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Study Examines Chronic Marijuana Use, Affect on Brain

A study on the effects of chronic marijuana use was presented at a recent annual meeting of the Society for Nuclear Medicine in San Antonio, Texas. The study was a collaboration between the US National Institute of Mental Health and US National Institute on Drug Abuse. It was presented on Monday night at the annual meeting of the Society of Nuclear Medicine.

What they highlighted in the presentation were imaging scans of chronic daily use of marijuana – images that they said show the detrimental effect of the brain that heavy use of marijuana causes. The researchers said that heavy use causes a decrease in the number of receptors that are involved in important functions such as concentration, pleasure, pain tolerance, memory, appetite and movement coordination.

They said when smoked or ingested, cannabis’ psychoactive chemical binds to numerous cannabinoid receptors in the brain and throughout the body, and then affects a range of mental states and actions.

The study was conducted comparing the brain scans of 30 daily marijuana smokers to the brain scans of non cannabis users over the course of four weeks. They used molecular imaging in the study and researchers were able to see the changes in participants brains. They found the CB1 receptor, one of the two known types of cannabinoid receptors, decreased by roughly 20 percent compared to the non-consumers.

Lead Author of the study, Dr. Jussi Hivonen said in a news release that with the study, they have been able to “show for the first time that people who abuse cannabis have abnormalities of the cannabinoid receptors in the brain”.

Interestingly, the researchers re-scanned 14 of the cannabis smokers after a one month of not using cannabis and found an increase in the receptor activity in the area that were deficient at the beginning of the study. They concluded with these findings that adverse effects of chronic marijuana use are reversible.

Even though we know that the receptors play a role in pleasure, appetite, pain tolerance, we do not yet understand the extent of the role or the extent to which reduction in the CB1 receptors cause mental or physical problems. The study was only presented, and has yet to be published in a peer-reviewed journal, so the data and the conclusions are preliminary.


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