Tuesday, July 7, 2015

Why Women Are Suffering More from Alzheimer Disease than Men are?

Heart disease is an equal-opportunity killer, the number one cause of death in men and women. Cancer follows at number two, irrespective of gender. However, from there on out, the way women leave this world compared to men begins to diverge.

The CDC offers the following ratings of the top 10 causes of death in the United States. The leading causes of death among American women by percentage:

1) Heart disease - 22.9 percent
2) Cancer - 21.8 percent
3) Stroke - 6.1 percent
4) Chronic lower respiratory diseases - 6.0 percent
5) Alzheimer's disease - 4.7 percent
6) Unintentional injuries - 3.7 percent
7) Diabetes - 2.8 percent
8) Influenza and pneumonia - 2.3 percent
9) Kidney disease - 1.8 percent
10) Septicemia - 1.5 percent

The leading causes of death among American men by percentage:
1) Heart disease - 24.6 percent
2) Cancer - 24.1 percent
3) Unintentional injuries - 6.3 percent
4) Chronic lower respiratory diseases - 5.4 percent
5) Stroke - 4.2 percent
6) Diabetes - 3.1 percent
7) Suicide - 2.5 percent
8) Alzheimer's disease - 2.0 percent
9) Influenza and pneumonia - 2.0 percent
10) Kidney disease - 1.8 percent

Based on the numbers above, significantly more women than men die of Alzheimer’s disease (4.7 percent vs. 2 percent). The cause of the gender discrepancy in Alzheimer’s diagnoses is still not completely understood, but there is a standard belief that the statistical difference is related to the women longer life expectancy. So, the women's longer life could a reason as any aliment shows up later in the life in the form of mental decline.

Now, the researchers are planning to study other potential factors, like genetic makeup, biological differences and lifestyle factors. Maria Carrillo, an Alzheimer's Association (AA) chief science officer, said that there are many biological factors that should be studied. As per a new AA report, a woman aged 65 year old has 1 in 6 chance of having an Alzheimer's diagnosis. In the case of men, the chance is one in 11.

Last month, the Alzheimer’s Association brought 15 leading scientists together to ask what is known about women’s risk. Later this summer, Carrillo said it plans to begin funding research to address some of the gaps.

The tricky part is determining how much of the disparity is due to women’s longevity or other factors. “It is true that age is the greatest risk factor for developing Alzheimer’s disease,” said University of Southern California professor Roberta Diaz Brinton, who presented data on gender differences at a meeting of the National Institutes of Health this year. But, she said, “on average, women live four or five years longer than men, and we know that Alzheimer’s is a disease that starts 20 years before the diagnosis.” That is how early cellular damage can quietly begin.

What drives the difference in Alzheimer’s cases is not clear, said Dr. Susan Resnick of the National Institutes of Health, pointing to conflicting research. “We really have had a tough time understanding whether or not women really are more affected by the disease, or it’s just that they live longer,” Resnick said.

Data from the long-running Framingham, Massachusetts, health study suggests that because more men die from heart disease in middle age, those who survive past 65 may have healthier hearts that in turn provide some brain protection. Many of the same factors — obesity, high cholesterol, diabetes — that damage arteries also are Alzheimer’s risks.

Brinton researches if menopause can be a tipping point that leaves certain women vulnerable.

There is also some evidence that once Alzheimer’s is diagnosed, women may worsen faster; scans show more rapid shrinkage of certain brain areas.

Nevertheless, gene research offers the most startling evidence of a sex difference. Stanford University researchers analyzed records of more than 8,000 people for a form of a gene named ApoE-4, long known to increase Alzheimer’s risk. Women who carry a copy of that gene variant were about twice as likely to develop Alzheimer’s eventually, as women without the gene, while men’s risk was only slightly increased, Stanford’s Dr. Michael Greicius reported last year.

It is not clear why. It may be in how the gene interacts with estrogen, Brinton said. But, that has been hard to pin down. Years ago, a major study found that estrogen therapy after 65 might increase risk of dementia, although later research showed hormone replacement around the onset of menopause was not a problem.

Brinton studies how menopause changes the brain. Estrogen helps regulate the brain’s metabolism, how it produces the energy for proper cognitive function, and it must switch to a less efficient backup method as estrogen plummets, she explained. “It’s like the brain is a little bit diabetic,” said Brinton, who is studying whether that may relate to menopausal symptoms in women who later experience cognitive problems.

Carrillo notes that 40 years ago, heart disease was studied mainly in men, with little understanding of how women’s heart risks can differ. “How do we make sure we’re not making that mistake when it comes to Alzheimer’s?” she asked.

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