American Heart Association Releases Statement on Cannabis and Brain Health 

A new American Heart Association (AHA) scientific statement published in Stroke states that although there is a perception that cannabis is harmless, there is some scientific evidence challenging that belief. The statement also notes there are many unanswered questions about its impact on brain health. This is the AHA’s first scientific statement on cannabis and brain health.

Studies have had mixed results with tetrahydrocannabinol (THC), the psychoactive component of cannabis, and cannabidiol (CBD), the nonpsychoactive component, use. Some suggest a higher risk of cognitive impairment, but further research is needed on exact consequences.

Cannabis is classified by Drug Enforcement Agency (DEA) as a schedule 1 controlled substance for having a high potential for abuse. The schedule 1 designation limits opportunities to do controlled prospective studies on the effects of cannabis and cannabinoid derivatives. 

Research needs include:
o    If cannabis’ impact on brain health differs with age,
o    Possible cannabis interactions with other medications,
o    Differences between recreational or prescribed use,
o    The amount of cannabis that is too much,
o     Effects of different types of cannabis,
o    Effects of smoking or consuming cannabis.

Limited observational studies suggest: 
o    THC-dominant cannabis may affect driving ability,
o    Use in pregnancy may affect offspring cognitive function,
o    Adolescent cannabis use shows thinning in the brain involved in cognition,
o    Structural changes in the brain were visible in cannabis users,
o    Users were found to have increased stroke risk.

“There’s a lot of uncertainty in the medical community about the health effects of marijuana. This scientific statement is intended to guide health care professionals in having a balanced and intentional discussion with patients about the potential known and unknown effects of marijuana on brain health,” said writing group chair Fernando D. Testai, MD, PhD, FAHA, a professor of neurology and rehabilitation at the University of Illinois at Chicago.

“Our understanding of the effects of marijuana on the brain is imperfect, and human research in this area is a work in progress. Still, the results of recent animal studies challenge the widely accepted idea that cannabinoids are harmless and call for caution when using marijuana, particularly while pregnant or during adolescence,” said Testai.