Cannabis use (CU) and cannabis use disorder (CUD) were significantly associated with psychotic and depressive symptoms, per longitudinal study data published in Addiction.
Researchers abstracted data from 2 existing studies: the Victoria Healthy Youth Survey (V-HYS) and the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC-III). The V-HYS administered biannual surveys to 662 youths 12 to 18 years old across 6 waves for 10 total years of observation. Participants reported cannabis and alcohol use, as well as any psychotic, depressive, or anxiety symptoms. The NESARC-III collected information on alcohol and substance use disorders and associated mental conditions in a nationally representative sample of 36,309 noninstitutionalized adults. Using time-varying effects models, investigators examined the association between CU and mental health disorders among both study samples.
In the V-HYS sample, more frequent CU was positively associated with psychotic symptoms after age 22 years, and with depressive symptoms between 16 and 19 years and after 25 years. CUD was associated with psychotic symptoms after age 23 years, and with depressive symptoms between 19 and 20 and after 25 years. CUD was also associated with anxiety symptoms at ages 26 to 27 years. Notably, the interaction with sex was significant after age 26 years, with women experiencing a stronger association between CUD and psychotic symptoms. Men, in contrast, showed a stronger association between depressive symptoms and CUD after age 25 years. Sex did not moderate the association between CUD and anxiety symptoms. Per time-varying analyses, age of onset of CU and CUD did not appear to moderate association with mental health disorders.
Data from the NESARC-III also indicated an association between more frequent CU and psychotic symptoms from age 18 to 65 years. Frequent CU was also positively associated with depressive symptoms from age 18 to 64 years, and anxiety symptoms from age 20 to 63 years. Similarly, CUD was associated with more psychotic symptoms from age 18 to 64 years, more depressive symptoms from age 18 to 61 years, and more anxiety symptoms from age 18 to 62 years. Time-varying interactions of CU with sex were significant for psychotic symptoms between age 20 and 24 and 47 and 61 years; during these age intervals, women had stronger associations between CU and symptoms. A similar trend was observed for depressive symptoms between ages 18 and 25 and 32 and 41 years, and for anxiety symptoms between ages 18 and 23 and 32 and 46 years. Time-varying interactions of CUD with sex were also significant, with women again indicating stronger associations than men. Similar to the V-HYS dataset, age of use onset did not appear to moderate the association between CU or CUD and symptoms.
These data indicate a strong association between CU or CUD and mental health disorders during adolescence, and that these associations persist into adulthood. Investigators emphasized the necessity of further research into proper treatment and rehabilitation for individuals experiencing symptoms after CU.
Leadbeater BJ, Ames ME, Linden-Carmichael AN. Age-varying effects of cannabis use frequency and disorder on symptoms of psychosis, depression, and anxiety in adolescents and adults [published online October 1, 2018]. Addiction. doi: 10.1111/add.14459