Cannabis Use, Gender and the Brain

Cannabis is the most widely used illicit drug in the U.S. and, as a result of legalization efforts for both medical remedy and for recreational use, is now the second leading reason (behind alcohol) for admission to addiction treatment in the U.S. The health consequences, cognitive changes, academic performance and numerous neuroadaptations have been debated ad nauseam. Like other drugs and medications, effects are different if exposure occurs in the young vs. the old or in males vs. females. Exposure in utero, early childhood, adolescence-young adult, adult and elderly may have different effects on the brain and outcomes. Yet the best available independent research shows that marijuana use is associated with consistent regionally specific alterations to important brain circuitry in the striatum and pre-frontal and post orbital regions. In this study, Chye and colleagues have investigated the association between marijuana use and the size of specific brain regions that are vitally important in goal-directed behavior, focus and learning within in the orbitol frontal cortex (OFC) and caudate. This investigation suggests that marijuana dependence and recreational use have distinct and region-specific effects.

Why Does This Matter?

This is an important finding, but distinction between cannabis use, abuse and dependence is not always clear, objective, linear or well understood. However, dependence-related medial OFC volume reduction was robust and highly significant. Lateral OFC volume reduction was associated with monthly marijuana use. Greater reductions in brain volume of specific regions were stronger among females who were marijuana dependent. This finding correlates with previous evidence of gender-dependent differences towards the various physiological, behavioral and the reinforcing effect of marijuana for both recreational use and addiction. The results highlight important neurological distinctions between occasional cannabis use and addiction. Specifically, Chye and colleagues found that smaller medial OFC volume may be driven by marijuana addiction-related mechanisms, while smaller lateral OFC volume may be due to ongoing exposure to cannabinoids. The results highlight a distinction between cannabis use and dependence and warrant future examination of gender-specific effects in studies of marijuana use and dependence.