| Alzheimer's Disease
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Etiology
•Familial types are known but most cases are sporadic.
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Pathogenesis
•The cause of Alzheimer's disease is unknown.
•May be due to deposition of amyloid in the parenchyma of
the brain which is toxic to neurons and oligodendroglia.
•An alternative hypothesis is that deposition of amyloid is a secondary
effect. The amyloid deposition is thought to be due to
an abnormality in the amyloid precursor protein.,
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Epidemiology
•Senile dementia is seen in over 32% of the population
over 85 years and increases rapidly after that.
•Alzheimer's
disease is the most common senile dementia in patients
greater than 65 years old. Alzheimer's disease is seen before
65 years of age and is called presenile dementia. Most
familial cases are presenile.
•Since the 85 years of age
and older group is increasing rapidly, Alzheimer'
disease is becoming an important disease.
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General Gross Description
•Generally atrophied with large ventricles.
•Examples:
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General Microscopic Description
•Alzheimer's disease is characterized by the formation
of round senile plaques often with an amyloid center
in the neuropil of the cerebral cortex as well as
neurofibrillary tangles within neurons.
•The diagnosis
is made by counting the number of senile plaques per
20x field and the number of neurofibrillary
tangles in the same area, using the Bielschowsky stain.
•Examples:
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References
• Poirer J et.al. Manual of basic neuropathology. Philadelphia: Saunders, 1990, pp.142.
• Cotran RS, Kumar V, Robbins SL: Robbins Pathologic Basis of Disease. 5th ed. Philadelphia, W.B. Saunders, 1994, pp. 1329-1331.
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| Alzheimer's Disease
| | Synopsis by: M. L. Grunnet M.D. (TX2000D85430)[356]
| |