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Dementia is an acquired syndrome in which intellectual ability decreases to the point that it interferes with daily function. There are two major causes of dementia in older persons: Alzheimer's disease and vascular dementia. Approximately 60 percent of dementing illnesses are caused by Alzheimer's disease, 15 percent are caused by vascular dementia and many of the remainder involve concurrent Alzheimer's disease.
Alsheimer disease is associated with diffuse neuron injury and death, with senile plaques and neurofibrillary tangles. The average duration of the disease is 10 years, during which afflicted persons progress from mild memory loss to the need for 24-hour supervision to total dependency and death. Risk factors for Alzheimer's disease are age, a family history of the disease, and Down syndrome.
Vascular dementia is generally one of two types: multi-infarct dementia or subcortical vascular dementia. In multi-infarct dementia, the neurologic examination reveals focal, asymmetric abnormalities, and multiple strokes are evident on computed tomography (CT) or magnetic resonance imaging (MRI) of the brain. Subcortical vascular dementia ( Binswanger's disease) is characterized by vascular disease.
Diagnostic evaluation
Dementia should be suspected whenever an older person is reported to have gradually increasing difficulty in the ability to learn and retain new information, handle complex tasks, or reason. Difficulties with spatial ability and orientation, language and behavior are common.
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Diagnostic Criteria for Delirium, Dementia, Alzheimer's Disease and Vascular Dementia |
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Diagnostic criteria for delirium A change in cognition or development of a perceptual disturbance is present and not explained by a preexisting, established or evolving dementia. The disturbance developed over a short period of time (usually hours to days) and tends to fluctuate. The level of consciousness (awareness of the environment) is disturbed or fluctuates. There is evidence that a drug, acute illness or metabolic disturbance is present that could explain the change in cognition. |
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Diagnostic criteria for dementia Cognitive impairment is present, as demonstrated by: (1) memory loss and (2) impairment of language, praxis, recognition or abstract thinking. The cognitive impairment is chronic and progressive and has resulted in functional decline. Delirium has been ruled out. |
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Diagnostic criteria for Alsheimer disease Dementia is present. History, physical and mental status examinations are consistent with Alzheimer's disease. Screening blood tests (CBC, BUN, calcium, liver function, thyroid function, vitamin B12) and review of medications do not reveal any cause of cognitive impairment. Brain imaging study (CT or MRI) is normal or shows atrophy. |
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Diagnostic criteria for vascular dementia Dementia is present. Two or more of the following are present: (1) focal neurologic signs on physical examination; (2) an onset that was abrupt, stepwise or stroke-related; (3) brain imaging study (CT or MRI) shows multiple strokes. |
Testing a blood sample for apolipoprotein E may be used as an adjunct to other diagnostic procedures; a positive test increases likelihood that the dementia is due to Alzheimer's disease.
Use of medication to delay symptom progression
Tacrine (Cognex) and donepezil (Aricept) are available for the treatment of Alzheimer's disease. Metrifonate and rivastigmine are in development and testing.
Estrogen replacement therapy has a significant protective effect and may delay the expression.
Nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin and ibuprofen have been associated with a lower incidence of dementia. Because of the risks of gastrointestinal and renal toxicity, these
Vitamin E supplementation may significantly slow the progression of moderate Alzheimer's disease.