White Matter Microstructural Alterations in Children with ADHD: Categorical and Dimensional Perspectives

Area of Science:

• Neuroimaging
• Developmental Neuroscience
• Child Psychiatry

Background:

• Attention-deficit/hyperactivity disorder (ADHD) presents heterogeneous brain alterations in children.
• Understanding white matter microstructure is crucial for ADHD pathophysiology.

Purpose of the Study:

• Investigate white matter microstructure in children with ADHD using categorical and dimensional definitions.
• Determine the functional consequences of observed white matter alterations on cognitive functions.

Main Methods:

• Tract-based spatial statistics (TBSS) on diffusion tensor imaging (DTI) data.
• Analysis of fractional anisotropy (FA) and diffusivity measures (MD, AD, RD).
• Examined associations with ADHD status, symptom severity, and cognitive performance (working memory, inhibition).

Main Results:

• Children with ADHD showed decreased FA and increased RD in widespread brain regions, including the corpus callosum and left hemisphere tracts.
• Decreased FA correlated with poorer inhibition performance in ADHD participants.
• Higher hyperactivity/impulsivity symptom severity was linked to increased FA in right hemisphere tracts, including the corpus callosum.

Conclusions:

• White matter microstructure alterations are associated with ADHD status and symptom severity.
• Observed patterns of decreased FA and increased RD may suggest altered myelination as a key factor in ADHD.
• Findings highlight the importance of considering both categorical and dimensional aspects of ADHD in neuroimaging research.