Self-reported psychotic symptoms in the general population: results from the longitudinal study of the British National Psychiatric Morbidity Survey.

BACKGROUND Scarce longitudinal data exist on the occurrence of psychotic symptoms in the general population. AIMS To estimate the incidence of, and risk factors for, self-reported psychotic symptoms in Great Britain. METHOD Data from the 18-month follow-up of a national survey were used. Incident cases were those who endorsed one or more items on the Psychosis Screening Questionnaire at follow-up, but not at baseline. The association between factors recorded at baseline and incident self-reported symptoms was examined. RESULTS At follow-up, 4.4% of the general population reported incident psychotic symptoms. Six factors were independently associated with incident symptoms: living in a rural area; having a small primary support group; more adverse life events; smoking tobacco; neurotic symptoms; and engaging in a harmful pattern of drinking. CONCLUSIONS A small but not insignificant percentage of the population of Great Britain reported incident psychotic symptoms over 18 months. The risk factors for psychotic symptoms showed some similarities with risk factors for schizophrenia, but there were also some striking differences. The relationship between such risk factors and the factors that perpetuate psychotic symptoms remains to be ascertained.