Cannabis abuse causes abnormalities of the cannabinoid receptors in the brain

It really, really – I mean really – ain’t your daddy’s dope any more. In fact, it ain’t the weed of the 60s, 70s or 80s. It’s not even the smoke of the 90s.

And now, (Surprise! Surprise! Or maybe not so!?!?) comes news that that today’s more powerful THC (delta-9-tetrahydrocannabinol – the psychoactive ingredient in marijuana) doesn’t just attach to receptor sites in the brain; it also attaches to receptors through the body and involved in a wide range of digestive, cardiovascular, respiratory and other systems. In the brain, it influences mental states including pleasure, concentration, perception of time and memory, sensory perception, and coordination of movement.

While CB1 receptors involve functions in the Central Nervous System, CB2 involved the immune system and stem cells in the circulatory system.

The effects of cannabis and receptors in the brain“With this study, we were able to show for the first time that people who abuse cannabis have abnormalities of the cannabinoid receptors of the brain,” reported Jussi Hirvonen, MD, PhD, lead author of a collaborative study between the National Institute of Mental Health and the National Institute on Drug Abuse. The report was issued during the Society of Nuclear Medicine’s 58th Annual Meeting, June 4-8, 2011, San Antonio, Texas.

One item of good news emerging from the study is that this research shows that the decreased receptors in people who abuse cannabis return to normal when they stop smoking the drug. In addition, this new information may provide critical information for the development of new treatments for cannabis abuse.

The researchers recruited 30 chronic cannabis smokers and monitored them closely at an inpatient facility for approximately four weeks. Positron Emission Tomography (PET) provided information about physiological processes in the body. Subjects received injections of a radioligant, 18F-FMPEP-d2 – a combination of radioactive fluorine isotope and a neurotransmitter analog that binds with CB1 brain receptors.

Results of the study indicate that – when compared to healthy control subjects with limited exposure to cannabis during their lifetime – chronic smokers experienced a decrease of about 20 percent in the number of receptors. These changes were found to have a correlation with the number of years subjects had smoked. After a month of abstinence, 14 of the subjects had a second PET scan that indicated that there was a marked increase in receptor activity in those areas that had been decreased at the outset of the study – an indicator that, although chronic cannabis smoking causes downregulation of CB1 receptors, the damage is reversible with abstinence.

For further information, see the SNM press release:

Posted in: Addiction, Neuroplasticity

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