Monitoring the Response of Treatment in Major Depressive Disorder with EEG: Could it be an Indicator of Returning to Health in Responders

Background: Quantitative electroencephalography (qEEG) data can facilitate the monitoring of treatment progress and the evaluation of therapeutic responses in patients with Major Depressive Disorder (MDD). This study aims to compare the qEEG data of MDD patients and healthy controls, both before and after treatment, to assess the effect of treatment response on neural activity. Methods: A total of 72 patients, aged 18–60, who had not used any psychopharmacological medication for at least two weeks, were included in the study. Based on a minimum 50% reduction in scores on the Hamilton Depression Rating Scale (HDRS-17) and Hamilton Anxiety Rating Scale (HARS), the patients were divided into two groups: responders (n = 51) and non-responders (n = 21). qEEG data were recorded before and after treatment. Results: Responders exhibited a significant shift in cortical activity—particularly in theta, alpha, and high-beta power—toward patterns resembling those observed in the healthy control group (improvement range: 15% to 67%). In contrast, non-responders showed minimal changes in cortical activity (improvement range: 38% to 46%). These findings suggest that while qEEG spectral data reflect marked neural changes in responders, no significant alterations occur in non-responders. Conclusion: The use of qEEG spectral analysis to monitor MDD patients provides valuable insights into treatment efficacy. The distinct patterns of cortical activity observed across most brain regions before treatment, compared to healthy individuals, highlight the potential of qEEG to predict treatment outcomes.