Cannabis Use Is Quantitatively Associated with Nucleus Accumbens and Amygdala Abnormalities in Young Adult Recreational Users

Abstract

Marijuana is the most commonly used illicit drug in the United States, but little is known about its effects on the human brain, particularly on reward/aversion regions implicated in addiction, such as the nucleus accumbens and amygdala. Animal studies show structural changes in brain regions such as the nucleus accumbens after exposure to ⌬9-tetrahydrocannabinol, but less is known about cannabis use and brain morphometry in these regions in humans. We collected high-resolution MRI scans on young adult recreational marijuana users and nonusing controls and conducted three independent analyses of morphometry in these structures: (1) gray matter density using voxel-based morphometry, (2) volume (total brain and regional volumes), and (3) shape (surface morphometry). Gray matter density analyses revealed greater gray matter density in marijuana users than in control participants in the left nucleus accumbens extending to subcallosal cortex, hypothalamus, sublenticular extended amygdala, and left amygdala, even after controlling for age, sex, alcohol use, and cigarette smoking. Trend-level effects were observed for a volume increase in the left nucleus accumbens only. Significant shape differences were detected in the left nucleus accumbens and right amygdala. The left nucleus accumbens showed salient exposuredependent alterations across all three measures and an altered multimodal relationship across measures in the marijuana group. These data suggest that marijuana exposure, even in young recreational users, is associated with exposure-dependent alterations of the neural matrix of core reward structures and is consistent with animal studies of changes in dendritic arborization.

Cannabinoids and Epilepsy

“…Long-term use of recreational cannabis in adolescents is associated with addiction (9 % overall but 17 % among adolescents) and impaired cognitive and academic performance [270][271][272][273][274]. Additionally, cannabis treatment in animal and human studies altered brain development (especially with use in early childhood) and structure [272,[275][276][277], creating long-lasting functional and structural brain abnormalities [277][278][279]. Early and/or heavy cannabis use is associated with neurochemical abnormalities on magnetic resonance spectroscopy [272], impaired maintenance of neuronal cytoskeleton dynamics [277], decreased white matter development or integrity [272,275,276], increased impulsivity [276], and abnormal activation patterns during cognitive tasks on functional magnetic resonance imaging [272,280].…”

“…Additionally, cannabis treatment in animal and human studies altered brain development (especially with use in early childhood) and structure [272,[275][276][277], creating long-lasting functional and structural brain abnormalities [277][278][279]. Early and/or heavy cannabis use is associated with neurochemical abnormalities on magnetic resonance spectroscopy [272], impaired maintenance of neuronal cytoskeleton dynamics [277], decreased white matter development or integrity [272,275,276], increased impulsivity [276], and abnormal activation patterns during cognitive tasks on functional magnetic resonance imaging [272,280]. In patients with multiple sclerosis, use of cannabis is associated with impaired cognition and activation patterns on functional magnetic resonance imaging [281].…”

Pain Management for the Young Adult Rheumatology Patient in an Era of Medicinal Marijuana Legalization

“…The nucleus accumbens and the amygdala are brain areas operative in addictive behavior. Marijuana use at least once a week by young people was associated with structural changes of these key brain regions, even when controlled for age, sex, alcohol, and cigarette use 17 . Dependence occurs for 9% of all users, with this number increasing to 17% for onset of use in adolescence, and climbing to 25%-50% for daily users 18 .…”

Marijuana, Experience of Temporality, and School Performance from a Qualitative and Quantitative Approach

“…deterioration of the neuronal connectivity in speciic brain zones has been described in this line of studies, such as the precuneus and hippocampus, zones involved in learning and memory, as well as in the prefrontal networks [14,15], which can lead to a poor school performance and school desertion [4,16]. In turn, alterations in the neuronal organization of the nucleus accumbens and the amygdala, as well as in their volume and shape, have been reported in young marijuana smokers [17]. Cognitive deiciencies and reduced IQs have been observed in adults that smoked marijuana regularly during their adolescence [18].…”