Vision Impairment Linked to Dementia in Older Adults

TOPLINE:

Poor vision and contrast sensitivity at baseline increase the likelihood of incident dementia in older adults; a decline in contrast sensitivity over time also correlates with the risk of developing dementia.

METHODOLOGY:

• Researchers conducted a longitudinal study to analyze the association of visual function with the risk for dementia in 2159 men and women (mean age, 77.9 years; 54% women) included from the National Health and Aging Trends Study between 2021 and 2022.
• All participants were free from dementia at baseline and underwent visual assessment while wearing their usual glasses or contact lenses.
• Distance and near visual acuity were measured as the log minimum angle of resolution (logMAR) units where higher values indicated worse visual acuity; contrast sensitivity was measured as the log contrast sensitivity (logCS) units where lower values represented worse outcomes.
• Dementia status was determined by a medical diagnosis, a dementia score of 2 or more, or poor performance on cognitive testing.

TAKEAWAY:

• Over the 1-year follow-up period, 192 adults (6.6%) developed dementia.
• Worsening of distant and near vision by 0.1 logMAR increased the risk for dementia by 8% (P = .01) and 7% (P = .02), respectively.
• Each 0.1 logCS decline in baseline contrast sensitivity increased the risk for dementia by 9% (P = .003).
• A yearly decline in contrast sensitivity by 0.1 logCS increased the likelihood of dementia by 14% (P = .007).
• Changes in distant and near vision over time did not show a significant association with risk for dementia (P = .58 and P = .79, respectively).

IN PRACTICE:

“Visual function, especially CS, might be a risk factor for developing dementia,” the authors wrote. “Early vision screening may help identify adults at higher risk of dementia, allowing for timely interventions.”

SOURCE:

The study was led by Louay Almidani, MD, MSc, of the Wilmer Eye Institute at the Johns Hopkins University School of Medicine, in Baltimore, and was published online on June 10, 2024, in the American Journal of Ophthalmology.

LIMITATIONS:

The study had a limited follow-up period of 1 year and may not have captured the long-term association between visual impairment and the risk for dementia. Moreover, the researchers did not consider other visual function measures such as depth perception and visual field, which might have affected the results.

DISCLOSURES:

The study did not have any funding source. The authors declared no conflicts of interest.