European Neuropsychopharmacology

Psychedelic drugs are emerging as potentially efficacious tools for treating psychiatric conditions and probing the neural basis of consciousness. Although drug administration context is widely believed to shape psychedelic effects, it remains unclear whether it can independently generate placebo and nocebo effects resembling psychedelic experiences and side effects. In a pre-registered experiment, 78 non-clinical participants inhaled inert medical air under placebo and control conditions while completing a time perception task and a resting-state period. In the placebo condition, the gas was presented as nitrous oxide, whereas in the control, it was correctly identified. Placebo administration increased altered states of consciousness, ego dissolution, dissociation, and side effects, but did not significantly impact time perception. Predictive modelling indicated that placebo-induced psychedelic effects were predicted by trait responsiveness to verbal suggestion and absorption. These findings demonstrate that context alone can induce psychedelic effects, with implications for its causal role in psychedelic action.

Background: The incidence of antidepressant withdrawal reactions in longer-term users and the influence of dosage is insufficiently understood. Objectives: Informed by neuropharmacological models and user surveys, this study examined symptom change during tapering and if increases were specifically associated with reductions below 75% of the minimum effective dose. Design: This was a prospective longitudinal cohort study with seven assessments over six months. Methods: Altogether 32 Swiss adult primary care patients who were on antidepressants for at least six months and in stable remission were assessed at baseline (week 0) before they started tapering and after 2, 4, 6, 8, 16, and 26 weeks. Withdrawal symptoms were measured repeatedly using an adapted version of the Discontinuation-Emergent Signs and Symptoms Scale (DESS) and the main outcome was intra-individual symptom change during intervals. Antidepressant dose was standardized relative to the minimum effective dose in the treatment of depressive and anxiety disorders. Results: Across intervals, reductions below 75% of the minimum effective dose were associated with symptom increases, while reductions above that threshold or no reductions were associated with symptom decreases. After adjusting for potential confounders, the rate of clinically relevant symptom increases contingent on dose reductions below 75% of the minimum effective dose was 33%, as compared to 13% during intervals with no dose reductions (OR=3.2, 1.4 to 7.4). We thus estimated that 60% of the risk of clinically relevant symptom increases was attributable to pharmacological withdrawal effects. The adjusted incidence rates for clinically relevant and severe withdrawal reactions were 32% and 11%, respectively. Conclusions: Consistent with neuropharmacological research findings, we found that antidepressant withdrawal symptoms emerge mostly following reductions below 75% of the minimum effective dose, affecting about one-third of patients. Even small reductions may trigger clinically relevant withdrawal reactions in this lowest dose-range, stressing the need for personalized tapering plans.

Major depressive disorder (MDD) is a highly prevalent psychiatric disorder with changes in motivation to work for rewards being a core symptom. Transcutaneous vagus nerve stimulation (tVNS) has emerged as a promising therapy but its effects on the core features of MDD, such as changes in motivation, remained relatively unexplored. In this randomised, single-blind, cross-over, controlled trial, we used a grip strength effort task to investigate how tVNS impacted choices to exert different levels of physical effort for varying monetary rewards in MDD patients (n=53) and a non-depressed control group (n=45). Compared to sham stimulation, tVNS enhanced the efficiency with which participants with severe depressive symptoms allocated physical effort for rewards (reward-effort efficiency). These effects were not seen in participants with less severe symptoms. Specifically, we found that the effect of tVNS on reward-effort efficiency was driven by reduced unnecessary effort, i.e., a reduction in choices to exert additional effort when this was not required to gain a larger reward. These findings suggest a potential motivational mechanism by which tVNS exerts its therapeutic effects in MDD. Determining whether the effects of tVNS are linked to broader changes in executive functioning, such as improvements in cognitive flexibility in MDD, should be a key aim for future work.

