Incidence of Brain Infarcts, Cognitive Change, and Risk of Dementia in the General Population (original) (raw)

B rain infarcts are common findings on magnetic resonance (MR) images in older adults and have been associated with cognitive decline and dementia. Their prevalence has been well documented in several population-based studies. 1-4 Imaging studies generally agree that the prevalence of brain infarcts increases steeply with increasing age, and it is >20% in the 70 to 79 age group and 35% in those older than 85. 4,5 Most studies with data on prevalence of brain infarcts show no sex disparity in infarct risk. 5 Information on the incidence of brain infarcts from population-based longitudinal studies is, however, scarce. Previous studies suggest that cerebrovascular abnormalities contribute to cognitive decline and the development of vascular dementia and Alzheimer's disease. 6,7 There is, however, limited information from imaging studies on whether this differs by brain region. The assessment of brain infarcts by region or type is important because the cause and clinical implications of cerebellar, cortical, and subcortical infarcts may differ. A distal branch middle cerebral artery occlusion resulting in a cortical stroke usually results from an embolus from either the heart, aortic arch, or carotid artery, whereas a small infarct in the subcortical white matter is usually because of a blockage of small penetrating artery (lacunar infarct). The most common causes of cerebellar infarcts are, however, thought to be atherosclerosis, cardiac embolism, and migraine. 8,9 Background and Purpose-The differentiation of brain infarcts by region is important because their cause and clinical implications may differ. Information on the incidence of these lesions and association with cognition and dementia from longitudinal population studies is scarce. We investigated the incidence of infarcts in cortical, subcortical, cerebellar, and overall brain regions and how prevalent and incident infarcts associate with cognitive change and incident dementia. Methods-Participants (n=2612, 41% men, mean age 74.6±4.8) underwent brain magnetic resonance imaging for the assessment of infarcts and cognitive testing at baseline and on average 5.2 years later. Incident dementia was assessed according to the international guidelines. Results-Twenty-one percent of the study participants developed new infarcts. The risk of incident infarcts in men was higher than the risk in women (1.8; 95% confidence interval, 1.5-2.3). Persons with both incident and prevalent infarcts showed steeper cognitive decline and had almost double relative risk of incident dementia (1.7; 95% confidence interval, 1.3-2.2) compared with those without infarcts. Persons with new subcortical infarcts had the highest risk of incident dementia compared with those without infarcts (2.6; 95% confidence interval, 1.9-3.4). Conclusions-Men are at greater risk of developing incident brain infarcts than women. Persons with incident brain infarcts decline faster in cognition and have an increased risk of dementia compared with those free of infarcts. Incident subcortical infarcts contribute more than cortical and cerebellar infarcts to incident dementia which may indicate that infarcts of small vessel disease origin contribute more to the development of dementia than infarcts of embolic origin in larger vessels.