Study Suggests Cannabis Use May Increase Brain Volume and Cognitive Function in Older Adults

While cannabis has recently faced criticism for potential negative health effects, a new study from the University of Colorado Anschutz Medical Campus indicates that moderate cannabis use might actually increase brain volume and cognitive fitness in middle-aged and older adults.

Researchers analyzed data from the UK Biobank, examining cannabis usage patterns, brain scans, and cognitive test results from more than 26,000 adults aged 40 to 77. Their findings revealed that cannabis users—particularly those reporting moderate lifetime usage—demonstrated larger volumes in several key brain regions.

“Compared to individuals with no history of cannabis use, those who reported using cannabis showed larger volumes in several brain regions characterized by a high density of cannabinoid (CB1) receptors—regions involved in processes such as memory, information processing and emotion regulation,” explained lead study author Anika Guha, PhD, a researcher at the University of Colorado Anschutz Medical Campus.

These cannabis users also performed better on cognitive tests measuring learning, processing speed, and executive function. This outcome differs significantly from previous research, which has typically focused on short-term cognitive impairment during or immediately following cannabis use.

“These findings suggest that the relationship between cannabis and the brain may differ across the lifespan, and that moderate use in mid-to-later adulthood may be associated with positive brain health outcomes,” Guha noted.

However, the study did find that not all brain regions benefited from cannabis use. The posterior cingulate, which plays a role in self-reflection and memory, showed lower volume with higher marijuana use.

Potential Implications for Aging Populations

As cannabis usage rises across all age groups, understanding its long-term effects becomes increasingly important. Matt Glowiak, PhD, chief addiction specialist with Recovered, an organization providing mental health and addiction treatment resources, believes this type of research is critical.

“Given the connection between cannabis use and larger brain volume, it is believed that it may help older individuals retain cognitive function that might otherwise naturally decline,” said Glowiak, who was not involved in the study. “This is a huge benefit, but one we need to explore a bit further, ahead of encouraging those who would otherwise not consider integrating cannabis into their healthcare regimen.”

Study Limitations Prompt Caution

Despite the promising findings, experts urge caution in interpreting the results. As an observational study, it establishes association rather than causation between cannabis use and brain health.

Dr. Marc Siegel, Fox News senior medical analyst, who was not involved in the research, pointed out that the study contradicts previous evidence. “The preponderance of previous evidence does not line up with improved cognitive function from chronic cannabis use,” Siegel said. “This study is an outlier, and though it cannot be ignored, it is not justification for use.”

The researchers also acknowledge significant limitations in their data. While the UK Biobank offered a large dataset, it only provided broad measures of lifetime cannabis use without details about consumption methods, potency, type of cannabis, or timing of heaviest use.

“Those details likely matter a great deal for understanding how cannabis affects the aging brain,” Guha emphasized. She suggested the findings should be viewed as a starting point for more targeted research rather than definitive evidence.

Medical Implications and Recommendations

Dr. Alex Dimitriu, double board-certified in psychiatry and sleep medicine, called this study an “outlier” compared to most previous research showing “detrimental effects” from cannabis use.

“Given the widespread use and legalization of cannabis, it would be great to know that it is net-positive for brain health—however, this feels too good to be true, and too early to claim,” he cautioned. “I would advise proceeding with caution and moderation.”

Experts agree that cannabis effects likely depend on numerous factors including age, dosage, frequency, product composition, and individual vulnerability. They emphasize that individuals should consult healthcare providers before initiating cannabis use, particularly those with mental health concerns, as THC can exacerbate symptoms such as psychosis in vulnerable individuals.

“The takeaway is not that people should start using more cannabis based on these findings alone,” Guha stressed. “While cannabis may have potential benefits in some contexts, a substantial body of research also documents important risks, underscoring that cannabis is neither completely beneficial nor completely harmful.”

As cannabis legalization continues to expand globally, researchers call for more comprehensive studies to fully understand its complex effects on brain health across different age groups.