Alzheimer's Affects Far More Women Than Men, and Here's Why

Researchers have determined that a single gene variant is responsible to giving aging women a much higher risk of developing Alzheimer's disease, compared to men of the same age.

The Alzheimer's Association's latest facts and figures have revealed that as things stand, nearly two-thirds of all patients (at a staggering 5.1 million) suffering from the debilitating disease are women. And more stunningly still, the disease kills more people each year than breast cancer and prostate cancer combined.

Interestingly, the report also explains that women in their 60s are nearly twice as likely to develop early symptoms of Alzheimer's than they are breast cancer, even when most medical attention is given to the latter when addressing women's' health.

And that should come as something of a surprise, especially because recent research has determined that women are more resistant to conventional memory loss (due to told age) compared to men.

Now, a study published in the journal Annals of Neurology suggests exactly why women are more likely to develop the disease than men.

According the study's senior author, Michael Greicius, he first became curious about the male vs. female risk rate of Alzheimer's back in 2012 after unearthing a paper published in a JAMA scientific journal back in 1997. The decade-old research suggested that a ApoE - a "genetic protein recipe" that is invaluable to the process of shipping fatty substances along nerve cell membranes - could be expressed in more potentially damaging varieties among women. One variety in particular, called ApoE4, was commonly expressed in women and was found to be leading to an increased risk of developing Alzheimer's disease. (Scroll to read on...)

While the 1997 study was never followed up on for various reasons, Greicius decided to get a team together to investigate this phenomenon using modern techniques to asses gene expression.

Analyzing public data on more than 8,000 people around the age of 60, who had been admitted to Alzheimer's centers in the United States, the team determined that the risk of developing full-blown Alzheimer's disease was highest in individuals carrying the ApoE4 gene variant.

Interestingly, when the researchers then compared risk rates among women with the gene compared to men with the gene, they were able to determine that the gene only led to a slight increase in risk among males. On the other hand, women who expressed the variant boasted nearly double the risk of developing Alzheimer's compared to women who did not express the gene in that manner.

Brain scans of the gene carriers showed a similar theme, where as men with the gene commonly showed brain scans no-different from their non-ApoE4 expressing counterparts, women with the gene variant showed remarkably different looking brain connection compared to non-carriers of the variant.

"These days, a lot of people are getting genotyped either in the clinic or commercially. People come to me and say, 'I have an ApoE4 gene, what should I do?'," said Greicius, who takes breaks form his research to see patients. "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."

He and his colleagues add that it is still unclear why the variant has such a more severe effect on the brains of women, but simply identifying the variant's influence is a huge step in the right direction.

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