The Benefits of Daily Cannabis for the Middle-Aged Brain. Chronic low-dose oral or inhaled cannabis may improve working memory.

Key points

• Regular, daily cannabis use in older adults, particularly after retirement, has quadrupled.
• Cannabis affects the brain differentially across the lifespan, and older brains may benefit from daily use.
• Daily cannabis use produced cognitive improvement and reduced brain inflammation in aged humans and animals.
• Low-dose, daily cannabis did not impair and can even provide significant benefits to middle-aged humans.

Cannabis use among older adults (over the age of 65) is growing rapidly.

The National Survey on Drug Use and Health indicated that between 2015 and 2023, the prevalence of self-reported previous year use increased from 2.4 to 6.9 percent. Cannabis use in older adults after retirement quadrupled during this same time. Among working-age older adults, aged 50 to 64 years, another recent study determined that 34 percent of women and 39 percent of men reported daily, or near-daily, use.

Most older users, primarily those between 50 and 60 years old, report that their most common reason for turning to cannabis is for pain reduction due to illness, particularly arthritis, or injury. Most patients report that cannabis has fewer unpleasant side effects than over-the-counter or prescription pain medications.

I’ve written extensively about how cannabis affects human brains differentially across the lifespan [go here to learn more about cannabis in the brain]. Most studies of cannabis use have focused on younger users—for good reason, as the developing or adolescent brain can experience serious negative effects from cannabis use. Research has shown that the normal development of the young or adolescent brain is significantly impaired, and the consequences can last into adulthood.

In contrast, numerous recent studies have shown the beneficial effects of long-term, low-level daily cannabis use in mature humans and animals. Zequeira et al. (2025), for example, examined the cognitive effects of cannabis administered via routes that more closely mimic those used frequently by older adults, such as via inhalation of burning plant product or voluntary oral consumption of purified THC (such as gummies). Their results in aged rats showed that repeated exposure to cannabis smoke enhanced working memory. The drug exposure had no effects on episodic or spatial memory. Chronic oral consumption of THC also enhanced working memory in aged animals. My laboratory published similar results previously (Marchalant et al., 2009).

Watson et al. (2022) assessed the relationship between long-term medical cannabis use and cognitive function in a sample of middle-aged and older patients with chronic pain. Their results suggest that the use of whole-plant medical cannabis does not have a negative impact on cognition in older patients.

It is critical to note that this study, as well as most other epidemiological studies, utilized the whole plant rather than specific extracts. The benefits of specific components of the plant remain to be fully defined. Indeed, the greatest benefits might only be realized from the aggregate actions of all the components of the plant.

Why Can Cannabis Be Beneficial in Old Age?

During normal aging, the number of endogenous cannabinoid receptors declines. The loss of these cannabinoid receptors correlates with an increased level of inflammation in these brain regions and a loss of neurons in the hippocampus.

This matters because the hippocampus is critical for learning and memory. The loss of cannabinoid receptors may contribute to age-related memory impairments.

Studies in my laboratory have shown that daily stimulation of cannabinoid receptors decreased brain inflammation and significantly increased hippocampal neurogenesis in old brains. These changes were associated with improved learning and memory. These results indicate that the potential benefits of cannabis for the aging brain are likely related to the reduction in regional neuroinflammation and the stimulation of available cannabinoid receptors on dormant stem cells.

Overall, the current evidence obtained from both human and animal research strongly indicates that low-dose, daily cannabis use does not impair—and may even provide significant benefit to—cognition in middle-aged humans and might effectively reduce the degenerative effects of chronic brain inflammation.

References

Courtesy of Psychology Today and the author Gary L. Wenk, PHD.