Alzheimer Disease

Alzheimer disease (AD) is the most common cause of dementia in western civilization. It affects more women than men, and the clinical course generally lasts approximately five years.  The younger the individual is at the onset of the disease, the more severe the deficits for the patient.  One famous contemporary who suffers from the disease is former U.S. President Ronald Reagan.

The cerebral cortex and some other forebrain regions atrophy so severely that the brain may weigh less than 1000g at death. Shrinkage is most pronounced in the frontal and temporal lobes.  The insula and the medial part of the temporal lobe tend to demonstrate the highest  number of neuritic plaques.  The greater the number of plaques the higher the degree of dementia.  The disease often causes vacuolization of the subpial layers of the temporal and parietal lobes.  The spongy state is associated with neuronal loss and is similar to the effects of Creutzfeldt-Jakob disease.

Researchers continue to search for causes and cures for AD.  The gene that codes for the B-amyloid protein located on chromosome 21 is implicated in the 20% of  patients for whom there is a family history of AD.  Head injury has been implicated in 3 to 5 % of AD cases.  There is a 70 to 90% decrease in the production of the enzyme that makes acetylcholine.  Other neurotransmitter abnormalities have also been implicated.

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