Familial Alzheimer disease (familial AD) is a degenerative disease of the brain that causes gradual loss of memory, judgment, and the ability to function socially. About 25% of all Alzheimer disease is familial (more than 2 people in a family have AD). When Alzheimer disease begins before 60 or 65 years of age (early-onset AD) about 60% of the cases are familial (also known as Early-onset familial AD). These cases appear to be inherited in an autosomal dominant manner.
There are three subtypes of early-onset familial AD which are each associated with changes (mutations) in unique genes:
(1) Alzheimer disease, type 1 is caused by mutations in the APP gene
(2) Alzheimer disease, type 3 is caused by mutations in the PSEN1 gene
(3) Alzheimer disease, type 4 is caused by mutations in the PSEN2 gene.
The condition known as late-onset familial AD includes only the subtype Alzheimer disease, type 2 and is associated with the APOE 4 allele on chromosome 19. This condition results in an increased risk of having AD.
- Gradual memory loss
- Gradual loss of judgment
- Gradual loss of ability to function
- Gradual loss of ability to perform familiar routine
- Gradual loss of ability to recognize familiar faces
- Gradual loss of ability to recognize familiar places
- Gradual loss of ability to remember names of objects
- Gradual loss of ability to feed oneself
- Gradual loss of ability to dress oneself
- Personality changes
- Behavioral changes
- Increasing inability to interact socially
- Speech problems
- Muscle twitching
- Muscle spasms
The cause of Alzheimer’s disease is unknown; however, several factors are thought to be implicated in this disease. These include neurochemical factors, such as deficiencies in the neurotransmitter acetylcholine, somatostatin, substance P, and norepinephrine; environmental factors; and genetic immunologic factors.
Course of disease can continue for up to 25 years.
Therapy consists of attempts to slow disease progression, manage behavioral problems, modify the home environment, and elicit family support. Some medications have proven helpful. Tacrine, a centrally acting anticholinesterase agent, is given to treat memory deficits. It has slowed progression of the disease and improved cognitive function in some patients. Other agents include donepezil and rivastigmine. Underlying disorders that contribute to the patient’s confusion, such as hypoxia, are also identified and treated.