American Heart Association statement warned marijuana may adversely affect brain health | Research

The takeaway

The American Heart Association issued a scientific statement concluding that marijuana use may impair cognition, particularly during neurodevelopment, and that combined with increased stroke risk, raises concerns about long-term brain health.

Healthcare providers counseling patients about marijuana use, policymakers, and marijuana users concerned about long-term brain health.

Major medical society warns marijuana may adversely affect brain health

What the researchers found

Cannabinoid receptors are concentrated in brain areas critical for cognition and behavior, especially during neurodevelopment. Animal models show exogenous cannabinoids disrupt synaptic plasticity and neurodevelopment. Observational human studies report higher cognitive impairment risk. Whether effects reverse with abstinence remains unclear.

Why it matters

The AHA scientific statement represents a major medical society taking a formal position on marijuana and brain health, carrying significant weight for clinical practice, policy, and public health messaging.

The numbers in context

Cannabinoid receptors are expressed at high density in cognition and behavior-related brain areas. Active ingredient concentrations in recreational cannabis have gradually increased. High-potency illicit cannabinomimetics have become available.

How the study worked

Scientific statement from the American Heart Association reviewing preclinical and clinical evidence on marijuana effects on brain health, including cannabinoid receptor distribution, neurodevelopmental effects, cognitive outcomes, and stroke risk.

What this study cannot tell us

As a scientific statement rather than original research, it synthesizes existing evidence. The statement acknowledges that it is unclear whether cognitive effects reverse with abstinence and that observational human data have limitations.

How to read the evidence

Strong: formal scientific statement from the American Heart Association synthesizing preclinical and clinical evidence.

When this study was published

Published in 2022.

The bigger picture

This statement combines two emerging concerns: marijuana's cognitive effects and its association with stroke. Together, they suggest that marijuana may affect brain health through multiple pathways, warranting more research and public awareness.

Questions still open

Does marijuana directly cause cognitive decline, or do shared risk factors explain the association? At what frequency and potency does marijuana use become a brain health concern? Should cardiovascular risk assessment include marijuana use screening?

Common questions

What does the AHA say about marijuana and the brain?

The AHA concludes that marijuana may adversely affect brain health, particularly during periods of active neurodevelopment (adolescence and young adulthood), and that this concern is compounded by marijuana's association with increased stroke risk.

Do the cognitive effects reverse if you stop using?

The AHA states this remains unclear. Some studies suggest partial recovery with abstinence, but whether full reversal occurs is not established.

Why is the AHA issuing a statement about marijuana?

The AHA is concerned about both the direct cardiovascular effects of marijuana (including stroke risk) and the potential long-term cognitive consequences, particularly as marijuana use and potency continue to increase.

Read the original research

Use of Marijuana: Effect on Brain Health: A Scientific Statement From the American Heart Association.

Stroke, 53(4), e176-e187

View on PubMed ↗Publisher’s paper ↗

Citation

Testai, Fernando D; Gorelick, Philip B; Aparicio, Hugo J; Filbey, Francesca M; Gonzalez, Raul; Gottesman, Rebecca F; Melis, Miriam; Piano, Mariann R; Rubino, Tiziana; Song, Sarah Y. (2022). Use of Marijuana: Effect on Brain Health: A Scientific Statement From the American Heart Association.. Stroke, 53(4), e176-e187. https://doi.org/10.1161/STR.0000000000000396