Abstract

Increased risk of dementia after myocardial infarction (MI) may be mediated by shared risk factors (eg, atherosclerosis) and post-MI stroke. We examined risk of dementia in 1-year survivors of MI.Using Danish medical registries, we conducted a nationwide population-based cohort study of all patients with first-time MI and a sex-, birth year-, and calendar year-matched general population comparison cohort without MI (1980-2012). Cox regression analysis was used to compute 1- to 35-year adjusted hazard ratios (aHRs) for dementia, controlled for matching factors and adjusted for comorbidities and socioeconomic status.We identified 314?911 patients with MI and 1?573?193 matched comparison cohort members randomly sampled from the general population (median age, 70 years; 63% male). After 35 years of follow-up, the cumulative incidence of all-cause dementia in the MI cohort was 9% (2.8% for Alzheimer disease, 1.6% for vascular dementia, and 4.5% for other dementias). Compared with the general population cohort, MI was not associated with all-cause dementia (aHR, 1.01; 95% confidence interval [CI], 0.98-1.03). Risk of Alzheimer disease (aHR, 0.92; 95% CI, 0.88-0.95) and other dementias (aHR, 0.98; 95% CI, 0.95-1.01) also approximated unity. However, MI was associated with higher risk of vascular dementia (aHR, 1.35; 95% CI, 1.28-1.43), which was substantially strengthened for patients experiencing stroke after MI (aHR, 4.48; 95% CI, 3.29-6.12).MI was associated with higher risk of vascular dementia throughout follow-up, and this association was stronger in patients with stroke. The risk of Alzheimer disease and other dementias was not higher in patients with MI.

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