Alzheimer's Disease

Within three years of the publication of Dr. Alzheimer's first case, the term "Alzheimer's disease" was applied to patients who developed significant difficulty in memory and other areas of cognition at an age less than sixty-five years. Individuals who developed such symptoms later in life, generally after the age of sixty-five, were said to be suffering from senility, a process considered a normal part of aging. The phrase "hardening of the arteries," implying narrowing of arterial size with a reduction in blood flow to the brain, was used by physicians and by laypersons to designate the reason for senility. However, a causal relationship between arterial narrowing and senility had not been established scientifically.

Critical research reports were published in 1968 and 1970 providing evidence that senility and the disease Alzheimer described were similar both clinically and pathologically. Patients in each category developed similar and multiple cognitive deficits. Patients in each category developed plaques and tangles, and the majority of those diagnosed with senility did not have evidence of "hardening of the arteries." Over the next decade senile dementia, Alzheimer's type, would replace senility as the accepted common cause of late-life dementia.

In 1984, consensus criteria for a clinical diagnosis of AD were established. Cardinal features include the insidious onset of decline in at least two areas of cognition, gradual progression of severity in these spheres resulting in dementia, onset of symptoms between the ages of forty and ninety years (most often after age sixty-five), and absence of another medical condition that by itself could cause dementia. Pathological study of tissue after death should reveal the characteristic findings of senile plaques in age-associated numbers (numbers larger than expected for the individual's age) and of neurofibrillary tangles. Using these criteria, both Alzheimer's disease as a presenile disorder and senile dementia, Alzheimer type, are subsumed into the broader diagnosis, Alzheimer's disease.