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Distinctiveness and overlap of depersonalization with anxiety and depression in a community sample: Results from the Gutenberg Heart Study
Psychiatry Research 188 (2011) 264–268
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Psychiatry Research j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / p s yc h r e s
Distinctiveness and overlap of depersonalization with anxiety and depression in a community sample: Results from the Gutenberg Heart Study Matthias Michal a,⁎, Jörg Wiltink a, Yvonne Till a,b, Philipp S. Wild b, Maria Blettner c, Manfred E. Beutel a a b c
Department of Psychosomatic Medicine and Psychotherapy, University Medical Center of the Johannes Gutenberg University Mainz, Germany Department of Cardiology, University Medical Center of the Johannes Gutenberg University Mainz, Germany Institute of Medical Biostatistics, Epidemiology, and Informatics, University Medical Center of the Johannes Gutenberg University Mainz, Germany
a r t i c l e
i n f o
Article history: Received 6 July 2010 Received in revised form 26 October 2010 Accepted 1 November 2010 Keywords: Depersonalization Depression Anxiety Screening
a b s t r a c t Depersonalization disorder is considered to be a common clinical phenomenon and disorder with an enormous gap between prevalence and detection partly due to the common interpretation of depersonalization (DP) being a negligible variant of anxiety and depression. Therefore, we sought to analyze (1) the prevalence rate of DP in a large community sample (n = 5000) according to a recently developed ultra brief two-item depersonalization screener; (2) the associations with depression, anxiety, physical and mental health status; and 93) whether DP contributes independently to the health status beyond anxiety and depression. The prevalence of clinically significant DP was 0.8% (n = 41), and 8.5% (n = 427) endorsed at least one symptom of DP. DP was independently associated with impairment of mental and physical health status as well as with a medical history of any depressive or anxiety disorder. Despite the consistent association of DP with anxiety and depression, the shared variances were small, and DP was clearly separated from symptoms of anxiety and depression in the principal component analysis. Therefore, we conclude that the implementation of depersonalization screening might be recommended. © 2010 Elsevier Ireland Ltd. All rights reserved.
1. Introduction After anxiety and depression, depersonalization has been considered to be the third most frequent symptom among psychiatric patients (Stewart, 1964). But although depersonalization (DP) is assessed routinely as part of the mental state examination in psychiatric and psychotherapeutic treatment, it is both underdetected and underdiagnosed (Simeon, 2004; Michal and Beutel, 2009; Sierra, 2009; Stein and Simeon, 2009). According to a recent evaluation of health insurance data of 1.5 million persons, the 1-year prevalence of the diagnosis of the depersonalization–derealization syndrome was only 0.007% (Michal et al., 2010a, 2010b, 2010c). This prevalence contrasts sharply with epidemiological studies reporting rates of 0.8–2% for clinically significant DP in the general population (Hunter et al., 2004; Michal et al., 2009). Reluctance of patients to report spontaneously about DP is one factor; another factor is the health care providers' relative lack of awareness, due to the common interpretation of DP as a negligible variant of anxiety and
⁎ Corresponding author at: Department of Psychosomatic Medicine and Psychotherapy, Untere Zahlbacher Str. 8, 55131 Mainz, Germany. Tel.: +49 6131 17 3567; fax: +49 6131 17 6439. E-mail address: [email protected] (M. Michal). 0165-1781/$ – see front matter © 2010 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.psychres.2010.11.004
depression (Simeon, 2004; Sierra, 2009). This neglect of DP however, may also have an impact on the treatment and outcome of depression and anxiety disorders. Several studies found that DP co-occurring with depression and anxiety is an index of disease severity, chronicity and poor treatment response (Katerndahl, 2000; Mula et al., 2007). Recently, we have shown in a large community sample that depersonalization severity was independently associated with suicidal ideation beyond depression and anxiety (Michal et al., 2010b). In order to overcome the lack of awareness for DP, questionnaires or structured interviews are extremely helpful (Edwards and Angus, 1972). For clinical and neurobiological research purposes, Sierra and Berrios (2000) developed the Cambridge Depersonalization Scale (CDS), measuring the complex phenomenology of depersonalization and derealization experiences comprehensively with 29 items (Sierra and Berrios, 2000). This scale is currently the most detailed and valid measure describing and quantifying depersonalization and derealization, but the CDS seems too costly for routine screening purposes. Therefore an ultra-brief two-item scale for DP was developed from the CDS, i.e., the two-item version of the Cambridge Depersonalization Scale (CDS-2, Michal et al., 2010c). The scoring format of the CDS-2 was adopted from the most common ultra-brief screeners for depression and anxiety (PHQ-2, Löwe et al., 2005; and GAD-2, Löwe et al., 2009) in order to establish an easy and brief screening for DP.
