The number of older Americans using cannabis has increased by 75% in recent years, a new analysis shows. But investigators caution that knowledge about the drug’s effects on older users has not kept pace.

The proportion of adults ages 65 and older who reported past-year marijuana use increased from 2.4% to 4.2% from 2015 to 2018, according to researchers from New York University’s Grossman School of Medicine. The uptick continues a trend since states began legalizing the drug in the mid-2000s. And while the increase appears to be driven by seniors who do not have multiple chronic diseases, evidence shows that people with diabetes are among the groups turning to greater use.

In addition, the analysis found more use among senior groups including women, white or nonwhite racial/ethnic minorities, people with a college education, people with higher incomes, those who are married, and adults who reported receiving mental health treatment or using alcohol.

The results highlight a need for caution as the clinical value of cannabis for seniors remains unclear, said authors Benjamin H. Han, M.D., MPH, and Joseph J. Palamar, Ph.D., MPH. 

“Older adults are especially vulnerable to potential adverse effects from cannabis, and with their increase in cannabis use, there is an urgent need to better understand both the benefits and risks of cannabis use in this population,” they concluded.

The study was published as a research letter in JAMA Internal Medicine.