Reduced Expression of Emotion: A Red Flag Signalling Conversion to Psychosis in Clinical High Risk for Psychosis (CHR-P) Populations.

Objective: In this hypothesis-testing study, which is based on findings from a previous atheoretical machine-learning study, we test the predictive power of baseline "reduced expression of emotion" for psychosis.Method: Study participants (N = 96, mean age 16.55 years) were recruited from the Prevention of Psychosis Study in Rogaland, Norway. The Structured Interview for Prodromal Syndromes (SIPS) was conducted 13 times over two years. Reduced expression of emotion was added to positive symptoms at baseline (P1-P5) as a predictor of psychosis onset over a two-year period using logistic regression.Results: Participants with a score above zero on expression of emotion had over eight times the odds of conversion (OR = 8.69, p < .001). Data indicated a significant dose-response association. A model including reduced expression of emotion at baseline together with the positive symptoms of the SIPS rendered the latter statistically insignificant.Conclusions: The study findings confirm findings from the previous machine-learning study, indicating that observing reduced expression of emotion may serve two purposes: first, it may add predictive value to psychosis conversion, and second, it is readily observable. This may facilitate detection of those most at risk within the clinical high risk of psychosis population, as well as those at clinical high risk. A next step could be including this symptom within current high-risk criteria. Future research should consolidate these findings.