Vascular dementia (VaD) is defined as permanent cognitive impairment produced by vascular damage to the brain. Although old textbooks, i.e., prior to 1980, suggested that most dementia is produced by strokes, recent autopsy brain studies show that vascular dementia is a far less common, i.e., third or fourth cause of intellectual loss in people over the age of 65.
The diagnostic criteria for vascular dementia include: 1) documented intellectual loss, 2) extensive vascular damage to the brain, and 3) a relationship in time between the occurrence of strokes and the appearance of intellectual symptoms. The timing of the strokes should coincide with the onset or progression of cognitive decline. Strokes are frequently seen in the brains of patients with other types of dementia, such as Alzheimer’s disease. Mixed dementia is intellectual loss produced by multiple disease processes in the same brain, e.g., Alzheimer’s and vascular dementia or Alzheimer’s and diffuse Lewy body disease. Mixed dementia is quite common; especially with vascular damage as one component.
The symptoms of vascular dementia cannot be definitively distinguished from Alzheimer’s symptoms based on history or mental status examination. Vascular dementia patients may have a stair-step clinical course in which they demonstrate significant drops of function following vascular injury to the brain (Table 1). Patients with vascular dementia develop cognitive, e.g.,
mnesia, aphasia, agnosia, and apraxia, as well as psychiatric symptoms, e.g., hallucinations, delusions, and behavioral disturbances that are common to most other types of dementia. The VaD patient may experience more behavioral problems and depression than Alzheimer patients.
The clinical findings in persons with vascular dementia may be distinct from Alzheimer’s disease. A significant number of VaD patients demonstrate focal neurological deficits that are not typically present in the Alzheimer’s patient. Frequently, these neurological findings are subtle, e.g., mild weakness on one side of the body, abnormal reflexes, etc. The VaD patient often demonstrates other evidence of cardiovascular disease, e.g., hypertension, past history of heart attacks, peripheral vascular disease, etc. Brain imaging studies, e.g., CT or MRI scans, may be helpful for documenting specific strokes or other types of vascular damage to the brain. Functional studies such as SPECT scans, i.e., Single Photon Emission Computed Tomography, may demonstrate a pattern of patchy abnormal brain function, i.e., hypoperfusion, that is distinct from Alzheimer’s disease. There is no blood test or genetic screen for vascular dementia. Neuropsychological testing may help distinguish VaD from other types of dementia.
Vascular dementia is produced by cumulative vascular damage to the brain. No specific type, location, or size of stroke will predict intellectual decline. Observable vascular brain damage occurs in almost half of persons over the age of 65 and multiple different types of injury are present in many older persons (Table 2). The five major types of vascular brain damage include: 1) strokes produced by atherosclerosis, 2) hypertensive changes, 3) anoxic brain damage, 4) ischemic white matter damage, and 5) hypotensive brain damage (Table 3).