Author(s): Taylor Hatchard, Peter A Fried, Matthew J Hogan, Ian Cameron and Andra M Smith
There is a growing body of evidence that marijuana use during adolescence, a critical period in neurocognitive development, may have lasting detrimental impact on executive functioning. The Ottawa Prenatal Prospective Study (OPPS) has followed participants over 20 years, from birth to young adulthood, and has collected data on potentially confounding lifestyle variables, such as prenatal drug exposure and current drug use. In the present study, we report the effects of heavy adolescent onset marijuana use on cognitive interference while performing a Counting Stroop task using fMRI in a sample of OPPS participants, while controlling for current nicotine use and prenatal marijuana exposure. Despite a lack of performance differences, the neural activity of young adults who use marijuana on a regular basis differed significantly compared to non-users while performing the task. This included increased activity in the right rolandic operculum, cerebellar tonsil, bilateral postcentral gyrus, cingulate gyrus, and right supplementary motor area. This recruitment of additional brain regions is suggestive of compensatory strategies among marijuana users in order to successfully complete the task, highlighting the impact of early marijuana use on neurocognitive development and altered brain function.
