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Dual Mediation of Cognitive Function by Prefrontal Cortical Thickness and Vowel Articulation in Healthy Adult Women

Poster Session F - Tuesday, March 10, 2026, 8:00 – 10:00 am PDT, Fairview/Kitsilano Ballroom

Neekan Nasiri¹ (), William Matchin²; ¹University of South Carolina

Cortical morphology and speech articulation both exhibit age-related decline, yet their interdependence and contributions to cognitive performance remain generally unexplored. This study tested whether prefrontal cortical thickness and vowel space area (VSA) jointly mediate the association between precuneus morphology and cognition in healthy adult women. Seventy-five participants (ages 20–78) from the ABC study completed speech production, MRI, and cognitive testing. Participants produced "hot," "hoot," "heat," "hat," and "hub" fifteen times each in a sound-attenuated booth. Acoustic formants (F1, F2) were extracted in Praat, and VSA was ascertained using elliptical modeling and k-means clustering in R. Cognitive ability was indexed by the Montreal Cognitive Assessment (MoCA). Spearman correlations revealed positive associations between MoCA and cortical thickness in the superior frontal gyrus (ρ = 0.24–0.28, p < .05) and precuneus (ρ = 0.22–0.26, p < .05), and between VSA and prefrontal thickness (ρ = 0.23, p = .048). Dual mediation analyses indicated significant indirect effects of precuneus thickness on MoCA via both prefrontal cortical thickness (β = 0.09, 95% CI [0.04, 0.16]) and VSA (β = 0.06, 95% CI [0.02, 0.10]), supporting integrated structural and behavioral pathways for cognitive maintenance. Exploratory analyses showed a marked reduction in VSA after age 50, suggesting that menopause-related hormonal changes may contribute to reduced articulatory precision and cortical thinning. Collectively, these findings provide novel insight into how speech articulation, quantified through vowel space, serves as a sensitive behavioral indicator of neural integrity and cognitive function across the adult lifespan.

Topic Area: PERCEPTION & ACTION: Development & aging