The influence of aerobic fitness on cerebral white matter integrity and cognitive function in older adults: results of a one-year exercise intervention

Abstract

Cerebral white matter (WM) degeneration occurs with increasing age and is associated with declining cognitive function. Research has shown that cardiorespiratory fitness and exercise are effective as protective, even restorative, agents against cognitive and neurobiological impairments in older adults. In this study, we investigated whether the beneficial impact of aerobic fitness would extend to WM integrity in the context of a one-year exercise intervention. Further, we examined the pattern of diffusivity changes to better understand the underlying biological mechanisms. Finally, we assessed whether training-induced changes in WM integrity would be associated with improvements in cognitive performance independent of aerobic fitness gains. Results showed that aerobic fitness training did not affect group-level change in WM integrity, executive function, or short-term memory, but that greater aerobic fitness derived from the walking program was associated with greater change in WM integrity in the frontal and temporal lobes, and greater improvement in short-term memory. Increases in WM integrity, however, were not associated with short-term memory improvement, independent of fitness improvements. Therefore, while not all findings are consistent with previous research, we provide novel evidence for correlated change in training-induced aerobic fitness, WM integrity, and cognition among healthy older adults.

Keywords: aging; anisotropy; cerebrum; cognition; diffusion tensor imaging; physical fitness.

Figure 1

Correlation between change in FA and aerobic fitness. Left and middle columns illustrate the patterns of increased fitness associated with increased regional FA for the walk (black) and the stretch (gray) groups. The left column plots raw data points; the middle column plots residuals, after correction for variance associated with age, sex, and program adherence. The right column illustrates representative views of the four a priori ROIs; ROIs (shown in blue) were manually defined on the mean skeleton (shown in green), according to the anatomical guidelines outlined in Head et al. 1987.

Figure 2

Correlation between change in short‐term memory and aerobic fitness. Figure illustrates the correlation between increased fitness and increased short‐term memory for the walk (black) and the stretch (gray) groups. The left column plots raw data points; the middle column plots residuals, after correction for variance associated with age, sex, and program adherence.