Alzheimer's Disease

Alzheimer's disease, broadly defined, is a complex genetic disorder: Multiple causative and susceptibility genes acting singly or in concert produce similar symptoms and pathologic changes in patients. In each of its forms, it manifests age-dependent penetrance, meaning that the older an individual becomes, the more likely it is that he or she will develop the disease. Disease manifestations (such as age of onset or rate of progression) may be influenced by environmental exposures (alcohol use, head injury) or other health conditions (such as cerebrovascular disease). Identification of AD genes will lead to a better understanding of the cellular processes that cause dementia.

Currently, amyloid production from amyloid precursor protein is the focus of much research, although debate continues about its role. Amyloid production and deposition in the brain are affected by each of the four known AD genes. Decrease in amyloid production or increase in amyloid metabolism with a resulting decrease in deposition may result in delayed age of onset or slower progression of disease. Thus, alteration of amyloid processing of sufficient magnitude might result in disease prevention. Once process-altering treatments become available, knowing who is at risk for the disease will be important.