Prevalence of psychotic disorder and community level of psychotic symptoms: an urban-rural comparison.
BACKGROUND
Urban and rural populations have different rates of psychotic illness. If psychosis exists as a continuous phenotype in nature, urban-rural population differences in the rate of psychotic disorder should be accompanied by similar differences in the rate of abnormal mental states characterized by psychotic or psychosislike symptoms.


METHODS
A random sample of 7076 individuals aged 18 to 64 years were interviewed by trained lay interviewers with the Composite International Diagnostic Interview. Approximately half of those with evidence of psychosis according to the Composite International Diagnostic Interview were additionally interviewed by clinicians. We investigated associations between a 5-level urbanicity rating and (1) any DSM-III-R diagnosis of psychotic disorder (sample prevalence, 1.5%), (2) any rating of hallucinations and/or delusions (sample prevalence, 4.2%), and (3) any rating of psychotic or psychosislike symptoms (sample prevalence, 17.5%).


RESULTS
Level of urbanicity was associated not only with DSM-III-R psychotic disorder (adjusted odds ratio [OR] over 5 levels, 1.47; 95% confidence interval [CI], 1.25-1.72), but also, independently, with any rating of delusion and/or hallucination (adjusted OR, 1.28; 95% CI, 1.17-1.40; clinician-assessed psychotic symptoms only: OR, 1.30; 95% CI, 1.03-1.64) and any rating of psychosislike symptom (adjusted OR, 1.18; 95% CI, 1.13-1.24). Psychotic symptoms were strongly and independently associated with psychotic disorder, regardless of the level of urbanization.


CONCLUSIONS
Community level of psychotic and psychosislike symptoms may be inextricably linked to the prevalence of psychotic disorder. The prevalence of abnormal mental states that facilitate development to overt psychotic illness increases progressively with level of urbanization.
van Os
J
J
Department of Psychiatry and Neuropsychology, Maastricht University, European Graduate School of Neuroscience, PO Box 616 (PAR 45), 6200 MD Maastricht, The Netherlands.
Hanssen
M
M
Bijl
R V
RV
Vollebergh
W
W
D000293:Adolescent; D000328:Adult; D016001:Confidence Intervals; D003702:Delusions / Q000175:diagnosis / Q000453:epidemiology; D005260:Female; D006212:Hallucinations / Q000175:diagnosis / Q000453:epidemiology; D006306:Health Surveys; D006801:Humans; D008297:Male; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D016017:Odds Ratio; D015995:Prevalence; D011569:Psychiatric Status Rating Scales / Q000706:statistics & numerical data; D011618:Psychotic Disorders / Q000175:diagnosis / Q000453:epidemiology*; D012424:Rural Population / Q000706:statistics & numerical data; D012680:Sensitivity and Specificity; D014505:Urban Population / Q000706:statistics & numerical data; D014507:Urbanization / Q000639:trends