The prevalence and etiology of COVID-19's impact on brain health and cognitive function is poorly characterized. With mounting reports of delirium, systemic inflammation, and evidence of ...neurotropism, a statement on cognitive impairment among COVID-19 cases is needed. A substantial literature has demonstrated that inflammation can severely disrupt brain function, suggesting an immune response, a cytokine storm, as a possible cause of neurocognitive impairments. In this light, the aim of the present study was to summarize the available knowledge of the impact of COVID-19 on cognition (i.e., herein, we broadly define cognition reflecting the reporting on this topic in the literature) during the acute and recovery phases of the disease, in hospitalized patients and outpatients with confirmed COVID-19 status. A systematic review of the literature identified six studies which document the prevalence of cognitive impairment, and one which quantifies deficits after recovery. Pooling the samples of the included studies (total sample
= 644) at three standards of quality produced conservative estimates of cognitive impairment ranging from 43.0 to 66.8% prevalence in hospitalized COVID-19 patients only, as no studies which report on outpatients met criteria for inclusion in the main synthesis. The most common impairment reported was delirium and frequent reports of elevated inflammatory markers suggest etiology. Other studies have demonstrated that the disease involves marked increases in IL-6, TNFα, and IL-1β; cytokines known to have a profound impact on working memory and attention. Impairment of these cognitive functions is a characteristic aspect of delirium, which suggests these cytokines as key mediators in the etiology of COVID-19 induced cognitive impairments. Researchers are encouraged to assay inflammatory markers to determine the potential role of inflammation in mediating the disturbance of cognitive function in individuals affected by COVID-19.
The majority of antidepressant medication trials have focused on adult populations (ages 18–65), with much less research in older and younger populations. Moreover, key differences in the efficacy ...and safety of antidepressants have been identified between these age groups. Ketamine has emerged as a promising new treatment for treatment resistant depression (TRD). The objective of this review is to summarize and synthesize the extant literature on the effectiveness, safety and tolerability of ketamine for depression in special age populations (age ≤18 and ≥ 60). Following PRISMA guidelines, a systematic review was performed, searching EMBASE, PsycInfo, and PubMed from inception through July 2020. Studies reporting the use of any ketamine formulation with variable routes of administration to treat clinically diagnosed depression in adolescents or older adults were included. Thirteen studies were included in the analysis and ten observed rapid (≤2 week latency) antidepressant effects following ketamine treatments, with better outcomes following larger, repeated doses, and in open-label rather than blinded settings. Two case reports in adolescents assessed measures of suicidal ideation and both found ketamine to effectuate rapid anti-suicidal effects. Ketamine appears to be safe and well-tolerated in adolescents and older adults. The small quantity, high heterogeneity, and generally low quality of available studies precludes statistical syntheses and significantly limits the strength of our conclusions. Preliminary proof-of-concept studies are promising, however, rigorously designed randomized controlled trials (RCTs) are still required to ascertain effectiveness, safety and tolerability in these groups.
•Antidepressant clinical trials often exclude individuals ≤18 or ≥65 years of age.•Many adolescents and older adults do not respond to antidepressant treatments.•Ketamine may offer rapid treatment for treatment resistant depression.•More studies dedicated to adolescents and older adults are required.
Ketamine is a NMDA receptor antagonist that has a rapid acting antidepressant effect with high efficacy in treatment-resistant patients. Ketamine is a beneficial antidepressant for many individuals ...with depression, but not all of the patients respond, and some even exhibit symptom deterioration. The discovery of repeatable and mechanistically relevant biomarkers would address a major gap in treatment response prediction. Numerous potential peripheral biomarkers have been reported, but their current utility is unclear. We conducted an umbrella review to evaluate the biomarkers of ketamine's antidepressant effect in individuals with depression. PubMed and copus were searched using terms appropriate to each area of research, from their inception until July 2022. Five systematic reviews and meta analyses including 108 studies with 4912 participants were included. Blood-based and neuroimaging biomarkers were investigated. The results of this review indicate that ketamine can produce an anti-inflammatory effect and decrease at least one inflammatory marker following administration. Data from neuroimaging studies demonstrated that the cingulate cortex is the key locus of ketamine's action. The majority of the blood-based, neuroimaging, and neurophysiological investigations reviewed herein indicate ketamine induced normalization of major depressive disorder pathogenesis via synaptic plasticity and functional connectivity. Currently, no biomarker/biosignature is sufficiently validated for clinical utility, but several are promising. Now that ketamine is more widely available, biomarker discovery and replication should be attempted in larger, real-world populations.
