As life expectancy increases, so does the prevalence of disease associated with old age. Previous cross-sectional investigations have suggested visual and cognitive functions are linked, but longitudinal reports offer mixed evidence. A recent study investigated the relationship between cognitive performance and visual impairment among older adults and found that self-reported visual impairment is associated with a greater likelihood of dementia over time, and vice versa.

The retrospective time-to-event study included 10,676 participants aged 65 and older from the National Health and Aging Trends Study. The researchers evaluated the impact of baseline visual impairment on dementia and baseline dementia on visual impairment.

Subsequent dementia was observed in 16% of patients with normal cognitive status at baseline. Subsequent visual impairment was reported in 22% of patients with normal self-reported vision at baseline.

“Our study demonstrates a strong temporal association between visual impairment and dementia over eight years of follow-up in a representative sample of US Medicare beneficiaries,” the researchers wrote in their paper. “We identified an approximately twofold increased likelihood in both directions: higher likelihood of developing new dementia when visual impairment was present at baseline and higher likelihood of developing new visual impairment when dementia was present at baseline.”

They concluded, “These findings have important implications for public health and examination recommendations in older adults.” They noted that there may be a role for ophthalmologists to advocate for dementia screening or geriatrics/neurology referrals for their visually impaired patients, especially if poor visual acuity is inadequately explained by a complete ophthalmic exam and testing.

Chen SP, Azad AD, Pershing S. Bidirectional association between visual impairment and dementia among US older adults over time. Ophthalmology. February 26, 2021. [Epub ahead of print].