Sympathetic Nervous System And Exercise Affects Cognition In Youth (sneacy)

Purpose: Given the importance of physical activity to cognitive and brain health, we examined changes in salivary alpha-amylase (sAA), a marker of sympathetic nervous system activity, as a candidate mechanism mediating the acute effects of a single exercise bout on cognition and academic achievement in children. Methods: 104 children (9-10 years) were exposed to exercise and compared to two control conditions: the Trier Social Stress Test (TSST; active) and seated rest (passive) using a within-subjects randomized crossover design. Before and after each intervention, cognition was assessed using a flanker task with congruent and incongruent trials. Math and reading achievement were assessed using the Wide Range Achievement Test-2. sAA was measured as a marker of the catecholaminergic stress response. Structural equation modeling was used to examine sAA as a mediator of the relationship between exercise and cognitive and academic outcomes. Participants were entered as random effects to account for the nesting structure of the data. Results: sAA following the exercise intervention was significantly lower than following the rest and TSST interventions, controlling for baseline sAA (b1 = -29.72, p < .001). The effects of exercise on flanker task performance variability was fully mediated by sAA post-exercise (b = -1.10, p = 0.02) when controlling for baseline sAA. This mediation, explaining 39% of the variance in task performance variability, highlights sAA as the primary mechanism by which exercise impacts performance variability. While the indirect effect on accuracy in the exercise intervention was marginal (b = 0.24, p = 0.06), no significant indirect effects were observed for mean reaction time (RT) in either incongruent or congruent conditions. For academic achievement, a significant effect of exercise was noted for math (b = 4.64, p = .01) with higher scores post-exercise (M ± SD: 118.0 ± 14.5) compared to rest (113.4 ± 13.8) and TSST (113.6 ± 14.1), which were not mediated by sAA. No significant effects were found for reading. Conclusion: This study is among the first to investigate the molecular underpinnings of acute exercise-induced changes in cognition in children using molecular, behavioral, and academic achievement measures. Findings suggest sAA as a mechanism by which acute exercise benefits cognition. R01 HD094054-01