Exploring Cognitive Load and Relative Neural Efficiency in Aging: : Preliminary Insights from fNIRS and the SLUMS
Nancy Getchell1,2,3, Elizabeth Orsega-Smith1,2,3, Serena Schade1,2,3
1Department of Kinesiology and Applied Physiology, College of Health Sciences, University of Delaware.
Objective:
To examine whether prefrontal cortex activation measured by functional near‑infrared spectroscopy (fNIRS) during the St. Louis University Mental Status (SLUMS) exam differs by cognitive status and whether relative neural efficiency (RNE) can serve as a physiological marker of cognitive impairment.
Methods:
This exploratory study was conducted in 2024 at a senior center in a small Mid‑Atlantic U.S. city. Thirteen community‑dwelling adults aged 65-85 years completed the SLUMS while wearing an fNIRS sensor positioned over the prefrontal cortex. Participants were classified as having normal cognition (NOR), mild cognitive disorder (MCD), or dementia (DEM) based on SLUMS scores. ΔHbO served as the indicator of cognitive effort, and RNE was calculated by combining normalized SLUMS performance and oxygenation values. Group differences were tested using ANOVA with confirmatory nonparametric analyses.
Results:
RNE differed significantly among groups (F₂,₁₀ = 5.26, p = 0.0275). Post‑hoc comparisons showed lower RNE in the DEM group compared with the NOR group (p = 0.0224). Confirmatory Kruskal‑Wallis testing supported these findings (p = 0.0287), with a significant DEM-NOR difference on Dunn's test (p = 0.0311). Descriptive hemodynamic patterns indicated higher ΔHbO and ΔHbR variability in the DEM group across SLUMS question blocks.
Conclusions:
Older adults with dementia demonstrated reduced neural efficiency during SLUMS administration, suggesting greater cognitive effort relative to performance. These preliminary findings indicate that SLUMS items impose different cognitive workloads depending on impairment level.
Policy Implications:
Integrating physiological markers such as neural efficiency into cognitive screening may enhance early identification of impairment, support more targeted referral pathways, and inform public health planning for Delaware's aging population.
