Despite years of effort and millions of dollars in research funding, only one gene, APOE, has been conclusively associated with Alzheimer’s disease risk so far. But now the results of two of the largest Alzheimer’s studies ever provide convincing evidence that three more genes affect risk for the disease.
“These findings are a leap forward for dementia research. At a time when we are yet to find ways of halting this devastating condition, this development is likely to spark off numerous new ideas, collaborations and more in the race for a cure,” said a statement from Rebecca Wood, Chief Executive of the Alzheimer’s Research Trust in the UK.
A British team, led by Julie Williams, found strong evidence that in the clusterin gene and in the PICALM gene are both associated with risk for Alzheimer’s. A French team, lead by Philippe Amouyel, also found strong evidence for an association between and Alzheimer’s risk, and suggestive evidence for an association with .
In addition, Amouyel’s research revealed that the A version of in the CR1 gene increases the odds of Alzheimer’s by 1.21 times. Suggestive evidence for this association was also seen in the work of Williams’ group.
The results from both teams were published online this week in the journal Nature Genetics.
Williams said in a statement that the number of people who fall victim to Alzheimer’s could be reduced by 20% if treatments addressing the effects of the three newly identified genes could be found.
The proteins made by the clusterin and CR1 genes are known to play a part in clearing out amyloid beta, the protein that forms plaques in the brains of people with Alzheimer’s. PICALM encodes a protein important for proper communication between brain cells, a process that is known to be disturbed in Alzheimer’s patients.
In total, the DNA of more than 10,000 people with Alzheimer’s disease and more than 18,000 controls from ten countries was analyzed by the two teams of researchers. But both groups agree that there is still much more to find. Williams’ team is already planning an even larger study involving 60,000 people that she believes can be completed within the next year.
Alzheimer’s, the most common cause of dementia in people 65 years and older, currently affects about five million people in the United States. As the population ages, many more people are expected to be afflicted; some estimate 14 million Americans will have Alzheimer’s by the year 2050.