January 9, 2021

New Research Shows How Marijuana Drops Blood Flow to the Brain. Should You Be Concerned?

Reported rates of marijuana use have more than doubled in the past decade. Medical marijuana is now legal in nearly half of US states, and is increasing access to the drug for current and potential future users. Although it is often portrayed as harmless, and sometimes even therapeutic, there has not been nearly enough studies done to prove this. In fact, marijuana is often prescribed for issues like anxiety, though studies cannot comprehensively show this to be true. The current available information of the impact marijuana has on the neurophysiology of the brain show, predominantly, depressive effects. 

In a recent study using PET imaging to demonstrate the release of dopamine in the striatum, a region of the brain that is involved in working memory, impulsive behavior, and attention, results showed that heavy marijuana use has similar dopamine releasing behaviors as cocaine and heroin. Several studies in chronic cannabis users show structural changes to the hippocampus persist, even after six months of abstinence. 

U.S. Surgeon General Dr. Vivek Gupta has already warned that we’re too quick to legalize the popular drug, when research still hasn’t shown whether or not it’s truly safe. With Dr. Daniel Amen’s new research, there is proof that Dr. Gupta’s concerns are well warranted.

Just published in the most recent Journal of Alzheimer’s Disease, the research finds that, after studying imaging of 1,000 cannabis users’ brains, there were signs of noticeable deficiencies of blood flow.  The study, which included 25,168 non-cannabis users, and 100 healthy controls, shows a scary and obvious difference in blood flow levels for those that used cannabis. Additionally, those that used marijuana showed significant lack of blood flow in the right hippocampus, the area of the brain that helps with memory formation. This part of the brain is severely affected with those that suffer from Alzheimer’s Disease.

Research has proven that marijuana users have lower cerebral blood flow than non-users. The most predictive region separating these two groups is low blood flow in the hippocampus on concentration brain SPECT imaging.This work suggests that marijuana use has damaging influences in the brain – particularly regions important in memory and learning and known to be affected by Alzheimer’s. Our research demonstrates that marijuana can have significant negative effects on brain function.The media has given the general impression that marijuana is a safe recreational drug, this research directly challenges that notion.

Several studies of perfusion imaging in marijuana users have shown similar results compared to ours. A small O15 PET study in a sample of 12 marijuana users used a randomized clinical trial design to examine brain perfusion before and after marijuana use. The study results found frontal, temporal and occipital lobe hypo-perfusion – all findings concordant with our study.

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