Investigating prefrontal hemodynamic responses in ADHD subtypes: A fNIRS study

The purpose of the present study was to examine the hemodynamic response and reaction time (RT) in healty children and attention deficit hyperactivity disorder (ADHD) subtypes as measured by functional near infrared spectroscopy (fNIRS) during the auditory oddball attention task. The sample was made up of 40 children divided into four groups: control group (n=14), inattenttive subtype (ADHD-I; n=9), hyperactive-impulsive subtype (ADHD-HI; n=6), and combined subtype (ADHD-C; n=11). Right prefrontal cortex heamodynamic responses and groups performance on RT was compared between subtypes and between controls and subtypes. fNIRS indicated that while control subjects exhibited higher activation than all ADHD subtypes; ADHD subtypes did not differ from one another. Relative to control subjects, longer RT observed in all ADHD subtypes. ADHD-I group showed significantly longer RTs compared to ADHD-HI and ADHD-C group. These results suggest a novel path of significant interest concerning reliable evaluation of fNIRS and RT studies in ADHD.