org/10.1016/j.schres.2020.01.018
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Table 1 Overall demographic characteristics of the sample and by PEs. Variables
Overall n = 974
PEs n = 195
No PE n = 779
p value
Age (years) Sex Male Female Sexual orientation Heterosexual/straight Other Race White Black Other Income b$20,000 $20,000-59,999 $60,000 or higher Nativity US born Foreign born Marital status Single Married Adverse childhood experiences Common mental disorders Three-Item Loneliness composite score
39.8 ± 15.1
32.6 ± 11.2
41.6 ± 15.4
p b 0.001 p = 0.12
382 (39.2) 592 (60.8)
86 (44.1) 109 (55.9)
296 (38.0) 483 (62.0)
883 (90.7) 91 (9.3)
171 (87.7) 24 (12.3)
712 (91.4) 67 (8.6)
435 (44.7) 401 (41.2) 138 (14.2)
64 (32.8) 103 (52.8) 28 (14.4)
371 (47.6) 298 (38.3) 110 (14.1)
196 (20.1) 400 (41.0) 378 (38.8)
50 (25.6) 84 (43.1) 61 (31.3)
146 (18.7) 316 (40.6) 317 (40.7)
859 (88.2) 115 (11.8)
170 (87.2) 25 (12.8)
689 (88.5) 90 (11.6)
627 (64.4) 347 (35.6) 1.8 ± 2.4 183 (18.8) 5.3 ± 1.9
141 (72.3) 54 (27.7) 3.5 ± 2.9 73 (37.4) 6.3 ± 1.8
486 (62.4) 293 (37.6) 1.4 ± 2.0 110 (14.1) 5.1 ± 1.8
p = 0.11 p b 0.001
p = 0.02
p = 0.62
p = 0.01
p = 0.006 p b 0.001 p b 0.001
Data are Mean ± SD or n (%). PE: psychotic experience, SD: standard deviation.
4. Discussion 4.1. Main findings In the current study, loneliness was positively correlated with PEs, when adjusted for sociodemographic factors, adverse childhood experiences, and common mental disorders. A similar strength of association was found between loneliness and delusional mood. On the other hand, non-significant associations were observed for delusion of reference and persecution, delusion of control, and hallucination when adjusted for these potential confounders. These results replicate those of previous studies that reported a positive correlation between loneliness and PEs (Meltzer et al., 2013; Michalska da Rocha et al., 2018; Riggio and Kwong, 2009). However, these studies showed the relationship adjusting for only a limited number of confounding factors (Meltzer et al., 2013; Michalska da Rocha et al., 2018). To the best of our knowledge, this study is the first to show the correlation between loneliness and PEs, after controlling for adverse childhood experiences and common mental disorders, as well as sociodemographic factors. A previous study suggested that loneliness can impact negatively on self-esteem (Michalska da Rocha et al., 2018). This might be important as poor self-esteem may result in maladaptive cognition about oneself and others, which may lead to the development of psychosis, especially delusions (Freeman et al., 2005; Kinderman and Bentall, 1996). Also, social deafferentation, in which may induce brain reorganization may result from a lack of social inputs and in turn lead to psychotic symptoms (Hoffman, 2007; Narita et al., 2019), provides a potential mechanism linking loneliness to delusional thoughts. While the positive correlation between loneliness and delusional mood in this study seems reasonable, it is difficult to determine the reason for the non-significant results for delusion of reference and persecution, delusion of control, and hallucinations. At a biological level, loneliness may induce a rise in cortisol (Adam et al., 2006), higher circulating cortisol levels (Cole et al., 2015; Doane and Adam, 2010), and reduced sensitivity of the glucocorticoid receptor (Cole, 2008; Cole et al., 2007), suggesting the activation of the hypothalamic-pituitary-adrenal axis. This mechanism may contribute to increased dopamine release in the striatum, which has been linked to PEs in biologically vulnerable individuals (Mizrahi et al.,
2012). Further studies should examine the occurrence and role of loneliness across the psychosis continuum to further elucidate this relation and the factors that might underlie it. 4.2. Implications A previous study reported that patients' subjective recovery from psychosis was significantly associated with decreased loneliness (Roe et al., 2011). While increased loneliness may play a role in the maintenance of psychosis, decreased loneliness may ameliorate PEs (Michalska da Rocha et al., 2018). The same could apply to the highrisk state of psychosis, which has been shown to benefit from evidence-based interventions such as cognitive behavioral therapy (Cacioppo et al., 2015; Fusar-Poli et al., 2013). Cognitive behavioral therapy and social skills training have been shown to improve social