Background: Dementia is a decline in cognitive ability severe enough to affect daily life and which affects approximately 5-7% of the world’s population over 60. Throughout our lives, the brain undergoes structural and functional changes to maintain cognitive performance in response to continuous neurodegenerative insults. Semantic memory task activation, measured via the famous name recognition task (FNRT), acts as a measure of neural efficiency and a predictor of future cognitive decline. Exercise has shown promise as a means for attenuating age and disease-related cognitive decline, however, there is a gap in our understanding of the mechanisms by which exercise affords these benefits.
Goal: The purpose of our study is to compare the effects of an acute bout of low versus high-intensity cycling exercise on functional magnetic resonance imaging activation during a semantic memory task in younger adults.
Objectives: We hypothesized that after both high and low-intensity exercise, subjects would exhibit greater semantic memory task activation compared to baseline pre-intervention measures. We also hypothesized that the intensity of the cycling condition would have an interactive effect on semantic memory task activation changes.
Approach: In a completely within-subject design, 12 participants (8 Male, 6 Female, Age = 24.1 (±4.1) Yrs.), on two separate days and in counterbalanced order, performed the FNRT while undergoing functional magnetic resonance imaging both before and after a 30-minute bout of high and low-intensity exercise.
Results: The extent of semantic memory task activation was significantly lower in the Left Middle Frontal Gyrus following exercise and no significant effect of exercise intensity was found. Mean semantic memory task activation within the Left Middle Frontal Gyrus was significantly lower following exercise, independent of exercise intensity (p<.001). These results indicate that a single bout of acute exercise may be beneficial for cognition via improvements in neural efficiency, independent of exercise intensity.
Importance to public health: These findings suggest participation in aerobic exercise may provide short-term benefits to neural efficiency. These short-term benefits may culminate over time, reducing strain on neural networks throughout the lifespan, therefore, providing protection from age-related cognitive decline and contributing to the healthy aging of the brain.