Ryan Nicholson, Una E. Choi, Ramin Mojtabai, Johannes Thrul
OBJECTIVE: The authors compared the risk of mental disorders between patients with cannabis use disorder (CUD) and those with other substance use disorders (SUDs). METHODS: The TriNetX Research Network was queried to identify patients with SUDs and no preceding mental disorders and compare 1) adult patients with CUD only versus those with other SUDs, 2) pediatric patients with CUD only versus those with other SUDs, and 3) adult patients with CUD plus another SUD versus those with comorbid noncannabis SUDs. Propensity score matching was performed on demographic characteristics and 24 risk factors or comorbidities. Subsequent diagnosis of schizophrenia and other common mental disorders was assessed. RESULTS: Compared to adults with other SUDs, those with noncomorbid CUD (N=345,903 for both cohorts) had a lower risk of schizophrenia (0.34% vs. 0.42%; relative risk [RR]=0.81, 95% CI=0.75, 0.88), depression (1.35% vs. 1.74%; RR=0.78, 95% CI=0.75, 0.81), and psychotic disorders (0.36% vs. 0.52%; RR=0.68, 95% CI=0.63, 0.73). Compared to pediatric patients with other SUDs, those with CUD (N=24,793 for both cohorts) had a higher risk of schizophrenia (0.29% vs. 0.19%; RR=1.52, 95% CI=1.06, 2.19), depression (1.65% vs. 1.27%; RR=1.30, 95% CI=1.13, 1.51), and anxiety disorders (8.13% vs. 6.71%; RR=1.21, 95% CI=1.14, 1.29). Compared to adult patients with other SUDs, those with CUD and a comorbid SUD (N=203,916 for both cohorts) had a decreased risk of schizophrenia (1.94% vs. 2.25%; RR=0.86, 95% CI=0.83, 0.90), depression (3.98% vs. 5.67%; RR=0.70, 95% CI=0.68, 0.72), bipolar disorder (4.23% vs. 5.60%; RR=0.76, 95% CI=0.74, 0.78), and anxiety disorders (16.20% vs. 21.36%; RR=0.76, 95% CI=0.75, 0.77). CONCLUSIONS: CUD-associated mental health risks varied by age and comorbid SUDs, possibly due to earlier onset of mental disorders in cannabis users or age-related differences in CUD effects.