Examining the relationship between adolescent health behaviors, brain health, and academic achievement using fNIRS

Background Several adolescent health behaviors have been hypothesized to improve academic performance via their beneficial impact on cognitive control and functional aspects of the prefrontal cortex (PFC). Specifically, exercise, restorative sleep, and proper diet are thought to improve PFC function, while substance abuse is thought to reduce it. Few studies have examined the relationships among all of these in the same sample, while quantifying downstream impacts on academic performance. Objective The primary objective of this study is to examine the association between lifestyle behaviors and academic performance in a sample of adolescents, and to examine the extent to which activity within the PFC and behavioural indices of inhibition may mediate this relationship. Methods Sixty-seven adolescents underwent two study sessions five days apart. Sleep and physical activity were measured using wrist-mounted accelerometry; eating habits, substance use and academic achievement were measured by self-report. Prefrontal function was quantified by performance on the Multi-Source Interference Task (MSIT), and task-related brain activity via functional near-infrared spectroscopy (fNIRS). Results Higher levels of accelerometer-assessed physical activity predicted higher MSIT accuracy scores ( ϐ = .321, ρ = 0.019) as well as greater task-related increases in activation within the right dlPFC ( ϐ =.008, SE = .004, ρ =.0322). Frequency of fast-food consumption and substance use were both negatively associated with MSIT accuracy scores ( ϐ = −.307, ρ = .023) and Math grades ( β = −3.702, SE = 1.563, ρ = .022) respectively. However, these effects were not mediated by indicators of PFC function. Conclusion Physical activity and eating behaviors predicted better interference task performance in adolescents, with the former mediated by greater task-related increases in right dlPFC activation. Substance use predicted worse Math grades, however, no other reliable effects of health behaviors on academic outcomes were evident.