Abstract

Objective: Previous literature states that processing speed (PS) mediates the relationship between age and cognition. The current study sought to replicate previous findings and explore the potential of critical flicker fusion (CFF), a measure of visual temporal PS, as a mediator between age and cognition. Method: Participants were forty community-dwelling older adults with a mean age of 72.5 years. They had no more than mild cognitive impairment (Clinical Dementia Rating Sum of Boxes ≤ 4.0), had no ocular disease, and had corrected visual acuity of 20: 40 or better. Cognition was assessed via the CNS Vital Signs (CNS-VS) cognitive battery. Attention, verbal and visual memory, reasoning, and executive function subtests of CNS-VS were averaged to compute global cognition. CNS-VS symbol digit coding was used as a measure of PS. CFF was the highest average frequency at which participants could detect a flickering 660 nanometer beam of light. Results: Initially, age significantly predicted cognition (p = .04). However, CFF attenuated the effect of age (p = .095) but significantly predicted cognition (p = .034). PS also attenuated the effect of age (p = .895) but significantly predicted cognition (p = .003). Additionally, a hierarchical regression indicated age explained 10.6% (p = .04), PS explained 19.3% (p = .003), and CFF explained 7.7% (p = .042) unique variance in cognition. Conclusion(s): Results replicate findings that PS mediates age and cognition, and demonstrate CFF also mediates that relationship. Additionally, CFF contributes unique variance not explained by age and PS. Thus, CFF is a potential variable of interest in future cognitive aging research.