AHA: Effects of marijuana on brain health, function still unclear

In a new statement, the American Heart Association presented scientific evidence that challenges the belief that marijuana is harmless and highlights uncertainty about the drug’s effect on brain health.

The statement was published in the Association’s journal, Stroke, and presented and discussed during a symposium at the AHA International Stroke Conference in New Orleans.

According to AHA, marijuana use in the U.S. is increasing, particularly among adolescents and young adults, with about one-third of high school seniors and nearly half of all college students reporting use of the drug in 2018.

In addition, medicinal and/or recreational use of marijuana has been legalized or decriminalized in many states in the past 20 years, and the concentration of THC in cannabis products has increased from approximately 4% in 1995 to 15% in 2018.

The FDA and DEA classify cannabis as a Schedule I controlled substance, similar to heroin and LSD, both of which possess high potential for abuse and lack medical benefits. In contrast, hemp-derived CBD is legal, as it contains less than 0.3% THC.

“There’s a lot of uncertainty in the medical community about the health effects of marijuana,” Fernando D. Testai, MD, PhD, FAHA, a professor of neurology and rehabilitation at the University of Illinois at Chicago, said in a press release. “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.”

Key findings from human research studies, which are summarized in the scientific statement, include:

• People scored worse on driving tests when using THC-dominant marijuana, compared with CBD-dominant marijuana or no marijuana.

• Young adults who participated in a 25-year heart disease research project showed a decline in verbal memory test scores as self-reportage of marijuana use increased.

• Mothers who reported marijuana use during pregnancy had children with psychological problems and poorer cognitive function.

• Cannabis users have an increased risk of clot-caused stroke, with one study revealing a 17% increase and another finding 24% more strokes among users.

The statement also highlights several questions on the effect of cannabis on brain health and emphasizes the need for further study.

“Our understanding of the effects of marijuana on the brain is imperfect, and human research in this area is a work in progress,” Testai said.

Reference:

Testai FD, et al. Stroke. 2022;doi:10.1161/STR.0000000000000396.