What is the relationship between visual impairment and cognitive function in octogenarians?

Abstract

Aims: To examine direct and indirect pathways between visual and cognitive function in advanced age.

Methods: We analysed cross-sectional baseline data from Life and Living in Advanced Age: A Cohort Study in New Zealand, which recruited equal sample sizes of Māori (n=421) and non-Māori (n=516) octogenarians. The Modified Mini-Mental State Examination assessed cognitive function. Vision was assessed with self-report and measured distance visual acuity. Associations between visual and cognitive function were explored using general linear models and structural equation modelling.

Results: Both Māori (mean age 82) and non-Māori (mean age 85) had good visual acuity [Māori: mean (standard deviation) 0.18 (0.20) logMAR; non-Māori 0.20 (0.17) logMAR] and cognitive function scores [Māori: median (interquartile range) 3MS=90 (11), non-Māori: 94 (8)]. Self-reported visual impairment was present almost 25% of the sample. Adjusting for confounders, no direct association was found between visual and cognitive function. For non-Māori, the path diagram showed the association between vision loss, and cognitive function was mediated by functional status.

Conclusion: Findings indicate that cognitive function is a multifactorial entity; rather than a direct effect of vision loss, mediating factors appear to contribute to cognitive decline in advanced age.