The Influence of Sunlight and Exercise on Adolescents with ADHD using fNIRS imaging

Purpose: With the growing prevalence of ADHD diagnoses in children, the world needs additional therapies to alleviate attention-related symptoms. Since both light exposure and physical activity have been linked with upregulating serotonin , and improving mood and focus levels ,, outdoor exercise – which combines the two – could serve as a non-invasive, low-cost tool that is easily implementable for most children. Although previous studies have looked qualitatively at the effect of exercise on mental health , this study takes a much more quantitative, neurological imaging-based approach. Functional Near-infrared Spectroscopy (fNIRS) imaging is a portable device that measures brain activity on the cerebral cortex. fNIRS allows for brain activity to be measured while performing cognitive tasks and physical activity. By measuring the levels of oxygenated and deoxygenated hemoglobin at each node’s location on the skull, the fNIRS machine allows us to estimate significant active brain regions while the study participant actively moves during a particular activity, providing a physiological explanation for potential differences in measured focus levels.
Methods: We used two separate fNIRS montages to measure brain activity before, during, and after an exercise activity: quiet rest, or no exercise (QR); indoor biking (ID); and outdoor biking (OD). Cognitive tests and light levels were measured during all study visits and all timepoints. The fNIRS AnalyzIR toolbox was then used to process the data. We used 10 participants.
Results: Several significant regions of interest were found, in particular between source 9 and its detectors, and source 10 and its detectors. This region, located in the left frontal lobe, seems to correspond with gyri that mediate working memory and rapid eye-moments. Lower brain activity occurs during post-activity tests.
Conclusions: Lower brain activity during post-activity tests could illustrate fatigue, or more efficient processing. Improvements in cognitive scores support the benefits of exercise. In addition, a future experimental design where participants exercised every day for a week, could allow for more varied analysis of the effect of exercise on focus.