Higher Risk of Vascular Dementia in Myocardial Infarction Survivors

BACKGROUND: 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. METHODS: 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. RESULTS: We identified 314911 patients with MI and 1573193 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). CONCLUSIONS: 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.