M. Michal et al. / Psychiatry Research 188 (2011) 264–268
Against this background the present study analyzes data from a large community sample of n = 5000 participants to examine the following research questions: 1) What is the current prevalence rate of DP in a large community sample according to the CDS-2 and how is DP related to depression and anxiety symptoms according to ultra-brief screeners and the respective medical histories? 2) Can DP be differentiated from anxiety and depression, and does DP have an independent effect on the subjective physical and mental health status in the community? Answers to these questions will help to determine whether DP contributes to the health status beyond anxiety and depression, and thus might ascertain the potential value of implementing the CDS-2 in routine screening procedures. 2. Methods 2.1. Study sample The sample comprises cross-sectional data of the first n = 5000 participants enrolled in the Gutenberg Heart Study (GHS) from April 2007 to October 2008. The GHS is a community-based, prospective, observational single-center cohort study focusing cardiovascular disease in the Rhein-Main-Region in western Mid-Germany (Michal et al., 2010b). The GHS has been approved by the local ethics committee and by the local and federal data safety commissioners. The sample was drawn randomly from the local registry in the city of Mainz and the district of Mainz-Bingen. The sample was stratified 1:1 for gender and residence, and in equal strata for decades of age. Inclusion criteria were age 35 to 74 years and written informed consent. Persons with insufficient knowledge of the German language, or a physical or mental inability to participate were excluded. The characteristics of the sample are displayed in Table 1. The response rate, defined as the number of persons with participation in or appointment for the baseline examination divided by the sum of number of persons with participation in or appointment for the baseline examination plus those with refusal and those who were not contactable, was 60.3%. Due to the ongoing recruitment of the GHS, which is conducted in waves, a concluding statement concerning the response rate cannot be made yet. 2.2. Assessment The 5-hour baseline-examination in the study center comprised evaluation of prevalent cardiovascular risk factors and clinical variables, laboratory examinations, a computer-assisted personal interview, and self rating questionnaires. Depersonalization was assessed with the CDS-2, the two- item version of the CDS. The CDS-2 comprises two items of the CDS that best discriminate between patients with clinically significant DP and patients without clinically significant DP (i.e. item 13 of the CDS “My surroundings feel detached or unreal, as if there was a veil between me and the outside world” and item 1 “Out of the blue, I feel strange, as if I were not real or as if I were cut off from the world”). The response format of the CDS2 was adopted from the Patient Health Questionnaire (“Over the last 2 weeks, how often have you been bothered by any of the following problems?/Not at all = 0/
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Several days = 1/More than half the days = 2/Nearly every day = 3” (Löwe et al., 2005; Michal et al., 2010c). The CDS-2 was originally tested in a sample of 38 patients with clinically significant DP-DR and 49 patients without or with only mild DP-DR. Scores were compared against clinical diagnoses based on the Depersonalization Severity Scale as the gold standard (DSS, Simeon et al., 2001; Michal et al., 2010c). The CDS-2 showed high reliability (Cronbach's Alpha = 0.92) and was able to differentiate patients with clinically significant DP well from other groups (cut-off of CDS-2 ≥ 3, sensitivity = 78.9%, specificity = 85.7%). The CDS-2 sum score (range 0–6) correlated strongly (r = 0.77) with depersonalization severity according to the DSS (Michal et al., 2010c). Anxiety was measured by using the two-item version of the GAD-7 (Löwe et al., 2010). A cut-off score of 3 or more detects current generalized anxiety disorder with a sensitivity of 86% and a specificity of 83%, and any current anxiety disorder (GAD, panic disorder, social phobia, post-traumatic stress disorder) with a sensitivity of 65% and specificity of 88% (Skapinakis, 2007). Depression was measured with the two-item Patient Health Questionnaire (PHQ2). A cut-off score of 3 or more yielded a sensitivity of 79% and a specificity of 86% for any depressive disorder (Löwe et al., 2005). Mental and somatic subjective health status was assessed by the questions “How would you describe your current mental health status?” and “How would you describe your current somatic health status?” (“very good = 1”, “good = 2”, “less good = 3”, “bad = 4”). A binary variable impaired physical resp. mental health status was denoted by recoding either “less good” or “bad” as impaired physical resp. mental health status and either “very good” or “good” as not impaired health status. A medical history (MH) of any depression and any anxiety disorder was assessed by two questions during the computer-assisted personal interview (“Have you ever received the definite diagnosis of any depressive disorder/any anxiety disorder by a physician?”). The socioeconomic status (SES) was defined according to Lampert's and Kroll's Scores (Lampert and Kroll, 2009) of SES with a range from 3 to 27 while 3 indicates the lowest SES and 27 the highest SES. 2.3. Statistical analysis The unweighted data were analyzed descriptively. The CDS-2 items were examined via Spearman correlations. Cronbach's Alpha was used to assess the CDS-2 reliability. Odds ratios, obtained from logistic regression analyses, were used to estimate the associations of impaired health status, medical histories of any depressive or anxiety disorder with PHQ-2, GAD-2 and CDS-2. A principal component analysis with varimax rotation was performed on the pooled items of the CDS-2, PHQ-2 and GAD-2 to evaluate the distinctiveness of the scales. To examine the difference in location parameter of the CDS-2 score, in groups with different symptoms of depersonalization, the Wilcoxon test was used. P-values are presented for descriptive purposes. All analyses were performed with the statistical software package SAS (Version 9.2, SAS Institute Inc., Cary, NC, USA).
3. Results 3.1. Characteristics of the sample stratified by CDS-2 ≥ 3 A percentage of 0.8% (0.6–1.1) of the participants scored in the range of clinically significant DP (CDS-2 ≥ 3, DP group). Subjects with clinically significant DP were less likely to live in a current
Table 1 Characteristics of the sample stratified by clinically significant depersonalization (CDS-2 ≥ 3). Total sample (N = 5000)
Age, years, mean ± SD Gender, female, % (N) Partnership, yes, % (N) Education Less than 10th grade, % (N) Completed 10th grade, % (N) Completed high school, % (N) Professional education College or university degree, % (N) SES (3–21), mean ± SD Anxiety, GAD-2 ≥ 3, % (N) Depression, PHQ-2 ≥ 3, % (N) MH of any depressive disorder, % (N) MH of any anxiety disorder, % (N) Physical health status (1–4), mean ± SD Mental health status (1–4), mean ± SD p b 0.05 in bold emphasis.
Comparison by CDS-2 ≥ 3
Crude OR (95% CI)
p
CDS-2 b 3 (N = 4859)
CDS-2 ≥ 3 (N = 41)
55.5 ± 10.9 49.2 (2460) 82.3 (4111)
55.4 ± 10.9 49.1 (2387) 82.6 (4010)
53.3 ± 10.0 48.8 (20) 65.9 (27)
0.98 (0.95–1.01) 0.99 (0.53–1.82) 0.41 (0.21–0.78)
0.21 0.96 0.0067
43.5 (2102) 22.3 (1077) 34.2 (1652)
43.0 (2021) 22.5 (1057) 34.6 (1626)
40.0 (16) 17.5 (7) 42.5 (17)
1.15 (0.81–1.64)
0.43
24.5 (1192) 12.7 ± 4.4 6.1 (299) 5.7 (282) 11.3 (562) 6.5 (325) 2.1 ± 0.7 2.0 ± 0.7
24.8 (1175) 12.8 ± 4.4 5.6 (269) 5.2 (251) 10.9 (527) 6.3 (304) 2.1 ± 0.7 2.0 ± 0.6
32.5 (13) 12.8 ± 4.9 63.4 (26) 70.7 (29) 53.7 (22) 26.8 (11) 2.8 ± 0.9 3.1 ± 0.7
1.29 (1.03–1.61) 1.00 (0.93–1.07) 30.80 (15.86–59.81) 44.26 (22.32–87.77) 9.50 (5.11–17.67) 5.48 (2.72–11.04) 3.93 (2.68–5.76) 7.15 (4.81–10.64)
0.025 0.97 b 0.0001 b 0.0001 b 0.0001 b 0.0001 b 0.0001 b 0.0001
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Table 2 Base rates for the two items of the CDS-2. Item score (Over the last 2 weeks, how often have you been bothered by any of the following problems?)