functioning among people with psychosis (Granholm et al., 2009), and may serve to address the potential worsening or maintenance of psychotic experiences within the context of loneliness. Further, non-clinical general population samples, including many or possibly most individuals experiencing PEs, may benefit from general wellness interventions (Davidson and McEwen, 2012) that do not require the specific identification and pathologization of a psychosis-risk state. As PEs may lead to future psychotic disorder and other detrimental outcomes such as suicidal behavior (Bromet et al., 2017; DeVylder et al., 2015; Kelleher et al., 2013; Yates et al., 2019), the findings obtained in the current study may also be of clinical relevance for the prevention of these outcomes. 4.3. Limitations Several limitations should be acknowledged in the present study. First, the analyses were based on data from a cross-sectional survey, and hence, did not allow us to determine the direction of the observed associations and also limited causal inference. Second, no biological data were analyzed to determine potential mechanisms that mediate the potential role of loneliness in the etiology of PEs. Third, the assessment of common mental disorder was not validated by a face-to-face diagnosis by a clinician. We also had no information about whether the mental health conditions were current or not, and no information
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Table 2 The association between loneliness and any PEs evaluated by multivariable logistic regression. Variables
Three-Item Loneliness composite score Age Sex Male Female Sexual orientation Heterosexual/straight Other Race White Black Other Income b$20,000 $20,000-59,999 $60,000 or higher Nativity US born Foreign born Marital status Single Married Adverse childhood experiences Common mental disorders
Model 1
Model 2
Model 3
OR of any PEs [95% CI]
OR of any PEs [95% CI]
OR of any PEs [95% CI]
1.42⁎⁎⁎ [1.30–1.55]
1.37⁎⁎⁎ [1.25–1.50] 0.96⁎⁎⁎
1.25⁎⁎⁎ [1.13–1.39] 0.96⁎⁎⁎
[0.95–0.97]
[0.95–0.98]
1.00 0.68⁎ [0.48–0.96]
1.00 0.58⁎⁎ [0.39–0.86] 1.00 0.88 [0.45–1.71] 1.00 1.31 [0.85–2.02] 0.98 [0.54–1.79] 1.00 0.96 [0.59–1.57] 1.05 [0.61–1.81] 1.00 1.33 [0.77–2.30] 1.00 0.91 [0.59–1.41] 1.30⁎⁎⁎ [1.20–1.40] 2.14⁎⁎⁎ [1.36–3.35]
Model 1: unadjusted. Model 2: adjusted for age and sex. Model 3: adjusted for all variables in Model 2, race, income, nativity, marital status, adverse childhood experiences, and common mental disorders. PE: psychotic experience; OR: odds ratio. ⁎ p b 0.05. ⁎⁎ p b 0.01. ⁎⁎⁎ p b 0.001.
about specific diagnoses. Notably, excluding this item from the analysis had minimal effect on results. Also, the assessment of loneliness may not directly reflect objective isolation, which is a distinct construct from subjective loneliness (Hughes et al., 2004). The focus of the present study was to evaluate how participants perceive isolation, rather than on objective indicators of isolation, and the Three-Item Loneliness Scale has a high validity in that respect (Hughes et al., 2004). Finally, we used data from an online survey that are geographically limited. The relatively high prevalence of PEs in this study suggests that the analyzed sample might not be fully representative of the general population. Future studies should confirm and expand upon our findings using longitudinal data, biological mechanisms, and using samples that are representative of the general population. Funding This study was funded by an intramural research grant from the School of Social Work, University of Maryland (DeVylder). Contributors ZN conducted the statistical analyses, reviewed the literature, and wrote the first and subsequent drafts of the manuscript. JD developed the study concept and hypothesis, managed data collection, contributed to the interpretation of the results, and assisted in writing the manuscript. AS contributed toward the interpretation of results, revised drafts
of the manuscript, and provided feedback. All authors contributed to and have approved the final manuscript. Declaration of competing interest The authors declare no conflict of interest in the current study. Acknowledgements Not applicable.
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Please cite this article as: Z. Narita, A. Stickley and J. DeVylder, Loneliness and psychotic experiences in a general population sample, Schizophrenia Research, https://doi.org/10.1016/j.schres.2020.01.018