The clinical manifestation of Alzheimer disease (AD) is dementia that typically begins with subtle and poorly recognized failure of memory and slowly becomes more severe and, eventually, incapacitating.AD is the most common cause of dementia in North America and Europe with an estimate of four million affected individuals in the US. The prevalence of the disease increases with age. Approximately 10% of all persons over the age of 70 years have significant memory loss and more than half of these individuals have AD No environmental agents (e.g., head trauma, viruses, toxins) have been proven to be directly involved in the pathogenesis of AD. About 25% of AD is familial, that is, two or more persons in a family have AD. Familial cases appear to have the same clinical and pathologic phenotypes as nonfamilial cases. Genetic counseling is the process of providing individuals and families with information on the nature, inheritance, and implications of genetic disorders to help them make informed medical and personal decisions. Genetic counseling for people with nonfamilial AD and their family members must be empiric and relatively nonspecific.First-degree relatives of a person with AD have a cumulative lifetime risk of developing AD of about 15-30%, which is typically reported as a 20-25% risk.Many individuals diagnosed as having early-onset Alzheimer disease have another affected family member, although family history is negative 40% of the time.
Individuals with early-onset familial Alzheimer disease have a 50% chance of transmitting the mutant allele to each child.The mainstay of treatment for AD is necessarily supportive and each symptom is managed on an individual basis. In general, affected individuals eventually require assisted living arrangements or care in a nursing home.Although the exact biochemical basis of AD is not well understood, it is known that deficiencies of the brain cholinergic system and of other neurotransmitters are present. Drugs that increase cholinergic activity by inhibiting acetylcholinesterase produce a modest but useful behavioral or cognitive benefit in a minority of affected individuals. The first such drug was tacrine; however, this agent is also hepatotoxic. Newer such drugs with similar pharmacologic action, such as Aricept (donepezil), Exelon (rivastigmime), and Galantamine , are not hepatotoxic.Treatment trials evaluating use of anti-inflammatory agents (NSAIDs), estrogens, nerve growth factors, and antioxidants are underway.