Brain Microbleeds and Cognitive Function

There has been increasing recognition of the role of cerebrovascular disease and its risk factors in the etiopathogenesis of dementia in older persons.1,2 Cerebral infarcts, white matter changes, hypertension, and diabetes have all been implicated as causal agents or risk factors for dementia.3 The public health impact of cerebrovascular disease on dementia is underscored by the observation that up to one third of older individuals have cerebral infarcts by neuroimaging4 or pathology,5 many without clinically recognized stroke.4–6 These infarcts, often subcortical in location,4–6 not only can result in dementia,7 but may also add to cognitive impairment,5 lower the threshold for dementia,8 and have a synergistic effect with Alzheimer disease pathology.9 Subcortical infarcts are most often secondary to small vessel disease, pathologically identified by lipohyalinosis of the straight penetrating arterioles. Hypertension and diabetes are both risk factors for this pathology and thereby risk factors for subcortical infarcts. Vessel wall changes can lead to hemorrhage as well as infarction. When the leakiness of blood vessels results in small amounts of extravasated blood and ultimately hemosiderin, this is known as microbleeds. Microbleeds are defined as …