CDS-2 item 1: “Surroundings feel detached or unreal …”
CDS-2 item 2: “I feel strange …”
0 = not at all 1 = several days 2 = more than half the days 3 = nearly every day ≥1
92.5% 6.7% 0.5% 0.3% 7.5%
94.3% 5.2% 0.3% 0.2% 5.7%
(3.5–4.6), n = 200), CDS-2 = 2 (3.7% (3.3–4.4), n = 183), CDS-2 = 3 (0.5% (0.3–0.7), n = 23), CDS-2 = 4 (0.16% (0.05–0.28), n = 8), CDS2 = 5 (0.041% (0.02–0.10, n = 2) and CDS-2 = 6 (0.16% (0.05–0.28), n = 8). At least one item of the CDS-2 was endorsed by 8.7% (7.9–9.4), n = 424) of the participants. 3.3. Association of depersonalization with depression, anxiety, and subjective mental and physical health status
Fig. 1. Overlap of CDS-2 scores with caseness of anxiety (GAD-2 ≥ 3), depression (PHQ2 ≥ 3), impaired physical and mental health status, MH of any depressive disorder and MH of any anxiety disorder. Scores above or equal to 2 were pooled to CDS-2 ≥ 2 and CDS-2 ≥ 3, because CDS-2 scores above 3 were rare.
partnership, were more affected by depression and anxiety, and endorsed a poorer physical and mental health status. With respect to sociodemographic characteristics, no differences regarding age, sex, education or SES emerged (Table 1).
Fig. 1 shows that caseness according to GAD-2 ≥3, PHQ-2≥3, physical impairment, mental impairment, MH of depression, and MH of anxiety increased with depersonalization severity according to the CDS-2. Only n=7 from n=41 individuals with clinically significant DP did not meet caseness of anxiety or depression. These seven (median CDS-2 score=4, interquartile range 3–6) do not differ significantly in DP severity from individuals with clinically significant DP and co-occurring anxiety or depression (median CDS-2 score=3, interquartile range 3–4) in the Wilcoxon Test (p =0.26). DP severity correlates significantly but moderately with depression (PHQ-2, r=0.32, p b 0.0001) and anxiety severity (GAD-2, r=0.32, pb 0.0001). The correlation between depression and anxiety was somewhat stronger (r=0.53, pb 0.0001). With regard to a medical history (MH) of any depressive disorder or a MH of any anxiety disorder, DP severity was independently associated with the respective histories beyond depression and anxiety severity as shown in Table 3. Further, DP severity also remained an independent predictor for impairment of physical (with a trend) and mental health status as shown in Table 3. 3.4. Overlap and distinctiveness of DP with depression and anxiety
3.2. Distribution of the items and scores of the CDS-2 in the sample Item 1 of the CDS-2 was endorsed at least with “several days” by 7.5% (6.7–8.2) and item 2 by 5.7% (5.1–6.4) of the participants (see Table 2). Both items correlated strongly with r = 0.67 (p b 0.001). Cronbach's Alpha of the CDS-2 in this sample was 0.83, whereas Cronbach's Alpha of the PHQ-2 was only 0.62, and Cronbach's Alpha of the GAD-2 was 0.70. The CDS-2 sum scores were distributed as follows: CDS-2 = 0 (91.3% (90.6–92.1), n = 4476), CDS-2 = 1 (4.1%
In order to determine the overlap of DP with depression and anxiety, a principal component analysis (PCA) with varimax rotation and Kaiser normalization was performed on the pooled items of the CDS-2, the PHQ-2 and the GAD-2. Factors were retained in the model based on inspection of the screeplot and eigenvalues N1. Two factors were identified, explaining 68% of the variance. PHQ-2 and GAD-2 loaded together on factor 1 (“distress”) and the CDS-2 items on factor 2 (“DP”) (see Table 4).
Table 3 Associations of impaired health status and medical histories of any depressive or anxiety disorder with severity of depression, anxiety and depersonalization.
PHQ-2 (0–6) GAD-2 (0–6) CDS-2 (0–6) Mental health status (1–4) Physical health status (1–4)
Impaired physical health (N = 1006)
Impaired mental health (N = 856)
MH of depression (N = 562)
MH of anxiety (N = 325)
Adj. OR (95% CI)
p
Adj. OR (95% CI)
p
Adj. OR (95% CI)
p
Adj. OR (95% CI)
p
1.25 (1.14–1.37) 1.11 (1.02–1.21) 1.13 (0.99–1.28) 2.60 (2.25–3.00) /
b 0.0001 0.015 0.068 b 0.0001
2.11 1.95 1.33 / 2.35
(1.90–2.34) (1.77–2.15) (1.14–1.56)
b0.0001 b0.0001 0.0002
b 0.0001 b 0.0001 b 0.0001
b0.0001
1.32 (1.17–1.49) 1.49 (1.34–1.67) 1.17 (1.00–1.37) / /
b 0.0001 b 0.0001 0.047
(2.03–2.73)
1.54 (1.39–1.70) 1.36 (1.24–1.49) 1.50 (1.31–1.72) / /
p b 0.05 in bold emphasis. Binary logistic regression analysis adjusted for age, sex and socioeconomic status. Impaired physical health (yes = 1): “less good” or “bad”physical health status versus either “very good” or “good”. Impaired mental health (yes = 1): “less good” or “bad”mental health status versus either “very good” or “good”. MH of depression (yes = 1): Positive answer to the question “Have you ever received the definite diagnosis of any depressive disorder?” MH of anxiety (yes = 1): Positive answer to the question “Have you ever received the definite diagnosis of any anxiety disorder?”
M. Michal et al. / Psychiatry Research 188 (2011) 264–268 Table 4 Principal component analysis with varimax rotation of the items of the CDS-2, PHQ-2 and GAD-2. Scale and items
F1 “Distress”
F2 “DP”
PHQ-2: Feeling down, depressed, or hopeless PHQ-2: Little interest or pleasure in doing things GAD-2: Feeling nervous, anxious, or on edge GAD-2: Not being able to stop or control worrying CDS-2: Surroundings feel detached or unreal CDS-2: I feel strange, as if I were not real Eigenvalue Explained variance
0.70 0.76 0.78 0.76 0.22 0.18 2.9 49%
0.10 0.24 0.14 0.21 0.90 0.91 1.1 19%
Bold print: factor loadings N 0.40.
