A recent study in JAMA Neurology found that individuals who required hospital-based care due to marijuana were at an increased risk of being diagnosed with dementia. Compared to the general population, this population of marijuana users was 1.7 times more likely to be diagnosed with dementia within 5 years.
The study, led by researchers in Canada, included 6,086,794 individuals aged 45 or older in Ontario, Canada, who had not been previously diagnosed with dementia. Among this group, 16,275 had an emergency department visit or hospitalization due to marijuana.
The study also found that the annual rates of marijuana-related acute care incidents increased five-fold between 2008 and 2021 for those between the ages of 45 and 64, while it increased 26.7-fold for those aged 65 or older.
The researchers explained that they “observed large increases in the incidence of acute care for cannabis use in older adults over time, with most of the increases starting in 2015, coinciding with the liberalization of medical cannabis in 2014 and the Canadian federal government’s commitment to the legalization of nonmedical cannabis in December 2015 (which was implemented in October 2018).”
While noting that the association with dementia may not be causal, the researchers posited that “cannabis use may directly result in changes in brain structure and cognition in ways that increase the risk of dementia.” They added that marijuana use is associated with other risk factors for dementia, including reductions in educational attainment, increased risk of hypertension, higher risk of head trauma via motor vehicle collisions, and greater risk of depression and social isolation.