Aerobic exercise training and neurocognitive function in cognitively normal older adults: A one-year randomized controlled trial

Abstract

Background: Current evidence is inconsistent on the benefits of aerobic exercise training for preventing or attenuating age-related cognitive decline in older adults.

Objective: To investigate the effects of a 1-year progressive, moderate-to-high intensity aerobic exercise intervention on cognitive function, brain volume, and cortical thickness in sedentary but otherwise healthy older adults.

Methods: We randomized 73 older adults to a 1-year aerobic exercise or stretching-and-toning (active control) program. The primary outcome was a cognitive composite score calculated from eight neuropsychological tests encompassing inductive reasoning, long-term and working memory, executive function, and processing speed. Secondary outcomes were brain volume and cortical thickness assessed by MRI, and cardiorespiratory fitness measured by peak oxygen uptake (VO₂ ).

Results: One-year aerobic exercise increased peak VO₂ by ∼10% (p < 0.001) while it did not change with stretching (p = 0.241). Cognitive composite scores increased in both the aerobic and stretching groups (p < 0.001 for time effect), although no group difference was observed. Total brain volume (p < 0.001) and mean cortical thickness (p = 0.001) decreased in both groups over time, while the reduction in hippocampal volume was smaller in the stretching group compared with the aerobic group (p = 0.040 for interaction). Across all participants, improvement in peak VO₂ was positively correlated with increases in cognitive composite score (r = 0.282, p = 0.042) and regional cortical thickness at the inferior parietal lobe (p = 0.016).

Conclusions: One-year aerobic exercise and stretching interventions improved cognitive performance but did not prevent age-related brain volume loss in sedentary healthy older adults. Cardiorespiratory fitness gain was positively correlated with cognitive performance and regional cortical thickness.

Keywords: aerobic exercise; aging; brain volume and cortical thickness; cardiorespiratory fitness; neurocognitive function.

Figure 1:

Flowchart for one-year exercise trial in cognitively normal older adults. Participants were randomized to a 12-month intervention of aerobic exercise training or stretching-and-toning program.

Figure 2:

A) Peak oxygen uptake (peak VO₂) in the aerobic exercise and stretching groups at baseline and six- and 12-month follow-ups. Estimated marginal means (solid lines), 95% confidence intervals (dashed lines), and p-values were calculated from the linear mixed model based on the intent-to-treat analysis. B) Percent changes in peak VO₂ compared between the aerobic and stretching groups at each time point. p-values were calculated from the linear mixed model based on complete outcome data. Both models were adjusted for baseline age and sex. *p<0.05 for post-hoc pairwise comparisons with the Bonferroni correction. Black lines represent mean values.

Figure 3:

A) Cognitive composite scores in the aerobic exercise and stretching groups at baseline and six- and 12-month follow-ups. Estimated marginal means (solid lines), 95% confidence intervals (dashed lines), and p-values were calculated from the linear mixed model based on the intent-to-treat analysis. B) Changes in cognitive composite scores compared between the aerobic and stretching groups at each time point. P-values were calculated from the linear mixed model based on complete outcome data. Both models were adjusted for baseline age, sex, and years of education. *P<0.05 for post-hoc pairwise comparisons with the Bonferroni correction. Black lines represent mean values.

Figure 4:

Vertex-wise analysis of symmetrized percent change (SPC) in cortical thickness over one year. A) Group comparison of SPC between the aerobic exercise and stretching groups and B) simple correlation of SPC with change in peak oxygen uptake over one year. The analysis was performed with FreeSurfer’s QDEC (Query, Design, Estimate, Contrast) software.

Figure 5:

Simple correlation between changes in peak oxygen uptake (VO₂) and cognitive composite score over one year. The correlation coefficient (r) and p-value were calculated by the Pearson product-moment correlation analysis.