Exploratory fNIRS Study of Prefrontal Activation in Drug-Naïve ADHD Across Developmental Stages
S. Lee, W. S. Kang, M. HongIntroduction
Attention-deficit/hyperactivity disorder (ADHD) is associated with alterations in executive function and prefrontal cortical activity. Functional near-infrared spectroscopy (fNIRS) provides a non-invasive method to assess task-related hemodynamic changes, yet developmental differences in drug-naïve ADHD populations remain insufficiently understood.
Objectives
This study aimed to investigate prefrontal activation patterns during executive function tasks in drug-naïve individuals with ADHD compared with healthy controls, and to explore age-related differences across childhood, adolescence, and adulthood.
Methods
We enrolled a total of 48 drug-naïve patients with ADHD (children, adolescents, and adults) and 50 healthy controls between March 2019 and February 2022. Participants were recruited from the outpatient clinic of the Child and Adolescent Psychiatry Department. All participants underwent standardized assessments, including IQ testing, ADHD symptom rating scales, and the Computerized Attention Test (CAT). Prefrontal cortical activation was measured using functional near-infrared spectroscopy (fNIRS) during the Trail Making Test A and B. Group comparisons were conducted between ADHD and control participants, as well as across age groups. The study was approved by the Ethical Committee (No. MJH 2010-08-025-001).
Results
ADHD participants showed significantly higher symptom severity compared with controls (all
p
< 0.001), as well as lower performance on the Computerized Attention Test (CAT) (
p
= 0.009) and reduced working memory and processing speed indices of IQ (
p
< 0.01) (Fig 1). fNIRS analyses during the Trail Making Tests revealed distinct activation patterns across groups and age strata.(Fig 2) While overall group-level effects were limited, exploratory ROI-level analyses indicated a significant difference in oxygenated hemoglobin response at ROI4 under specific task conditions, suggesting localized prefrontal hypoactivation in ADHD (Fig 3).
Image 1: Long description.