Effects in rats of adolescent exposure to cannabis smoke or THC on emotional behavior and cognitive function in adulthood

Rationale Cannabis use is common among adolescents and some research suggests that adolescent cannabis use increases the risk for depression, anxiety, and cognitive impairments in adulthood. In human studies, however, confounds may affect the association between cannabis use and the development of brain disorders. Objectives These experiments investigated the effects of adolescent exposure to either cannabis smoke or THC on anxiety- and depressive-like behavior and cognitive performance in adulthood in Long-Evans rats. Methods Adolescent rats of both sexes were exposed to either cannabis smoke from postnatal days (P) 29–49 or ascending doses of THC from P35–45. When the rats reached adulthood (P70), anxiety-like behavior was investigated in the large open field and elevated plus maze, depressive-like behavior in the sucrose preference and forced swim tests, and cognitive function in the novel object recognition test. Results Despite sex differences on some measures in the open field, elevated plus maze, forced swim, and novel object recognition tests, there were no effects of either adolescent cannabis smoke or THC exposure, and only relatively subtle interactions between exposure conditions and sex, such that sex differences on some performance measures were slightly attenuated. Conclusion Neither cannabis smoke nor THC exposure during adolescence produced robust alterations in adult behavior after a period of abstinence, suggesting that adverse effects associated with adolescent cannabis use might be due to non-cannabinoid concomitants of cannabis use.