Selected Health Factors (Pulse Pressure, Type 2 Diabetes) and Genetic Polymorphisms (ApoE, IDE rs6583817) Play Independent and Interactive Roles in Patterns of Cognitive Performance and Change in Older Adults

Abstract

Objective: This gene x environment (health) dissertation focused on concurrent and longitudinal change in performance on executive function (EF) and declarative memory (DM) latent variables by normal aging adults. Specifically, we report three studies that tested the independent and interactive effects of (a) Insulin degrading enzyme (IDE) and type 2 diabetes (T2D) across 2 waves of EF data, (b) IDE and pulse pressure (PP) across 3 waves of EF data, and (c) Apolipoprotein E (ApoE) and PP across 3 waves of DM data for older adults from the Victoria Longitudinal Study. Method: We assembled a sample of non-demented older adults (n = 683, M age = 71, Age range = 53-95) from which we drew a slightly different group for each study. We used latent growth modeling to test a series of similar research goals within each study. Results: First, for Study 1, we confirmed a single factor EF model and reported independent but unrelated (non-interactive) effects of T2D and IDE on EF performance. Second, for Study 2, we confirmed a single factor EF model and reported independent and interactive effects of PP and IDE on EF performance. Regarding the interactive effect of PP x IDE, higher PP differentially affected EF performance in older adults with the IDE G allele. Third, for Study 3, we confirmed a DM model made up of a single factor episodic memory (EM) model and a single factor semantic memory (SM) model that we ran in parallel. We reported independent effects of PP on the baseline level of EM but not SM but no independent effects of ApoE on EM or SM performance patterns. Regarding the interactive effect of PP x ApoE, EM performance and change was differentially affected by higher PP for adults with an ApoE ε3 or ε4 allele as compared with carriers of the potentially protective ε2 allele. Discussion: Genetic x health interaction analyses as performed on both concurrent and longitudinal data can reveal differential and magnifying effects of biological risk factors on cognitive aging. In the present case both IDE x PP and ApoE x PP affect concurrent and changing cognitive health in aging.