medical question

i wonder if progressive physical debilitations such as arthritis or macular degeneration correlate with increased incidence of alzheimers disease.

there is the story of the man who was a championship chess player who complained that when he got older he just couldn't see 5 moves ahead any more, he could only see 3 moves, but he was completely normal mentally otherwise. after he died they discovered that he had advanced alzheimers but it seems to have been covered up by how strong he had developed his brain.

what if now he couldn't see the pieces any more, or he couldn't otherwise play chess at all because of a physical ailment. would it be more likely for the alzheimers to set in right then? it seems likely. deserves a scientific study if there hasn't been one already.