Study Shows Lifetime Cannabis Use Not Associated with Cognitive Decline or Dementia Risk in Older Adults

New Haven, CT - Cannabis use by older adults is not associated with either accelerated cognitive decline or greater risk of dementia, according to findings published in the journal BMJ Mental Health.

Investigators affiliated with Yale University and the University of Oxford in the United Kingdom assessed cognitive performance in lifetime cannabis consumers and non-users across various domains — including memory, intelligence, and problem solving. Data was drawn from two large nationally representative cohorts (the UK Biobank and the US Million Veteran Program), consisting of several hundred thousand participants.

Researchers reported that those with a history of cannabis use “demonstrated significantly better cognitive performance,” a finding that is consistent with prior studies. Cannabis use “was not associated with increased risk of dementia” and researchers found “no supporting evidence of a causal link with [longitudinal] cognitive decline in later life.”

The study’s authors concluded: “This study represents one of the largest observational investigations to date examining the relationship between cannabis use, cognitive function and dementia risk in older adults. … Our findings are broadly consistent with prior population-based longitudinal studies that have not observed accelerated age-related cognitive decline associated with cannabis use. … Clinicians can consider that occasional or prior cannabis use may not be a major contributor to cognitive aging in this population.”

Commenting on the findings, NORML’s Deputy Director Paul Armentano said: “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.”

Several other recent studies have reported similar results. For example, an Israeli study of over 67,000 older adults reported that participants with a history of cannabis use “performed better across all cognitive domains: attention, executive function, processing speed, visual and working memory. … Additionally, past use was associated with a slower decline in executive function.”

A Danish study similarly concluded that cannabis consumers experienced “significantly less cognitive decline” over their lifetimes than did non-users.

Most recently, a study published in January in the Journal of Studies on Alcohol and Drugs concluded: “Greater lifetime [cannabis] use was also associated with better performance on cognitive tasks assessing learning, memory, processing speed, and task switching, aligning with growing evidence of potential neuroprotective effects of cannabis in aging populations. … This study adds to a growing body of evidence that cannabis use may be associated with greater brain volume and cognitive performance in aging adults, especially in regions rich in cannabinoid receptors.”

The full text of the study, “Cannabis use, cognitive function and dementia risk in older adults: Observational and genetic analysis,” is available online. Additional information is available from the NORML Fact Sheet, “Marijuana Exposure and Cognitive Performance.”

NORML advocates for changes in public policy so that the responsible possession and use of marijuana by adults is no longer subject to criminal penalties. NORML further advocates for a regulated commercial cannabis market so that activities involving the for-profit production and retail sale of cannabis and cannabis products are safe, transparent, consumer-friendly, and are subject to state and/or local licensure. Finally, NORML advocates for additional changes in legal and regulatory policies so that those who use marijuana responsibly no longer face either social stigma or workplace discrimination, and so that those with past criminal records for marijuana-related violations have the opportunity to have their records automatically expunged.

Find out more at norml.org and read the NORML Fact Sheets on the most common misconceptions and myths regarding cannabis and cannabis policies.