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Incident stroke more than doubles dementia risk

Results from a systematic review and meta-analysis published in Alzheimer’s & Dementia showed that people who had a recent stroke were more than twice as likely to develop dementia.

“[Prior] studies highlight the central causal role of symptomatic stroke, rather than the underlying vascular risk factors,” Elzbieta Kuma, PhD, from University of Exeter Medical School, England, and colleagues wrote. “Given the current lack of disease-modifying treatments and the complexity of multiple pathologies contributing to dementia, estimating the excess risk of dementia after stroke has the potential to inform preventive strategies to reduce the global burden of dementia.”

To quantify the link between stroke and dementia, researchers searched clinical databases for studies assessing prevalent or incident stroke vs. a no-stroke comparison group and the risk for all-cause dementia. They then performed random effects meta-analysis to pool adjusted estimates across studies and meta-regression to examine potential effect modifiers.

The investigators analyzed 36 studies of prevalent stroke, comprising data from 1.9 million people, and 12 studies of incident stroke, comprising a further 1.3 million people.

Participants with prevalent stroke had a higher risk for incident dementia than those without stroke (HR = 1.69; 95% CI, 1.49-1.92). Incident stroke more than doubled the risk for all-cause dementia compared with no incident stroke (RR = 2.18, 95% CI: 1.9-2.5), according to the results. There were also significant associations between stroke and higher incident dementia risk even after adjusting for common stroke-related modifiable risk factors such as hypertension, diabetes, myocardial infarction and heart disease.

The researchers reported significant between-study heterogeneity, of which 50.2% was explained by sex, indicating the risk for dementia related to stroke was higher among men vs. women (P = .04).

“Given the consequences for people with dementia and their families and the significant implications for social and health care costs, stroke prevention strategies should be integrated in multimodal health interventions to reduce dementia risk,” Kuma and colleagues wrote. “The stronger association observed for incident stroke suggests risk is greater near the time of stroke occurrence. More detailed reporting of the interval between stroke occurrence and dementia diagnosis in future studies will help to better characterize the role of time since stroke in the risk of dementia.” – by Savannah Demko

Disclosure: The authors report no relevant financial disclosures.