(EA03-19-25) The Neurocognitive Efficiency Score: Derivation, Validation, and Application to Cognitive Processing and Iron Deficiency

Scientific conference where the work was recently presented: Society for Neuroscience, 2024 Annual Meeting

Date on which the work was previously presented at the scientific conference listed: October 9, 2024

Objectives: Propose, validate, and apply a novel measure of the efficiency of energy expenditure in cognitive work and apply it to characterizing efficiency as a function of iron status in women of reproductive age.

Methods: We analyzed unpublished data from a previous study (Wenger, DellaValle, Murray-Kolb, & Haas, 2017) in which we collected simultaneous behavioral, EEG and metabolic data (O₂ consumed and CO₂ expired) during the performance of a cognitive task that was systematically varied in difficulty. Critical data were the hazard function of the reaction time distribution, global field power (GFP) of the EEG data, and metabolic energy expenditure.

Results: We show that, in these data, GFP and energy expended are regularly related and that both track variations in workload. We then used unpublished data from another previous study (Newbolds & Wenger, 2024) in which two groups of women, one iron sufficient (IS) and a second iron deficient and non-anemic (IDNA), performed a contrast detection threshold task with concurrent EEG. We find that that IS women had a higher level of neural efficiency than did IDNA women and this was true across the range of RTs. The components of the NES were regularly related to biomarkers indicative of both the body’s iron stores and iron’s role in O₂ transport, and that the NES was reliably related to thresholds. Finally, we showed that the relationship between iron levels and thresholds was completely mediated by neural efficiency.

Conclusions: The results support the plausibility of the NES as an indirect measure of the relationship between the amount of mental work accomplished and the amount of brain energy expended as well as the general applicability in studying cognition in both normal and perturbed physiological states.

Funding Sources: NIH, NIEHS 1 K18 ES021624
The University of Oklahoma Office of Vice President for Research and Partnerships