•Five systematic reviews and meta analyses including 108 studies with 4912 participants were included.•Ketamine can induce anti inflammatory effect and decrease at least one inflammatory marker.•IL-6, TNF-α and CRP were the most studied inflammatory biomarkers in included studies.•The cingulate cortex is the key locus of ketamine's action.
OBJECTIVEKetamine has demonstrated rapid and significant antidepressant effects in patients with treatment resistant depression (TRD). Herein, we conducted a systematic review to determine ketamine's ...efficacy as a function of the stage of treatment resistance (e.g., number of failed treatments) among individuals with TRD. METHODSA systematic search of PubMed and Scopus from inception to August 2021 was conducted. Where applicable, the studies were categorized into low and high stages of resistance, where low category included studies where the mean number of failed antidepressants was <3 or had a higher proportion of subjects with ≤2 antidepressant trials. Reported indicators of treatment resistance and efficacy were extracted from randomized-controlled trials (RCTs) assessing ketamine or esketamine for TRD. RESULTSIn total, 18 RCTs were included in the current review. There was variability across reported indicators of disease severity, definition of treatment resistance, as well as treatment protocols, preventing clear direct and indirect comparison of relative efficacy of ketamine at different stages of treatment resistance. Ketamine was effective in reducing depressive symptoms in RCTs at both lower and higher stages of treatment resistance; however, the effect size and duration of effects was greater in RCTs of lower stage of treatment resistance. CONCLUSIONSOur findings suggested that ketamine has antidepressant efficacy across all identified stages of treatment resistance, however with increasing failed treatment trials, treatment might be less efficacious. At this time, the comparative efficacy as a function of resistance stage remains to be well-established. Evaluation of participant level data is required to more clearly determine the association between level of treatment resistance and likelihood of response.
Ketamine is a dissociative anesthetic used worldwide for anesthesia, pain management, treatment resistant depression (TRD) and suicidality. Predictors of antidepressant response and adverse effects ...to ketamine remain poorly understood due to contradictory results. The objective of the systematic review herein is to identify and evaluate the extant literature assessing pharmacogenomic predictors of ketamine clinical benefits and adverse effects. Electronic databases were searched from inception to July 2021 to identify relevant articles. Twelve articles involving 1,219 participants with TRD, 75 who underwent elective surgeries and received ketamine as an anesthetic, 49 with pain, and 68 healthy participants met the inclusion criteria and enrolled to this review. While identified articles reported mixed results, three predictors emerged: 1) Val66Met (rs6265) brain derived neurotrophic factor (BDNF; Met allele) was associated with reduced antidepressant and anti-suicidal effects, 2) CYP2B6*6 (e.g., CYB2B6 metabolizer) was associated with more severe dissociative effects and 3) NET allelic (rs28386840) variant were associated with greater cardiovascular complications (e.g., moderate to severe treatment emergent hypertension). Several important limitations were identified, most notably the small sample sizes and heterogeneity of study design and results. Taken together, preliminary evidence suggests the potential for pharmacogenomic testing to inform clinical practices; however, further research is needed to better determine genetic variants of greatest importance and the clinical validity of pharmacogenomics to help guide ketamine treatment planning.
Electrophysiologic measures provide an opportunity to inform mechanistic models and possibly biomarker prediction of response. Serotonergic psychedelics (SPs) (i.e., psilocybin, lysergic acid ...diethylamide (LSD)) and ketamine represent new investigational and established treatments in mood disorders respectively. There is a need to better characterize the mechanism of action of these agents.
We conducted a systematic review investigating the spectral signatures of psilocybin, LSD, and ketamine in persons with major depressive disorder (MDD), treatment-resistant depression (TRD), and healthy controls.
Ketamine and SPs are associated with increased theta power in persons with depression. Ketamine and SPs are also associated with decreased spectral power in the alpha, beta and delta bands in healthy controls and persons with depression. When administered with SPs, theta power was increased in persons with MDD when administered with SPs. Ketamine is associated with increased gamma band power in both healthy controls and persons with MDD.
The studies included in our review were heterogeneous in their patient population, exposure, dosing of treatment and devices used to evaluate EEG and MEG signatures. Our results were extracted entirely from persons who were either healthy volunteers or persons with MDD or TRD.
Extant literature evaluating EEG and MEG spectral signatures indicate that ketamine and SPs have reproducible effects in keeping with disease models of network connectivity. Future research vistas should evaluate whether observed spectral signatures can guide further discovery of therapeutics within the psychedelic and dissociative classes of agents, and its prediction capability in persons treated for depression.
•Serotonergic psychedelics (SPs) decreased gamma power in healthy controls.•Ketamine & SPs increased theta power in persons with depression.•Ketamine & SPs decreased alpha, beta, and delta power in healthy and MDD persons.•Ketamine increased gamma power in both healthy and MDD persons.
