or those without dementia are more likely to get cataract surgery? Do dementia patients read?
“Do dementia patients read?”
They don’t care.
“or those without dementia are more likely to get cataract surgery? Do dementia patients read?”
That’s a good point. I wonder about the results of the study for a similar reason; maybe cataract surgery is more likely to happen for people who are in a higher cognitive group, who would already be less likely to later develop dementia. For example, if persons getting cataract surgery have a higher average income, and people with a higher average income already have 30% lower dementia, the cataract surgery wouldn’t be causative for the improved results.
A good study would correct for these types of things, although you always wonder how well they can really do that. According to the article, the observational study adjusted for a number of potential confounders, yet still yielded a strong association, so I am guessing that there actually is a real cognitive benefit to having cataract surgery. The idea that the brain is getting better input with improved vision seems like a reasonable explanation.