Moderate Cannabis Use Linked to Better Cognition in Older Adults
/By Pat Anson
As cannabis use grows among older adults, researchers are beginning to focus on the effects – good and bad — on aging brains.
A recent study found that 18.5% of Americans adults aged 50 to 64, and 5.9% of adults over the age of 65 reported using cannabis products in the past year. About one in four used cannabis for medical purposes.
“More older adults are using cannabis. It's more widely available and is being used for different reasons than in younger folks – such as for sleep and chronic pain,” said Anika Guha, PhD, a clinical psychologist and researcher at the University of Colorado Anschutz Medical Campus.
“Plus, people are living longer. We have to be asking, ‘What are the long-term effects of cannabis use as we continue to age?’”
Guha is the lead author of a study, recently published in the Journal of Studies on Alcohol and Drugs, that analyzed the brain scans and cognitive test results of over 26,000 UK adults between the ages of 40 and 77.
Researchers found larger brain volumes and better cognitive function among middle aged and older adults who used cannabis, especially those who used it moderately. .
“We did see that for many of our outcome measures, moderation seemed to be best. For the brain regions and cognitive tests that demonstrated an effect, the moderate-use group generally had larger brain volumes and better cognitive performance,” Guha explained.
Moderate use of cannabis was associated with better performance in learning, processing speed, short-term memory, and cognition than non-users.
Guha was surprised by the extent of the positive findings, but also cautious about interpreting them. Cannabis research is difficult due to the wide range in potency and different forms of ingestion for cannabis products.
Guha and her team are particularly interested in brain regions that have more cannabinoid receptors – called CB1s – which are more likely to be impacted by cannabis use.
“Some studies will just say there was an impact of cannabis on overall gray (brain) matter. However, we wanted to take a more nuanced approach by looking at effects on specific brain regions, especially those with high CB1 receptor density, as well as on cognitive processes like memory, which is, of course, very relevant to aging,” Guha explained.
“For example, the hippocampus was one of the regions we looked at since it contains many CB1 receptors and plays an important role in memory, especially as we age, and is also implicated in dementia.”
Brain volume has a tendency to shrink as we age, due to atrophy and neurodegeneration. The decrease is often associated with reduced cognitive function and increased dementia risk.
Cannabis use was associated with reduced volume in only one part of the brain – the posterior cingulate – which helps process memory, learning, and emotion.
“I think the main takeaway is that the story is nuanced. It’s not a case of cannabis being all good or all bad. I think sometimes people have seen my poster on this project or they see the headline and they say, "Great, I'll just use more cannabis." But it’s more complicated than that,” Guha said. “There’s so much more to explore.”
Most medical organizations still take a dim view of cannabis. The American College of Physicians (ACP) released a new guideline last year that recommends against the use of medical cannabis.
The ACP said physicians should warn patients that the harms of cannabis outweigh its potential benefits. Medical cannabis may produce small improvements in pain, function and disability, but the ACP warns it could lead to addiction and cognitive issues, as well as cardiovascular, gastrointestinal and pulmonary problems.
