Effects of persistent cannabis use on depression, psychosis, and suicidality following cannabis‐induced psychosis: A longitudinal study

People who keep using cannabis after a first episode of psychosis have persistently higher depression and suicidal thoughts than those who stop, even when psychotic symptoms improve. The study followed 44 people aged 16-50 in northern Italy for 9 months. Those who continued cannabis had slower recovery from psychotic symptoms and higher relapse rates (59.9% vs. 18.8%). Overall functioning improved only in those who stopped cannabis. The authors argue that continued use is linked to treatment-resistant depression, pointing to the need for integrated care.

Study at a glance

Abstract

AbstractBackground and ObjectivesCannabis use is associated with psychotic disorder onset and exacerbation. This study examines how continued cannabis use affects depressive symptoms, psychotic symptoms, and suicidal behaviors following cannabis‐induced first‐episode psychosis (FEP).MethodsSixty‐five participants (aged 16–50 years) with FEP were recruited from psychiatric inpatient facilities in northern Italy. Participants were categorized into two groups: non‐cannabis users (NCU) and cannabis users (CU), based on substance use during the 9‐month follow‐up. Twenty‐one participants (32.3%) were lost to follow‐up, with a final sample of 44 subjects (NCU = 22, CU = 22). Assessments were conducted at baseline, 3 months, and 9 months using PANSS, CDSS, SSI, and GAF scales).ResultsCU exhibited persistently higher depression (CDSS) and suicidality (SSI) scores than NCU throughout follow‐up, with significant differences at both 3 months (CDSS: p = .000006; SSI: p < .001) and 9 months (CDSS: p = .0000001; SSI: p < .001). Positive psychotic symptoms improved in both groups, though CU showed slower recovery and higher relapse rates (59.9% vs. 18.8%). PANSS positive subscale scores remained significantly higher in CU at 3 months (p = .001) and 9 months (p < .0002). GAF scores improved significantly only in NCU (p = .024 at 9 months).Discussion and ConclusionsContinued cannabis use adversely affects depressive and psychotic symptoms and suicidality in FEP patients, while cannabis cessation is associated with improved clinical outcomes.Scientific SignificanceThis study tracks depressive symptoms, suicidality, and psychotic manifestations in cannabis‐induced FEP, demonstrating that continued use is associated with treatment‐resistant depressive symptoms even when psychotic symptoms improve, highlighting the need for integrated clinical approaches.