Absence of differences in resting-state EEG spectral power and cognitive impairments between first-episode,...

Accumulating evidence indicates that resting-state brain oscillations are altered in patients with major depressive disorder (MDD). However, the neurophysiology and neuropathology of patients with MDD with or without suicidal ideation (MDD-SI or MDD-NSI) are poorly understood.

Ninety first-episode and drug-naïve patients with MDD (FEDN) and forty-four healthy control participants were recruited for this study. The Beck Scale for Suicide Ideation (BSSI) was employed to evaluate suicidal ideation. The MATRICS Consensus Cognitive Battery (MCCB) was used to assess neurocognitive function. Resting-state electroencephalography (EEG) was recorded for 10 min with eyes closed.

A reduction in relative alpha power in the occipital region was observed in patients with major depressive disorder (MDD), both with and without suicidal ideation (SI), compared to healthy controls (HCs). No significant differences in occipital relative alpha power were found between the MDD-SI and MDD-NSI groups. Additionally, MDD patients without SI exhibited increased relative delta power in both the left and right occipital regions (Relative-LO-delta: p = 0.013; Relative-RO-delta: p = 0.002) compared to HCs. Compared to HCs, MDD-SI exhibited significantly increased relative gamma power in the right occipital region (Relative-RO-gamma: p = 0.027), while MDD-NSI showed elevated relative gamma power in the left frontal region (Relative-LF-gamma: p = 0.011). A significant reduction in frontal alpha asymmetry (FAA) was observed in MDD-NSI patients compared to HCs. Furthermore, negative correlations were found between relative alpha power in occipital regions and attention performance in the MDD-NSI group, but not in the MDD-SI group or HCs.

The relatively small sample size and the cross-sectional nature of the study may limit the generalizability of these findings.

Our findings indicate that brain oscillations are altered in first-episode, drug-naïve MDD patients regardless of suicidal ideation status. However, based on the present study, rsEEG is not a suitable biomarker for screening MDD-SI from MDD-NSI in drug-treatment naïve patients. The utility of rsEEG as a biomarker for distinguishing suicide risk among drug-treated MDD patients remains to be validated. Additionally, cognitive impairment and related alpha power alterations may serve as state-like markers particularly in MDD-NSI patients.