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Effects of a 12-week exercise intervention on resting state brain networks in mild cognitive impairment and healthy elders

      Background

      It is important to identify treatments to improve brain function in Mild Cognitive Impairment (MCI), an early stage of Alzheimer’s Disease (AD). Previous studies have shown a disruption in resting state brain networks on the AD continuum, and while physical activity appears to delay the onset of AD, it is unknown if it alters resting state brain networks in clinical populations. We investigated the effects of a 12-week treadmill walking intervention on resting state brain networks in MCI and healthy elders.

      Methods

      Sixteen MCI and 16 healthy elders, ages 60-88, engaged in a supervised 12-week treadmill walking exercise intervention. Functional MRI (fMRI) was acquired at rest, and the voxel time courses were parceled into 90 brain regions using the AAL atlas. Correlation matrices (90x90) for each subject were entered into the NBS Connectome.

      Results

      Using the FDR option [paired t-test; 10,000 permutations] significant connection changes (p<0.05) were found in the healthy elders but not in the MCI. Healthy elders decreased connectivity between the left thalamus and left superior orbital gyrus. Reducing permutations to 5,000 revealed decreased connectivity between the left superior orbital gyrus and the following nodes: left caudate nucleus, left pallidum, and right thalamus.

      Conclusions

      These findings suggest 12-weeks of exercise alter functional connectivity patterns in the healthy elders, yet there is an apparent maintenance of network function in MCI. This indicates that walking may provide protective benefits to resting state networks in healthy elders while delaying the disruption of these networks in MCI. These findings continue to lend support to the use of exercise as a therapeutic intervention in MCI. It must be noted that the small number of subjects does limit the sensitivity of the analysis to detect differences.