Stroke May Increase Dementia Risk by 80%
Although past studies have shown that a stroke can increase one’s risk for certain diseases, new research has been able to quantify the risk for dementia after an ischemic stroke or intracerebral hemorrhage. The hope is that showing a direct link between stroke and dementia, as well as the timing of dementia after stroke, can inform not only additional research, but also the planning and delivery of interventions. This is particularly important as people are living longer and there is a growing number of people experiencing and surviving strokes.
The Research
A team of researchers from McMaster University analyzed data from more than 15 million people in Ontario and identified approximately 181,000 who had experienced one of the following incidents but survived without dementia for at least 90 days:
• ischemic stroke (caused by a clot in arteries around the brain)
• intracerebral hemorrhage (a burst blood vessel in the brain)
The participants were then matched to two control groups:
• Group #1 included people who had NOT experienced a stroke or heart attack.
• Group #2 included people who had experienced a heart attack but not a stroke.
The Results
An analysis of the data showed that dementia risk was 80% higher compared to each of the control groups. In addition, dementia risk was almost three times higher in the first year after experiencing a stroke. And while the risk remained elevated 20 years later, it declined to a 1.5-times increased risk by the five-year mark.
“We were able to show that the elevated risk of dementia persisted even after matching to control groups with the same age, sex, neighborhood socioeconomic status, and vascular risk factors,” explains Lead Author Dr. Raed Joundi, an investigator at the Population Health Research Institute—a joint institute of McMaster University and Hamilton Health Sciences. “We found a three-fold risk of dementia between three and 12 months after stroke. The first three months after stroke were not included as it is usually too early to make a definitive diagnosis of dementia.”
Dr. Joundi says that the higher risk of dementia in the first year isn’t that surprising, considering that there is a brain injury that can impact cognition and daily function. “Physicians are following up closer with patients in the first year and therefore more likely to make a diagnosis of dementia,” he explains. “The more surprising aspect was that the increased risk of dementia persisted throughout 20 years of follow-up, compared to matched controls, so there are many indirect mechanisms that may be acting long-term to promote a higher risk of dementia after stroke.”
The findings haven’t been published in a peer-reviewed journal yet, but they are being presented at the American Stroke Association’s international conference in 2024.
MBJ
Wendy Burt-Thomas writes about the brain, mental health and parenting.
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