Impact of visual impairments on cognitive functions in older adults: insights from NHANES data.

Background: Visual impairments (VI) are common in the older adults and may affect cognitive functions through mechanisms such as reduced sensory input and increased social isolation. Although current understanding of this association is incomplete, evidence suggests a potential link between poor vision and cognitive decline. This study aims to investigate the relationship between Subjective Visual Impairment (SVI), Objective Visual Impairment (OVI), and cognitive decline in the older adults, and assess whether these associations remain significant after controlling for multiple confounding factors.

Methods: Data from the National Health and Nutrition Examination Survey (NHANES) for the years 1999-2002 were utilized, focusing on participants aged 60 and above. A total of 2,522 eligible participants were analyzed to assess their cognitive function and visual status. Weighted logistic regression models were used to explore the relationship between cognitive status and VI, progressively adjusting for confounding variables. Non-linear associations between cognitive score and VI were further explored using restricted cubic spline analysis.

Results: Visual impairments were significantly associated with worse cognitive function. Participants with SVI had a 3.437-fold higher risk of cognitive decline compared to those without SVI (95% CI: 2.648-4.461,  < 0.001). After adjusting for multiple covariates, the association remained significant (adjusted for SVI: 1.921, 95% CI: 1.346-2.742,  = 0.001; adjusted for OVI: 3.075, 95% CI: 1.740-5.433,  = 0.001). The restricted cubic spline analysis revealed a non-linear relationship between cognitive score and visual impairment, suggesting that the impact of visual impairment on cognitive decline varies across different levels of cognitive function.

Conclusion: This study highlights a significant association between visual impairment and cognitive decline, even after controlling for multiple potential influencers. The findings support the integration of vision assessments into older adults care to identify and address vision problems early, potentially mitigating cognitive decline. The discovery of non-linear relationships further suggests that vision interventions may be particularly vital at certain stages of cognitive scores.