Amitriptyline is commonly prescribed for chronic pain, yet treatment response and tolerability vary substantially. Genetic variation in CYP2C19 and CYP2D6 influences amitriptyline metabolism, but evidence linking pharmacogene status to clinical outcomes in chronic pain is limited. Amitriptyline is typically prescribed for chronic pain at lower doses than for depression, which may reduce pharmacogenomic effects on clinical outcomes. We analysed 1,146 participants with chronic pain from the Australian Genetics of Depression Study who reported amitriptyline use, treatment outcomes, and genotype data. Metaboliser phenotypes were assigned using PharmCAT. Associations with self-reported effectiveness and discontinuation due to side effects were examined using regression models adjusted for age and sex. Only CYP2C19 intermediate metabolisers showed nominally lower odds of discontinuation and reduced likelihood of reporting moderate effectiveness. Overall, pharmacogenetic phenotypes were not significantly associated with patient-reported amitriptyline outcomes in chronic pain, potentially reflecting the lower doses typically prescribed for pain management.

BackgroundKetamine is a rapid-acting antidepressant that produces acute dissociative symptoms. In routine care, the respective contributions of therapeutic expectations and dissociative symptoms to antidepressant response, and the directionality of their associations with depressive symptom change, remain poorly characterized. MethodsWe conducted a retrospective longitudinal observational cohort study of 100 adults with major depressive disorder or bipolar depression receiving six open-label intravenous racemic ketamine infusions over 3 weeks. Therapeutic expectations were rated at baseline and before each infusion. Post-infusion, dissociative symptoms (CADSS) were assessed first, followed by depressive symptom severity (MADRS) within the same session. Linear mixed-effects, mediation, and random intercept cross-lagged panel models (RI-CLPM) were used to distinguish within-person from between-person effects. ResultsDepressive symptoms improved across the induction course, with 45% of participants meeting response criteria. At each session, therapeutic expectations consistently predicted post-infusion improvement in depressive symptoms at the within-person level, independently of dissociative symptoms. Moreover, expectations became stronger across sessions in treatment responders. Dissociative symptoms were associated with improvement when examined alone, but were not observed after adjustment for expectations, and were not linked to improvement in depression at the within-person level from session to session. They were associated with greater overall antidepressant benefit at the between-person level. A notable indirect pathway was identified at the between-person level, where expectations determined changes in depression through initial dissociative symptoms and early depressive symptom reductions. This pathway explained 3.2% of the total effect of expectations on improvement in depression by the end of treatment. ConclusionsTherapeutic expectations and dissociative symptoms contributed to antidepressant response through distinct pathways: expectations functioned at the individual level as a dynamic within-person driver, whereas dissociative propensity served on the group level as a stable between-person marker of outcome, highlighting complementary clinical targets to optimize treatment response in routine care.

Esketamine is a fast-acting antidepressant drug which induces acute psychoactive effects. The most frequent is a dissociative state which seems unrelated to therapeutic efficacy. Other esketamine-induced effects, including psychedelic-like mystical experiences, have been poorly studied in terms of phenomenology and frequency, and may carry specific therapeutic relevance. In this study, we characterised esketamine-induced mystical experiences in relation with clinical outcomes. We conducted a longitudinal observational study and systematically measured acute subjective effects in patients receiving esketamine for treatment-resistant depression after each administration across the induction phase. A total of 45 patients were included, from two independent centres, totalling 352 esketamine administrations. Principal Component Analysis (PCA) supported the validity of the Mystical Experience Questionnaire (MEQ-30) for assessing esketamine-induced subjective effects, with components recovering dimensions previously validated with classic psychedelics. Mystical experiences (MEQ-30 score above 60) occurred in 58% of patients, with high inter- and intra-individual variability in frequency, intensity, and phenomenology across sessions. Higher mean and peak MEQ scores were associated with greater improvement in Montgomery-Asberg Depression Rating Scale scores from pre- to post-treatment, whereas the intensity of dissociative or other non-mystical effects was not. Positive mood and mystical MEQ dimensions in particular predicted therapeutic outcomes. Baseline spirituality also significantly predicted treatment outcomes and peak MEQ scores in the first week of treatment. These findings add to the growing body of evidence suggesting that psychedelic-like mystical experiences may be associated to therapeutic efficacy, not only in classic psychedelic-assisted therapy, but also in esketamine treatment.

