Unique white matter microstructural patterns in ADHD presentations-a diffusion tensor imaging study

Area of Science:

• Neuroscience
• Developmental Psychology
• Radiology

Background:

• Attention-deficit/hyperactivity disorder (ADHD) likely comprises distinct subtypes, including predominantly inattentive (ADHD-PI) and combined (ADHD-C) presentations.
• Neuroanatomical, neurochemical, and neuropsychological differences exist between ADHD subtypes, yet specific white matter (WM) distinctions remain underexplored.

Purpose of the Study:

• To investigate white matter (WM) microstructure differences between ADHD-PI and ADHD-C presentations using diffusion tensor imaging (DTI).
• To identify specific WM regions that differentiate ADHD subtypes and correlate with neuropsychological outcomes.

Main Methods:

• Utilized tract-based spatial statistics (TBSS) analysis on DTI data from 20 ADHD-PI, 18 ADHD-C, and 27 typically developing children.
• Performed voxel-wise analysis of fractional anisotropy (FA) and diffusivity measures (axial diffusivity (AD), mean diffusivity (MD), radial diffusivity (RD)) in major white matter tracts.
• Correlated WM diffusivity abnormalities with neuropsychological performance across groups.

Main Results:

• ADHD-PI group showed higher FA in anterior thalamic radiations (ATR), bilateral inferior longitudinal fasciculus (ILF), and left corticospinal tract (CST) compared to controls.
• ADHD-C group exhibited higher FA in the bilateral cingulum bundle (CB) compared to controls.
• Differences in FA, AD, MD, and RD were observed in specific WM regions (e.g., ATR, ILF, CST, CB, forceps minor (FMi)) between ADHD subtypes and controls, and these correlated with neurobehavioral performance.

Conclusions:

• Distinct white matter microstructure differences support the classification of ADHD-PI and ADHD-C as separate disorders.
• Aberrant white matter integrity in specific regions may serve as a biomarker for executive and behavioral functioning across ADHD presentations.