A gene associated with Alzheimer’s disease appears especially dangerous to women and may be one reason that more women than men are diagnosed with the disease.
The gene, known as APOE4, increases the risk of developing Alzheimer’s in both sexes. But a study published Monday in the Annals of Neurology found that the gene had only a minimal effect on men, while in women it nearly doubled the risk of developing Alzheimer’s or a related condition called mild cognitive impairment.
“We believe that there is an increased risk for Alzheimer’s in women, and it may be that APOE4 is playing a sizable role in this,” says Michael Greicius, one of the study’s authors and head of the Stanford Center for Memory Disorders.
Women make up nearly two-thirds of the 5 million people in the U.S. diagnosed with Alzheimer’s. One reason is that women are more likely than men to live long enough to develop the disease. But there have been hints that factors beyond longevity could be contributing to the disparity, Greicius says.
Studies dating to the 1990s have suggested that one of these factors could be the APOE4 gene. About 15 percent of the general population carries the gene, but about 50 percent of people diagnosed with Alzheimer’s have it. The gene variant is just one risk factor for Alzheimer’s, but scientists say it seems to be an important one.
Greicius and his colleagues reviewed medical records of more than 8,000 older people. Some had the APOE4 gene, some didn’t. The records — many of them part of a data set funded by the National Institute on Aging — showed which people developed Alzheimer’s disease over a three- or four-year period.
And when it came to the subset of people who carry the APOE4 gene, Greicius says, there was a clear pattern. Men with the gene were only slightly more likely to develop Alzheimer’s, while women with the gene faced 1.8 times the risk compared with other women.READ MORE.