Abstract Background Ketamine has emerged as an effective rapid-acting treatment for treatment-resistant depression (TRD), producing significant antidepressant effects within hours of administration. Given ketamine's capacity to induce states of heightened neuroplasticity and psychological openness, psychotherapy may represent a meaningful complement to its pharmacological effects - facilitating emotional processing, cognitive restructuring, and the consolidation of therapeutic gains. However, the adjunctive potential of structured psychotherapeutic support in ketamine-based interventions remains largely unexplored. Methods This preliminary, non-randomized, open-label clinical trial evaluated the adjunctive effects of ketamine-assisted psychotherapy (KAP) in an outpatient setting. Forty-six patients with TRD received eight weekly sessions of subcutaneous esketamine (0.5-1.0 mg/kg) and were allocated into two groups: esketamine without psychotherapeutic support (n = 23) and esketamine combined with structured KAP encompassing preparation, dosing accompaniment, and post-session integration (n = 23). Depressive symptoms were assessed using the Montgomery-Asberg Depression Rating Scale (MADRS) and the Beck Depression Inventory-II (BDI-II) at multiple timepoints during treatment and at follow-up assessments up to six months after protocol completion. Results Both groups showed significant reductions in depressive symptoms throughout treatment. The KAP group demonstrated greater clinical improvement by the end of treatment, with between-group differences on the MADRS emerging at sessions 7 and 8. MADRS response and remission rates were 52.2% and 34.8% in the KET group, and 78.3% and 78.3% in the KAP group, respectively. BDI-II scores indicated earlier subjective improvement in the KAP group, with between-group differences emerging as early as the second session and persisting across multiple timepoints. No significant between-group differences were observed during the six-month follow-up, with both groups maintaining symptom reductions comparable to end-of-treatment levels. Conclusions These findings suggest that structured psychotherapeutic support may be associated with early clinical response and remission rates in subcutaneous esketamine treatment for TRD, potentially through facilitation of emotional processing, psychological flexibility, and behavioural change. Further controlled studies are needed to clarify the specific contribution of psychotherapy, investigate the mechanisms underlying this interaction, and optimize integrated treatment approaches for TRD. The trial was registered at https://ensaiosclinicos.gov.br/rg/RBR-1072m6nv . Keywords: esketamine; treatment-resistant depression; ketamine-assisted psychotherapy; innovative therapies.

BackgroundCognitive-behavioral therapy (CBT) is a widely used treatment for mental disorders, yet the biological mechanisms underlying its effects, and the factors contributing to response, remain poorly understood. DNA methylation, an epigenetic mechanism shaped by both genetic and environmental factors, may offer insights into individual differences in psychotherapy outcomes. MethodsSaliva samples were collected before treatment, after treatment, and three months post-treatment from individuals with OCD undergoing the Bergen 4-Day Treatment (n = 889). DNA methylation was measured using the Illumina EPIC v02 array, followed by epigenome-wide DNA methylation analyses of CBT response. ResultsWe identified ten differentially methylated regions (DMRs) associated with treatment response at baseline, 23 DMRs showing consistent associations with response across multiple time points, and three DMRs displaying longitudinal methylation changes associated with response. These loci were annotated to genes with roles in neuroplasticity, stress response, immune function, mitochondrial processes, and gene regulation. Baseline and stable methylation signals were largely influenced by genetic variation, whereas all longitudinal associations appeared to be confounded by psychoactive medication use and psychiatric comorbidities. In addition, changes in monocyte and CD4+T cell proportions were associated with treatment response. ConclusionsWe identified DNA methylation markers associated with CBT response in OCD at baseline. Stable methylation patterns associated with treatment response are likely driven by genetic factors. Longitudinal methylation analyses should be interpreted cautiously, as medication and comorbidities can exert substantial effects - even when they remain unchanged over time. Baseline methylation profiles may ultimately help predict treatment outcomes, thereby advancing precision psychiatry.

