It is said that smoking cannabis sharpens all the senses except the common one. New research out of the United Kingdom indicates that lifetime cannabis use is associated with “better cognitive performance” from age 40 to 70 than non-users.

The research is not a small sample size. As is often the case with studies done in countries that have national healthcare, the sample size is orders of magnitude larger than most U.S. studies. The researchers compared the results from 26,362 lifetime cannabis users against 500,000 non-users.

The data came from the UK Biobank and involved examining the brain scans of individuals from 40 to 70 years of age. The analysis came from two researchers at the Department of Psychiatry at the University of Colorado Anschutz and two researchers at the TReNDS Center at Georgia State University.

The study was published late last year in the Journal of Studies on Alcohol and Drugs. The key findings include:

Lifetime cannabis use was positively associated with regional brain volume in CB1-rich regions, including the caudate, putamen, hippocampus, and amygdala. Greater lifetime use was also linked to better performance in learning, processing speed, and short-term memory.

In what sounds like an advertisement for THC products, the researchers conclude that cannabis “potentially offers protective effects in older age while posing risks earlier in development.” Cannabis? Protective effects? Better short-term memory? This sounds seriously at odds with everything we know about cannabis use disorder.

In an interview for MedicalXpress, lead author Anika Guha, Ph.D., a clinical psychologist and faculty research associate at the University of Colorado Anschutz, indicated that cannabis shows promise for treating mental health disorders and even dementia.

Dr. Guha cautions that more brain volume is not necessarily a good sign. However, low brain volume is associated with “reduced cognitive function and increased dementia risk.” Asked if she was surprised by the findings, Dr. Guha replied:

I was a little surprised that every cognitive measure that demonstrated a significant effect showed better performance among cannabis users. It goes against your default assumptions, because I think a lot of research out there has shown cannabis is associated with worse cognitive function, at least acutely.

The New York Post reports that one in five people ages 50-65 used marijuana in the past year, and 6% of those over 65 report using the drug. They say that usage among seniors is on the rise due to “chronic pain, sleep disorders and anxiety.”

The New York Post also points to a study from Denmark of 5,162 men that showed “significantly less cognitive decline” for lifetime cannabis users. That study was published in the journal Brain and Behavior at the end of 2024.

What this research points to, more than anything else, is the need for a lot more research. Dr. Guha would like to be able to isolate the impacts of CBD vs. THC use, but none of the databases currently have this information. Also, gender differences were observed in the U.K. data, and the Danish study was conducted with men only.

We have much more to learn about both the negative and positive impacts of using marijuana, cannabis, CBD, and THC. Fortunately, the lower classification of marijuana is making it easier to get research funded. Certainly, huge studies such as the U.K. study demand greater investigation.

Written by Steve O’Keefe. First published February 18, 2026.

Sources:

“Lifetime Cannabis Use Is Associated with Brain Volume and Cognitive Function in Middle-Aged and Older Adults,” Journal of Alcohol and Drugs, December 11, 2025.

“Q&A: Cannabis usage in middle-aged, older adults linked to larger brain volume, better cognitive function,” MedicalXpress, February 3, 2026.

“Researchers ‘surprised’ by the brain benefits of cannabis usage in adults over 40,” New York Post, February 7, 2026.

“Cannabis Use and Age‐Related Changes in Cognitive Function From Early Adulthood to Late Midlife in 5162 Danish Men,” Brain and Behavior, November 7, 2024.

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