Disrupted axonal fiber connectivity in schizophrenia

Area of Science:

• Neuroscience
• Psychiatry
• Brain Imaging

Background:

• Schizophrenia is linked to abnormal neural process integration and aberrant brain connectivity.
• Evidence for anatomical dysconnectivity in schizophrenia is inconsistent.
• Few studies have investigated whole-brain axonal fiber connectivity in schizophrenia.

Purpose of the Study:

• To model and analyze cortico-cortical anatomical connectivity as a network in schizophrenia.
• To identify specific regions with impaired connectivity in patients.
• To assess network attributes like efficiency and small-worldness in schizophrenia.

Main Methods:

• Diffusion tensor imaging (DTI) and whole-brain tractography were used to map axonal fiber bundles.
• Network nodes represented 82 functionally specific cortical regions.
• Connectivity was compared between 74 schizophrenia patients and 32 controls, analyzing nodal degree, small-worldness, efficiency, path length, and clustering.

Main Results:

• Schizophrenia patients exhibited impaired connectivity in a distributed network including medial frontal, parietal/occipital, and left temporal regions.
• While small-world attributes were conserved, cortical connectivity was sparser and up to 20% less efficient in patients.
• Brain efficiency correlated with intellectual performance in controls, but not in schizophrenia patients.

Conclusions:

• This study provides evidence for widespread white-matter dysconnectivity in schizophrenia.
• The findings suggest a multifaceted pathophysiology involving both axonal and synaptic mechanisms.
• Impaired brain network efficiency may contribute to cognitive deficits in schizophrenia.