Heart Rate Variability and MOXO d-CPT Relationship in Children with in Attention Deficit Hyperactivity Disorder

Abstract This study examined heart rate variability (HRV) in children with attention deficit hyperactivity disorder (ADHD) using a case–control design. A total of 52 children aged 6–12 years participated. ADHD diagnosis was confirmed by a child psychiatrist according to DSM-5 criteria, and comorbidities (e.g., anxiety, ODD) were excluded. Participants were then stratified into ADHD (n = 33; 17 boys, 16 girls) and control groups (n = 19; 12 boys, 7 girls), with MOXO d-CPT used to characterize performance profiles. Resting-state HRV was recorded for 5 min using the validated Polar H10 device. Time-domain (SDNN, RMSSD), frequency-domain (VLF, LF, HF), and non-linear indices were analyzed. The Good performance group demonstrated significantly lower VLF power compared to the Weak group ( η 2 = 0.176, p < 0.05), and the SNS Index was significantly higher in the Weak hyperactivity group (d = 0.49, p = 0.048), indicating increased sympathetic activation associated with poorer performance. Non-significant trends were observed for SDNN ( η 2 = 0.08) and RMSSD ( η 2 = 0.07), suggesting modest parasympathetic differences, though these did not reach statistical significance. These findings highlight VLF and the SNS Index as the most robust HRV metrics associated with impulsivity and hyperactivity performance on the MOXO d-CPT, while other HRV domains showed only preliminary or non-significant effects. Future longitudinal studies are needed to evaluate HRV’s potential for monitoring treatment response and its specificity to cognitive subdomains in ADHD.