Effector memory CD4(+) T cells are associated with cognitive performance in a senior population

Abstract

Objective: Immunosenescence and cognitive decline are common markers of the aging process. Taking into consideration the heterogeneity observed in aging processes and the recently described link between lymphocytes and cognition, we herein explored the possibility of an association between alterations in lymphocytic populations and cognitive performance.

Methods: In a cohort of cognitively healthy adults (n = 114), previously characterized by diverse neurocognitive/psychological performance patterns, detailed peripheral blood immunophenotyping of both the innate and adaptive immune systems was performed by flow cytometry.

Results: Better cognitive performance was associated with lower numbers of effector memory CD4(+) T cells and higher numbers of naive CD8(+) T cells and B cells. Furthermore, effector memory CD4(+) T cells were found to be predictors of general and executive function and memory, even when factors known to influence cognitive performance in older individuals (e.g., age, sex, education, and mood) were taken into account.

Conclusions: This is the first study in humans associating specific phenotypes of the immune system with distinct cognitive performance in healthy aging.

Figure 1. Distinct cognitive performers present differences in the cell populations of the adaptive immune system

The profile (cell counts per mL of blood) of good (black) and poor (red) cognitive performers with regard to B cells (A); T cells (B); CD4⁺ and CD8⁺ T-cell subpopulations (C); CD4⁺ and CD8⁺T-cell compartments (D and E), subdivided as naive, central memory (CM), effector memory (EM), and late differentiated (LD) T cells; CD4⁺ regulatory T cells (Tregs) (F), subdivided as naive Tregs, activated Tregs, and nonsuppressive Tregs (G). Each dot represents one individual and the line represents the mean of the group. *p < 0.05.