I have 2 uncles. One was a brilliant electrical engineer who worked directly for the Navy then later as a consultant to the Navy. Now he’s lucky to know who his wife is. He is late 80s. As one person said, he’s forgotten more than most of the rest of us will never know.
His brother just turned 90 and totally lucid. You’d NEVER know he is 90! Still lives alone, still drives sometimes. Amazing.
And then their sister, my mother. She is amazing - has had a great memory all her life. Starting to repeat herself now but nothing like Alzheimers.
You just never know.
My mom is 97 and just started medication.
At that age is is very difficult to distinguish Alzheimers from a normal aging process (brain scans aren’t reliable). Perhaps the plasma phospholipid test would be useful in doing so.