The risk of developing Alzheimer's disease that the APOE4 allele confers is higher for women, according to a new study in the Annals of Neurology.
Researchers led by Stanford University's Michael Greicius examined conversion risk in nearly 5,500 controls and more than 2,500 people with mild cognitive impairment — risk of developing MCI or Alzheimer's . In controls, he and his colleagues found that APOE4 allele carriers were more likely to convert, but that the effect was more pronounced in women than in men, with a hazard ratio of 1.81 for women and 1.27 for men.
"There is no question that APOE4 is a potent genetic risk factor for Alzheimer's," Greicius tells the New Scientist. "[But] it appears from our study to vary strongly as a function of sex."
The study doesn't, NPR adds, address whether women as a group are more likely to develop Alzheimer's disease than men of the same age. But according to the Mayo Clinic's Michelle Mielke, it does suggest that Alzheimer's risk factors can be different for women and men.
"What is interesting in relation to this paper is that animal and cellular studies suggest that there is an interaction between APOE4 and estrogen," she tells NPR. "So that may possibly be explaining the findings we're seeing here in humans."