Getting your eyes checked regularly and actually wearing your prescribed glasses/contacts also reduces dementia risk. I always assumed it was a correlation not causation type deal (surely people who are on top of their their optical health, and care about that sort of thing, are going to be generally healthier?) but after seeing this I'm starting to believe having sharp senses simply does a lot of good for your long-term neurological health.
Wondering if your eyes and ears are getting less input over time that the brain adapts and reduces sensitivity.