Cannabis use is becoming more widespread—and more openly discussed—raising important questions about how it affects the brain, especially as people age. With growing acceptance and increased availability of marijuana products, more individuals are turning to cannabis for both recreational and medical purposes. But beyond the immediate “high,” researchers are still uncovering its longer-term effects on brain health.
Recent data from the Substance Abuse and Mental Health Services Administration shows that about 15.4 percent of Americans aged 12 and older used cannabis within the past month in 2024. The trend is rising, particularly among older adults, with those aged 60 and above now the fastest-growing group of users. Many in this age group report using cannabis to manage conditions like pain, arthritis, sleep issues, anxiety, and depression.
Memory and Cognitive Effects
Cannabis use has been consistently linked to reduced working memory—the ability to hold and process short-term information. According to research published in JAMA Network Open in 2025, heavy lifetime users showed lower brain activity during memory tasks compared to nonusers. While this effect is most noticeable during intoxication, long-term users may also experience lingering memory challenges.
However, current evidence does not show a strong link between cannabis use and overall cognitive decline or dementia risk, though experts emphasize that more long-term studies are needed.
Changes in Brain Structure
Long-term cannabis use has also been associated with structural changes in the brain. Research highlighted in the journal Addiction found reduced volume in the amygdala, a region involved in emotional processing.
Interestingly, some studies suggest a more complex picture. Research published in the Journal of Studies on Alcohol and Drugs found that adults who began using cannabis later in life (after age 25) showed greater brain volume in certain regions. This has led researchers to explore possible “neuroprotective” effects, meaning cannabis might help protect the brain from age-related decline in some cases.
Mental Health Impacts
The relationship between cannabis and mental health remains unclear. A review in The Lancet Psychiatry found insufficient evidence to determine whether cannabinoids help or harm conditions like anxiety, depression, or PTSD.
Experts note that while cannabis may provide short-term relief from symptoms, it may not address underlying issues and in some cases, could worsen them over time. Early and heavy use, especially during adolescence, has also been linked to a higher risk of serious mental health conditions, including psychosis.
Risk of Dependence
Despite perceptions that cannabis is relatively harmless, studies suggest that between 22 and 30 percent of users may develop cannabis use disorder. The risk is significantly higher for those who start young and use frequently.
Research Challenges and the Road Ahead
Studying cannabis remains difficult due to its classification as a Schedule I substance by the Drug Enforcement Administration, which limits scientific research. As a result, many questions remain unanswered, including how different methods of use such as smoking, vaping, or edibles affect the brain.
The Bottom Line
Cannabis may offer benefits, particularly for older adults seeking relief from chronic conditions. However, it also carries potential risks, especially for memory, brain development, and mental health. As research continues to evolve, experts recommend making informed decisions and consulting a healthcare professional especially when considering cannabis for medical use.
