Structural and Functional Brain Abnormalities in Attention-Deficit/Hyperactivity Disorder and Obsessive-Compulsive...

Area of Science:

• Neuroscience
• Psychiatry
• Neuroimaging

Background:

• Patients with attention-deficit/hyperactivity disorder (ADHD) and obsessive-compulsive disorder (OCD) exhibit shared deficits in inhibitory control.
• The underlying neurobiological basis, whether shared or disorder-specific, remains unclear.

Purpose of the Study:

• To identify shared and disorder-specific structural and functional brain abnormalities in ADHD and OCD during inhibitory control tasks.
• To compare gray matter volume (GMV) and functional magnetic resonance imaging (fMRI) findings between ADHD and OCD using voxel-based meta-analysis.

Main Methods:

• Conducted a comprehensive literature search of VBM and fMRI studies on inhibitory control in ADHD and OCD populations.
• Performed voxel-wise meta-analyses to compare GMV and fMRI differences between patients and controls.
• Quantitatively compared disorder-specific and shared abnormalities between ADHD and OCD.

Main Results:

• Patients with ADHD showed decreased GMV and function in the bilateral basal ganglia/insula compared to controls and OCD patients.
• Patients with OCD exhibited increased GMV and function in the bilateral basal ganglia/insula compared to controls.
• Disorder-specific abnormalities included reduced function in the right ventrolateral prefrontal cortex in ADHD and reduced function/structure in the anterior cingulate/medial prefrontal cortex in OCD. Shared ventromedial prefrontal GMV reduction was observed in both disorders.

Conclusions:

• Impaired inhibitory control in ADHD and OCD is associated with distinct, rather than shared, neurobiological abnormalities.
• ADHD is characterized by smaller, underfunctioning ventrolateral prefrontal/insular-striatal regions.
• OCD involves larger, hyperfunctioning insular-striatal regions potentially poorly regulated by smaller, underfunctioning medial prefrontal regions.