Long-Term Risk of Dementia Among Survivors of Ischemic or Hemorrhagic Stroke

Abstract

Background and Purpose— Stroke is a risk factor for dementia, but the risk of dementia after different stroke types is poorly understood. We examined the long-term risk of dementia among survivors of any first-time stroke and of first-time ischemic stroke, intracerebral hemorrhage, and subarachnoid hemorrhage. Methods— We conducted a 30-year nationwide population-based cohort study using data from Danish medical databases (1982–2013) covering all Danish hospitals. We identified 84 220 ischemic stroke survivors, 16 723 intracerebral hemorrhage survivors, 9872 subarachnoid hemorrhage survivors, and 104 303 survivors of unspecified stroke types. Patients were aged ≥18 years and survived for at least 3 months after diagnosis. We formed a comparison cohort from the general population (1 075 588 patients without stroke, matched to stroke patients by age and sex). We computed absolute risks and hazard ratios of dementia up to 30 years after stroke. Results— The 30-year absolute risk of dementia among stroke survivors was 11.5% (95% confidence interval, 11.2%–11.7%). Compared with the general population, the hazard ratio (95% confidence interval) for dementia among stroke survivors was 1.80 (1.77–1.84) after any stroke, 1.72 (1.66–1.77) after ischemic stroke, 2.70 (2.53–2.89) after intracerebral hemorrhage, and 2.74 (2.45–3.06) after subarachnoid hemorrhage. Younger patients regardless of stroke type faced higher risks of poststroke dementia than older patients. The pattern of hazard ratios by stroke type did not change during follow-up and was not altered appreciably by age, sex, or preexisting diagnoses of vascular conditions. Conclusions— Stroke increases dementia risk. Survivors of intracerebral hemorrhage and subarachnoid hemorrhage are at particularly high long-term risk of poststroke dementia.