Developmental Differences in White Matter Microarchitecture in Youth with ADHD: Longitudinal Findings from the ABCD...

Area of Science:

• Neuroscience
• Developmental Neuroscience
• Neuroimaging

Background:

• Attention-deficit/hyperactivity disorder (ADHD) is a common neurodevelopmental disorder.
• ADHD is a risk factor for subsequent brain disorders.
• Understanding white matter integrity in ADHD is crucial for early intervention.

Purpose of the Study:

• To investigate the relationship between ADHD and white matter cellularity across development.
• To examine the impact of ADHD medication on white matter integrity.
• To utilize a novel biophysical diffusion MRI model in a pediatric cohort.

Main Methods:

• Longitudinal cohort study (ABCD Study®) with three MRI waves.
• Diffusion-weighted imaging (DWI) and tractography to delineate 27 white matter tracts.
• Restriction Spectrum Imaging (RSI) model to quantify intracellular isotropic (RNI) and directional (RND) diffusion.

Main Results:

• ADHD associated with decreased RNI in 20 tracts at age 9, with developmental attenuation.
• Enduring ADHD-associated decreases in RND observed in 16 tracts (ages 9-14).
• Methylphenidate showed effects on RND in 2 tracts; RNI findings were robust to motion sensitivity.

Conclusions:

• ADHD is associated with reduced isotropic diffusion in white matter tracts.
• Findings suggest atypical glial cellularity in white matter in children with ADHD.
• Directional diffusion alterations may also be present in select tracts.