Shift in sex and age of individuals at a clinical high risk (CHR) for psychosis: relation to differences in recruitment methods and effect on sample characteristics.

Historically, large samples of individuals at clinical high risk (CHR) for psychosis have mirrored overt psychotic disorders in both sex (predominantly male) and age representation (adolescent to early adulthood onset). We report on a recent CHR sample suggesting a shift in these distributions and explore contributing factors and clinical implications. We hypothesized that demographic differences would be related to recruitment sources and that age, sex, and recruitment sources would be related to baseline clinical profiles. Baseline data were included from the recent computerized assessment of psychosis risk (CAPR) study and the second and third waves of the North American Prodrome Longitudinal Study (NAPLS-2 and 3). Hierarchical regression was used to examine differences in sex, age, and recruitment sources between samples and relationships with clinical characteristics. Univariate analyses revealed a significant shift to female predominance, older age, and a change in recruitment source from NAPLS to CAPR. Multivariate analyses indicated that between-study differences in sex and age were conditional on recruitment source, with the apparent study effect driven by differences in the non-self-referred groups. More than 60% of participants recruited through internet self-referrals were female across samples. Clinical heterogeneity was partly related to age, sex, and recruitment source differences. Internet-based self-referrals were older and showed less severe negative symptoms, disorganization, and general symptoms and higher role functioning than non-self-referred participants. Findings highlight the importance of recruitment sources for CHR sample characteristics. Recruitment source effects, including those from internet sources, should be investigated in other CHR samples.