Why are women at higher risk of Alzheimer's? Two differences identified

It has been revealed that women are twice as likely to develop Alzheimer's disease as men. Scientists say they are now on the way to understanding why and have identified two clear differences between men and women.

THERE ARE TWO MAIN DIFFERENCES: First, women have different chromosomes than men. Second, they experience menopause: a process that occurs when a woman's reproductive hormones naturally decline in her 40s and 50s. According to the Alzheimer's Association, one in three older Americans dies from Alzheimer's or another form of dementia. Nearly two-thirds of Americans with Alzheimer's are women.

THE X CHROMOSOME CARRIES ALZHEIMER'S When we look inside the body, women have two "X" chromosomes, while men have one "X" and one "Y" chromosome. Chromosomes are thread-like DNA structures inside our cells that carry hundreds or even thousands of genes.

Genes determine a person's physical characteristics. Differences between the genes found on the X and Y chromosomes may increase the risk of developing Alzheimer's disease in women. Recent research suggests that genes on the X chromosome are associated with Alzheimer's disease, and that women with Alzheimer's live longer than men with the disease because of their second X chromosome.

Menopause is a piece of the puzzle. Women's different dominant hormones, such as estrogen, which acts on the brain, may also play a role. Experts say menopause is one piece of the puzzle, perhaps the biggest. Because the ovaries stop producing estrogen and progesterone during menopause, some women turn to hormone replacement therapy. This treatment can help relieve symptoms like hot flashes that occur due to low hormone levels. However, experts say hormone therapy can increase serious health risks for some women, including heart attack, stroke, breast cancer, blood clots, and gallbladder disease.

TAU PROTEIN AND ALZHEIMER According to Rachel Buckley, Associate Professor of Neurology at Harvard Medical School, levels of the protein tau are significantly higher in women taking hormone replacement therapy after age 70. Tau protein accumulation is considered an early indicator of Alzheimer's disease. The rate of cognitive decline was also found to be higher in women in this same group.