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Research identifies symptoms that predict psychosis

Recent study findings show severity of unusual thought content, suspiciousness, reduced ideational richness and difficulty focusing or concentrating predicted risk for psychosis among individuals considered at high-risk for psychosis.

“An early study examining psychosis conversion in persons meeting high-risk diagnostic criteria reported a 45% 2-year conversion rate, however subsequent studies found 2-year conversion rates that ranged from 15% to 30%,” Diana O. Perkins, MD, MPH, of the University of North Carolina, Chapel Hill, and colleagues wrote. “Prominent among the scales used to evaluate symptoms associated with psychosis risk is the Scale of Psychosis-Risk Symptoms (SOPS). The SOPS comprises 19 symptoms in four domains that include: positive (unusual thought content/delusional ideas, suspiciousness/persecutory ideas, grandiose ideas, perceptual abnormalities/hallucinations, disorganized communication), negative (social anhedonia, avolition, decreased expression of emotion, decreased experience of emotions and self, reduced ideational richness, reduced occupational functioning), disorganized (odd behavior or appearance, bizarre thinking, trouble with focus and attention, impaired hygiene), and general (sleep disturbance, dysphoric mood, motor disturbances, impaired stress tolerance).”

To identify SOPS items that best predicted psychosis conversion, performance of these items was assessed among two cohorts from the North American Prodrome Longitudinal Study. In the first cohort (n = 296) researchers developed a classifier that included SOPS items that best detected psychosis conversion. The second cohort (n = 592) served as an independent test set. Study participants, aged 12 to 35 years, met criteria for at least one of the following high-risk syndromes: attenuated psychotic symptoms syndrome, brief intermittent psychotic symptoms syndrome, or genetic risk and deterioration syndrome.

Researchers derived two-item and four-item subscales, both of which included unusual thought content and suspiciousness. The four-item subscale also included reduced ideational richness and difficulty focusing/concentrating.

The concordance index, measuring discrimination, was similar for both subscales.

The four-item subscale performed better in 742 of 1,000 random selections of 80% subsets of the second study cohort, according to researchers.

Subscale calibration was proportional between cohorts, though absolute conversion risk predicted in the first cohort was higher than that predicted in the second cohort.

“In terms of assessing psychosis risk, I think this study shows we need to be emphasizing the person’s thought process, and appreciate that perceptual disturbances may not be a specific early warning sign,” Perkins said in a press release. “I think that will affect how we develop our diagnostic system in the future for people who are at high risk for psychosis.” – by Amanda Oldt

Disclosure: The study was funded by the NIMH. Please see the full study for a list of all authors’ relevant financial disclosures.