Change in visual acuity over a 12-year period predicts cognitive decline in older adults: identifying social engagement as a potential mediator.

Objectives: Deterioration in vision is an important dementia risk factor yet few studies have examined objectively measured changes in visual acuity over time. Visual decline may also reduce social engagement, highlighting the need to examine visual changes in concert with broader social function.

Method: The relationship between change in visual acuity (logMAR) and cognitive decline was examined in 2,281 participants from the PATH study using hierarchical linear regression. Step 2 determined whether social network significantly enhanced model fit. Exploratory mediation analysis examined the indirect effect of vision change on overall cognition via social networks.

Results: Adjusted models showed deterioration in visual acuity significantly predicted poorer cognition across domains (MMSE, β = -0.08, p ≤ 0.001; TMT B-A, β =  0.09, p = 0.004; SDMT, β = -0.07, p ≤ 0.001). Model 2 significantly improved model fit for overall cognition only (MMSE, F^change(1,1421)= 6.03, p = 0.014). The indirect effect of social network was marginally significant (β = -0.004, SE = 0.002, BCa 95%CI = -0.0088, -0.0002).

Conclusion: Deterioration in visual acuity significantly predicted multi-domain cognitive decline highlighting the importance of visual screening and treatment for vision loss. Social engagement partially mediated the relationship between vision change and overall cognition suggesting psychosocial factors may help to reduce the impact of visual decline.