Two European research teams have identified three genes that affect a person's risk of developing Alzheimer's disease, the most common cause of dementia in the elderly.
The new genes appear to have at least as big a role as four others discovered in the last 15 years that are known to play a role in Alzheimer's.
"The message here is that genes are important in Alzheimer's disease...and there may be multiple ways of reducing the risk that the genes produce," said Julie Williams, a neuroscientist at Cardiff University in Wales who helped lead one of the teams.
All so-called Alzheimer genes have normal roles in brain physiology; they don't exist solely to cause dementia. Instead small variations in their DNA alter their function and, through processes only now being uncovered, increase or reduce a person's risk of developing the disease.