Study Finds No Link Between Lifetime Cannabis Use and Cognitive Decline in Older Adults

Research shows cannabis use is not associated with increased dementia risk or accelerated cognitive aging.

Published on Mar. 5, 2026

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A new study published in the journal BMJ Mental Health has found that cannabis use by older adults is not associated with either accelerated cognitive decline or greater risk of dementia. Researchers from Yale University and the University of Oxford analyzed data from two large national cohorts, the UK Biobank and the US Million Veteran Program, consisting of hundreds of thousands of participants. The study concluded that those with a history of cannabis use 'demonstrated significantly better cognitive performance' compared to non-users, and that cannabis use 'was not associated with increased risk of dementia' or evidence of a causal link to cognitive decline in later life.

Why it matters

These findings contradict longstanding stereotypes about cannabis use and cognitive aging, which often go unchallenged in the media. The results add to a growing body of research suggesting cannabis may have neuroprotective effects and could even be associated with better brain health and function in older populations, especially in brain regions rich in cannabinoid receptors.

The details

The study's authors assessed cognitive performance across various domains including memory, intelligence, and problem solving. They reported that lifetime cannabis consumers 'demonstrated significantly better cognitive performance' compared to non-users. The researchers found 'no supporting evidence of a causal link with [longitudinal] cognitive decline in later life' and that cannabis use 'was not associated with increased risk of dementia'.

  • The study was published on March 5, 2026 in the journal BMJ Mental Health.

The players

Yale University

A prestigious Ivy League research university where some of the study's investigators were affiliated.

University of Oxford

A renowned British research university that also had investigators involved in the study.

UK Biobank

A large national cohort study in the United Kingdom that provided data for the research.

US Million Veteran Program

A national cohort study in the United States that also contributed data for the analysis.

NORML

The National Organization for the Reform of Marijuana Laws, whose Deputy Director Paul Armentano commented on the findings.

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What they’re saying

“These results contradict one of the more prominent and longstanding stereotypes about cannabis and cannabis consumers. It is unfortunate that these stereotypes often go unchallenged in the media and elsewhere. It is even more unfortunate that studies refuting these long-held stereotypes seldom receive the type of mainstream attention they deserve.”

— Paul Armentano, Deputy Director, NORML (NORML)

The takeaway

This study adds to a growing body of evidence suggesting that cannabis use may have neuroprotective effects and could even be associated with better cognitive performance and brain health in older adults, challenging longstanding stereotypes about the drug's impact on the aging brain.