Every time a headline about cannabis and the brain pops up, most people jump to one of two extremes: “See, it’s harmful” or “See, it’s medicine.”
This new dataset based study out of CU Anschutz is a good reminder that reality is usually more nuanced.
Using UK Biobank data, researchers looked at 26,362 adults ages 40 to 77 and asked a simple (but important) question: How does lifetime cannabis use relate to brain structure and cognitive performance in midlife and older age?
What they found (in plain English)
1) Larger volume in several brain regions
Lifetime cannabis use was positively associated with regional brain volume in several CB1 rich areas, including the caudate, putamen, hippocampus and amygdala.
2) Better performance on several cognitive measures
Greater lifetime use was also linked with better performance in learning, processing speed, and short term memory (in this sample).
3) “Moderation” often looked best
In the CU Anschutz summary and Q&A, the researcher notes that moderate use frequently showed the most favorable pattern across many outcomes, with a few exceptions.
4) It wasn’t uniformly “positive”
They also observed at least one region where higher use related to lower volume (posterior cingulate), which reinforces the point that cannabis effects can be complex and region specific.
5) Sex differences showed up
The paper reports sex differences in cannabis effects on brain volume and cognition, which is consistent with what we understand about biological variability in the endocannabinoid system.
The part people must not skip: what this study can’t prove
This is observational, population level research. It shows associations, not cause and effect.
A few key limitations (and they matter a lot):
- No product details. The dataset doesn’t tell us THC vs CBD, potency, route of administration, or exact patterns over time.
- Lifetime use is self reported. Helpful, but imperfect.
- Cannabis “then” isn’t cannabis “now.” Many participants used cannabis years ago, when products looked very different than today’s high potency market.
So no, this is not a green light to say “more cannabis = better brain.”
What I take away from this as an evidence first educator
If you work with older adults (or you are one), this research adds an important counterweight to the one sided narrative that cannabis and cognition only move in one direction.
It suggests we need better questions, like:
- What type of cannabis (THC dominant vs CBD dominant) matters most for brain aging?
- What dose range is “helpful,” “neutral,” or “harmful” for different people?
- How do sleep, pain, inflammation, mental health, alcohol use and medications interact with cannabis use in aging brains?
And most importantly: we need the next step, which is well designed clinical trials in older adults that reflect what people actually use today.
Practical, responsible guidance (not medical advice)
If someone is considering cannabis for sleep, pain, or quality of life in midlife or older age, the safest evidence aligned approach is still:
- Start low, go slow
- Prefer clear labeling and third party testing
- Be cautious with high THC products, especially if fall risk, anxiety, or cognitive concerns exist
- Talk to a clinician if there are cardiac issues, anticoagulants, sedatives, opioids, or complex medication regimens
CTA
If you want more evidence based breakdowns like this, follow my work through Herbal IQ Education. I translate the science into plain language, separate signal from noise, and keep the conversation honest, especially when the data is nuanced.
If you’re a clinician, caregiver, retailer, or public health leader, drop a comment with the question you wish researchers would answer next about cannabis and aging.
References
- CU Anschutz News (Feb 3, 2026). Study Finds Cannabis Usage in Middle Aged and Older Adults Associated With Larger Brain Volume, Better Cognitive Function.
- Guha A, Fu Z, Calhoun V, Hutchison KE. Lifetime Cannabis Use Is Associated with Brain Volume and Cognitive Function in Middle Aged and Older Adults. Journal of Studies on Alcohol and Drugs. 2025 Dec 11. doi:10.15288/jsad.25-00346.
Disclaimer
Educational content only. This is not medical advice, and it’s not a recommendation to use cannabis. Cannabis products can impair attention, coordination, and judgment, and may interact with medications. Regulations vary by state. Nothing here is intended to diagnose, treat, cure, or prevent any disease.
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