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

BACKGROUND

Major depressive disorder (MDD) is closely linked to suicidal ideation (SI), which has been associated with cognitive dysfunction and abnormal brain network connectivity. However, the relationships among SI, cognitive functioning, and large-scale brain dynamics in MDD remain unclear. Resting-state EEG microstate analysis provides a novel method for exploring these associations by capturing transient global brain activity patterns.

METHODS

Eighty-eight drug-naïve, first-episode MDD patients were divided into SI (n = 54) and noSI (n = 34) groups, with 34 age- and gender-matched healthy controls. SI was assessed using the Beck Scale for Suicide Ideation (BSSI), and cognition was evaluated with the MATRICS Consensus Cognitive Battery (MCCB). Resting-state EEG was recorded, and microstate parameters were analyzed. Group differences were tested with ANOVA and ANCOVA, correlations examined with Pearson and partial analyses, and multiple comparisons controlled by FDR correction.

RESULTS

The noSI group showed greater microstate D coverage (p = 0.037) and higher transition probability from microstate A to D (p = 0.011) than the SI group; these effects remained after controlling for depressive and anxiety symptoms and agitation and FDR correction. In the SI group, both measures correlated positively with SDMT scores, and SI severity was negatively related to microstate C coverage and transition probability from microstate B to C; however, none of these correlations survived adjustment.

CONCLUSION

MDD patients with SI show alterations in EEG microstate dynamics that are associated with reduced processing speed. These findings indicate that large-scale brain network instability may contribute to neurocognitive dysfunction related to suicidality. EEG microstates may provide preliminary insights into its neural basis and represent exploratory biomarkers that require replication and longitudinal validation. CLINICAL TRIAL NUMBER: Not applicable. This study is not a clinical trial. It is an observational study designed to investigate the relationship between EEG microstates and cognitive function in depressed patients with and without suicidal ideation. Therefore, no clinical trial registration number is applicable to this research.