0.Clozapine is the gold-standard for treatment-resistant schizophrenia despite its severe metabolic complications, including metabolic syndrome (MetS) and type 2 diabetes (T2D) risk. A better understanding of the genetic factors influencing clozapine pharmacokinetics and their relationship to metabolic risk could help inform precision medicine approaches to clozapine prescribing. Using a series of genetic-epidemiological approaches, we aimed to identify candidate biomarkers associated with clozapine-induced metabolic dysfunction. We first used two-sample Mendelian randomization (MR) leveraging genome-wide association summary data to investigate evidence of causal relationships between clozapine metabolism and cardiometabolic traits. These analyses indicated that higher plasma clozapine levels and a higher clozapine-norclozapine ratio were both associated with a higher risk of T2D and higher blood pressure. We then applied a Phenome-scan-colocalization-MR pipeline to identify traits influenced by clozapine-metabolism loci that might serve as biomarkers of cardiometabolic risk. This pipeline identified 28 colocalizing candidate biomarkers associated with clozapine metabolising genetic loci. Subsequent MR highlighted associations for 16 of these 28 biomarker candidates with cardiometabolic outcomes, which included haematological markers and excretory traits (e.g. gamma-glutamyl transferase, red cell distribution width, and urea). These findings may inform the development of biomarker-guided monitoring approaches for risk stratification and early intervention, enabling a shift from reactive monitoring to predictive approaches in managing clozapine-induced metabolic dysfunction with appropriate clinical validation. These findings may also help to mitigate the risk of metabolic dysfunction associated with other antipsychotic medications.

Background: The biological mechanisms linking generalized anxiety disorder (GAD) and COVID-19 remain poorly understood, despite substantial evidence of their comorbidity. To address this gap, we examined genetic and epigenetic factors underlying their co-occurrence. Methods: In a multi-ancestry sample of 893 participants, we conducted genome-wide and epigenome-wide analyses of GAD and COVID-19 severity. Integrating large-scale genome-wide datasets and information regarding methylation quantitative trait loci, complementary analytic approaches were used to identify regional methylation patterns, assess genetically regulated DNA methylation in blood and brain tissue, and evaluate causal loci shared between GAD and COVID-19. Results: GAD was associated with epigenome-wide significant variation in loci involved in chromatin regulation and synaptic signaling. Conversely, COVID-19-related epigenetic signals were enriched in immune-inflammatory and host-response pathways. Mild COVID-19 was epigenetically related to endothelial-inflammatory signals, while severe COVID-19 was linked to epigenetic changes implicated in myeloid and thrombo-inflammatory pathways. Epigenetic signals shared between GAD and COVID-19 implicated processes related to stress adaptation and tissue homeostasis. Genetically informed analyses identified 60 shared loci, including MAPT, ZFP57, and FBXL18, indicating pleiotropy between GAD and COVID-19 in genetically regulated DNA methylation variation. Brain-specific analyses further highlighted convergence in additional loci (i.e., MICB and HLA-DPB1), suggesting neuroimmune mechanisms underlying GAD-COVID-19 shared methylation patterns. Conclusions: These findings support that GAD and COVID-19 share epigenetic and genetic architecture involving pathways related to vascular integrity, immune function, and cellular adaptation, highlighting a potential neuroimmune basis for their co-occurrence.

Antidepressants are widely prescribed for major depressive disorder, yet only one-third of patients achieve remission after initial treatment. Previous genome-wide association studies (GWAS) of clinically assessed antidepressant response combined multiple antidepressant classes, potentially obscuring class-specific effects. This study focused on selective serotonin reuptake inhibitors (SSRIs), often first-line due to better tolerability. Data from 15 cohorts across four ancestries were integrated: European (N = 3887; 11 studies), East Asian (N = 1068; 4), African (N = 277; 1), and Admixed American (N = 250; 1). GWAS of non-remission and percentage improvement were conducted within cohorts, followed by ancestry-specific meta-analyses and trans-ancestry meta-regression. Single nucleotide polymorphism (SNP)-based heritability was estimated in European samples. Polygenic scores were used for leave-one-out prediction and to assess shared genetic architecture with psychiatric traits. Gene-level and gene-set enrichment analyses were also performed. No genome-wide significant variants were identified for either outcome in any ancestry-specific or trans-ancestry analyses. However, trans-ancestry meta-regression yielded eight independent loci with suggestive associations (p < 1 x 10-5) for non-remission and 17 for percentage improvement. Gene-set analyses revealed nominal enrichment of the serotonergic synapse pathway for non-remission. SNP-based heritability estimates were not significantly different from zero for either outcome. Better SSRI response was nominally associated with lower genetic predisposition to major depressive disorder, post-traumatic stress disorder, and schizophrenia. This study represents the largest trans-ancestry GWAS of SSRI response, highlighting emerging biological signals. Limited power emphasises the need for larger and ancestrally diverse cohorts to better characterise the genetic architecture of antidepressant response.

