Translational Psychiatry

Background: Metabolomic studies of depression have yielded heterogeneous findings, potentially because metabolic correlates differ across symptoms and metabolic states. We examined symptom-specific metabolomic associations and whether body mass index (BMI) modifies these relationships. Methods: We analyzed 83,717 Estonian Biobank participants (70.6% female) with 249 Nightingale metabolite measures and 14 lifetime depressive symptoms. Logistic regression models progressively adjusted for sociodemographic, lifestyle, medication, and BMI factors. BMI-related attenuation and metabolite x BMI interactions were evaluated, followed by self-organizing map analyses of broader metabolic context. Results: Before BMI adjustment, 660 metabolite-symptom associations were Bonferroni-significant; 136 were significant after BMI adjustment, including 105 retained associations. Weight-related associations showed the strongest BMI dependence: none of 199 weight-gain associations and 2 of 115 weight-loss associations were retained. Among 691 preselected metabolite-symptom pairs, 211 (30.5%) showed significant metabolite x BMI interactions after false discovery rate correction. Six systemic metabolic profiles were identified, but only 3 of 211 BMI-sensitive pairs showed additional profile-dependent heterogeneity. Conclusions: Circulating metabolic correlates of depressive symptoms are heterogeneous and strongly dependent on symptom phenotype and BMI-related metabolic context. These findings suggest that metabolic biomarkers in depression should be interpreted in relation to both symptom presentation and metabolic state rather than as uniform correlates of the disorder.

Major Depressive Disorder (MDD) shows marked gender differences in prevalence and molecular signatures. Transcriptomic studies of post-mortem human brain tissue have reported alterations in the expression of synapse-related genes in MDD, including gender-specific patterns. But it remains unclear whether transcriptional changes observed in the brains of women with MDD are detectable in peripheral blood and conserved in experimental stress models. Whole-blood RNA sequencing was performed in women with MDD (n = 6) and matched healthy controls (n = 4). Differentially expressed genes (DEGs) were compared with previously reported female-specific blood and post-mortem brain transcriptomic datasets where selected overlapping synapse-associated genes were evaluated in the hippocampus and prefrontal cortex of female mice exposed to Chronic Variable Mild Stress (CVMS). Peripheral blood analysis identified DEGs enriched for synaptic organization, neuronal structure, and ion transport pathways. A substantial proportion of DEGs overlapped with previously reported datasets from peripheral blood, female MDD brain transcriptomic studies, and genes showing exclusive/enriched expression in the normal human brain. Network-based prioritization identified seven synapse-associated genes (SHANK2, SHANK3, CACNG8, GPHN, PICK1, NRXN2 and DNM2) for further analysis. In the female CVMS model, several of these genes showed altered expression in the hippocampus and/or prefrontal cortex, alongside behavioural changes and reduced dendritic spine density. These findings highlight shared transcriptional signals across human blood and human brain datasets, as well as in the mouse brain. However, larger studies are required to confirm and validate these observations.

Suicidal behavior results from complex behavioral and biological changes. Previous cross-sectional studies indicate that proinflammatory immunobiological factors are often increased in close temporal proximity to a suicide attempt. Suicidal individuals may also exhibit a biological trait vulnerability to stress and inflammation, due to persistent epigenetic modifications. We enrolled 130 individuals with major depressive disorder (MDD), 83 with suicidal behavior at intake, and followed them for 12 months with up to eight clinical assessments. Quantification of plasma inflammatory markers and metabolites was performed by high-sensitivity electrochemiluminescence and Ultra High-Performance-Liquid-Mass Spectrometry (UPLC-MS), respectively. Epigenetic changes were identified using Illumina EPIC arrays. We identified 15 genes with altered DNA-methylation associated with suicidal behavior and attempts at baseline. Childhood trauma predicted lifetime suicide attempts and was associated with altered methylation of seven genes. Increased neutrophils and lower plasma serotonin at baseline predicted future suicide attempts over the following year (neutrophil estimate = 0.42, P = 0.016; serotonin OR = 0.58, 95% CI: 0.39-1.13). Utilizing biomarkers from baseline and epigenetic data from the genes with highest predictive values (STBD1 ,PRDM8, and TRIM15), we achieved an area under the curve (AUC) of 0.84 for suicide attempts over the year. Suicidal behavior in MDD was associated with specific epigenetic signatures. Several of the identified genes, such as MAD1L1, have been implicated in psychiatric disease, suicidal behavior and the immune response. These findings support the usefulness of epigenetic and immunometabolic blood markers for identifying suicidal individuals in clinical settings, potentially enhancing preventative efforts.

