By David Brown, Washington Post Staff Writer—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.
Two of the genes described in the new research may be involved in determining the brain’s capacity to clear itself of toxic “amyloid” proteins that collect outside neurons, eventually poisoning them.
The most important previously known Alzheimer gene promoted overproduction of amyloid. The new findings suggest that at least two processes — production of amyloid and its removal — are involved in the disease.
At least 5 million Americans have Alzheimer’s disease. By one estimate, one in seven people aged 72 and older have dementia, with Alzheimer’s the most common form.