Having a copy of a certain gene variant increases women's risk for Alzheimer's disease much more than it does for men, a new study indicates.
 

Stanford University researchers analyzed data from more than 8,000 people, most older than 60, who were tracked over a long period of time at about 30 Alzheimer's centers across the United States.
 

Overall, having a copy of the ApoE4 gene variant increased the risk of Alzheimer's. But further analysis showed that women with a copy of this gene variant were about twice as likely to develop Alzheimer's as those who did not have the variant. Men with the ApoE4 variant had only a slightly increased risk of developing Alzheimer's, according to the study in the April 14 issue of the Annals of Neurology.
 

The findings could help improve understanding of the underlying causes of Alzheimer's disease, according to senior study author Dr. Michael Greicius. He's an assistant professor of neurology and neurological sciences, and medical director of the Stanford Center for Memory Disorders.
 

Greicius noted that women are much more likely than men to develop Alzheimer's, and that this difference is only partly due to the fact that women tend to live longer than men.

"Even after correcting for age, women appear to be at greater risk," Greicius said in a Stanford news release.
 

The findings also suggest that doctors need to take different approaches when dealing with women and men.
 

"These days, a lot of people are getting genotyped [genetic testing] either in the clinic or commercially. People come to me and say, 'I have an ApoE4 gene, what should I do?' If that person is a man, I would tell him that his risk is not increased much if at all. If it's a woman, my advice will be different," Greicius said.
 

Between 5 million and 6 million Americans have Alzheimer's, and that number could more than double by mid-century, according to experts.