White Matter Alterations of the Goal-Directed System in Patients With Obsessive-Compulsive Disorder and Their...

Area of Science:

• Neuroscience
• Psychiatry
• Neuroimaging

Background:

• Obsessive-compulsive disorder (OCD) symptoms, particularly compulsive behaviors, are theorized to stem from altered goal-directed and habitual learning systems.
• The relationship between these learning system changes and white matter structure in OCD patients and their relatives is not well understood.

Purpose of the Study:

• To investigate white matter structural changes in the goal-directed and habitual learning networks in patients with OCD and their unaffected first-degree relatives (UFDRs).
• To explore the association between white matter connectivity, OCD symptom severity, and cognitive flexibility.

Main Methods:

• Diffusion tensor imaging (DTI) was used to acquire data from 32 OCD patients, 32 UFDRs, and 32 healthy controls.
• Seed-based probabilistic tractography reconstructed white matter tracts within goal-directed and habitual networks.
• Partial least squares path modeling analyzed the covariation between white matter connectivity, psychiatric symptoms, and cognitive flexibility.

Main Results:

• Patients with OCD exhibited reduced white matter connectivity in the goal-directed network compared to controls.
• OCD symptom severity was negatively associated with goal-directed network connectivity.
• Reduced goal-directed network connectivity was also observed in UFDRs, and cognitive flexibility was negatively correlated with specific tracts in OCD patients.

Conclusions:

• OCD is characterized by disrupted learning system balance, primarily affecting the white matter of the goal-directed network.
• Impaired goal-directed network function may underlie OCD symptoms and reduced cognitive flexibility.
• The presence of similar alterations in UFDRs suggests the impaired goal-directed system could be an endophenotype of OCD.