In just four years, marijuana use grew by 75% among Americans aged 65 and older, according to a new study, and researchers expressed concern over a lack of information on the potential health implications. The increase was most pronounced in women, those with higher incomes and more education, according to a report published on Monday in JAMA Internal Medicine. The findings continue a trend seen over the last decade, said the study’s lead author, Benjamin Han, an assistant professor of geriatric medicine and palliative care at the New York University School of Medicine. “Consider that not even 10 years ago 0.4% of adults 65 and older said they had used marijuana in the past year, and now it’s 10 times that at 4%,” Han said. The trend is concerning, Han said, because of the lack of research on the effects of cannabis on older people. Some prescription and even over-the-counter medicines, such as Benadryl, affect older people differently, he said.