D-cycloserine augmentation of cognitive behavioral therapy for delusions: A randomized clinical trial

A transdiagnostic meta-analysis of acute augmentations to psychological therapy

At least half of all patients with mental health disorders do not respond adequately to psychological therapy. Acutely enhancing particular biological or psychological processes during psychological therapy may improve treatment outcomes. However, previous studies are confined to specific augmentation approaches, typically assessed within single diagnostic categories. Our objective was to assess to what degree acute augmentations of psychological therapy reduce psychiatric symptoms and estimate effect sizes of augmentation types (for example, brain stimulation or psychedelics). We searched Medline, PsycINFO and Embase for controlled studies published between database inception and 25 May 2022. We conducted a preregistered random-effects meta-analysis (PROSPERO CRD42021236403). We identified 108 studies (N = 5,889). Acute augmentation significantly reduced the severity of mental health problems (Hedges' g = -0.27, 95% CI: [-0.36, -0.18]; P < 0.0001), particularly for the transdiagnostic dimensions 'Fear' and 'Distress'. This result survived a trim-and-fill analysis to account for publication bias. Subgroup analyses revealed that pharmacological, psychological and somatic augmentations were effective, but to varying degrees. Acute augmentation approaches are a promising route to improve outcomes from psychological therapy.

D-cycloserine rescues scopolamine-induced deficits in cognitive flexibility in rats measured by the attentional set-shifting task

Cognitive flexibility facilitates adaptions to a changing environment in humans and animals and can be assessed with the attentional set shifting task (ASST). In various learning paradigms for laboratory rodents, the partial NMDA receptor agonist D-cycloserine has been found to have pro-cognitive effects. However, D-cycloserine has not yet been investigated for its effects on cognitive flexibility. The aim of the present study was to determine whether D-cycloserine is able to improve cognitive flexibility measured by the ASST in rats. Rats were first pre-treated with the muscarinic antagonist scopolamine (0.5 mg/kg) before the D-cycloserine administrations (20 mg/kg) to induce deficits in ASST performance. Our findings showed impaired ASST performance after scopolamine administration with significant effects on reversal phases and extra-dimensional shift. D-cycloserine treatment selectively improved the performance in the extra-dimensional shift and the last reversal phase, where scopolamine effects were most pronounced. These findings suggest that D-cycloserine can rescue deficits in cognitive flexibility.

Parsing neural circuits of fear learning and extinction across basic and clinical neuroscience: Towards better translation

Over the past decades, studies of fear learning and extinction have advanced our understanding of the neurobiology of threat and safety learning. Animal studies can provide mechanistic/causal insights into human brain regions and their functional connectivity involved in fear learning and extinction. Findings in humans, conversely, may further enrich our understanding of neural circuits in animals by providing macroscopic insights at the level of brain-wide networks. Nevertheless, there is still much room for improvement in translation between basic and clinical research on fear learning and extinction. Through the lens of neural circuits, in this article, we aim to review the current knowledge of fear learning and extinction in both animals and humans, and to propose strategies to fill in the current knowledge gap for the purpose of enhancing clinical benefits.

Exposure to Epstein Barr virus and cognitive functioning in individuals with schizophrenia

Cognitive deficits are a central feature of schizophrenia whose etiology is not fully understood. Epstein Barr Virus (EBV) is a potentially neurotropic infectious agent that can generate persistent infections with immunomodulatory effects. Previous studies have found an association between EBV antibodies and cognitive functioning in different populations, but there has been limited investigation in schizophrenia. In this study, 84 individuals with schizophrenia were administered a comprehensive neuropsychological battery, the MATRICS Consensus Cognitive Battery (MCCB). Participants also provided a blood sample, from which antibodies to the EBV whole virion and specific proteins were measured. Multivariate models were constructed to determine the association between these antibodies and cognitive performance on the MCCB overall and domain scores. Using these models, we found a significant association between the MCCB overall percent composite score and level of antibodies to the EBV Nuclear Antigen-1 (EBNA-1) protein, the Viral Capsid Antigen (VCA) protein, and the EBV whole virion. A significant association was also found for the MCCB social cognition domain with the level of antibodies to the EBV Nuclear Antigen-1 (EBNA-1) protein, the Viral Capsid Antigen (VCA) protein, and the EBV whole virion. In all cases, a higher level of antibodies was associated with a lower level cognitive performance. These findings suggest that exposure to EBV may contribute to cognitive deficits in schizophrenia, a finding which may have implications for new methods of prevention and treatment.

Efficacy of adjunctive D-Cycloserine for the treatment of schizophrenia: a systematic review and meta-analysis of randomized controlled trials

D-Cycloserine is a partial agonist at the glycine site of the N-methyl-D-aspartate (NMDA) receptor. Results have been inconsistent in trials on the efficacy of D-Cycloserine in patients with schizophrenia. We examined the efficacy of D-Cycloserine against negative and cognitive symptoms (primary and co-primary outcomes). Secondary outcomes were efficacy of D-Cycloserine against positive symptoms and the examination of early treatment outcomes. A systematic literature search was carried out using following selection criteria: Population = Patients with Schizophrenia; Intervention = Trials using D-Cycloserine either as monotherapy or adjuvant therapy; Comparison = Placebo or active comparator; Outcome = Change in negative symptoms, cognitive symptoms and positive symptoms; Study design = Randomized controlled trials with parallel design. We used the Cochrane Collaboration tool for risk of bias for study quality appraisal. Effect sizes for trials were calculated separately for negative, positive and cognitive symptom dimensions using the DerSimonian-Laird random effects model. Seven studies (pooled N = 413) provided data for meta-analysis. The pooled Standardized Mean Difference (SMD) for negative, cognitive, and positive symptom change scores were - 0.32 (95% CI, - 0.75 to 0.11), - 0.05 (95% CI, - 0.91 to 0.81), and - 0.08 (95% CI, - 0.37 to 0.20), respectively. No significant improvement was noted with regard to early outcome. I² values for heterogeneity were 61%, 67%, and 0% for studies assessing negative, cognitive, and positive symptom ratings, respectively. D-Cycloserine did not exhibit significant efficacy in treating negative, cognitive, or positive symptoms of schizophrenia at either study-defined endpoint (4-36 weeks) or at four weeks (early outcome).