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

Background: Attention-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.

Methods: This 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.

Results: Compared 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.

Conclusions: This 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.