Grant: CIHR Fellowship

Frequent heavy use of cannabis is increasingly common in young Canadians. Approximately 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 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 cannabis to better understand how these drugs affect brain cell communication during this critical period of development. It will determine whether frequent (~daily) use of cannabis is associated with loss or damage of synapses in youth between the ages of 16 and 24, and test whether this is linked to problems with brain functions like learning, memory and cognition. Results from this study could boost efforts towards effective harm reduction for this broadly used legal substance. A better understanding of how heavy use of cannabis during adolescence affects these basic processes would allow us to design better public health measures to provide guidance on safe use of these substances.