4. Discussion With respect to the prevalence of DP the current study demonstrates further evidence that DP is common in the general population of Germany. However, compared to previous studies the prevalence rate of 0.8% for clinically significant DP was only in the lower range of previous studies (Hunter et al., 2004). For example, in another recent survey we found a prevalence of 3.4% in the general population for clinically significant DP by using the CD2-2 (Michal et al., 2011), and with another abridged version of the CDS a prevalence rate of 1.9% was reported for the general population in Germany (Michal et al., 2009). The exclusion of individuals below age 35 years might account for this low prevalence rate, because the age of onset of depersonalization disorder usually occurs in the period of adolescence or young adulthood (Baker et al., 2003; Simeon, 2004; Sierra, 2009) and, according to some surveys, symptoms of DP seem to be more prevalent in younger ages (Aderibigbe et al., 2001). Another reason for the low prevalence of clinically significant DP in the Gutenberg Heart Study could be that the study is primarily designed to identify cardiovascular risk factors and might therefore appeal especially to people with cardiovascular concerns, which might be underrepresented in persons with depersonalization (Michal et al., 2009). With regard to the sociodemographic correlates, the nearly 1:1 gender ratio of DP was confirmed again (Simeon, 2004). Concerning educational attainment, persons with clinically significant DP had a significantly higher proportion of college or university degrees than persons without clinically significant DP. This finding is in line with reports from a clinical sample of n = 204 patients with depersonalization disorder, where 54% had some form of higher education (Baker et al., 2003). The rates of depression and anxiety according to the ultra-brief screeners corresponded to those found in studies with interviewbased methods (Wittchen et al., 1999). Our survey confirmed that a very high percentage of persons with clinically significant DP also suffer from depression and anxiety (Baker et al., 2003; Simeon et al., 2003; Michal et al., 2005). But given the moderate correlations of CDS2 with depression and anxiety, the results of this study argue against the reduction of DP to a negligible variant of anxiety and depression. The shared variances of DP with anxiety or depression were only around 10%, whereas the shared variance of depression/anxiety was nearly thrice as high (28%, according to the Spearman's correlation coefficients). Whereas the principal component analysis could not replicate the separateness of the PHQ-2 and GAD-2 in this community sample (Kroenke et al., 2009), it substantiated clearly the distinctiveness of depersonalization from anxiety and depression. This corroborates the results of a principal component analysis of the pooled items of the CDS-2 and the Hospital Anxiety and Depression Scale (Zigmond and Snaith, 1983; Herrmann et al., 1991) in a sample of the general population (Michal et al., 2011). The clear distinctiveness of the scales stands against the common belief that depersonalization is just an irrelevant variant of depression or anxiety. It is in line with a
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recent study of patients with mood and anxiety disorders, which showed that anhedonia (i.e. diminished capacity to experience pleasant emotions) and affective depersonalization (i.e. inability of the self to imbue perceptions with emotional feelings) are two distinct psychopathological dimensions (Mula et al., 2007). Furthermore, an independent impact of DP on the physical and mental health status beyond anxiety and depression could be shown. Thus, DP severity contributes significantly to the individual health status independently from depression and anxiety. Even with regard to a medical history of any depressive and any anxiety disorder, DP severity was independently associated with prior diagnosis of these disorders. Both results are in line with the interpretation of DP as a marker of disease severity (Mula et al., 2007). Limitations of our study pertain mainly to the lack of clinicianadministered diagnostic interviews. Strengths are the size and representativeness of the sample. In conclusion, the present findings support assertions that depersonalization is common, that it contributes independently to the mental and also somatic health status beyond anxiety and depression, and that depersonalization can be clearly differentiated from anxiety and depression. Therefore, specific efforts to assess depersonalization should be undertaken. In order to improve diagnostic awareness of depersonalization, the implementation of the CDS-2 into the ultra-brief screening scales for depression and anxiety (Löwe et al., 2010) could be an easy step to improve diagnostic awareness of depersonalization. References Aderibigbe, Y.A., Bloch, R.M., Walker, W.R., 2001. Prevalence of depersonalization and derealization experiences in a rural population. Social Psychiatry and Psychiatric Epidemiology 36, 63–69. Baker, D., Hunter, E., Lawrence, E., Medford, N., Patel, M., Senior, C., Sierra, M., Lambert, M.V., Phillips, M.L., David, A.S., 2003. Depersonalisation disorder: clinical features of 204 cases. The British Journal of Psychiatry 182, 428–433. Edwards, J.G., Angus, J.W., 1972. Depersonalization. The British Journal of Psychiatry 120, 242–244. Herrmann, C., Scholz, K.H., Kreuzer, H., 1991. Psychologic screening of patients of a cardiologic acute care clinic with the German version of the Hospital Anxiety and Depression Scale. Psychotherapie, Psychosomatik, Medizinische Psychologie 41, 83–92. Hunter, E.C., Sierra, M., David, A.S., 2004. The epidemiology of depersonalisation and derealisation. A systematic review. Social Psychiatry and Psychiatry Epidemiology 39, 9–18. Katerndahl, D.A., 2000. Predictors of the development of phobic avoidance. The Journal of Clinical Psychiatry 61, 618–623. Kroenke, K., Spitzer, R.L., Williams, J.B., Lowe, B., 2009. An ultra-brief screening scale for anxiety: validation and depression: the PHQ-4. Psychosomatics 50, 613–621. Lampert, T., Kroll, L.E., 2009. Die Messung des sozioökonomischen Status in sozialepidemiologischen Studien. In: Richter, M., Hurrelmann, K. (Eds.), Gesundheitliche Ungleichheit: VS Verlag für Sozialwissenschaften, pp. 309–334. Löwe, B., Kroenke, K., Gräfe, K., 2005. Detecting and monitoring depression with a twoitem questionnaire (PHQ-2). Journal of Psychosomatic Research 58, 163–171. Löwe, B., Wahl, I., Rose, M., Spitzer, C., Glaesmer, H., Wingenfeld, K., Schneider, A., Brähler, E., 2010. A 4-item measure of depression and anxiety: Validation and standardization of the Patient Health Questionnaire-4 (PHQ-4) in the general population. Journal of Affective Disorders 122, 86–95. Michal, M., Beutel, M.E., 2009. Weiterbildung CME: depersonalization/derealization— clinical picture, diagnostics and therapy. Zeitschrift für Psychosomatische Medizin und Psychotherapie 55, 113–140. Michal, M., Sann, U., Grabhorn, R., Overbeck, G., Röder, C.H., 2005. Zur Prävalenz von Depersonalisation und Derealisation in der stationären Psychotherapie. Psychotherapeut 50, 328–339. Michal, M., Wiltink, J., Subic-Wrana, C., Zwerenz, R., Tuin, I., Lichy, M., Brahler, E., Beutel, M.E., 2009. Prevalence, correlates, and predictors of depersonalization experiences in the German general population. The Journal of Nervous and Mental Disease 197, 499–506. Michal, M., Beutel, M.E., Grobe, T.G., 2010a. How often is the Depersonalization– Derealization Disorder (ICD-10: F48.1) diagnosed in the outpatient health-care service? Zeitschrift für Psychosomatische Medizin und Psychotherapie 56, 74–83. Michal, M., Wiltink, J., Till, Y., Wild, P.S., Münzel, T., Blankenberg, S., Beutel, M.E., 2010b. Type-D personality and depersonalization are associated with suicidal ideation in the German general population aged 35–74: results from the Gutenberg Heart Study. Journal of Affective Disorders 125, 227–233. Michal, M., Zwerenz, R., Tschan, R., Edinger, J., Lichy, M., Knebel, A., Tuin, I., Beutel, M., 2010c. Screening for depersonalization–derealization with two items of the
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Distinctiveness and overlap of depersonalization with anxiety and depression in a community sample: Results from the Gutenberg Heart Study Matthias Michal a,⁎, Jörg Wiltink a, Yvonne Till a,b, Philipp S. Wild b, Maria Blettner c, Manfred E. Beutel a a b c
Department of Psychosomatic Medicine and Psychotherapy, University Medical Center of the Johannes Gutenberg University Mainz, Germany Department of Cardiology, University Medical Center of the Johannes Gutenberg University Mainz, Germany Institute of Medical Biostatistics, Epidemiology, and Informatics, University Medical Center of the Johannes Gutenberg University Mainz, Germany
a r t i c l e
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Article history: Received 6 July 2010 Received in revised form 26 October 2010 Accepted 1 November 2010 Keywords: Depersonalization Depression Anxiety Screening
a b s t r a c t Depersonalization disorder is considered to be a common clinical phenomenon and disorder with an enormous gap between prevalence and detection partly due to the common interpretation of depersonalization (DP) being a negligible variant of anxiety and depression. Therefore, we sought to analyze (1) the prevalence rate of DP in a large community sample (n = 5000) according to a recently developed ultra brief two-item depersonalization screener; (2) the associations with depression, anxiety, physical and mental health status; and 93) whether DP contributes independently to the health status beyond anxiety and depression. The prevalence of clinically significant DP was 0.8% (n = 41), and 8.5% (n = 427) endorsed at least one symptom of DP. DP was independently associated with impairment of mental and physical health status as well as with a medical history of any depressive or anxiety disorder. Despite the consistent association of DP with anxiety and depression, the shared variances were small, and DP was clearly separated from symptoms of anxiety and depression in the principal component analysis. Therefore, we conclude that the implementation of depersonalization screening might be recommended. © 2010 Elsevier Ireland Ltd. All rights reserved.
