Relationships between clinical symptoms, cognitive functioning, and TMS-evoked potential features in patients with...

Cognitive impairment is a common clinical symptom of patients with major depressive disorder (MDD). Transcranial magnetic stimulation-evoked potentials (TEPs) detect cortical excitability and connectivity and provide potential biomarkers for MDD patients and their cognitive impairment. This study aimed to investigate the interrelationships between clinical symptoms, cognitive function, and electrophysiological marker TEPs in patients with MDD.

A total of 117 participants were recruited, including 59 MDD patients and 58 healthy controls. Clinical symptoms were assessed by the Hamilton Depression Rating Scale and Hamilton Anxiety Rating Scale, and cognitive functioning was assessed by the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). TEPs were recorded by transcranial magnetic stimulation combined with electroencephalography (TMS-EEG).

MDD patients exhibited lower RBANS total (P < 0.001), immediate memory (P = 0.001), language (P = 0.003), attention (P < 0.001), and delayed memory (P = 0.008) scores than HCs. Patients with MDD had larger amplitudes for N100 (P = 0.040) and N280 (P = 0.037), compared to HCs. Correlation analysis indicated significant correlations between the following RBANS scores and TEPs: language and N45 amplitude (r = 0.222, P = 0.024), language and P60 amplitude (r = 0.278, P = 0.004), attention and P180 amplitude (r = 0.213, P = 0.030), RBANS total score and P30 amplitude (r = 0.198, P = 0.044), visuospatial/constructional index and N100 amplitude (r = -0.272, P = 0.005).

The results of this study indicate that cortical dysfunction and cognitive impairment are present in patients with MDD and that there is a strong correlation between them, suggesting that TEPs detected by the TMS-EEG may be used as a biomarker for MDD patients and their cognitive impairment.