Power Spectral Slope as a Novel Brain Functional Marker for Major Depressive Disorder

Area of Science:

• Neuroscience
• Psychiatry
• Medical Imaging

Background:

• Major depressive disorder (MDD) is often studied using resting-state functional magnetic resonance imaging (rs-fMRI), focusing on low-frequency fluctuations.
• Brain activity encompasses both low- and high-frequency fluctuations, which are not fully captured by traditional rs-fMRI analyses.

Purpose of the Study:

• To evaluate brain activity in MDD using the power spectral slope (PSS), a novel approach analyzing both low- and high-frequency fluctuations.
• To investigate the effect of antidepressant treatment on PSS in patients with MDD.

Main Methods:

• rs-fMRI data were collected from 109 MDD patients and 78 healthy controls.
• A subset of MDD patients underwent follow-up scanning after 12 weeks of antidepressant treatment (escitalopram/duloxetine).
• Baseline group comparisons and follow-up within-group comparisons were performed using t-tests with Gaussian random-field correction.

Main Results:

• MDD patients exhibited significantly more negative PSS in the ventral striatum and temporal pole compared to controls.
• Following treatment, PSS in the ventral striatum normalized, while the temporal pole's PSS remained unchanged.
• No significant correlation was found between PSS and depression severity scores.

Conclusions:

• MDD is associated with altered brain activity characterized by more negative PSS in key affective regions.
• The normalization of ventral striatum PSS after treatment indicates a region-specific therapeutic response.
• PSS shows potential as a novel neuroimaging biomarker for major depressive disorder.