1. Introduction After anxiety and depression, depersonalization has been considered to be the third most frequent symptom among psychiatric patients (Stewart, 1964). But although depersonalization (DP) is assessed routinely as part of the mental state examination in psychiatric and psychotherapeutic treatment, it is both underdetected and underdiagnosed (Simeon, 2004; Michal and Beutel, 2009; Sierra, 2009; Stein and Simeon, 2009). According to a recent evaluation of health insurance data of 1.5 million persons, the 1-year prevalence of the diagnosis of the depersonalization–derealization syndrome was only 0.007% (Michal et al., 2010a, 2010b, 2010c). This prevalence contrasts sharply with epidemiological studies reporting rates of 0.8–2% for clinically significant DP in the general population (Hunter et al., 2004; Michal et al., 2009). Reluctance of patients to report spontaneously about DP is one factor; another factor is the health care providers' relative lack of awareness, due to the common interpretation of DP as a negligible variant of anxiety and
⁎ Corresponding author at: Department of Psychosomatic Medicine and Psychotherapy, Untere Zahlbacher Str. 8, 55131 Mainz, Germany. Tel.: +49 6131 17 3567; fax: +49 6131 17 6439. E-mail address: [email protected] (M. Michal). 0165-1781/$ – see front matter © 2010 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.psychres.2010.11.004
depression (Simeon, 2004; Sierra, 2009). This neglect of DP however, may also have an impact on the treatment and outcome of depression and anxiety disorders. Several studies found that DP co-occurring with depression and anxiety is an index of disease severity, chronicity and poor treatment response (Katerndahl, 2000; Mula et al., 2007). Recently, we have shown in a large community sample that depersonalization severity was independently associated with suicidal ideation beyond depression and anxiety (Michal et al., 2010b). In order to overcome the lack of awareness for DP, questionnaires or structured interviews are extremely helpful (Edwards and Angus, 1972). For clinical and neurobiological research purposes, Sierra and Berrios (2000) developed the Cambridge Depersonalization Scale (CDS), measuring the complex phenomenology of depersonalization and derealization experiences comprehensively with 29 items (Sierra and Berrios, 2000). This scale is currently the most detailed and valid measure describing and quantifying depersonalization and derealization, but the CDS seems too costly for routine screening purposes. Therefore an ultra-brief two-item scale for DP was developed from the CDS, i.e., the two-item version of the Cambridge Depersonalization Scale (CDS-2, Michal et al., 2010c). The scoring format of the CDS-2 was adopted from the most common ultra-brief screeners for depression and anxiety (PHQ-2, Löwe et al., 2005; and GAD-2, Löwe et al., 2009) in order to establish an easy and brief screening for DP.
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Against this background the present study analyzes data from a large community sample of n = 5000 participants to examine the following research questions: 1) What is the current prevalence rate of DP in a large community sample according to the CDS-2 and how is DP related to depression and anxiety symptoms according to ultra-brief screeners and the respective medical histories? 2) Can DP be differentiated from anxiety and depression, and does DP have an independent effect on the subjective physical and mental health status in the community? Answers to these questions will help to determine whether DP contributes to the health status beyond anxiety and depression, and thus might ascertain the potential value of implementing the CDS-2 in routine screening procedures. 2. Methods 2.1. Study sample The sample comprises cross-sectional data of the first n = 5000 participants enrolled in the Gutenberg Heart Study (GHS) from April 2007 to October 2008. The GHS is a community-based, prospective, observational single-center cohort study focusing cardiovascular disease in the Rhein-Main-Region in western Mid-Germany (Michal et al., 2010b). The GHS has been approved by the local ethics committee and by the local and federal data safety commissioners. The sample was drawn randomly from the local registry in the city of Mainz and the district of Mainz-Bingen. The sample was stratified 1:1 for gender and residence, and in equal strata for decades of age. Inclusion criteria were age 35 to 74 years and written informed consent. Persons with insufficient knowledge of the German language, or a physical or mental inability to participate were excluded. The characteristics of the sample are displayed in Table 1. The response rate, defined as the number of persons with participation in or appointment for the baseline examination divided by the sum of number of persons with participation in or appointment for the baseline examination plus those with refusal and those who were not contactable, was 60.3%. Due to the ongoing recruitment of the GHS, which is conducted in waves, a concluding statement concerning the response rate cannot be made yet. 2.2. Assessment The 5-hour baseline-examination in the study center comprised evaluation of prevalent cardiovascular risk factors and clinical variables, laboratory examinations, a computer-assisted personal interview, and self rating questionnaires. Depersonalization was assessed with the CDS-2, the two- item version of the CDS. The CDS-2 comprises two items of the CDS that best discriminate between patients with clinically significant DP and patients without clinically significant DP (i.e. item 13 of the CDS “My surroundings feel detached or unreal, as if there was a veil between me and the outside world” and item 1 “Out of the blue, I feel strange, as if I were not real or as if I were cut off from the world”). The response format of the CDS2 was adopted from the Patient Health Questionnaire (“Over the last 2 weeks, how often have you been bothered by any of the following problems?/Not at all = 0/
