Development of depressed mood predicts onset of psychotic disorder in individuals who report hallucinatory experiences.

Objectives: Current psychological theories state that the clinical outcome of hallucinatory experiences is dependent on the degree of associated distress, anxiety, and depression. This study examined the hypothesis that the risk for onset of psychotic disorder in individuals with self-reported hallucinatory experiences would be higher in those who subsequently developed depressed mood than in those who did not.

Design: A prospective cohort study of a general population sample.

Methods: A sample of 4,670 individuals with no lifetime evidence of any psychotic disorder were interviewed with the Composite International Diagnostic Interview Schedule (CIDI) at baseline and 1 and 3 years later. At Year 3, individuals with CIDI evidence of psychotic symptoms were interviewed by clinicians to identify potential onset of psychotic disorder. Psychotic disorder was specified at three levels; two involving severity of positive symptoms of psychosis, and one using additional clinical judgment of need for care.

Results: Given the presence of hallucinatory experiences at baseline, the increase in risk of having the psychosis outcome at Year 3 was higher in the group with depressed mood at Year 1 than in the group without depressed mood at Year 1 (any level of psychotic symptoms: risk difference 17.0%, 95% CI - 1.7, 35.7; severe level of psychotic symptoms: risk difference 21.7%, 95% CI 3.2, 40.2; needs-based diagnosis of psychotic disorder: risk difference 16.8%, 95% CI 0.4, 33.3).

Conclusion: The results are in line with current psychological models of psychosis that emphasize the role of secondary appraisals of psychotic experiences in the onset of clinical disorder.