A small study has found that a 12-week exercise program significantly improved cognition in both older adults with MCI and those who were cognitively healthy, but that effect on blood flow in the brain was different in these two groups.
While the exercise increased cerebral blood flow in the frontal cortex of those in the healthy group, those with MCI experienced decreases in cerebral blood flow. It has been speculated that the brain responds to early difficulties by increasing cerebral blood flow. This suggests that exercise may have the potential to reduce this compensatory blood flow and improve cognitive efficiency in those who are in the very early stages of Alzheimer's Disease.
The exercise training program consisted of four 30-minute sessions of moderate-intensity treadmill walking per week.
Both working memory and verbal fluency were tested (using the Rey Auditory Verbal Learning Test, and the Controlled Oral Word Association Test).
Changes in cerebral blood flow were measured in specific brain regions that are known to be involved in the pathogenesis of Alzheimer's disease, including the insula, the anterior cingulate cortex, and the inferior frontal gyrus.
Among those with MCI, decreased blood flow in the left insula and anterior cingulate cortex was strongly associated with improved verbal fluency.
Alfini, A. J. et al. 2019. Resting Cerebral Blood Flow After Exercise Training in Mild Cognitive Impairment. Journal of Alzheimer's Disease, 67 (2), 671-684.