Ketamine Treatment in Depression: A Systematic Review of Clinical Characteristics Predicting Symptom Improvement

EEG-vigilance regulation is associated with and predicts ketamine response in major depressive disorder

Ketamine offers promising new therapeutic options for difficult-to-treat depression. The efficacy of treatment response, including ketamine, has been intricately linked to EEG measures of vigilance. This research investigated the interplay between intravenous ketamine and alterations in brain arousal, quantified through EEG vigilance assessments in two distinct cohorts of depressed patients (original dataset: n = 24; testing dataset: n = 24). Clinical response was defined as a decrease from baseline of >33% on the Montgomery-Åsberg Depression Rating Scale (MADRS) 24 h after infusion. EEG recordings were obtained pre-, start-, end- and 24 h post- infusion, and the resting EEG was automatically scored using the Vigilance Algorithm Leipzig (VIGALL). Relative to placebo (sodium chloride 0.9%), ketamine increased the amount of low-vigilance stage B1 at end-infusion. This increase in B1 was positively related to serum concentrations of ketamine, but not to norketamine, and was independent of clinical response. In contrast, treatment responders showed a distinct EEG pattern characterized by a decrease in high-vigilance stage A1 and an increase in low-vigilance B2/3, regardless of whether placebo or ketamine had been given. Furthermore, pretreatment EEG differed between responders and non-responders with responders showing a higher percentage of stage A1 (53% vs. 21%). The logistic regression fitted on the percent of A1 stages was able to predict treatment outcomes in the testing dataset with an area under the ROC curve of 0.7. Ketamine affects EEG vigilance in a distinct pattern observed only in responders. Consequently, the percentage of pretreatment stage A1 shows significant potential as a predictive biomarker of treatment response.Clinical Trials Registration: https://www.clinicaltrialsregister.eu/ctr-search/trial/2013-000952-17/CZ Registration number: EudraCT Number: 2013-000952-17.

Ketamine for suicidality: an umbrella review

The urgent need for appropriate treatment for suicide, the tenth leading cause of death, has led to numerous studies. This study aims to systematically identify and appraise systematic reviews with or without meta-analyses investigating ketamine in suicidal ideation and behaviors. The study protocol was published in PROSPERO (CRD42021285320). Scopus, ISI, Embase, PubMed, CINAHL, PsycINFO, Cochrane Library, Google Scholar, and two registries were searched on October 29 without any restrictions for systematic reviews investigating the efficacy of ketamine on suicidal ideation and behaviors. The primary outcome was the final inference of ketamine effectiveness. A formal narrative synthesis was conducted, and the AMSTAR-2 tool was used to evaluate the quality of the studies. No funding was received. Of 27 studies that addressed ketamine for suicidal ideation, only four reported mixed or negative results, and out of nine reviews, esketamine was significantly beneficial only in five. A transient rise in pulse rate and blood pressure, dissociation, confusion, blurred vision, nausea, and vertigo were of the most common adverse effects; however, most were mild. More than two-thirds of the included studies qualified as low or critically low quality. Preliminary evidence for the short-term efficacy of ketamine in suicidality was noted by the majority of reviews; however, long-term effects remained unknown. Due to the non-high quality of many studies and the limitations of core studies, further studies are required.