Immediate Effects of Acceptance and Commitment Therapy in Children with ADHD: A Pilot Resting-State fNIRS Study

Background: Children with ADHD exhibit deficits not only with attentional control but also with emotional dysregulation and experiential avoidance. Acceptance and Commitment Therapy (ACT) directly targets these processes by enhancing psychological flexibility and reducing maladaptive responses to internal experiences. Functional Near-Infrared Spectroscopy (fNIRS) offers a feasible and reliable method for assessing cortical hemodynamics in the ADHD population due to its portability and robustness to motion. This study aimed to investigate the immediate effects of a single-session ACT intervention on resting-state prefrontal hemodynamic activity in children with ADHD. Methods: Twenty children with ADHD underwent a single session of emotion regulation-focused ACT intervention. Resting-state fNIRS data were acquired immediately before and after the intervention. Changes in oxygenated (HbO) and deoxygenated hemoglobin (HbR) concentrations were statistically compared using paired t-tests. Results: All participants completed the protocol, and fNIRS acquisition was well tolerated. Post-intervention analyses revealed significant hemodynamic alterations after the session, marked by increased HbO at 0-240 s in the right lateral prefrontal cortex. HbO levels after the intervention were associated with SNAP hyperactivity scores. Conclusions: These findings provide preliminary evidence that single-session ACT intervention may be associated with short-term changes in resting hemodynamic activity in children with ADHD. fNIRS may demonstrate utility as a sensitive modality for detecting short-term intervention-related changes in neural activity. Given the exploratory nature of the study, future research with larger, controlled, and longitudinal designs is needed to evaluate the reproducibility of these findings and the clinical relevance of the observed hemodynamic changes.