The number of seniors who admit to using pot has increased drastically over the past five years, according to a new study by New York University’s Grossman School of Medicine.

This study, recently published in the JAMA Internal Medicine journal, estimates that cannabis use among adults age 65 or older grew by as much as 75 percent between 2015 and 2018. Researchers used data from the National Survey on Drug Use and Health (NSDUH), an annual survey that asks Americans of all ages to self-report their drug use. In 2006, only 0.4 percent of seniors said they used cannabis in the past year. In 2015, that percentage grew to 2.4 percent, and by 2018, it rose to 4.2 percent.

"Marijuana use among seniors is not bouncing up and down like with other drugs," said study co-author Joseph Palamar, associate professor of population health at NYU Grossman, to CNN. "It's a straight line up." The study reports that seniors who were married, college-educated, or had mental health issues were more likely to use cannabis than others. Women and minorities were also more likely to admit to using weed.

“Our study shows cannabis use is increasingly popular nationwide among older adults,” said lead author, Benjamin Han, MD, MPH, assistant professor of Geriatric Medicine, Palliative Care and Population Health at NYU Grossman, in a statement. “As more older adults use cannabis, whether for therapeutic or recreational purposes, it is important for health care providers to counsel their patients despite the very limited evidence-base on the benefits and harms of cannabis use among older adults.”

"I was curious to see if it was people who are more sick, with say, multiple chronic conditions, trying cannabis, or is it the healthier people, perhaps with only one health condition," Han explained to CNN. "And it appears it's the healthier older people who are trying cannabis more."

Researchers did find a few concerning trends, however. The number of seniors using cannabis and alcohol together, which could increase the risk of adverse side effects, increased by 6.3 percent. The study also notes that the rate of cannabis use among seniors with diabetes rose by 180 percent between 2015 and 2018. "I'm not sure why older people with diabetes are increasingly using cannabis," Han said, noting that there's little evidence suggesting medical marijuana can treat this condition.

The study does have a number of limitations. Specifically, the survey's cannabis questions are outdated. The NSDUH only asks if respondents have smoked or ingested marijuana, hashish, pot, grass, or hash oil, but does not mention vapes or legal medical cannabis products like CBD oils or topical products. (Honestly, though, who asks if people smoke grass?) Palamar told Cannabis Wire that he doesn't think this limits the accuracy of the study, though, because “other research suggests that most people who vape also use via other methods.”

But, the self-report nature of the study is also limiting. As the overall stigma against cannabis continues to decline, it is unclear whether more seniors are actually using pot, or if more are simply willing to admit their pot use. The researchers believe the former conclusion is the most accurate, however.

“We believe use will continue to increase as ‘social acceptability’ of weed use increases among older populations,” said Palamar to Cannabis Wire. “I think the majority of use among older people is for medical reasons, although we need more research to confirm this. I think older people who use weed are using for things like sleep.”

Han and his team have used NSDUH data to track seniors' cannabis use for years now. Last year, Han co-authored a study that found the prevalence of marijuana use among adults over 65-years-old increased by seven times from 2006 to 2016. Two independent studies from last year also found that, in recent years, nearly ten times as many American and Canadian seniors are using weed. Now that's something to spark up to! 

Palamar suggests that cannabis researchers should be conducting deeper investigations into seniors' use of cannabis, rather than simply tracking annual increases of usage. “We’re in 2020," Palamar said. "I honestly don’t think increases in marijuana use should be considered such a big deal."