Cannabis use is on the rise. As legal access to this medical and recreational drug has increased over the last decade, more and more people have started using cannabis. And this year Covid-19 stresses have only increased the demand for cannabis, causing big increases in cannabis use. Older adults have been no exception to this trend, with more seniors turning to cannabis for medical needs like treating chronic pain, depression and sleep disturbances or as a recreational option. Still, some have worried that older adults (who may already have increased risks of cognitive decline) could be putting themselves at additional risk by using this mind-altering plant.
But now a new study suggests medical cannabis use isn't associated with cognitive problems in older adults.
Previous studies have tied cannabis use in young adults to risk of mild but long-term cognitive impairments like small drops in IQ. While other research suggests that cannabis isn't actually to blame for these drops, it is still an open question and has raised concerns that cannabis may impact cognition in another vulnerable group - seniors.
To add to the complex pictures, some animal studies suggest that THC, the most common chemical in cannabis, may actually improve cognitive function in seniors - as it did in some studies on elderly mice.
This has led researchers to wonder what impact cannabis and its active chemicals might actually have when it comes to cognitive function in older adults. Could it improve cognitive functioning or worsen it? Might it have no effect at all?
Unfortunately, few human studies have looked specifically at this question, and the studies on younger cannabis users can't be used to evaluate risks for older adult.
"The brain in late-life differs from that of young individuals as it goes through multiple changes including in global and regional volumes, and in patterns of neural activity" the authors of the study explain. "Hence, results from studies of early-life exposure to cannabis use are unlikely to translate to elderly users."
The new study, conducted by researchers in Israel, looked specifically at whether adults over 65 were at risk from cognitive impairment when using medical cannabis.
To test whether elderly medical cannabis patients were more likely to have cognitive issues, researchers recruited older patients with a chronic pain condition. 63 of these patients used medical cannabis, while 62 did not. Then, at a time when the medical cannabis patients had not used cannabis for at least 3 hours, they assessed their cognitive function with a variety of measures for assessing psychomotor reaction time, attention, working memory and new learning.
The results showed no statistically relevant differences between the two groups when it came to cognitive function. Both before and after the researchers made adjustments for potential confounding factors - the medical cannabis users showed similar cognitive abilities to the group that wasn't using cannabis. Researchers even evaluated whether cognitive differences could be tied to differences in dosage, the frequency or length of use, or the concentration of THC or CBD, but found no significant associations.
The authors of the study conclude that "these results suggest that use of whole plant medical cannabis does not have a widespread impact on cognition in older chronic pain patients" adding that "considering the increasing use of medical cannabis in older populations, this study could be a first step towards a better risk– benefit assessment of medical cannabis treatment in this population."
Still the authors point out the study has some limitations. For one thing, the study design doesn't give us information about cause and effect relationships between cannabis and cognitive function. They can't say for sure from this that cannabis doesn't cause cognitive issues for older adults, they just have added evidence that the two aren't statistically associated with each other. While this gives us some evidence for assessing risk, future studies with a different design could tell us more about whether cannabis plays a causal role in cognitive changes for older adults.
The researchers also didn't collect information on other medications the participants were taking, which could have played a role in cognitive functioning outcomes. It's also possible that cannabis could impact areas of cognition that weren't measured in this study - or that the measures used weren't sensitive enough to pick up differences that existed between the two groups.
To add to this, the study looked specifically at patients with chronic pain. While chronic pain is the most common reason people use medical cannabis, it’s possible that the results would vary when using cannabis for other conditions.
Thus the authors say that while their study provides moderately strong evidence for the lack of an association between cannabis use and cognitive decline in older adults, "future studies are urgently needed to further clarify the implications of late-life cannabis use for brain health."