Decreased callosal thickness in attention-deficit/hyperactivity disorder

Area of Science:

• Neuroimaging
• Neuropsychology
• Developmental Neuroscience

Background:

• Attention-deficit/hyperactivity disorder (ADHD) is associated with brain structural abnormalities.
• The corpus callosum (CC), a key white matter tract, is consistently reported as smaller in individuals with ADHD.
• Previous studies show conflicting results regarding specific CC segments affected in ADHD.

Purpose of the Study:

• To precisely map callosal alterations in ADHD using advanced geometrical modeling.
• To investigate the location and extent of corpus callosum (CC) thickness differences.
• To enhance understanding of neuroanatomical underpinnings of ADHD.

Main Methods:

• Employed novel surface-based geometrical modeling for high-resolution analysis.
• Measured corpus callosum (CC) thickness at 100 midsagittal points.
• Compared 19 individuals with ADHD to 19 age-matched typically developing controls.

Main Results:

• Significantly reduced CC thickness observed in ADHD subjects, especially in anterior and posterior sections.
• Covarying for intelligence did not alter the observed effects.
• Anterior CC differences disappeared when accounting for total brain volume and excluding comorbid oppositional defiant disorder.

Conclusions:

• Decreased CC thickness in ADHD may indicate fewer or less myelinated fibers.
• This could impair interhemispheric communication crucial for attention and motor control.
• Further research is needed to determine if CC abnormalities are maturational delays or persistent traits.