Neural substrates underpinning intra-individual variability in children with ADHD: A voxel-based morphometry study

Area of Science:

• Neuroscience
• Developmental Psychology
• Radiology

Background:

• Increased intra-individual variability (IIV) in reaction time (RT) is a hallmark of attention-deficit/hyperactivity disorder (ADHD).
• The neurobiological basis of IIV in ADHD remains largely unexplored.

Purpose of the Study:

• To investigate the neurobiological correlates of IIV in youths with ADHD.
• To compare brain structure associations with IIV parameters between ADHD and typically developing control (TDC) groups.

Main Methods:

• Assessed 55 youths with ADHD and 55 TDC using MRI and the Conners' Continuous Performance Test.
• Estimated IIV using ex-Gaussian distribution parameters σ (sigma) and τ (tau).
• Correlated regional brain volumes (voxel-based morphometry) with IIV parameters.

Main Results:

• Identified distinct and shared correlations between brain structure and IIV parameters across groups.
• Found significant group-by-parameter interactions in gray matter (cingulate cortex, thalamus, inferior frontal gyrus) and white matter (corpus callosum, corona radiata, cerebellum).
• Observed shared associations between IIV parameters and regional volumes in the cerebellum, insula, and internal capsule.

Conclusions:

• Brain regions involved in motor control, salience processing, and information integration are associated with heightened IIV in ADHD.
• These findings elucidate the neurobiological underpinnings of reaction time variability in ADHD.
• Highlights potential targets for understanding and managing ADHD-related cognitive differences.