Symptomatic and functional outcomes of substance use disorder persistence 2 years after admission to a first-episode psychosis program

Substance use disorders (SUD) in first-episode psychosis (FEP) are highly prevalent and linked with poor outcomes. However, most longitudinal studies investigating their impacts in FEP have not reported proportions of patients who ceased SUD. Our aim was to examine the influence of SUD course on functional and symptomatic outcomes as well as service use in FEP. We performed a 2-year longitudinal study of 212 FEP patients, aged between 18 and 30 years, admitted to 2 early psychosis services in Montréal, Québec, Canada. We observed that cannabis was the first substance abused (42.9% at baseline), followed by alcohol (19.3%). The SUD rate decreased by approximately 30% during the first year. Patients with persistent SUD had worse functional outcomes (Quality of Life Scale, Social and Occupational Functioning Assessment Scale, employment), more symptoms (Positive and Negative Symptoms Scale) and heavier service use (emergency and hospitalization). SUD persistence was associated with illness severity, homelessness and cluster-B personality. Those living with their parents and financially supported by them were more likely to cease SUD. Our results indicate that SUD course was more significant than having SUD at admission; persistent SUD was associated with worse outcomes. SUD decreased during a general early psychosis intervention program (with no specialized SUD treatment). An integrated, specialized approach targeting FEP patients with predictive factors of SUD persistence during the first years of treatment might increase SUD cessation and possibly improve outcomes.