Hallucinatory experiences and onset of psychotic disorder: evidence that the risk is mediated by delusion formation.
OBJECTIVE
To examine the hypothesis that the risk for onset of psychotic disorder in individuals with self-reported hallucinatory experiences (HE) would be higher in those who developed delusional ideation (DE) than in those who did not.


METHODS
A population sample of 4673 individuals were interviewed with the Composite International Diagnostic Interview at baseline and 1 and 3 years later. At year 3, clinical re-interview took place to identify onset of psychotic disorder.


RESULTS
Given the presence of HEs at baseline, the increase in risk of having the psychosis outcome at year 3 was much higher in those with DE at year 1 than in those without DE (risk difference between individuals with and without DE: 18.72%, 95% CI: 2.22-35.23, chi(2) = 4.94, df = 1, P = 0.026).


CONCLUSIONS
The results are in line with current psychological theories stating that clinical outcome of psychosis-like experiences is related to the development of secondary beliefs and appraisals.
Krabbendam
L
L
Department of Psychiatry and Neuropsychology, South Limburg Mental Health Research and Teaching Network, EURON, Maastricht University, Maastricht, The Netherlands. l.krabbendam@sp.unimaas.nl
Myin-Germeys
I
I
Hanssen
M
M
Bijl
R V
RV
de Graaf
R
R
Vollebergh
W
W
Bak
M
M
van Os
J
J
D000328:Adult; D001007:Anxiety / Q000175:diagnosis / Q000453:epidemiology; D010054:Brief Psychiatric Rating Scale; D003702:Delusions / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology; D003863:Depression / Q000175:diagnosis / Q000453:epidemiology; D005260:Female; D006212:Hallucinations / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology; D006801:Humans; D015994:Incidence; D008297:Male; D015995:Prevalence; D011618:Psychotic Disorders / Q000150:complications / Q000175:diagnosis / Q000453:epidemiology; D012307:Risk Factors; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires