Prevalence and correlates of self-reported psychotic symptoms in the British population

The psychosis phenotype is generally thought of as a categorical entity. However, there is increasing evidence that psychosis exists in the population as a continuum of severity rather than an all-or-none phenomenon.

To investigate the prevalence and correlates of self-reported psychotic symptoms using data from the 2000 British National Survey of Psychiatric Morbidity.

A total of 8580 respondents aged 16-74 years were interviewed. Questions covered mental health, physical health, substance use, life events and socio-demographic variables. The Psychosis Screening Questionnaire (PSQ) was used to identify psychotic symptoms.

Of the respondents, 5.5% endorsed one or more items on the PSQ. Factors independently associated with psychotic symptoms were cannabis dependence, alcohol dependence, victimisation, recent stressful life events, lower intellectual ability and neurotic symptoms. Male gender was associated with paranoid thoughts, whereas female gender predicted hallucinatory experiences.

Self-reported psychotic symptoms are less common in this study than reported elsewhere, because of the measure used. These symptoms have demographic and clinical correlates similar to clinical psychosis.