Grant: Project Grant

Frequent heavy use of cannabis and alcohol is increasingly common in young Canadians (16-25 years old). Approximately 35% of adolescent and emerging adults report regular, high-intensity drinking ('binge drinking'), and 20-29% of youth who use cannabis describe using it almost daily. This pattern of use during adolescence is believed to affect the growth and development of the brain, potentially by disrupting communication between brain cells and increasing the risk for impaired brain function, mental illness and addiction in adulthood. Despite these significant impacts, there are currently no studies looking at how frequent use of cannabis or alcohol affects brain cell communication in young people. The building blocks of communication in the brain are synapses, which pass messages between brain cells and continually grow, shrink, and reorganize themselves across the lifespan. New imaging tools can measure synapses in the human brain, giving us a window into how brain cell communication is shaped in living people. This study will use brain synapse imaging in young people with heavy use of alcohol or cannabis to better understand how these drugs affects brain cell communication during this critical period of development. It will determine whether binge drinking or frequent (~daily) use of cannabis is associated with loss or damage of synapses in youth between the ages of 16 and 25 years old, and test whether this is linked to problems with brain functions like learning and memory. Results from this study could help us understand the effects of these two broadly used legal substances on basic brain processes during adolescence and young adulthood. This information would help us design better public health measures to provide guidance on safe use of these substances.