Association between the exposome score for schizophrenia and functioning in remitted first-episode psychosis: results from the HAMLETT study

BACKGROUND: Environmental risk factors contribute to functional impairment, which can persist even after symptomatic remission of a first episode of psychosis (FEP). To quantify this effect, we calculated the association between exposome score for schizophrenia (ES-SCZ), a cumulative environmental liability score, and functioning in remitted FEP patients.

METHODS: Data of 286 participants were derived from the HAMLETT study. General functioning was assessed using the Global Assessment of Functioning (GAF) scale at baseline, when participants were in remission for 3-6 months. ES-SCZ was calculated based on previously validated estimates and included childhood adversity domains (emotional and physical neglect; emotional, physical and sexual abuse; and bullying), cannabis use, hearing impairment, and winter birth. The association between ES-SCZ and GAF was evaluated in three multiple linear regression models, with each successive model including additional covariates.

RESULTS: ES-SCZ was negatively associated with the GAF score, even after accounting for age, sex at birth, education, migrant status, antipsychotic type, and FEP duration [B = -1.51 (-2.78 to -0.24), p = .022]. This final model explained 8.6 % of the variance (R2) in the GAF score, with ES-SCZ being the primary contributor, accounting for 35.5 % of this explained variance.

CONCLUSIONS: This study independently replicated the finding that ES-SCZ predicts general functioning in FEP, showing its potential for forecasting functioning in remitted FEP patients.