Altered Small-World Networks in First-Episode Schizophrenia Patients during Cool Executive Function Task

Area of Science:

• Neuroscience
• Psychiatry
• Network Science

Background:

• Schizophrenia (SZ) is a mental disorder with poorly understood brain functional connectivity.
• Cool executive function deficits are common in first-episode SZ patients.

Purpose of the Study:

• To investigate brain functional connectivity and network topology in first-episode SZ patients during a cool executive function task.
• To compare network properties between SZ patients and healthy controls using electroencephalography (EEG).

Main Methods:

• Used the Trail Making Test-B (TMT-B) to assess cool executive function.
• Recorded EEG data from 14 first-episode SZ patients and 14 healthy controls.
• Analyzed brain functional connectivity using mutual information (MI) and graph theory, applying absolute threshold, mean degree, and orthogonal minimal spanning trees (OMST) filtering.

Main Results:

• Theta band analysis revealed significantly longer characteristic path length and smaller cluster coefficient in SZ patients under absolute threshold.
• Characteristic path length remained longer in SZ patients when analyzed by mean degree, though cluster coefficient showed no significant change.
• OMST scheme identified a significantly longer characteristic path length in SZ patients compared to controls.
• Characteristic path length positively correlated with TMT-B executive time in the combined group, but not in SZ patients alone.

Conclusions:

• First-episode SZ patients exhibit less optimal brain network organization during cool executive function tasks.
• Findings suggest alterations in brain network topology contribute to executive dysfunction in early schizophrenia.
• Results provide insights into the pathophysiologic mechanisms of schizophrenia.