Well, I went out to disprove your thesis, thinking we can easily look at countries where men live longer than women in another country.

For example, women in the US have a lower life expectancy than men in Australia (go figure). Now women are less than 1.4 times more likely than men to get dementia in australia, but about 2 times more likely to get alzheimer in the US. So that kind of points in your direction, but that is of course wildly inaccurate, cause one is mentioning dementia the other only alzheimer and whatnot.

https://www.worldometers.info/demographics/life-expectancy/ https://www.aihw.gov.au/reports/dementia/dementia-in-aus/con... https://www.alz.org/getmedia/ef8f48f9-ad36-48ea-87f9-b740346...

Edit: qwen and glm seem to also agree with parent. "Age is the dominant risk factor".