Aberrant amplitude of low-frequency fluctuation and functional connectivity in children with different subtypes of ADHD: a resting-state fNIRS study

BackgroundAttention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder with different subtypes of pathogenesis. Insufficient research on the subtypes of ADHD has limited the effectiveness of therapeutic methods.MethodsThis study used resting-state functional near-infrared spectroscopy (fNIRS) to record hemodynamic signals in 34 children with ADHD-combined subtype (ADHD-C), 52 children with ADHD-inattentive subtype (ADHD-I), and 24 healthy controls (HCs). The amplitude of low-frequency fluctuation (ALFF) and the functional connectivity (FC) analysis were conducted for all subjects.ResultsCompared with HCs, the ADHD group exhibited significantly increased ALFF and decreased FC. The ADHD-C group showed significantly higher ALFF in partial brain regions and significantly lower FC between multiple brain regions than participants with ADHD-I. The male group displayed a significant increase in ALFF in some brain regions, while no significant difference was found in FC when compared to the female group.ConclusionsThis study provides evidence to support the subtype classification of ADHD-I and ADHD-C, and the combined analysis of ALFF and FC has the potential to be a promising biomarker for the diagnosis of ADHD.