Cannabis use linked to increased dementia risk after emergency care

Persons with a visit to the emergency department or hospitalization due to cannabis run 23% and 72% more risk of a new dementia diagnosis compared to persons with an ED visit or hospital admission for a different reason or the general population, according to a new study published in Jama Neurology.

Long -term and heavy cannabis use is associated with memory problems in the midlife, together with changes in the brain structure associated with dementia. We wanted to estimate the risk that dementia was diagnosed with a group of people whose cannabis use resulted in a visit to first aid or required hospitalization for treatment. ”

Dr. Daniel Myran, Canada Research Chair in Social Accountability, University of Ottawa, ICES Deputy Scientist, researcher at the Bruyère Health Research Institute and Associate Scientist, the Ottawa Hospital

The study included 6 million adults aged 45 or older from Ontario, Canada, who had no history of dementia when they came to the study cohort between 2008 and 2021. The individuals were followed until 2022.

Health data at ICEs were used to compare new diagnoses of dementia for persons with patterns of cannabis use required acute care defined as a visit to the Emergency Department (ED) or hospitalization. They were compared with three groups: 1) persons with an acute care visit for all causes; 2) the general population; and 3) Persons with acute care as a result of alcohol consumption.

Most important findings:

• During the study, 16,275 (0.3%) of people aged 45 or older had acute care as a result of cannabis and 60% were male.

• The annual rate of people older than 45 with a first acute care visit for cannabis use increased more than five times during the study period of 353 (6.9 per 100,000 people) in 2008 to 2,508 (37.6 per 100,000 people) in 2021. Increases were even greater for individuals 65+ years (26.7-fold increase).

• 5% and 19% of people aged 45 or older with treatment for cannabis in acute care were diagnosed with dementia within 5 and 10 years, compared to 3.6% and 14.8% for people with acute care for a different reason and 1.3% and 5.5% in the general population.

• After considering differences in social factors, other diagnoses for mental health and chronic disorders, people with acute care as a result of cannabis were on a higher risk of 1.23 and 1.72-time higher risk than persons with labor session and the general population respectively.

The authors make two warnings about the findings of the study. First, although they saw a connection between patterns of cannabis use seriously enough to lead to an acute visit in health care, they have not investigated patterns of cannabis use that did not require acute medical care. Secondly, the findings do not show that cannabis use causes dementia.

Although the evidence about the association between cannabis use and dementia continues to increase, the authors emphasize potential mechanisms that can lead to cannabis to dementia.

“Regular use of cannabis can increase the risk of dementia directly due to changes in the brain structure. It is also possible that cannabis use regularly increases the risk of other established risk factors for dementia, including high blood pressure, head trauma and other injuries, and a higher risk of depression and social isolation,” says co-author Dr. Colleen Webber, scientist at Bruyère Institute.

“Although we need more research together to better understand the potential risks of regular cannabis use on cognition and dementia, we hope that these findings can inform the discussion between patients and caregivers,” says Myran.