Objectives: Elevated peripheral inflammatory markers among older adults are associated with cognitive decline, particularly for women, for whom cognitive decline is more prevalent and rapid. Few prospective studies have examined gender-specific associations between inflammation and cognitive decline or examined stable, mean differences (i.e., between-person effects) versus fluctuations (i.e., within-person effects) in inflammation.
Methods: Participants (N = 235) were older adults (Mage= 75.1, range = 60-92) from a longitudinal study that included neuropsychological assessments and blood draws every six months for up to 12 years. Systemic inflammation was operationalized as serum interleukin-6 (IL-6). The Trail Making Test measured psychomotor processing speed (TMT-A), task-switching (TMT-B), and executive functioning (TMT-B-TMT-A). Multilevel models tested associations between cognition and inflammation and moderation by gender. Models controlled for relevant covariates (e.g., age, gender, education, body mass index, cardiovascular medication count).
Results: Higher mean IL-6 was associated with slower TMT-A performance for women (γ = .036, p = .04) but not men (γ = -.01, p = .45). Higher mean IL-6 was associated with slower TMT-B performance (γ = .036, p = .02), but not after covariate adjustment (γ = .016, p = .28) and there was no significant moderation by gender. There were no significant associations between within-person IL-6 and any outcome, between- or within--person IL-6 and TMT B-A performance, or any 3-way interactions between gender, IL-6, and study wave on any outcome.
Discussion: Psychomotor speed, but not executive function, was sensitive to changes in systemic inflammation in a gender-specific way. -Gender-specific differences in neurological aging remain a fruitful direction and critical target for future intervention research aimed at addressing preclinical Alzheimer's disease and accelerated aging.
Keywords: cognition; inflammaging; systemic inflammation.
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