Previous studies have investigated the relationship between vision impairment and cognitive decline, as the number of people with dementia worldwide increases year after year due to the increasing older population. But results have been inconsistent and limited and haven’t focused on differing backgrounds and ethnicities, which is why researchers recently examined whether vision impairment and eye diseases were predictive of memory decline. They simultaneously studied subjects in China and the United States, using data with representative population-based samples from each country.
The Chinese dataset included 8,315 participants and the US group included 8,939; all were age 50 or higher. During a four-year follow-up, the researchers found that distance vision impairment is associated with a larger decrease in memory, in both China and the United States. History of cataract surgery or glaucoma did not affect the results in either group.
“The magnitude of the inverse association between vision impairment and change in memory was larger in the United States than in China,” possibly owing to the older age of the US participants resulting in a larger decrease in memory, the researchers wrote in their paper. “Participants in the United States who reported vision impairment might have more severe eye problems than those in China,” also strengthening the association in that cohort.
“Our analysis showed individuals with distance vision impairment were more likely to have a lower education and a higher prevalence of psychiatric disorders, diabetes and hypertension that are well-known risk factors for dementia.” Adjusting for these factors did not substantially change the association between distance vision impairment and change in memory, they found “suggesting the potential effects of vision impairment on memory decline may be via other pathways.”
The researchers suggest that screening for and treating vision impairment in older adults may help prevent or delay memory decline and the development of dementia.
Shang X, Zhu Z, Wang W, He M. Associations of vision impairment and eye diseases with memory decline over four years in China and the United States. American Journal of Ophthalmology 2021. Epub ahead of print.