Cannabis-Related ED Visits, Hospitalizations Tied to Higher Dementia Risk

Compared with the general population or individuals who receive all-cause hospital-based care, those with acute care due to cannabis use may be at an increased risk for incident dementia, according to study results published in JAMA Neurology.

Previous research has shown a link between cannabis use and short-term memory impairment, however, there are limited data about the effect of disordered cannabis use on risk of developing dementia.

In a population-based, retrospective, matched cohort study, researchers studied the association between cannabis-related emergency department (ED) visits or hospitalizations and a new dementia diagnosis.

Eligible participants were aged at least 45 years in Canada between January 2008 and December 2021 and had public health insurance. All participants were followed up until December 2022 to observe for dementia diagnoses.

Multiple data sources were used to identify and record patient information regarding the use of health care services, ED visits, acute care hospitalizations, primary and specialist visits, and prescriptions. Information on sociodemographic features, such as age, sex, and immigration status, as well as mental health and substance use care, was also collected.

Exposure of interest was incident acute care due to cannabis use, defined as a first related visit to the ED or hospitalization, based on International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD-10) criteria.

Participants with cannabis-related incident acute care were matched with individuals receiving all-cause acute care; the general population with no acute care due to cannabis use; and individuals with incident acute care due to alcohol use.

Primary outcome was dementia diagnosis, including Alzheimer disease, and secondary outcomes were early-onset dementia and incident acute care for nondrug-induced delirium.

A total of 6,086,794 were enrolled in the analysis, of whom 16,275 (mean age, 55.2 years; 60.3% men) had incident acute care due to cannabis use.

In the primary analysis, individuals with cannabis-related acute care (ED, 76.4%; Hospitalization, 23.6%) were compared with those with all-cause acute care, with a median follow-up of 4 years. Participants with acute care due to cannabis vs all-cause were more likely to have a history of substance use and receive mental health care, but less likely to be diagnosed with diabetes, hypertension, cancer, or heart disease.

The researchers also analyzed trends over time. Annual rate of incident cannabis-related acute care increased by 5.4-fold between 2008 and 2021 in individuals aged 45 years and older, with a larger increase (26.7-fold) seen in individuals aged 65 years and older vs 45 to 64 years.

At 5 years, 5.0%, 3.6%, and 1.3% of individuals with acute care due to cannabis use, all-cause acute, and in the general population, respectively, were diagnosed with dementia. At 10 years, the rate of dementia diagnosis increased to 18.6% among individuals with cannabis-related acute care.

Adjusted risk for dementia at 5 years in individuals with acute care due to cannabis use was 1.2-fold greater (adjusted hazard ratio [aHR], 1.23; 95% CI, 1.09-1.39; E-value=1.76) than that in individuals with all-cause acute care and 1.7-fold greater (aHR, 1.72; 95% CI, 1.38-2.15; E-value=2.84) than that in the general population.

The researchers also noted that cannabis-related vs alcohol-related acute care encounters were associated with reduced risk for a new dementia diagnosis (aHR, 0.69; 95% CI, 0.62-0.76).

Limitations of the analysis were lack of information on duration, frequency, and type of cannabis use and the possibility of residual confounding despite the strong association between acute care due to cannabis use and dementia.  

“Large increases in regular cannabis use and related acute care visits in older adults highlight the potential importance of heavy cannabis use as an emerging risk factor for dementia in older adults,” the researchers concluded.