neurologic disorders
Vascular Cognitive Impairment and Dementia
Etiology of Vascular Cognitive Impairment and Dementia
Vascular cognitive impairment and dementia typically results from multiple Ischemic Stroke (or sometimes hemorrhages). Although each infarct may be only minimally symptomatic in itself, the combination of multiple infarcts can cause enough neuronal or axonal loss to impair brain function. There are four major types of vascular cognitive impairment and dementias ( Etiology reference ): Subcortical ischemic vascular cognitive impairment and dementia Multi-infarct dementia Poststroke dementia Mixed dementia Subcortical ischemic vascular cognitive impairment and dementiais caused mainly by small vessel disease. Subcortical lacunar lesions may develop, as may white matter lesions, which are mainly subcortical. Subcortical ischemic vascular cognitive impairment and dementia may include Multiple lacunar infarction:Multiple lacunar infarcts occur deep within hemispheric white and gray matter. Binswanger dementia:This variant is associated with severe, poorly controlled hypertension and systemic vascular disease. It causes diffuse and irregular loss of axons and myelin with widespread gliosis, tissue death due to an infarction, or loss of blood supply to the white matter of the brain. Multi-infarct dementiaaffects medium-sized blood vessels, leading to large cortical infarcts. Post-stroke dementiais immediate and/or delayed irreversible cognitive decline that begins within 6 months after stroke. Mixed dementiais characterized by both vascular cognitive impairment, dementia, and other coexisting pathology (eg Alzheimer disease, dementia with Lewy bodies). Uncommon types of vascular cognitive impairment and dementia include the following: Strategic single-infarct dementia:A single infarct occurs in a crucial area of the brain (eg, angular gyrus, thalamus). Cerebral amyloid angiopathy: Clinical history includes slowly progressive cognitive decline, episodic transient focal neurologic episodes (so-called amyloid spells), and sudden-onset focal neurologic deficits secondary to cortical lobar intracerebral hemorrhages. Hereditary vascular dementia:Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a cerebral small vessel disease caused by mutations in theNOTCH3(NOTCH receptor 3) gene, which codes for a transmembrane receptor located on vascular smooth muscle cells. Cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy (CARASIL) is also a small vessel disease; it is caused by mutations in theHTRA1gene. Cerebral amyloid angiopathy (CAA) is the accumulation of beta-amyloid in cerebral blood vessel walls, which results in a high risk of intracerebral hemorrhages. CAA occurs in several types of hereditary disorders but usually occurs sporadically. Cognition can be normal; however, prevalence of CAA is much higher in patients with Alzheimer's disease than in the general population. 1.Skrobot OA, O’Brien J, Black S, et al: The Vascular Impairment of Cognition Classification Consensus Study.Alzheimers DementJun;13 (6):624–633, 2017. doi: 10.1016/j.jalz.2016.10.007 