Spectral changes of EEG following a 6-week low-dose oral ketamine treatment in adults with major depressive disorder and chronic suicidality

This analysis of EEG data (n=25) from a study that used repeated ketamine oral tablets (6x, flexible dosing) for treating depression (MDD) found significant changes in alpha (during), theta and low-beta frequencies (after) brainwaves.

Abstract

“Background Ketamine has considerable therapeutic potential in alleviating major depressive disorder (MDD) and chronic suicidality. However, the clinical diagnosis of neuropsychiatric disorders requires more robust diagnostic criteria. Electroencephalography (EEG) has shown promise in classifying depressive and suicidal patients from healthy individuals. The present study aimed to identify changes in the spectral properties of EEG in patients with MDD and chronic suicidality after completing the 6-week Oral Ketamine Trial on Suicidality (OKTOS) with follow-up occurring 4 weeks after final ketamine treatment and determine associations between EEG spectral output and clinical symptoms.

Methods Participants (N=25) had 4-minutes eyes closed resting state EEG recorded at frontal, temporal, centro-parietal, and occipital regions. Spectral analysis was performed with Welch’s power spectrum density method, and the power of four distinct frequency bands was analysed – theta, alpha, low-beta, and high-beta. Correlation analyses between changes in clinical symptoms and spectral power were done using Spearman’s ranked correlation.

Results Between pre- and post-treatment, only centro-parietal alpha power decreased. Between post-treatment and follow-up, centro-parietal alpha increased again in addition to increases in temporal alpha, centro-parietal and temporal theta, occipital low-beta, and decreases in occipital theta and temporal low-beta. Additionally, the decrease of occipital theta positively correlated with clinical subscales for depression and stress.

Conclusions EEG spectral analysis revealed significant changes in theta, alpha, and low-beta frequency bands. Alpha band showed initial changes after treatment; however, this trended back towards baseline levels after the treatment cessation. In contrast, theta and low-beta showed significant power changes only after the treatment had ended.”