Alzheimer’s disease
Also known as primary degenerative dementia, Alzheimer’s disease accounts for more than half of all dementias. An estimated 5% of people over age 65 have a severe form of this disease, and 12% suffer from mild to moderate dementia. Because this is a primary progressive dementia, the prognosis is poor.
Causes
Several factors contribute to the progression of Alzheimer’s disease. They include neurochemical factors, such as deficiencies in acetylcholine (a neurotransmitter), somatostatin, substance P, and norepinephrine; environmental factors, such as aluminum and manganese; viral factors, such as slow-growing central nervous system viruses; trauma; and genetic immunologic factors.
The brain tissue of a patient with Alzheimer’s disease typically shows cortical atrophy, the hallmark features being neurofibrillary tangles, neuritic plaques, and granulovascular degeneration.
