Alzheimer's Disease

Alzheimer's disease (AD) is the leading cause of dementia in seniors. Although the condition also occurs in persons under age 65 (known as earlyonset AD), this is extremely rare (approximately 2#x0025; of all cases) and involves a drastically accelerated version of the more typical disease course. Individuals with late-onset, or typical, AD can survive for 20 years with the condition, whereas those with early onset live only 3 to 5 years after diagnosis on average. Estimates purport that by 2050 the number of AD cases in developed countries will exceed 36.7 million. Currently, AD is estimated to impact 4 million Americans, or 8#x0025; of the U.S. population over age 65, with projections reaching 12 million by 2050.

Historical Background

In 1906, German psychiatrist Alois Alzheimer described the first case of what became known as Alzheimer's disease. Auguste D., a 51-year-old German housewife, presented at an asylum in Frankfurt with jealousy, paranoia, difficulty remembering, and nervous pacing and died after 4 years of progressive decline. Upon autopsy, her brain revealed innumerable concentrations of tiny clusters and dead neurons in the cerebral cortex; these amyloid, or neuritic, plaques and neurofibrillary tangles are now considered hallmarks of the disease. Dr. Alzheimer's second case, Johann F., a 56-year-old man who was forgetful, could not find his way, and was unable to perform [Page 36]simple tasks was observed from 1907 to 1910. He died within 3 years of presenting symptoms, and countless amyloid plaques were found postmortem. Unlike Auguste D., however, neurofibrillary tangles were not detected.

With the advent of medical dominance in the 20th century, the question of whether or not old age, and thus senility, could be cured became a subject of intense debate. Therefore, Dr. Alzheimer described the cases of Auguste D. and Johann F. amid an existing controversy about the relationship between aging and senility. Because dementia was at the time considered a psychosis rather than an anatomical disorder, these cases were seminal in establishing a biological basis for insanity. In 1910, the eponym Alzheimer's disease was first used by Emil Kraepelin, a founder of modern psychiatry, in the eighth edition of his Handbook of Psychiatry. This assignment was based on the knowledge of only four documented cases despite the different neuropathology observed and the reticence of Dr. Alzheimer, who felt his cases demonstrated accelerated versions of the condition called “presenile dementia” rather than the discovery of a novel state.

Historians have suggested that Kraepelin may have rushed the definition of AD as a separate disease category unrelated to age to promote his own interests in discovering physical lesions. Accordingly, the ability to distinguish between normal and pathological brains was an important component in the establishment of AD. The term Alzheimer's disease, then, originally referred to dementia in patients with presenile onset of symptoms, whereas senile dementia was used when symptoms began after 65 years of age and was considered a natural part of aging despite the fact that clinically and pathologically the two conditions were strikingly similar.

Because AD can only be definitively diagnosed upon autopsy, from 1906 until the late 1970s its diagnosis was largely rendered postmortem. During this period, AD remained an extremely rare condition affecting only younger people. As early as 1933, however, the neurofibrillary tangles associated with AD were discovered in the majority of normal senile brains. Allegedly, most seniors experienced a degree of forgetfulness without it necessarily interfering with their daily living.

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