DURHAM, N.C., Nov. 3 (UPI) -- A new study indicates the genes that influence the risk of developing Alzheimer's disease may vary over the course of an individual's lifetime.
Researchers at Duke University Medical Center found two chromosomal regions not previously known to influence Alzheimer's disease: one linked to the disorder in families that first show symptoms early in life and another in families with very late Alzheimer's disease onset.
While earlier studies identified genes underling early- versus late-onset Alzheimer's disease, the new study is the first to indicate distinct genes might also determine the very late onset of Alzheimer's disease, in which symptoms first appear after the age of 80.
Alzheimer's disease affects up to 4 million Americans and is the most common cause of dementia among people over the age of 65. However, some patients first experience at age 50 the mild forgetfulness characteristic of the disease's earliest stages; for others, symptoms appear at age 80 or older.
The research findings appear in the November issue of The American Journal of Human Genetics.