Inadequate outcomes with monoamine-based treatments in depressive disorders are common and provide the impetus for mechanistically-novel treatments. Esketamine is a proven treatment recently approved ...for adults with Treatment-Resistant Depression (TRD) while psilocybin is an investigational treatment. Translation of the clinical meaningfulness for these foregoing agents in adults with TRD is required. Herein we evaluate the Number Needed to Treat (NNT) and Harm (NNH) of esketamine and psilocybin in adults with TRD.
We conducted a systematic review of randomized controlled trials, comparing the clinical efficacy of oral psilocybin to the co-commencement of intranasal esketamine with an oral antidepressant in adults with TRD.
25 mg psilocybin had a significant reduction in depressive symptoms at 21-days post-dose, the NNT was 5 95 % CI = 3.1, 18.5. Psilocybin-induced nausea had a significant NNH = 5. Fixed-dosed esketamine at 56 mg and 84 mg had a significant effect at 28-days post-dose, (NNT of 7 95 % CI56mg = 3.5, 46.7, 95 % CI84mg = 3.6, 142.2). Esketamine-induced headache, nausea, dizziness, and dissociation had NNHs <10.
The preliminary results may only reflect a small portion of the patient population. These results require replication and longer term studies investigating maintenance therapy.
Relatively few pharmacologic agents are proven safe and effective in adults with TRD. NNT estimates for investigational psilocybin and esketamine in TRD indicate clinical meaningfulness. The NNH profile for both aforementioned agents is clinically acceptable. Our results underscore the clinical relevance of these treatment options in adults with TRD.
•Oral 25 mg psilocybin had a NNT of 5 after 21 days.•Psilocybin-induced nausea had a NNT of 5 after day 1.•Fixed-dosed esketamine (56 mg and 84 mg) had NNTs of 7 after 28 days.•Esketamine-induced headache, nausea, dizziness, and dissociation had clinically relevant NNHs.
Suicide accounts for approximately 800,000 deaths per year globally. Previous research has shown that intranasal esketamine and intravenous ketamine can rapidly decrease the severity of depressive ...symptoms and suicidal ideation. However, the majority of clinical trials excluded individuals with moderate to high baseline suicidality scores (e.g., suicidal ideation with plan/intent at the time of recruitment). The current review aims to evaluate the effect of esketamine and ketamine in patients with suicidal ideation at baseline. A systematic search was conducted on EMBASE, PsychInfo and PubMed from inception to July 2020 following the PRISMA guidelines. 15 studies met inclusion criteria. Results from esketamine trials did not demonstrate antisuicidal effects, as between-group differences were not found. Intravenous ketamine appeared to rapidly decrease the severity of suicidal ideation and depressive symptoms in individuals with baseline suicidal ideation, though retrospective studies suggest that these effects may be short-lasting. During the double-blind treatment phases, 2.4% of patients from the treatment groups and 1.5% of patients from control groups attempted suicide, with zero deaths by suicide in both the treatment and control groups during this phase. Based on the overall pooled samples, studies were assessed to be relatively safe, and the continual inclusion of this study population in future clinical trials is encouraged. Future research should aim to assess the longitudinal efficacy of ketamine in patients with baseline suicidality.
•IV ketamine is associated with rapid & robust decreases in suicidal ideations.•Esketamine has antidepressant effects in patients with baseline suicidality.•The proportion of suicide attempts and death by suicide during these trials was low.•Future trials should consider including patients with baseline suicidality.
•6 articles involving 42 patients (mean age: 15,7) with depression were included in this systematic review.•Ketamine was significantly associated with reduced depressive symptoms in pediatric with ...depression.•Ketamine was well tolerated without serious adverse events.
Pediatric depression is a common psychiatric disorder that is associated with significant morbidity and mortality. Ketamine is a non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist with demonstrated antidepressant effects in the adult population, however, the efficacy and safety of ketamine for the treatment of pediatric depression remains poorly understood. Electronic databases were searched from inception to June 2022 to identify relevant articles. Six articles involving 46 participants with a mean age of 15.7 years were included in this systematic review. Out of six articles, three were case reports, one was a randomized clinical trial (RCT) and two were open-label trials. All studies used 0.5 mg/kg intravenous ketamine except for one, which used 2–7 micrograms/kg. Ketamine was significantly associated with reduced depressive symptoms without severe adverse events. Taken together, the results of these studies demonstrated the potential role of ketamine for treating pediatric depression. Several important limitations were identified, most notably the small sample sizes of the component studies, and that all studies administered intravenous ketamine. Further studies with larger sample sizes and different administration modalities are needed to better determine the efficacy and safety of ketamine in pediatric depression.
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