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Several days = 1/More than half the days = 2/Nearly every day = 3” (Löwe et al., 2005; Michal et al., 2010c). The CDS-2 was originally tested in a sample of 38 patients with clinically significant DP-DR and 49 patients without or with only mild DP-DR. Scores were compared against clinical diagnoses based on the Depersonalization Severity Scale as the gold standard (DSS, Simeon et al., 2001; Michal et al., 2010c). The CDS-2 showed high reliability (Cronbach's Alpha = 0.92) and was able to differentiate patients with clinically significant DP well from other groups (cut-off of CDS-2 ≥ 3, sensitivity = 78.9%, specificity = 85.7%). The CDS-2 sum score (range 0–6) correlated strongly (r = 0.77) with depersonalization severity according to the DSS (Michal et al., 2010c). Anxiety was measured by using the two-item version of the GAD-7 (Löwe et al., 2010). A cut-off score of 3 or more detects current generalized anxiety disorder with a sensitivity of 86% and a specificity of 83%, and any current anxiety disorder (GAD, panic disorder, social phobia, post-traumatic stress disorder) with a sensitivity of 65% and specificity of 88% (Skapinakis, 2007). Depression was measured with the two-item Patient Health Questionnaire (PHQ2). A cut-off score of 3 or more yielded a sensitivity of 79% and a specificity of 86% for any depressive disorder (Löwe et al., 2005). Mental and somatic subjective health status was assessed by the questions “How would you describe your current mental health status?” and “How would you describe your current somatic health status?” (“very good = 1”, “good = 2”, “less good = 3”, “bad = 4”). A binary variable impaired physical resp. mental health status was denoted by recoding either “less good” or “bad” as impaired physical resp. mental health status and either “very good” or “good” as not impaired health status. A medical history (MH) of any depression and any anxiety disorder was assessed by two questions during the computer-assisted personal interview (“Have you ever received the definite diagnosis of any depressive disorder/any anxiety disorder by a physician?”). The socioeconomic status (SES) was defined according to Lampert's and Kroll's Scores (Lampert and Kroll, 2009) of SES with a range from 3 to 27 while 3 indicates the lowest SES and 27 the highest SES. 2.3. Statistical analysis The unweighted data were analyzed descriptively. The CDS-2 items were examined via Spearman correlations. Cronbach's Alpha was used to assess the CDS-2 reliability. Odds ratios, obtained from logistic regression analyses, were used to estimate the associations of impaired health status, medical histories of any depressive or anxiety disorder with PHQ-2, GAD-2 and CDS-2. A principal component analysis with varimax rotation was performed on the pooled items of the CDS-2, PHQ-2 and GAD-2 to evaluate the distinctiveness of the scales. To examine the difference in location parameter of the CDS-2 score, in groups with different symptoms of depersonalization, the Wilcoxon test was used. P-values are presented for descriptive purposes. All analyses were performed with the statistical software package SAS (Version 9.2, SAS Institute Inc., Cary, NC, USA).
3. Results 3.1. Characteristics of the sample stratified by CDS-2 ≥ 3 A percentage of 0.8% (0.6–1.1) of the participants scored in the range of clinically significant DP (CDS-2 ≥ 3, DP group). Subjects with clinically significant DP were less likely to live in a current
Table 1 Characteristics of the sample stratified by clinically significant depersonalization (CDS-2 ≥ 3). Total sample (N = 5000)
Age, years, mean ± SD Gender, female, % (N) Partnership, yes, % (N) Education Less than 10th grade, % (N) Completed 10th grade, % (N) Completed high school, % (N) Professional education College or university degree, % (N) SES (3–21), mean ± SD Anxiety, GAD-2 ≥ 3, % (N) Depression, PHQ-2 ≥ 3, % (N) MH of any depressive disorder, % (N) MH of any anxiety disorder, % (N) Physical health status (1–4), mean ± SD Mental health status (1–4), mean ± SD p b 0.05 in bold emphasis.
Comparison by CDS-2 ≥ 3
Crude OR (95% CI)
p
CDS-2 b 3 (N = 4859)
CDS-2 ≥ 3 (N = 41)
55.5 ± 10.9 49.2 (2460) 82.3 (4111)
55.4 ± 10.9 49.1 (2387) 82.6 (4010)
53.3 ± 10.0 48.8 (20) 65.9 (27)
0.98 (0.95–1.01) 0.99 (0.53–1.82) 0.41 (0.21–0.78)
0.21 0.96 0.0067
43.5 (2102) 22.3 (1077) 34.2 (1652)
43.0 (2021) 22.5 (1057) 34.6 (1626)
40.0 (16) 17.5 (7) 42.5 (17)
1.15 (0.81–1.64)
0.43
24.5 (1192) 12.7 ± 4.4 6.1 (299) 5.7 (282) 11.3 (562) 6.5 (325) 2.1 ± 0.7 2.0 ± 0.7
24.8 (1175) 12.8 ± 4.4 5.6 (269) 5.2 (251) 10.9 (527) 6.3 (304) 2.1 ± 0.7 2.0 ± 0.6
32.5 (13) 12.8 ± 4.9 63.4 (26) 70.7 (29) 53.7 (22) 26.8 (11) 2.8 ± 0.9 3.1 ± 0.7
1.29 (1.03–1.61) 1.00 (0.93–1.07) 30.80 (15.86–59.81) 44.26 (22.32–87.77) 9.50 (5.11–17.67) 5.48 (2.72–11.04) 3.93 (2.68–5.76) 7.15 (4.81–10.64)
0.025 0.97 b 0.0001 b 0.0001 b 0.0001 b 0.0001 b 0.0001 b 0.0001
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Table 2 Base rates for the two items of the CDS-2. Item score (Over the last 2 weeks, how often have you been bothered by any of the following problems?)
