A recent study from Canada indicates that individuals aged 45 and older who required emergency department (ED) or acute hospital care for cannabis use may face an increased risk of developing dementia. The research, which involved a matched cohort of 6 million Canadians, revealed that those receiving acute care for cannabis use had a 23% higher risk of being diagnosed with dementia compared to patients seeking acute care for other reasons.
Among adults without a prior history of dementia, the risk of a new dementia diagnosis within five years for those needing acute care due to cannabis use was 1.5 times higher than those who had an all-cause acute care encounter. Specifically, the absolute risk was 5% for cannabis users compared to 3.6% for other patients, according to findings published by Daniel Myran, MD, MPH, from the University of Ottawa, and his colleagues.
The study also found that individuals who required acute care due to cannabis use had a 3.9 times greater risk of a new dementia diagnosis compared to the general population, with an absolute risk of 5% versus 1.3%. Even after considering sociodemographic factors and existing health conditions, the risk remained elevated. The adjusted hazard ratios were 1.23 compared to all-cause acute care patients and 1.72 compared to the general population, as reported in JAMA Neurology.
Interestingly, while the risk of dementia from cannabis use was significant, it was lower than the risk associated with alcohol-related acute care, which had an adjusted hazard ratio of 0.69. Long-term or heavy cannabis use has already been linked to cognitive issues in midlife, and imaging studies have indicated structural changes in the brains of regular cannabis users.
Co-author Colleen Webber, PhD, from the Ottawa Hospital Research Institute, noted that regular cannabis use could potentially increase the risk of dementia through alterations in brain structure. Additionally, she suggested that it may heighten the risk of other known dementia risk factors, such as high blood pressure, head trauma, and social isolation.
The study encompassed 6,086,794 Canadians aged 45 and older from Ontario who had no prior history of dementia when they entered the cohort between 2008 and 2021. During this timeframe, the rate of acute care visits due to cannabis use surged dramatically, increasing fivefold for individuals aged 45-64 years and nearly 27 times for those aged 65 and older.
In total, 16,275 individuals, or 0.3% of the study group, sought acute care specifically for cannabis use, with a mean age of 55.2 years. The majority, 60.3%, were male, and most (76.4%) received care in the emergency department, while 23.6% were hospitalized.
Overall, this study adds important insights into the relationship between cannabis use and dementia, although the authors acknowledged that existing research on this topic has been limited and mixed. They believe this to be the largest longitudinal study to date examining the connection between cannabis-related acute care and dementia diagnoses.
