DISCUSSION
MDD, depression, chronic suicidality, anxiety
SECONDARY
The main objective of this study was to explore spectral changes of EEG in patients with MDD and chronic suicidality following 6 weeks of low-dose oral ketamine treatment. A second objective was to investigate correlations between changes in EEG spectral results and changes in clinical measures of suicidality, depression, anxiety, and stress.The most conclusive finding was the hypothesized alpha band power change at the centro-parietal region. Between pretreatment and posttreatment timepoints, the alpha band power decreased at the centro-parietal region. Following the final ketamine treatment between posttreatment and follow-up, alpha band power increased again at the same region (Illustrative visualization of brain regions and significant changes in band powers between Pre-Post (left), Post-FUP (middle), and Pre-FUP (right) timepoints. Created with BioRender.com.For theta band, we did not find any power changes immediately following the treatment period (i.e., posttreatment), but there were significant changes between posttreatment and follow-up timepoints; power was decreased at the occipital region and increased at the temporal and centro-parietal regions (High-beta band showed no significant power changes across timepoints (While none of the power spectra changes correlated with the main clinical outcome (BSS), several significant relationships with the secondary measure (DASS-21) were found. One of the most relevant correlation findings was that the theta band power at the occipital region showed a moderate positive correlation with DASS-S and weak positive correlation with DASS-D between posttreatment and follow-up timepoints (In this study, there were several limitations that may have impacted the results. Firstly, the sample size was relatively small, which may have impacted the results. Secondly, this study focused only on the whole group-level ketamine treatment effects without categorically examining the differences between (1) responders (n = 17; 68%) and nonresponders (n = 8; 32%), according to BSS changes from Pre to Post timepoints; and (2) prolonged responders (n = 11; 44%) and prolonged nonresponders (n = 14; 56%), according to BSS changes from Pre to FUP timepoints. According to This study found that long-term, low-dose oral ketamine treatment caused significant changes in EEG power spectra in adults with MDD and chronic suicidality. However, further studies of low-dose oral ketamine in suicidality are needed using a randomized control study design and larger sample size to address the limitations of the current open-label trial.