Disrupted Resting-State Functional Connectivity in Nonmedicated Bipolar Disorder

Area of Science:

• Neuroimaging
• Psychiatry
• Systems Neuroscience

Background:

• Bipolar disorder (BD) is a complex mood disorder.
• Understanding the neural underpinnings of BD is crucial for developing targeted treatments.

Purpose of the Study:

• To investigate whole-brain intrinsic functional connectivity patterns in patients with bipolar disorder II (BD II).
• To identify specific brain networks and regions affected by functional connectivity alterations in BD.

Main Methods:

• Prospective study involving 37 nonmedicated BD II patients and 37 healthy controls.
• Resting-state functional magnetic resonance (MR) imaging was utilized.
• Graph theory approach, specifically functional connectivity strength (FCS), was applied for whole-brain connectivity analysis.

Main Results:

• Patients with BD II showed decreased FCS in the default mode network (medial prefrontal cortex, middle temporal gyrus, precuneus, posterior cingulate cortex) and other regions.
• Increased FCS was observed in the bilateral temporal pole (amygdala, parahippocampal gyrus), anterior cingulate cortex, and cerebellum in BD II patients.
• Statistical significance was determined using two-sample t tests, nonparametric correlation analysis, and AlphaSim correction (P < .05).

Conclusions:

• Bipolar disorder is associated with disrupted intrinsic functional connectivity, primarily within the default mode network and limbic system.
• These connectivity alterations may represent a core pathophysiological feature of bipolar disorder.
• Findings contribute to understanding the neurobiological basis of BD.