Relationship between patterns of cannabis use and functional and symptomatic trajectories in first-episode psychosis

Cannabis use is common in first-episode psychosis (FEP) but evidence is mixed about the extent to which cannabis use predicts symptoms and functional outcomes among those who seek treatment. This study sought to characterize cannabis use patterns and examine the relationship with clinical outcomes, including interactions with early intervention services (EIS). Data were drawn from the Recovery After an Initial Schizophrenia Episode-Early Treatment Program (RAISE-ETP) study including FEP individuals receiving treatment at sites randomized to provide either EIS (NAVIGATE) or community care (CC). Cannabis use was assessed monthly and symptom and functioning data were collected at baseline, 6, 12, 18, and 24 months. Among the 404 participants enrolled, 334 were classified into four cannabis use groups (consistent, sporadic, stopped, and never users) based on their use during the first year. Consistent and sporadic cannabis users were younger, whereas those who had stopped using were older. Sporadic users had the highest depression and the lowest functioning at baseline and improved less during treatment in negative emotions and intrapsychic foundations (e.g., motivation and sense of purpose) than non-users. However, sporadic users who received NAVIGATE improved more in overall symptoms and functioning than those who received CC. Consistent users did not tend to differ in their trajectories from non-users. Individuals with FEP who use cannabis sporadically showed less clinical improvement than non-users. However, EIS treatment reduced the negative effects of sporadic cannabis use on clinical outcomes. Those who use cannabis sporadically may have unique needs that require attention in EIS.