Major depressive disorder (MDD) is strongly associated with dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, systemic inflammation, and gut microbiota dysbiosis. Although selective serotonin reuptake inhibitors such as escitalopram are standard treatments, their efficacy is often constrained by partial response and gastrointestinal adverse effects. In this 12-week, randomized, double-blind, placebo-controlled trial, we evaluated the clinical efficacy and microecological mechanisms of adjunctive Lactiplantibacillus plantarum PS128 (PS128; 6*1010CFU/day) in MDD patients on stable escitalopram therapy. Adjunctive PS128 significantly enhanced clinical response compared to placebo, yielding substantial reductions in HAMD-17 and MADRS, alongside a higher remission rate. 16S rRNA sequencing and PICRUSt2 profiling revealed that PS128 enriched key short-chain fatty acid producers (Faecalibacterium, Coprococcus), counteracting the Klebsiella expansion seen in placebo. Functionally, PS128 up-regulated neuroprotective cofactor, B vitamins, biosynthesis and down-regulated the neurotoxic kynurenine pathway. Network analysis demonstrated that PS128 maintained a resilient, integrated microbial co-occurrence topology, whereas the placebo network showed structural segregation. This stabilized ecosystem attenuated peripheral inflammatory signaling and normalized salivary cortisol levels. Overall, adjunctive PS128 augments escitalopram efficacy by enhancing gut network stability, supporting cellular energetics, and modulating neuroendocrine activity, offering a promising multimodal strategy for MDD.

Background: Bipolar disorder (BIP) and obsessive-compulsive disorder (OCD) frequently co-occur and show evidence of genetic overlap, yet the specific pleiotropic loci and their functional mechanisms remain unclear. Methods: We conducted large-scale genetic analyses using GWAS summary statistics for BIP and OCD, excluding 23andMe data. We applied conjunctional FDR analysis to identify pleiotropic variants jointly associated with BIP and OCD, followed by integrative annotation through transcriptomic (eQTL, sQTL), epigenomic (mQTL, haQTL), and proteomic (pQTL, histone PTM) data. SMR analysis was used to prioritize putative regulatory effects, while AlphaGenome predictions and targeted histone proteomics were employed to evaluate allele-specific chromatin changes. Results: We observed a significant genetic correlation (rg = 0.38, P = 3.8 x 10-29) and extensive polygenic overlap between BIP and OCD. Bidirectional MR supported causal effects in both directions, with stronger evidence for BIP influencing OCD risk. ConjFDR analysis revealed 2,143 pleiotropic SNPs jointly associated with BIP and OCD, with convergent signals at the ITIH3/ITIH4 locus. Summary-data-based Mendelian randomization (SMR) and colocalization with multi-omic QTLs (eQTL, pQTL, mQTL, and haQTL) further prioritized the ITIH3/4 locus, where multiple SNPs (e.g., rs3774364) colocalized with H3K27ac histone acetylation QTLs in the prefrontal cortex (PP_H4 > 0.5). Integrated PBMC RNA-seq and complementary histone mass spectrometry linked immune--ECM transcriptional activity to exploratory global histone acetylation changes in BIP and OCS-BIP, with suggestive alterations in H3K27ac-containing peptides. Conclusions: Our multi-omic analysis highlights ITIH3/ITIH4 as a prioritized pleiotropic locus for BIP and OCD. Epigenetic regulation, particularly through histone acetylation, may underlie shared susceptibility and offers a novel mechanistic link between these psychiatric disorders.

Treatment-resistant depression (TRD) remains a major clinical challenge, yet the biological processes distinguishing TRD from non-treatment-resistant depression (nTRD) are incompletely defined. While circulating serum proteomes reflect broad systemic alterations associated with depression, extracellular vesicles (EVs) could provide a more selective representation of intercellular signaling relevant to treatment resistance. Here, we carried out a pilot study to evaluate the extent that parallel proteomic profiling of serum and serum-derived EVs could distinguish healthy controls (CON), nTRD, and TRD individuals. In this exploratory and hypothesis-generating study, serum proteomes exhibited robust global differences between depression groups and controls, largely reflecting shared systemic biology across nTRD and TRD. In contrast, EV proteomes showed limited global separation but revealed subtype-associated pathway differences. Relative to controls, nTRD EVs were enriched for immune and inflammatory pathways. By contrast, TRD EVs were characterized by enrichment of mitochondrial metabolism, oxidative phosphorylation, translational initiation, and MYC-regulated pathways, together with depletion of synaptic signalling, membrane trafficking, and cytoskeletal pathways. Comparative analysis of pathways significant in both contrasts revealed that these bioenergetic and translational signatures were selectively amplified in TRD relative to nTRD. Our exploratory analyses identified that the circulating EV cargo may reflect a treatment-resistance-specific reorganization of biological pathways not apparent in bulk serum proteomics. This study highlights parallel serum and EV proteomics as a complementary approach for molecular stratification in antidepressant resistance.