Mental illness poses a substantial global burden, yet existing psychotherapies and psychopharmacologies often produce limited outcomes. Psychedelic assisted therapies have emerged as potential transdiagnostic interventions. In particular, 3,4 methylenedioxymethamphetamine assisted therapy (MDMA AT) has generated interest for its rapid psychological effects and potential to enhance psychotherapy outcomes. However, the incremental efficacy of MDMA AT relative to control interventions across transdiagnostic outcomes remains unclear. Further, there have been emerging concerns regarding harm reporting quality in MDMA AT clinical trials. We conducted a systematic review and meta analysis of MDMA AT randomized controlled trials. Eleven publications representing eight controlled trials with 10 analyzed subgroups (n = 295 participants) were included in meta-analyses. Two additional secondary publications were included for harm reporting syntheses (k = 13 total). Across 114 extracted effect sizes, MDMA AT demonstrated a significant moderate-to-large incremental reduction in psychopathology relative to controls (g = 1.03, 95% CI [0.46, 1.60]), though heterogeneity was high (I squared = 76%). Incremental effects were larger versus inert placebos (g = 1.27) than active controls (g = 0.75). Symptom specific analyses indicated strong incremental effects for trauma reduction (g=1.46 [95% CI: 0.67, 2.25]) and smaller non-significant effects for depression (g=0.51 [95% CI: -0.06, 1.08]). Harm reporting quality synthesis showed only 23% of publications met high-quality reporting standards. Overall, MDMA AT demonstrates potential transdiagnostic efficacy, but small samples, confounding factors, and mediocre harm reporting highlight the need for larger more transparent clinical trials.

BackgroundMajor depressive disorder (MDD) is a highly heterogeneous condition that is frequently co-morbid with type 2 diabetes (T2D), and yet the biological mechanisms linking these diseases remain unclear. We aim to identify distinct biological pathways in depression that may modify T2D risk. MethodsUsing Clustered Mendelian randomisation (MR-Clust), we analysed 621 genome-wide significant MDD variants to identify clusters of variants with similar causal effects on T2D. These clusters were validated, and their causal effects were comprehensively tested against glycaemic traits, depression subtypes, T2D risk factors, and cardiometabolic biomarkers using external GWAS data and the UK Biobank. Functional annotation of these clusters was performed using FUMA. ResultsMR-Clust identified three distinct clusters of MDD-associated variants. Two clusters (MDD1 and MDD2) were causal for higher T2D and its related risk factors, adverse glycaemic and cardiometabolic profiles. Functional annotation implicated brain expression that overlapped strongly with depression-related traits such as smoking and neuroticism. By contrast, MDD3 was causal for lower T2D risk, more favourable glycaemic and cardiometabolic biomarker profiles, and was enriched for gene sets linked to fatty acid metabolism and steroid biosynthesis. MDD1 and MDD2 clusters were associated with atypical-like depression symptoms, whereas MDD3 was associated with melancholic depression symptoms. ConclusionOur findings demonstrate a heterogenous genetic architecture for depression, with distinct biological pathways conferring opposing effects on cardiometabolic health. Understanding this heterogeneity could help tailor prevention and treatment strategies for people with depression at greatest metabolic risk.

