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Regular smoking of tobacco decreases the number of cannabinoid CB1 receptors, the “pot receptor” in human brain. CB1 receptors play a role in smoking. According to previous studies that report the same finding in people who abuse cannabis or alcohol, suggesting that reduction of CB1 receptors is a common feature of addiction.
Researchers measured the number of receptors in the participants by using a brain imaging technique to detect a drug that binds to CB1 receptors. The analysis indicated close to 20 percent reduction in CB1 receptors in the brains of smokers compared to non-smokers. The reduced receptor number was present throughout the brain with some regions more affected than others.
According to Jussi Hirvonen, MD, Ph.D., of NIH and University of Turku, Finland. Dr. Hirvonen and Paolo Zanotti-Fregonara, MD, Ph.D., of NIH and Houston Methodist Research Institute, Texas, reduction of CB1 receptors may be unhealthy because these receptors are involved in many normal brain functions, such as memory and coping with stress.
A drug that blocks CB1 receptors- rimonabant has been tested in clinical trials for smoking cessation. Although the drug seemed to help people quit smoking, it caused problematic psychiatric side effects. The findings have important and immediate implications for research examining the role of the brain’s cannabinoid system in the cause of neuropsychiatric disorders. Smoking is common in people with neuropsychiatric disorders.