Cannabis use is becoming more common among older adults. But emerging data suggest that heavy use may be linked to a higher risk of dementia, especially when it leads to hospitalization.
A population-based study published in JAMA Neurology shows that people who use cannabis and visit the emergency room or are hospitalized are up to four times as likely as people in the general population to be diagnosed with dementia within five years. [1]
This finding has sparked growing concern over how cannabis could impact long-term brain health in aging populations.
Cannabis use and emerging dementia risks
Dementia is a general term for conditions that impair memory, thinking, and daily functioning, progressing over time. [1] Until recently, the link between problematic cannabis use and dementia risk remained largely unclear. [1]
Although cannabis is often viewed as relatively harmless, prior research shows that chronic use can impair memory and executive function. [2] One cross-sectional study found that heavy cannabis use was associated with poorer working memory performance in healthy young adults. These effects persist even after cessation. [2] Other research proposes that marijuana use can cause long-term structural changes in the brain, affecting regions responsible for memory and decision-making. [1]
While the recent study doesn't prove a direct link between cannabis use and dementia, the findings are significant enough to warrant serious concern. The researchers found that people with cannabis-related emergency department visits or hospitalizations denoting severe or problematic use were at a higher risk of receiving a new dementia diagnosis than those who received other hospital-based care or the general population. [1]
Understanding the study: What the data shows
The study provides strong evidence linking heavy cannabis use with later dementia. Researchers analyzed health records from over 6 million adults in Ontario, Canada, aged 45 and older, with no prior dementia diagnosis. [1] Within this group of people, 16,275 (0.3%) individuals had a documented cannabis-related emergency department visit or hospitalization. [1]
The results were telling. Roughly 5% of patients who had cannabis-related hospital visits developed dementia within five years, compared to just 1.3% in the general population. In other words, having a cannabis-related emergency department visit or hospitalization was associated with a 72% higher risk of developing dementia within five years compared to individuals in the general population of the same age and sex who had no such cannabis-related care. [1]
As mentioned, and importantly, this study demonstrates an association rather than proof of causation.
Is the risk the same for all cannabis users?
A natural question is whether occasional cannabis users may face the same danger. Based on the data, the answer appears to be no. The elevated risk was mainly in those whose cannabis use led to medical care. The study links heavy cannabis use, not casual or moderate use, to increased dementia risk. [1]
The authors of the study cautioned readers about their observed association, noting that many heavy cannabis users also smoke cigarettes or drink heavily. [1] So, some of the risks may at least partially stem from these other habits.
Biological mechanisms behind cannabis and dementia risk
Heavy cannabis use could harm the brain in multiple ways. High doses of THC might directly damage neurons, and cannabis’s impact on the cardiovascular system, such as raising blood pressure and stroke risk, may also affect the brain. [3]
“There’s certainly a pathway where there’s potential inflammation and microvascular damage from marijuana,” noted Dr. Daniel Myran, lead author of the study. “That’s one biological mechanism that could explain our findings.” [1]
Using cannabis heavily may also contribute to poorer mental health. Additionally, THC intoxication makes falls and other injuries more likely, especially in older adults. In such cases, severe head trauma is a known risk factor for dementia. [4][5]
Why hospitalization matters: Severity of cannabis use and cognitive impact
Requiring hospital care due to cannabis use typically indicates heavy or problematic consumption. In these cases, the person likely consumed far more THC than their body could handle, triggering a medical emergency or serious accident. These events often involve high THC exposure and direct injury.
Cannabis might not directly ‘cause’ dementia. However, when someone is hospitalized, it adds to a mix of overlapping risks. These vascular, psychological, and neurological risks collectively raise dementia likelihood. Thus, a cannabis-related hospitalization is a serious red flag for future cognitive (brain) health concerns.
Rising rates of hospital visits among older adults
A striking finding was the increase in cannabis-related medical visits among older adults. From 2008 to 2021, the annual rate of visits to the hospital due to cannabis use in people over 45 jumped over fivefold. [1] In adults over 65, the increase was even steeper – nearly 27-fold over the study period. [1]
This trend coincided with changing laws and attitudes about cannabis. Canada’s adoption of medical cannabis in 2014 and legalized recreational marijuana use in 2018 [6] may have played a role in more seniors experimenting with cannabis.
Even moderate use in older adults can cause dizziness or confusion, increasing the risk of falls. [7] The sharp rise in hospital visits suggests that many older users may be encountering adverse effects, perhaps due to higher-potency products, drug interactions, an individual’s perception of their current marijuana tolerance, or increased metabolic sensitivity with age.
Managing risks: What users and caregivers should know
The most crucial principle to remember is moderation. Using the lowest effective dose and avoiding very high-THC products can help minimize potential harm. Older adults, in particular, should be cautious. If you are using cannabis at all, start with extremely low doses and see how it affects you. Then, adjust accordingly.
Caregivers should stay alert to changes in memory or behavior in loved ones who use cannabis, and avoid brushing off these signs as 'just aging.’
Open communication with healthcare providers is essential. Doctors can help weigh the pros and cons, monitor a patient’s memory over time, and adjust other medications to avoid harmful interactions. The study authors even encourage patients and doctors to routinely discuss cannabis use and cognitive health as part of routine care. [1]
Treatment and support: Pathways to cognitive health
For those struggling to cut back on cannabis, seeking help for cannabis use disorder is best. Professional treatment (counseling, support groups, or medication therapy) can assist in breaking heavy use habits and potentially protect brain health.
For free and confidential guidance, call the SAMHSA National Helpline at 1-800-662-HELP (4357).
Treatment options for cannabis use disorder include cognitive behavioral therapy (CBT), motivational enhancement therapy, and support groups tailored to older adults. Caregivers can consult psychiatrists or addiction specialists to coordinate care. Early intervention can reduce long-term cognitive harm, especially through primary care providers.
Final thought
Anyone noticing memory or thinking problems, whether or not cannabis is involved, should ideally go for a medical evaluation. Addressing issues early can make a big difference, often slowing the progression of cognitive decline or uncovering other treatable causes of cognitive impairment.
Though research continues to evolve, caution remains key. Cannabis is not harmless for the aging brain. Limiting your use and focusing on other healthy lifestyle measures are sensible steps to protect your cognitive well-being.
Cannabis-related hospitalizations shouldn’t be dismissed as isolated incidents — they may signal deeper risks to long-term brain health, especially in aging adults.
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