Resting-state EEG activity in depression: a systematic review and meta-analysis

Area of Science:

• Neuroscience
• Psychiatry
• Biomedical Engineering

Background:

• Depression is a widespread and debilitating mental health disorder with poorly understood pathophysiology.
• Current depression treatments have limited efficacy, highlighting the need for novel therapeutic strategies.
• Electrophysiological markers, particularly from electroencephalography (EEG), offer potential insights into brain mechanisms and neuromodulation targets for depression.

Purpose of the Study:

• To systematically review resting-state electroencephalography (EEG) activity in adult patients diagnosed with depression.
• To assess quantitative EEG measures, including power, cordance, peak frequency, and alpha asymmetry, in depressed individuals compared to controls.
• To identify potential EEG biomarkers and neuromodulatory targets for depression.

Main Methods:

• A PROSPERO-registered systematic review following PRISMA guidelines.
• Inclusion of 52 studies reporting cross-sectional or correlational data on quantitative EEG measures in adult depression.
• Semiquantitative analyses (albatross plots) and meta-analyses, with study quality assessed using the Newcastle-Ottawa Scale.

Main Results:

• A trend for increased low-frequency (delta, theta) and high-frequency (beta, gamma) power, and left frontal alpha asymmetry in depressed patients.
• Meta-analysis confirmed a significant increase in beta power in depressed individuals compared to healthy controls.
• Data on disease severity correlations, peak alpha frequency, and cordance were insufficient for definitive conclusions; risk of bias was high.

Conclusions:

• Increased beta oscillations represent a potential electrophysiological correlate of depression.
• These beta oscillations may indicate disrupted corticolimbic control and reward processing, overlapping with mechanisms in chronic pain and fatigue.
• Further research is needed to explore beta oscillations as a diagnostic tool, biomarker, or neuromodulatory treatment target for depression.