ImportanceConventional repetitive transcranial magnetic stimulation (rTMS) can be ineffective in individuals who have previously failed brain stimulation, ketamine and/or multiple lines of therapies. Modern accelerated rTMS protocols using image-guided targets have not been systematically investigated in these individuals. The goal of this study was to assess the feasibility and efficacy of personalized, connectivity-guided, accelerated intermittent theta-burst stimulation (iTBS) in patients with treatment-resistant depression (TRD) of varying refractoriness. ObjectiveTo assess whether connectivity-guided, accelerated iTBS produces significant reductions in depression severity, and to what extent this benefit extends to ultra treatment-resistant depression (UTRD). DesignThis was an open-label feasibility trial of connectivity-guided, accelerated iTBS in patients with TRD. Two distinct groups of participants were recruited from a neurosurgical-psychiatry clinic with UTRD and an interventional psychiatry clinic with TRD. Patients were stratified into a priori treatment-resistance subgroups. Patients received five days of open-label treatment. Outcome measures were collected immediately prior to and after treatment, as well as at 4- and 12-weeks post-treatment. SettingThis trial (NCT05813093) was conducted between November 2023 and July 2025 at Sunnybrook Health Sciences Centre in Toronto, Ontario, Canada. ParticipantsPatients with major depressive disorder. A total of 96 participants were screened, with 73 meeting eligibility criteria (UTRD=30, TRD=43). One withdrew due to inability to tolerate the baseline MRI, and the other withdrew voluntarily prior to treatment. InterventionParticipants underwent a neuronavigated accelerated iTBS (600 pulses) protocol using personalized left dorsolateral prefrontal cortex (dlPFC) targets derived from functional magnetic resonance imaging (fMRI), comprising eight daily treatments, repeated over five days. Main OutcomesPrimary outcomes were i) change in Hamilton Depression Rating Scale (HAM-D17) from baseline to the end of the fifth day of treatment, and ii) the difference in change in HAM-D17 between UTRD and TRD subgroups. ResultsConnectivity-guided fMRI targeting yielded personalized targets clustered around the anterolateral dlPFC. Accelerated iTBS elicited rapid antidepressant effects ({Delta}HAM-D17 -9.01 [SD 6.06], t = -12.45, p < 0.001) regardless of treatment-resistance group ({Delta}HAM-D17 -9.64 [SD 5.94] vs -8.10 [SD 6.12], t = -1.05, p = 0.299), which were sustained up to 12 weeks after treatment. Overall response and remission rates at the end of treatment were 40.8% and 16.9%. Self-report scales revealed broad symptomatic relief outside of core depressive symptoms. Conclusions & RelevanceThis study demonstrated that fMRI connectivity-guided, accelerated iTBS induces sustained antidepressant effects and broader psychiatric benefits in patients across the spectrum of TRD. In a cohort unlikely to respond to most antidepressant therapies, connectivity-guided, accelerated iTBS offers a safe, well-tolerated option that can achieve benefit, or when ineffective, allow patients to expeditiously proceed with subsequent therapies than conventional rTMS. Trial RegistrationThis clinical trial was registered at clinicaltrials.gov with NCT05813093.

BackgroundPsilocybin is a classic psychedelic that acutely alters brain functional connectivity. These changes are linked to therapeutic doses and subjective effects, with some evidence that changes persist beyond acute drug administration. However, the effects of lower doses on sustained connectivity changes remain unclear. MethodsTen healthy volunteers received three psilocybin doses (between 5 and 20 mg) in a randomized and blinded order, with at least one week between doses. Resting-state functional magnetic resonance imaging was completed at baseline and one week after a single dose. Functional connectivity changes were analyzed in relation to dose and altered conscious states at both the level of individual brain region connections (edges) and resting-state networks. ResultsDose-dependent changes in 77 edges (76 increases, 1 decrease, of 1275 possible) were observed, but none survived multiple-comparison correction. At the network level, we observed one dose-dependent between-network increase (of 21 possible), and one dose-dependent within-network increase (of seven possible); the latter surviving correction. Alterations in conscious state were positively associated with widespread connectivity changes (dose-adjusted), with many network-level associations surviving correction. These directional patterns showed that lower doses and smaller conscious state alterations were linked to decreased connectivity, whereas higher doses and greater conscious state alterations were linked to increased connectivity. ConclusionsDose level and acute subjective effects were positively associated with multiple functional connectivity changes one week after a low-to-moderate psilocybin dose. Further research is warranted to characterize these sustained effects and their therapeutic relevance to inform studies adopting similar dosing regimens in clinical cohorts. Trial RegistrationAustralian New Zealand Clinical Trials Registry: ACTRN12621000560897 Date registered: 12 May 2021 URL: https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=381526&isReview=true

