Despite not yet having identified a definitive cause for Alzheimer’s disease, scientists have discovered a very revealing clue as to why more women than men develop this disease. The key is in the genes .
A study carried out by researchers at the Stanford University School of Medicine (USA) has determined that having a copy of the variant of the gene called ApoE4 confers a substantially higher risk for Alzheimer’s disease in women than in men . The work has been published in the Annals of Neurology .
For the research, thousands of people were examined, most of them older than 60 years, who were monitored for several years in different Alzheimer’s centers. The researchers evaluated the medical history of all of them, finding that 2,200 people had shown signs of mild cognitive impairment, and 5,000 people had normal results. In both groups, being a carrier of ApoE4 increased the likelihood of Alzheimer’s disease , as expected.
However, for those who had apparently obtained normal results with the ApoE4 gene, in men the increase in risk – over time – was insubstantial and, in women, on the contrary, the risk doubled .
“Our study showed that, among older healthy controls, having one copy of the ApoE4 variant confers a significant risk of Alzheimer’s disease in women, but not in men,” says Michael Greicius, assistant professor of Neurology and Neurological Sciences and medical director of the Stanford Center for Memory Disorders and study leader.
Most people carry two copies of the ApoE3 gene variant, one from each parent, but about one in five people carry at least one copy of ApoE4 and a tiny percentage carry two ApoE4 copies. It is confirmed that a single copy of the ApoE4 gene increases the risk of Alzheimer’s by two or even four times . Carrying two copies of the gene condemns us to having ten times the risk of Alzheimer’s disease than anyone else.
