Young people at risk for psychosis: case finding and sample characteristics of the Oulu Brain and Mind Study

Set within the general population-based Northern Finland Birth Cohort 1986, the Oulu Brain and Mind Study aims to explore the causes and pathogenesis of psychotic illness by following young people at risk for psychosis due to having a first-degree relative with psychotic illness or due to having experienced psychotic-like symptoms themselves. We report the study methods and explore the relationship between these definitions of high risk for psychosis and operational criteria for a prodromal psychosis syndrome based on interview.

Prospectively collected data from earlier follow-ups of this cohort were combined with health register data to categorize subjects as those with familial risk (n = 272), symptomatic risk (n = 117), psychosis (n = 78), attention deficit hyperactivity disorder (ADHD) (n = 103) and a sample of controls (n = 193) drawn randomly from the remaining cohort. The Structured Interview for Prodromal Syndromes (SIPS) was applied to all, 295 participants together with questionnaires measuring psychosis vulnerability and schizotypal traits.

There were 29 (10%) current prodromal cases. Criteria for the current prodromal syndrome were fulfilled by 12% of the familial risk group and 19% of the symptomatic risk group, compared with 5% of the ADHD group and 4% of controls.

We successfully detected young people with a prodromal psychosis syndrome although relatively few subjects deemed to be at high risk met the full operational criteria according to the SIPS interview. Combining methods from familial, clinical and psychometric high-risk approaches provides a tractable method for studying risk of psychosis in the general population.