Attenuated positive psychotic symptoms and low global functioning show convincing evidence for increasing transition risk in clinical high risk for psychosis (CHR-P), according to a study published in Schizophrenia Bulletin.
In this meta-analysis, 2 independent researchers performed a 2-step systematic search of literature published between 1998 and May 13, 2018, using the Ovid database to identify 128 studies that investigated the effect of risk and protective factors for transition to psychosis in individuals with CHR-P (N=17,967). Articles meeting the inclusion criteria were original cohort studies written in English examining the association between risk/protective factors and psychotic disorders in the CHR-P population, which included individuals with CHR-P defined by standard psychometric instruments.
Highly suggestive evidence showed that attenuated positive psychotic symptoms were associated with increased transition risk (standardized mean difference [SMD] 0.348; 95% CI, 0.280-0.415), and global functioning was associated with decreased transition risk (SMD -0.291; 95% CI, -0.370 to -0.211). There was suggestive evidence (class III, >1000 cases; P <.01; class I/II criteria not met) that negative psychotic symptoms increased the risk for transition to psychosis (SMD 0.393; 95% CI, 0.317-0.469). Evidence of an association with transition to psychotic disorders was absent or weak for the 16 other factors.
This meta-analysis is limited by the relatively small size of CHR-P literature compared with other areas of psychiatry. The CHR-P paradigm is intrinsically embedded in prospective cohort studies; future studies could potentially move class III factors into higher classes, which would improve the evidence base. The vast majority of factors assessed in the current literature are risk factors as opposed to protective factors like self-esteem, social support, and resilience. Finally, there is clinical heterogeneity in the CHR-P population.
The current research is characterized by substantial sampling biases. Because the CHR-P field is epidemiologically weak, future CHR-P research should be collaborative, scalable, and better harmonized in terms of assessment of intake criteria and outcomes.
Oliver D, Reilly TJ, Baccaredda Boy O, et al. What Causes the Onset of Psychosis in Individuals at Clinical High Risk? A Meta-analysis of Risk and Protective Factors [published online June 20, 2019]. Schizophr Bull. doi: 10.1093/schbul/sbz039