CDS-2 item 1: “Surroundings feel detached or unreal …”
CDS-2 item 2: “I feel strange …”
0 = not at all 1 = several days 2 = more than half the days 3 = nearly every day ≥1
92.5% 6.7% 0.5% 0.3% 7.5%
94.3% 5.2% 0.3% 0.2% 5.7%
(3.5–4.6), n = 200), CDS-2 = 2 (3.7% (3.3–4.4), n = 183), CDS-2 = 3 (0.5% (0.3–0.7), n = 23), CDS-2 = 4 (0.16% (0.05–0.28), n = 8), CDS2 = 5 (0.041% (0.02–0.10, n = 2) and CDS-2 = 6 (0.16% (0.05–0.28), n = 8). At least one item of the CDS-2 was endorsed by 8.7% (7.9–9.4), n = 424) of the participants. 3.3. Association of depersonalization with depression, anxiety, and subjective mental and physical health status
Fig. 1. Overlap of CDS-2 scores with caseness of anxiety (GAD-2 ≥ 3), depression (PHQ2 ≥ 3), impaired physical and mental health status, MH of any depressive disorder and MH of any anxiety disorder. Scores above or equal to 2 were pooled to CDS-2 ≥ 2 and CDS-2 ≥ 3, because CDS-2 scores above 3 were rare.
partnership, were more affected by depression and anxiety, and endorsed a poorer physical and mental health status. With respect to sociodemographic characteristics, no differences regarding age, sex, education or SES emerged (Table 1).
Fig. 1 shows that caseness according to GAD-2 ≥3, PHQ-2≥3, physical impairment, mental impairment, MH of depression, and MH of anxiety increased with depersonalization severity according to the CDS-2. Only n=7 from n=41 individuals with clinically significant DP did not meet caseness of anxiety or depression. These seven (median CDS-2 score=4, interquartile range 3–6) do not differ significantly in DP severity from individuals with clinically significant DP and co-occurring anxiety or depression (median CDS-2 score=3, interquartile range 3–4) in the Wilcoxon Test (p =0.26). DP severity correlates significantly but moderately with depression (PHQ-2, r=0.32, p b 0.0001) and anxiety severity (GAD-2, r=0.32, pb 0.0001). The correlation between depression and anxiety was somewhat stronger (r=0.53, pb 0.0001). With regard to a medical history (MH) of any depressive disorder or a MH of any anxiety disorder, DP severity was independently associated with the respective histories beyond depression and anxiety severity as shown in Table 3. Further, DP severity also remained an independent predictor for impairment of physical (with a trend) and mental health status as shown in Table 3. 3.4. Overlap and distinctiveness of DP with depression and anxiety
3.2. Distribution of the items and scores of the CDS-2 in the sample Item 1 of the CDS-2 was endorsed at least with “several days” by 7.5% (6.7–8.2) and item 2 by 5.7% (5.1–6.4) of the participants (see Table 2). Both items correlated strongly with r = 0.67 (p b 0.001). Cronbach's Alpha of the CDS-2 in this sample was 0.83, whereas Cronbach's Alpha of the PHQ-2 was only 0.62, and Cronbach's Alpha of the GAD-2 was 0.70. The CDS-2 sum scores were distributed as follows: CDS-2 = 0 (91.3% (90.6–92.1), n = 4476), CDS-2 = 1 (4.1%
In order to determine the overlap of DP with depression and anxiety, a principal component analysis (PCA) with varimax rotation and Kaiser normalization was performed on the pooled items of the CDS-2, the PHQ-2 and the GAD-2. Factors were retained in the model based on inspection of the screeplot and eigenvalues N1. Two factors were identified, explaining 68% of the variance. PHQ-2 and GAD-2 loaded together on factor 1 (“distress”) and the CDS-2 items on factor 2 (“DP”) (see Table 4).
Table 3 Associations of impaired health status and medical histories of any depressive or anxiety disorder with severity of depression, anxiety and depersonalization.
PHQ-2 (0–6) GAD-2 (0–6) CDS-2 (0–6) Mental health status (1–4) Physical health status (1–4)
Impaired physical health (N = 1006)
Impaired mental health (N = 856)
MH of depression (N = 562)
MH of anxiety (N = 325)
Adj. OR (95% CI)
p
Adj. OR (95% CI)
p
Adj. OR (95% CI)
p
Adj. OR (95% CI)
p
1.25 (1.14–1.37) 1.11 (1.02–1.21) 1.13 (0.99–1.28) 2.60 (2.25–3.00) /
b 0.0001 0.015 0.068 b 0.0001
2.11 1.95 1.33 / 2.35
(1.90–2.34) (1.77–2.15) (1.14–1.56)
b0.0001 b0.0001 0.0002
b 0.0001 b 0.0001 b 0.0001
b0.0001
1.32 (1.17–1.49) 1.49 (1.34–1.67) 1.17 (1.00–1.37) / /
b 0.0001 b 0.0001 0.047
(2.03–2.73)
1.54 (1.39–1.70) 1.36 (1.24–1.49) 1.50 (1.31–1.72) / /
p b 0.05 in bold emphasis. Binary logistic regression analysis adjusted for age, sex and socioeconomic status. Impaired physical health (yes = 1): “less good” or “bad”physical health status versus either “very good” or “good”. Impaired mental health (yes = 1): “less good” or “bad”mental health status versus either “very good” or “good”. MH of depression (yes = 1): Positive answer to the question “Have you ever received the definite diagnosis of any depressive disorder?” MH of anxiety (yes = 1): Positive answer to the question “Have you ever received the definite diagnosis of any anxiety disorder?”
M. Michal et al. / Psychiatry Research 188 (2011) 264–268 Table 4 Principal component analysis with varimax rotation of the items of the CDS-2, PHQ-2 and GAD-2. Scale and items
F1 “Distress”
F2 “DP”
PHQ-2: Feeling down, depressed, or hopeless PHQ-2: Little interest or pleasure in doing things GAD-2: Feeling nervous, anxious, or on edge GAD-2: Not being able to stop or control worrying CDS-2: Surroundings feel detached or unreal CDS-2: I feel strange, as if I were not real Eigenvalue Explained variance
0.70 0.76 0.78 0.76 0.22 0.18 2.9 49%
0.10 0.24 0.14 0.21 0.90 0.91 1.1 19%
Bold print: factor loadings N 0.40.
