Analyze Insights

Brain Changes Associated with Chronic, Heavy Cannabis Use

cannabis backgroundSeveral recent studies indicate that heavy cannabis usage appears to be associated with significant structural changes of key brain regions over time. With recent legal changes in social and medical consumption of cannabis in several countries, questions over the drug’s effects on the morphology of brain structures continue to arise.

The psychoactive ingredient in cannabis is tetrahydrocannabinol (THC) which overstimulates naturally occurring cannabinoid receptors in the brain. These receptors are part of a neural communication network called the endocannabinoid system and are found in high density in areas that influence short-term memory, problem-solving, concentration, coordination and time perception.

Researchers from the University of Melbourne, Australia, recently investigated anatomical changes across multiple brain regions caused by long-term heavy cannabis use. The subjects of the study were 15 males with 21 years of regular use who on average consumed 212 joints per month. The investigators used high-resolution MRI to analyze areas of the brain rich in cannabinoid receptors, the alteration of which is associated with cannabis exposure. From these images, Analyze software was used to manually segment and measure volumetric changes of the orbitofrontal and anterior cingulate cortices, pituitary gland, hippocampus and amygdala, all regions involved in cognition and regulation of  stress levels and emotion.

When comparing cannabis users to a control group, the investigators demonstrated that heavy cannabis usage results in a reduction in the volume of the hippocampus – the area of the brain most closely associated with memory. This finding is in accordance with other studies in this field. However, the study also showed, for the first time, that heavy cannabis usage leads to a reduction in the volume of the amygdala, one of the primary brain regions involved in regulating anxiety. The evidence that cannabis has significant consequences on this structure is highly important for understanding how this drug exerts its behavioral effects.

This study provides valuable insights into the selective and detrimental neurobiological consequences of prolonged and heavy cannabis use on the anatomy of brain structures. To further interpret these results, future studies will investigate the detrimental effects of cannabinoids on functional and structural connectivity in these brain regions.

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