Grant: CIHR Fellowship

Abuse of cannabis or alcohol causes profound harm to the brain, resulting in impaired cognitive functioning. These harms may be exacerbated when these drugs are abused together, which typically happens for the first time during adolescence. Since the brain does not fully mature until young adulthood, adolescent boys and girls who co-abuse alcohol and cannabis are vulnerable to developing impairments in memory and impulse control. These cognitive functions are supported by a network of brain regions, where specific signaling mechanisms (e.g., the dopamine and endogenous cannabinoid systems) can be disrupted by drug abuse. It is unknown how co-abuse of cannabis and alcohol impacts the development of these systems, and how cognition is compromised as a result. In view of the impending legalization of cannabis in Canada, it is critical that the associated harms be identified. This research will characterize the long-term cognitive impairments caused by the co-abuse of cannabis and alcohol during adolescence, using male and female rats as a model. During a developmental period that corresponds with human adolescence, rats will be exposed to either the psychoactive ingredient of cannabis (e.g., THC); alcohol; THC plus alcohol; or no drugs at all, each day for three weeks. After two weeks, the degree of cognitive impairment in impulse control and memory will be assessed using touchscreens, a method that is analogous to cognitive tasks used in humans. Using imaging techniques, the impact of drug exposure on the dopamine and endogenous cannabinoid systems will be quantified and correlated with the changes in cognition observed. This research will identify the cognitive impairments caused by the co-abuse of cannabis and alcohol during adolescence, and their neural foundations. These findings will advise policy-makers and the general population of the potential consequences of simultaneous alcohol and cannabis use.