Women Get More Dementia Because of Life History and Biology

Women are more likely than men to develop dementia, and the explanation runs on two tracks at once, one rooted in life history and one rooted in biology. Henry Brodaty, a professor, says both social and environmental reasons and biological reasons appear to be at work.

The first track is about how brains build a buffer. More years of schooling and jobs that demand heavy thinking help build what researchers call cognitive reserve, a kind of backup capacity that can delay decline. In generations now reaching old age, women often had less education and fewer chances at those mentally demanding occupations, so they built less reserve.

The same life history includes health. Women have faced higher rates of midlife obesity and high blood pressure, plus more likelihood of depression. Each of those three conditions raises the later risk of dementia.

The second track is inside the body. The female hormone estrogen may help protect brain cells, an effect scientists have proposed but are still studying. Women may also carry more of a toxic substance called amyloid beta protein, a sticky material that builds up in the brain and is the main driver of Alzheimer's disease.

A clue points to hormones as part of the story. Women who had their ovaries removed before menopause, and who then took HRT, a treatment that replaces hormones, were less likely to develop dementia later in life. That pattern supports the idea that estrogen has a protective role in the brain, which matters because new Alzheimer's treatments are now aimed at clearing the amyloid protein.