Grant: Travel Awards - Institute Community Support

Research suggests that teen cannabis use may be a risk factor for common mental health problems including depression and anxiety. However, most studies have relied on 20th century data when cannabis was less potent than today in terms of THC. It is therefore possible that today's cannabis is more harmful to the developing brain. Additionally, few studies have explored the roles of sex and gender in this relationship. We used data from a survey of grade 7-12 students across Ontario, Canada, conducted every two years from 2013 to 2023 (N=56,420). We examined the association between cannabis use frequency and mental health problems, and looked at whether the association became stronger over time. We also explored whether the association differed by sex and/or gender identity. We found a significant association between cannabis use frequency and mental health problems, which increased over time, particularly among the most frequent users. Greater cannabis use frequency was associated with mental health problems among females, but not among males. The association was also stronger among girl-identifying teens compared to boys and transgender/gender diverse teens. In conclusion, teen cannabis use is significantly associated with common mental health problems, particularly among females and teens identifying as girls. The association between frequent cannabis use and mental health problems appears to be increasing over time, possibly reflecting increasing potency of cannabis. Cannabis prevention strategies that target female/girl/woman adolescents are warranted.