Polygenic risk scores (PRS) have shown increasing utility for risk stratification across complex diseases, but for psychiatric disorders such as bipolar disorder (BD), current PRS explain only a fraction of disorder liability (~1-9%), with predictive performance further diminished in non-European populations and real-world clinical cohorts. To explore the potential of integrating social and environmental risk factors alongside genetic liability to improve risk prediction, we evaluated the relationship between a PRS for BD (PRSBD) and six social risk measures - perceived stress, discrimination in medical settings, neighborhood social cohesion, perceived neighborhood disorder, cost-related medication nonadherence, and adverse childhood experiences - to BD case status in 115,275 participants (7,000 cases; 108,275 controls) from the All of Us Research Program. PRSBD was associated with BD case status across ancestry groups, though liability-scale variance explained was attenuated relative to what has been reported for curated research cohorts (R2 = 1.86% in European, 0.60% in African, 1.65% in Latino/Admixed American ancestries). Each social risk factor tested exhibited a larger effect size than PRSBD, with perceived stress (OR = 2.05 per SD) and adverse childhood experiences (OR = 2.68 for [&ge;]4 ACEs) demonstrating the strongest associations. Individuals in the lowest genetic risk decile with high social burden exhibited BD prevalence comparable to or exceeding those in the highest genetic risk decile with low social burden. These findings demonstrate the substantial explanatory power of social risk factors and support the development of integrated genetic-social risk frameworks for more accurate and equitable psychiatric risk prediction.

Background. Major depressive disorder (MDD) is characterized by altered frontal alpha oscillations. Transcranial alternating current stimulation (tACS) can normalize aberrant oscillations in MDD, yet the daily dynamics of tACS target engagement of alpha oscillations in depression remain unclear. Methods. In a double-blind randomized controlled trial (NCT03994081), 20 participants with MDD received verum or sham 10 Hz tACS (40 min/day, 5 days) targeted to left and right dorsolateral prefrontal cortex (F3/F4). High-density EEG was collected pre/post-stimulation each day to quantify within-session and cumulative changes in alpha power and functional connectivity (wPLI). Results. Verum stimulation produced late-emerging, session-specific alpha power decreases compared to sham, with robust day (D)4 post-pre reductions at both IAF and 10 Hz across frontal and parietal regions (t=-2.42 to -3.82, p<0.05; parietal t=-3.82, pFDR<0.05). Whole-brain topographical analysis confirmed a distinct condition x D4 effect at left prefrontal cortex (t=2.9, pFWE<0.05, cluster permutation). Connectivity changes emerged earlier and more transiently, with D2 bilateral frontal wPLI reductions (t=-2.53, p<0.05). Cumulative analyses (change from D1) showed significant wPLI decreases on D2 and D3 (t=-2.65 and t=-2.46; p<0.05). Exploratory clinical correlations showed that the D4 IAF power decrease was associated with increased reward sensitivity (spearman rho= -0.6, p<0.05, cluster-corrected). Conclusions. Alpha-tACS produced a temporally distinct neural response: an early, transient decrease in functional connectivity on D2, which may have driven a later suppression of left prefrontal alpha power on D4, correlated with clinical and behavioral improvements. These results delineate target engagement and validation mechanisms in a multi-day tACS trial, supporting optimized dosing in future tACS interventions.

Background: Generalized anxiety disorder (GAD) is associated with substantial psychological burden, autonomic dysregulation, and limitations of existing pharmacological and psychotherapeutic treatments. Transcutaneous auricular vagus nerve stimulation (taVNS) has emerged as a promising non-invasive neuromodulation approach, but evidence regarding home-based application in GAD remains limited. Objective: To evaluate the feasibility, safety, and preliminary clinical and physiological outcomes of a home-based taVNS intervention in adults with psychologist-confirmed moderate-to-severe GAD. Methods: In this prospective single-arm feasibility study, 48 participants initiated a 4-week home-based taVNS intervention consisting of two daily stimulation sessions performed five days per week. Clinical assessments were conducted at baseline, Week 2, Week 4, and follow-up visits at Weeks 6 and 8. Ambulatory electrocardiographic monitoring was performed before treatment initiation, at Week 2, and at the end of treatment to assess heart rate variability (HRV) using the root mean square of successive differences (RMSSD). Primary outcomes included feasibility, safety, adherence, and change in clinician-rated anxiety severity (HAM-A). Results: Thirty-four participants completed the study and were included in the primary analyses. HAM-A scores decreased significantly from baseline to Week 4 ([EMD] -6.9, 95% CI -10.4 to -3.4, p = 0.001), with partial maintenance during follow-up. Improvements were also observed in Beck Anxiety Inventory scores, whereas changes in GAD-7, perceived stress, depressive symptoms, and sleep quality were not statistically significant. RMSSD increased significantly from baseline to Week 4 (EMD 6.7 ms, 95% CI 2.1-11.3, p = 0.009). Greater increases in RMSSD were associated with larger reductions in HAM-A (R^2 = 0.18, p = 0.031) and BAI scores (R^2 = 0.21, p = 0.019). No serious adverse events occurred. Mean adherence was 79.8%, and 73.5% of participants completed at least 70% of prescribed stimulation sessions. Conclusions: Home-based taVNS was feasible and generally well tolerated in adults with moderate-to-severe GAD. Preliminary improvements in clinician-rated anxiety severity and autonomic physiological measures were observed; however, the single-arm design precludes causal inference. These findings support further evaluation of home-based taVNS in adequately powered randomized sham-controlled trials.

