US life expectancy in 2024 for women was 81.4 years; for men, 76.5 [1]; “non-early” symptoms of Alzheimer's typically begin after 65 [2]. I don’t think that the life expectancy average offset of ~5 years is the main factor here.

1. https://www.cdc.gov/nchs/products/databriefs/db548.htm 2. https://www.mayoclinic.org/diseases-conditions/alzheimers-di...

It also said "comfortable lives".

Also compare retirement ages, years worked, income (hard mental work)... it is well known that alzhaimer is corellated with brain activity (like solving suduku puzzles). Watching tv all day is not very healthy for brain...