Transient Ischemic Attack Tied to Long-Term Dementia Risk

TOPLINETransient ischemic attack (TIA) was linked to an increased risk for dementia in nearly 1 in 5 patients, with the increase being highest in the first year and persisting for two decades, a study showed. Long-term risk for dementia after TIA converged with that seen after stroke within about 5 years, and dementia occurred about three times more often than a subsequent stroke.METHODOLOGYA population-wide matched cohort study was conducted using linked administrative health data from Ontario, Canada, covering health system encounters from 2002 to 2022.Investigators identified 113,081 adults with a first TIA (mean age, 70 years; 50% women) from emergency department visits or hospital admissions and matched them to control individuals without TIA based on age, sex, rurality, neighborhood deprivation, and vascular comorbidities.A separate cohort of 100,048 patients with TIA was propensity score matched to individuals with first stroke based on demographic and vascular risk factors.Incident dementia was identified using a validated algorithm requiring hospitalization for dementia, three or more physician claims at least 30 days apart but within 2 years, or prescriptions for cholinesterase inhibitors or memantine, with follow-up starting 90 days after the index event.The follow-up ranged up to 21.3 years, with a mean follow-up of 7.11 years for the TIA group and 7.65 years for the control group.TAKEAWAYDementia was diagnosed in 19.3% of patients with TIA vs 15.2% of matched control individuals, with overall dementia rates of 2.71 vs 2.03 per 100 person-years. The cause-specific risk for dementia was higher in the TIA group than in the matched control group over more than 20 years of follow-up (hazard ratio [HR], 1.34; 95% CI, 1.31-1.36). It peaked in the first year (HR, 1.75; 95% CI, 1.66-1.85) and remained high at 5 years (HR, 1.46; 95% CI, 1.42-1.50) and 10 years (HR, 1.38; 95% CI, 1.35-1.41).The risk for dementia after TIA was lower than that after stroke in the first year (HR, 0.67; 95% CI, 0.64-0.70), but the risks converged at 5 years (HR, 0.81, 95% CI, 0.79-0.83) and 10 years (HR, 0.85, 95% CI 0.83-0.87).After TIA, the incidence rate of dementia was about three times higher than that of incident stroke and adjusting for incident stroke only slightly reduced the risk for dementia (HR, 1.26; 95% CI, 1.24-1.29 vs unadjusted HR, 1.34), indicating that the elevated risk for dementia was not driven by strokes occurring after the index TIA. No absolute numbers in the main textIN PRACTICE"Perception of TIA as a transient and less deleterious event without permanent injury to the brain might lead to less strict adherence to secondary prevention therapies. In addition to the subsequent stroke risk, an even higher rate of dementia risk demonstrated in TIA with this study might change this perspective and lead to better execution of modifying vascular risk factors, increased vigilance for cognitive testing in follow-up, and investigate preventative strategies for dementia on top of stroke prevention," the author of an accompanying editorial wrote.SOURCEThe study was led by Raed A. Joundi, Population Health Research Institute and McMaster University, Hamilton, Ontario, Canada. It was published online on September 23 in Neurology. The editorial was authored by Nilüfer Yeşilot, Istanbul University, Istanbul Faculty of Medicine, Turkey.LIMITATIONSThe study was limited by reliance on diagnostic codes for identifying TIA and dementia, the lack of baseline imaging data to identify covert disease, the lack of cognitive testing, the possibility of having missed some mild cases of dementia, and the lack of assessment of dementia subtypes.DISCLOSURESThe study was funded by Brain Canada, the Heart & Stroke Foundation, and the Canadian Stroke Consortium. Disclosure information for the study investigators is available in the original study publication. The editorial received no funding, and its author reported no relevant conflicts of interest.This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.