More severe forms of unusual thoughts, suspicion, and reduced richness of ideas can predict risk of psychosis, according to an analysis involving 888 individuals, all of whom met the Criteria of Psychosis-Risk States.
For the first cohort (n=296), investigators created a classifer that drew from the parts of the Scale of Psychosis-Risk Symptoms that identified those without psychosis who eventually experienced psychosis. The remaining patients (n=592) served as an independent test group.
Researchers used 2-item and 4-item subscales that included unusual thought content and suspiciousness. The larger subscale also addressed reduced ideational richness and focus/concentration difficulties.
The Concordance Index, a measure of discrimination, was similar for each subscale in both cohorts. In cohort 2, the authors found that the 4-item subscale performed better than its 2-item counterpart.
Although subscale calibration between both cohorts was proportional, cohort 1 produced better absolute conversion risk than cohort 2. Investigators noted that this was a reflection of differences between the two groups in 2-year conversion rates.
The authors concluded that scales based on these symptoms may have clinical utility once they are validated.
Citation: Perkins D, Jeffries C, Cornblatt B, et al. Severity of thought disorder predicts psychosis in persons at clinical high-risk. Schizophr Res. 2015; October 2, 2015. doi: DOI: http://dx.doi.org/10.1016/j.schres.2015.09.008.