Chronic Pot Smoking Affects Brain Chemistry, Scans
TUESDAY, June 7 (HealthDay News) -- Imaging scans show that
chronic daily use of marijuana can have a detrimental effect on the
brain, according to a new report.
In the study, researchers revealed that chronic use of the drug
caused a decrease in the number of receptors involved in a wide
array of important mental and bodily functions, including
concentration, movement coordination, pleasure, pain tolerance,
memory and appetite.
Marijuana, also known as cannabis, is abused more than any other
illegal drug in America, according to the U.S. National Institute
on Drug Abuse. When smoked or ingested, the drug's psychoactive
chemical binds to numerous cannabinoid receptors in the brain and
throughout the body, which influence a range of mental states and
actions. One of two known types of cannabinoid receptors, called
CB1, is involved primarily in the central nervous system.
In conducting the study, researchers compared the brains of 30
chronic daily marijuana smokers to non-smokers over the course of
roughly four weeks. Using molecular imaging, researchers were able
to visualize changes in the participants' brains and found the
cannabinoid CB1 receptors of the smokers had decreased by roughly
20 percent compared to the otherwise healthy people with limited
lifetime exposure to marijuana.
"With this study, we were able to show for the first time that people who abuse cannabis have abnormalities of the cannabinoid receptors in the brain," lead author Dr. Jussi Hirvonen said in a Society of Nuclear Medicine news release.
The researchers re-scanned 14 of the smokers after one month of
abstinence and found a notable increase in receptor activity in
areas that were deficient at the beginning of the study. These
findings, the investigators concluded, suggest the adverse effects
of chronic marijuana use are reversible.
"This information may prove critical for the development of novel treatments for cannabis abuse. Furthermore, this research shows that the decreased receptors in people who abuse cannabis return to normal when they stop smoking the drug," Hirvonen added.
The study, which was a collaboration between the U.S. National
Institute of Mental Health and U.S. National Institute on Drug
Abuse, was slated for presentation Monday at the annual meeting of
the Society of Nuclear Medicine in San Antonio, Texas. Because this
study was presented at a medical meeting, the data and conclusions
should be viewed as preliminary until published in a peer-reviewed
The U.S. National Institute on Drug Abuse has more on
marijuana and its effects on the brain.
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