Sensory function and cognition in the Vietnam Era Twin Study of Aging
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Age is associated with alterations in sensation and cognition, but little is known of how sensory-cognitive interactions change over time, especially during late middle age. This project examined the change in relations between sensation and cognition and their consistency with established models of neurocognitive aging. Three studies examined associations between visual contrast sensitivity (CS), auditory pure tone acuity (PTA), and cognition among male twins from the Vietnam Era Twin Study of Aging (VETSA), who were assessed twice (VETSA 1, x̅𝑎𝑔𝑒 = 56, n =1,237, VETSA 2, x̅𝑎𝑔𝑒 = 62, n =1,016). Study 1 examined sensory relations, with the hypothesis of more and stronger correlations between CS and PTA at VETSA 2 than at VETSA 1 and a larger genetic correlation at VETSA 2 than at VETSA 1. Heritability at VETSA 1 and VETSA 2 was significant for multiple CS and PTA frequencies, and heritability increased with age. At VETSA 2, there were more shared genes between CS and PTA than at VETSA 1. Studies 2 and 3 examined sensory-cognitive associations. The Study 2 hypotheses of more and stronger associations between CS and cognition at VETSA 2 than VETSA 1 were not supported. Performance in five of nine cognitive domains was correlated with low frequency CS at VETSA 1. Four of these five correlations were significant at VETSA 2. The Study 3 hypotheses of increasing associations between PTA and cognition also were not supported. Low frequency PTA correlated with performance in six cognitive domains at VETSA 1 and in four at VETSA 2. High frequency PTA and episodic memory significantly interacted with age. Neither CS nor PTA was associated with cognition dependent on the sensory modality in which the cognitive tests were presented. The hypothesis that correlations between CS and PTA would increase with age was partially supported, and the hypothesis that correlations between sensory function (vision, audition) and cognition would increase with age was not supported, in both cases because these correlations were independent of age. The results did not follow a single established model of cognitive aging, supporting a model-agnostic approach to future aging research.
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