I was startled to find that "older age alone is not sufficient to cause Alzheimer’s dementia." ref79 p14 That's what a 159 page 2024 report says:
https://www.alz.org/media/documents/alzheimers-facts-and-figures.pdf
So what helps? What brain is Good for: COGNITIVE engagement. And that does not mean only high brow academic work but also stuff that uses brain: learning another language, playing music, brain stimulating talks. ( I must confess, I am heart broken to find a professor who posited a scenario abou race for feed back from others but simply did not wanted to hear anything that challenged his position. What tragedy! whe come with curiosity filled to our ears and the most 'knowing' seem to have lost our basic strength.)

Equally forgiving of nature was another study that looked into the brains of very old people who died Without any Symptoms of alzheimer's but their brain autopsies shows they were riddled with alz disease! Go figure and give nature/biology/Divine a big kiss for being so generous to us if we just lived our lives fully engaged -- with people discussing ideas or connecting with music, and/or with nature.

I am meeting a local alz group tomorrow. But Connecting with people to live a full-fledged life is all what health often seems to ask for.