Default mode network shows alterations for low-frequency fMRI fluctuations in euthymic bipolar disorder

Area of Science:

• Neuroscience
• Psychiatry
• Medical Imaging

Background:

• Bipolar disorder (BD) presents with mood dysregulation, and neuropsychological deficits persist even in euthymic phases.
• Functional magnetic resonance imaging (fMRI) characterization of euthymic BD patients is limited, particularly regarding resting-state networks.
• The default mode network (DMN) is crucial for self-referential processing and is implicated in various psychiatric conditions.

Purpose of the Study:

• To identify neural and behavioral correlates of the DMN in euthymic BD patients using fractional amplitude of low-frequency fluctuations (fALFF).
• To investigate the utility of fALFF derived from DMN time series as a biomarker for psychiatric conditions.

Main Methods:

• Eighteen euthymic BD patients and sixteen healthy controls (HC) underwent resting-state fMRI scans.
• Independent component analysis (ICA) was used to extract the DMN.
• fALFF was computed from the DMN time series and correlated with clinical scales.

Main Results:

• No significant differences in DMN regions were found between BD patients and HC.
• fALFF analysis revealed increased low-frequency fluctuations and decreased high-frequency fluctuations in BD patients compared to HC.
• Higher frequency fALFF correlated with lower mania and higher anxiety, while lower frequency fALFF correlated with lower depression.

Conclusions:

• fALFF derived from DMN time series is a viable method for investigating resting-state network correlates in psychiatric conditions.
• Altered low-frequency fluctuations in the DMN may reflect underlying pathophysiological mechanisms in euthymic BD.
• fALFF could serve as a potential biomarker for differentiating symptom profiles in BD.