Physical activity, vascular risk and cognitive performance in young adults

A growing body of literature suggests that higher levels of physical activity and cardiorespiratory fitness, as well as an alternative treatment such as low level laser therapy (LLLT), have beneficial effects on cognition, while sedentary lifestyle-induced obesity and vascular risk negatively influence cognition. However, the relationship between cardiorespiratory fitness and vascular risk on cognitive function and the effect of an acute bout of very vigorous aerobic exercise (acute exercise) on cognitive performance has not yet been investigated. Additionally, the effects of combined acute exercise and LLLT treatments on cognitive performance have not yet been characterized. Therefore, the goal of this dissertation was to conduct a series of three research studies ranging from a cross-sectional exploratory study about the association of cardiorespiratory fitness, obesity, and vascular risk on cognitive function, to an experimentally designed study that compared the effects of acute exercise, LLLT, and the combination of these two treatments on cognitive performance in young adults. Study1 examined the relationship among cardiorespiratory fitness (maximal oxygen consumption, VO2max), obesity indices (body mass index, BMI; waist circumstance), and vascular risk (C-reactive protein; CRP). Cognitive function included crystalized intelligence (Kaufman Brief Intelligence Test; KBIT), executive functions of inhibition (Stroop test), switching (Trail making test; TMT), attention (Psychomotor Vigilance Task; PVT), and working memory (Delayed-Match-to-Sample, DMS). Study 2 determined the effect of acute exercise on cognitive performance including executive response inhibition (Stroop test) and response switching (TMT) and brain-derived neurotrophic factor (BNDF). Study 3 compared the effectiveness of LLLT and acute exercise on cognitive performance, which included attention (PVT) and working memory (DMS). Results demonstrated there was a beneficial effect of physical exercise-induced improvements in cardiorespiratory fitness on vascular risk and cognitive functions particularly in working memory and inhibitory control (Study1). Acute exercise improved performance in inhibitory control and increased the BNDF level compared to the control condition, suggesting the acute exercise-induced the increase in BDNF level may be at least in part of mediating the cognitive performance improvement (Study 2). All three conditions (acute exercise, LLLT, or the combination) improved performance in attention and working memory, as measured by reaction time and response accuracy, when compared to a control group. Specially, the combined group showed a trend of greater improvement in attention and worming memory performance (Study 3). Taken together, the results of this research series suggest that acute exercise and LLLT can improve cognitive performance, which is also mediated by health indices including cardiorespiratory fitness, obesity, and vascular risk. It is anticipated that these findings will make substantive contributions to the empirical literature concerning the beneficial effect of exercise and LLLT on cognitive health in young adults, given the current paucity of research.