Association between EEG microstate and cognitive function in depressed patients with and without suicidal ideation

Area of Science:

• Neuroscience
• Psychiatry
• Cognitive Science

Background:

• Major Depressive Disorder (MDD) is linked to suicidal ideation (SI), cognitive dysfunction, and abnormal brain network connectivity.
• The precise relationships among SI, cognitive function, and large-scale brain dynamics in MDD are not fully understood.
• Resting-state electroencephalography (EEG) microstate analysis offers a novel approach to investigate these associations by examining transient global brain activity patterns.

Purpose of the Study:

• To investigate the differences in EEG microstate dynamics between MDD patients with and without suicidal ideation (SI).
• To explore the association between EEG microstate parameters, cognitive functioning, and SI severity in MDD patients.
• To determine if EEG microstate alterations in MDD are related to neurocognitive deficits, particularly processing speed.

Main Methods:

• Eighty-eight drug-naïve, first-episode MDD patients were categorized into SI (n=54) and noSI (n=34) groups, alongside 34 healthy controls.
• Suicidal ideation was assessed using the Beck Scale for Suicide Ideation (BSSI), and cognitive function was evaluated with the MATRICS Consensus Cognitive Battery (MCCB).
• Resting-state EEG data were analyzed for microstate parameters, with group differences examined using ANOVA/ANCOVA and correlations analyzed via Pearson/partial methods, controlling for multiple comparisons with FDR correction.

Main Results:

• The noSI group exhibited significantly greater microstate D coverage and higher A-to-D transition probability compared to the SI group, even after controlling for covariates and FDR correction.
• In the SI group, microstate D coverage and A-to-D transition probability positively correlated with processing speed (SDMT scores).
• SI severity was negatively associated with microstate C coverage and B-to-C transition probability, though these findings did not survive statistical adjustments.

Conclusions:

• MDD patients with SI demonstrate altered EEG microstate dynamics, specifically linked to reduced processing speed.
• These findings suggest that large-scale brain network instability may underlie neurocognitive dysfunction associated with suicidality in MDD.
• EEG microstates show potential as exploratory biomarkers for the neural basis of suicidality in MDD, warranting further validation.