Background: The Neuro-Immune-Metabolic-Oxidative Stress (NIMETOX) theory identified systemic dysregulation in Major Depressive Disorder (MDD), yet the precise gut-derived metabolic triggers initiating this cascade remain elusive. This study investigated the interplay between fecal short-chain fatty acids (SCFAs), systemic immune activation, and clinical phenotypes to identify a potential gut-immune biotype for MDD. Methods: Fecal SCFA profiles and serum immune-inflammatory markers were quantified in 102 patients with MDD and 38 matched healthy controls. A multistage statistical approach was employed: binary logistic regression and 10-fold cross-validated linear discriminant analysis (LDA) were utilized to evaluate diagnostic accuracy, while multivariable regression models were applied to identify robust predictors of clinical phenotypes, including the overall severity of depression (OSOD), physiosomatic symptoms, and recurrence of illness (ROI). Results: MDD patients exhibited a significant depletion of protective straight-chain SCFAs (acetate, propionate, butyrate) and an elevation in branched-chain SCFAs (BSCFAs), indicating a pathological shift from saccharolytic to proteolytic fermentation. This metabolic shift correlated with elevated acute phase-inflammatory index (API) and epidermal growth factor (EGF). A multidimensional model combining BSCFAs, acetate, API, EGF, and T helper 2 discriminated MDD from controls with adequate accuracy (AUC = 0.874). Furthermore, elevated BSCFAs and decreased protective SCFAs strongly predicted higher OSOD, more severe physiosomatic symptoms, and increased ROI. Notably, 5-Hydroxytryptamine receptor 1A agonists were independently associated with elevated BSCFAs. Conclusion: MDD is characterized by a distinct gut-immune biotype tightly linked to toxic proteolytic gut fermentation. This metabolic-immune fingerprint offers an objective diagnostic tool and highlights the need for microbiome-targeted interventions in precision psychiatry.

Background Chronic pain and depression are common disorders and leading causes of disability worldwide. They frequently co-occur and show substantial genetic correlation, indicating a shared genetic basis. However, the locus-specific architecture of this overlap remains poorly characterised and may yield important insights into the pathophysiology of their comorbidity. Methods Using the largest currently available European-ancestry genome-wide association studies of major depressive disorder (MDD) (n = 1,639,572) and multisite chronic pain (MCP) (n = 387,649), we estimated the polygenic overlap between traits using the bivariate causal mixture model (MiXeR), identified shared loci via conjunctional false discovery rate (conjFDR), and tested colocalisation with each trait and genetically regulated gene expression in 13 brain tissues. Results MiXeR analysis demonstrated a high degree of directionally consistent polygenic overlap between MDD and MCP. Subsequent conjFDR analysis identified 375 shared loci, 22 of which showed cross-trait colocalisation between the MDD and MCP signals. Gene mapping and enrichment of shared loci implicated several biological processes, including cadherin-mediated cell-cell adhesion and translational initiation. Gene expression colocalisation in brain tissue highlighted protein phosphatase 6 catalytic subunit (PPP6C) and suppressor of cancer cell invasion (SCAI) in both disorders. Conclusion Overall, these findings have enhanced our understanding of the complex relationship between chronic pain and depression by identifying shared molecular mechanisms that warrant further study as targets for prevention and treatment.