4. Discussion With respect to the prevalence of DP the current study demonstrates further evidence that DP is common in the general population of Germany. However, compared to previous studies the prevalence rate of 0.8% for clinically significant DP was only in the lower range of previous studies (Hunter et al., 2004). For example, in another recent survey we found a prevalence of 3.4% in the general population for clinically significant DP by using the CD2-2 (Michal et al., 2011), and with another abridged version of the CDS a prevalence rate of 1.9% was reported for the general population in Germany (Michal et al., 2009). The exclusion of individuals below age 35 years might account for this low prevalence rate, because the age of onset of depersonalization disorder usually occurs in the period of adolescence or young adulthood (Baker et al., 2003; Simeon, 2004; Sierra, 2009) and, according to some surveys, symptoms of DP seem to be more prevalent in younger ages (Aderibigbe et al., 2001). Another reason for the low prevalence of clinically significant DP in the Gutenberg Heart Study could be that the study is primarily designed to identify cardiovascular risk factors and might therefore appeal especially to people with cardiovascular concerns, which might be underrepresented in persons with depersonalization (Michal et al., 2009). With regard to the sociodemographic correlates, the nearly 1:1 gender ratio of DP was confirmed again (Simeon, 2004). Concerning educational attainment, persons with clinically significant DP had a significantly higher proportion of college or university degrees than persons without clinically significant DP. This finding is in line with reports from a clinical sample of n = 204 patients with depersonalization disorder, where 54% had some form of higher education (Baker et al., 2003). The rates of depression and anxiety according to the ultra-brief screeners corresponded to those found in studies with interviewbased methods (Wittchen et al., 1999). Our survey confirmed that a very high percentage of persons with clinically significant DP also suffer from depression and anxiety (Baker et al., 2003; Simeon et al., 2003; Michal et al., 2005). But given the moderate correlations of CDS2 with depression and anxiety, the results of this study argue against the reduction of DP to a negligible variant of anxiety and depression. The shared variances of DP with anxiety or depression were only around 10%, whereas the shared variance of depression/anxiety was nearly thrice as high (28%, according to the Spearman's correlation coefficients). Whereas the principal component analysis could not replicate the separateness of the PHQ-2 and GAD-2 in this community sample (Kroenke et al., 2009), it substantiated clearly the distinctiveness of depersonalization from anxiety and depression. This corroborates the results of a principal component analysis of the pooled items of the CDS-2 and the Hospital Anxiety and Depression Scale (Zigmond and Snaith, 1983; Herrmann et al., 1991) in a sample of the general population (Michal et al., 2011). The clear distinctiveness of the scales stands against the common belief that depersonalization is just an irrelevant variant of depression or anxiety. It is in line with a
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recent study of patients with mood and anxiety disorders, which showed that anhedonia (i.e. diminished capacity to experience pleasant emotions) and affective depersonalization (i.e. inability of the self to imbue perceptions with emotional feelings) are two distinct psychopathological dimensions (Mula et al., 2007). Furthermore, an independent impact of DP on the physical and mental health status beyond anxiety and depression could be shown. Thus, DP severity contributes significantly to the individual health status independently from depression and anxiety. Even with regard to a medical history of any depressive and any anxiety disorder, DP severity was independently associated with prior diagnosis of these disorders. Both results are in line with the interpretation of DP as a marker of disease severity (Mula et al., 2007). Limitations of our study pertain mainly to the lack of clinicianadministered diagnostic interviews. Strengths are the size and representativeness of the sample. In conclusion, the present findings support assertions that depersonalization is common, that it contributes independently to the mental and also somatic health status beyond anxiety and depression, and that depersonalization can be clearly differentiated from anxiety and depression. Therefore, specific efforts to assess depersonalization should be undertaken. In order to improve diagnostic awareness of depersonalization, the implementation of the CDS-2 into the ultra-brief screening scales for depression and anxiety (Löwe et al., 2010) could be an easy step to improve diagnostic awareness of depersonalization. References Aderibigbe, Y.A., Bloch, R.M., Walker, W.R., 2001. Prevalence of depersonalization and derealization experiences in a rural population. Social Psychiatry and Psychiatric Epidemiology 36, 63–69. Baker, D., Hunter, E., Lawrence, E., Medford, N., Patel, M., Senior, C., Sierra, M., Lambert, M.V., Phillips, M.L., David, A.S., 2003. Depersonalisation disorder: clinical features of 204 cases. The British Journal of Psychiatry 182, 428–433. Edwards, J.G., Angus, J.W., 1972. Depersonalization. The British Journal of Psychiatry 120, 242–244. Herrmann, C., Scholz, K.H., Kreuzer, H., 1991. Psychologic screening of patients of a cardiologic acute care clinic with the German version of the Hospital Anxiety and Depression Scale. Psychotherapie, Psychosomatik, Medizinische Psychologie 41, 83–92. Hunter, E.C., Sierra, M., David, A.S., 2004. The epidemiology of depersonalisation and derealisation. A systematic review. Social Psychiatry and Psychiatry Epidemiology 39, 9–18. Katerndahl, D.A., 2000. Predictors of the development of phobic avoidance. The Journal of Clinical Psychiatry 61, 618–623. Kroenke, K., Spitzer, R.L., Williams, J.B., Lowe, B., 2009. An ultra-brief screening scale for anxiety: validation and depression: the PHQ-4. Psychosomatics 50, 613–621. Lampert, T., Kroll, L.E., 2009. Die Messung des sozioökonomischen Status in sozialepidemiologischen Studien. In: Richter, M., Hurrelmann, K. (Eds.), Gesundheitliche Ungleichheit: VS Verlag für Sozialwissenschaften, pp. 309–334. Löwe, B., Kroenke, K., Gräfe, K., 2005. Detecting and monitoring depression with a twoitem questionnaire (PHQ-2). Journal of Psychosomatic Research 58, 163–171. Löwe, B., Wahl, I., Rose, M., Spitzer, C., Glaesmer, H., Wingenfeld, K., Schneider, A., Brähler, E., 2010. A 4-item measure of depression and anxiety: Validation and standardization of the Patient Health Questionnaire-4 (PHQ-4) in the general population. Journal of Affective Disorders 122, 86–95. Michal, M., Beutel, M.E., 2009. Weiterbildung CME: depersonalization/derealization— clinical picture, diagnostics and therapy. Zeitschrift für Psychosomatische Medizin und Psychotherapie 55, 113–140. Michal, M., Sann, U., Grabhorn, R., Overbeck, G., Röder, C.H., 2005. Zur Prävalenz von Depersonalisation und Derealisation in der stationären Psychotherapie. Psychotherapeut 50, 328–339. Michal, M., Wiltink, J., Subic-Wrana, C., Zwerenz, R., Tuin, I., Lichy, M., Brahler, E., Beutel, M.E., 2009. Prevalence, correlates, and predictors of depersonalization experiences in the German general population. The Journal of Nervous and Mental Disease 197, 499–506. Michal, M., Beutel, M.E., Grobe, T.G., 2010a. How often is the Depersonalization– Derealization Disorder (ICD-10: F48.1) diagnosed in the outpatient health-care service? Zeitschrift für Psychosomatische Medizin und Psychotherapie 56, 74–83. Michal, M., Wiltink, J., Till, Y., Wild, P.S., Münzel, T., Blankenberg, S., Beutel, M.E., 2010b. Type-D personality and depersonalization are associated with suicidal ideation in the German general population aged 35–74: results from the Gutenberg Heart Study. Journal of Affective Disorders 125, 227–233. Michal, M., Zwerenz, R., Tschan, R., Edinger, J., Lichy, M., Knebel, A., Tuin, I., Beutel, M., 2010c. Screening for depersonalization–derealization with two items of the
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