Background and aimVery preterm birth (VPT; [≤]32 weeks gestation) is associated with an increased risk of later psychiatric disorders, including psychosis. Although psychosis typically emerges in adulthood, subclinical early signs along the psychosis continuum, such as psychotic-like experiences (PLEs), can be observed much earlier. We therefore aimed to study PLEs in childhood in VPT individuals recruited from a clinical cohort compared with full-term (FT) controls. We subsequently investigated whether findings could be replicated in an independent population-based cohort. MethodsPrimary analyses were conducted in the Brain, Immunity and Psychopathology (BIPP) study, including 197 children born VPT recruited through Neonatal Intensive Care Units and 72 FT controls assessed at a mean age of 10.50{+/-}1.77 years. Between-group differences in PLEs were then examined in the Adolescent Brain Cognitive Development (ABCD) study, including 149 children born VPT and 9519 FT controls assessed at a mean age of 9.94 {+/-} 0.63 years. PLEs were assessed using the Prodromal Questionnaire-Brief Child Version (PQ-BC), yielding frequency and distress-related scores for both the total scale and three specific domains (unusual thought content, perceptual abnormalities, disorganised speech). Regression models tested associations between birth status (VPT and control) and PQ-BC scores adjusting for age, sex, and socio-economic status, with secondary models additionally adjusting for cognitive ability and broader psychopathology. Pooled analyses examined cohort effects (BIPP and ABCD) and cohort-by-group status (VPT and control) interactions. ResultsIn BIPP, VPT birth was associated with higher PQ-BC total ({beta}=1.61, p=0.004) and distress scores ({beta}=0.78, p=0.039), with the strongest and most consistent associations observed for perceptual abnormalities across total score (sum of endorsed items), distressing items, and distress severity scores (all p[≤]0.01). These associations were attenuated but largely persisted after adjustment for cognitive ability and broader psychopathology, particularly for perceptual abnormalities. In ABCD, VPT birth was not significantly associated with global or domain-specific PQ-BC outcomes. DiscussionVPT birth is associated with increased vulnerability to PLEs in childhood, particularly in the domain of perceptual abnormalities. The lack of clear replication in the population-based ABCD cohort may reflect differences in the composition of its VPT subgroup, which may not fully represent VPT individuals typically seen in clinical cohorts.

Psilocybin acutely alters neurotrophic, neurochemical, and immune markers, but the relationships between these responses and circulating microRNAs (miRNAs), i.e. non-coding RNAs that regulate post-transcriptional gene expression, remain unclear. In a randomized, double-blind, placebo-controlled study of 62 healthy adults who received psilocybin (0.17 mg/kg) or placebo, we previously demonstrated that let-7g-5p and miR-150-5p were transiently differentially expressed 360 minutes after psilocybin administration. Here, we examined whether changes in these miRNAs were associated with concurrent neurotrophic, inflammatory, pharmacokinetic, and glutamatergic measures. Expression changes from baseline to 360 min and 7 days were analysed using linear regression against changes in BDNF, TNF-, IL-6, C-reactive protein, cortisol, medial prefrontal cortex glutamate/total creatine, and psilocin concentrations. Psilocybin increased let-7g-5p and decreased miR-150-5p expression. Changes in let-7g-5p were positively associated with psilocin concentrations, suggesting sensitivity to inter-individual pharmacokinetic variability, whereas miR-150-5p showed no concentration-dependent association. In both groups, miRNA changes were negatively related to baseline expression: lower baseline let-7g-5p predicted larger increases, whereas higher baseline miR-150-5p predicted larger decreases. BDNF changes were associated with both miRNAs under placebo but not psilocybin, consistent with reduced between-subject variability and a flattened BDNF-miRNA relationship following treatment. Medial prefrontal glutamate was negatively associated with miR-150-5p change under psilocybin. No associations were found with immune biomarkers. Together, these findings support the predicted involvement of let-7g-5p and miR-150-5p in neuroplasticity and their potential as accessible blood-based biomarkers of individual neurobiological responsiveness to psilocybin and other psychedelics.

Psychiatric disorders are complex conditions characterized by substantial overlap in genetic risk and shared biological mechanisms. However, how individual risk genes contribute to shared disease mechanisms and disorder-specific phenotypes remains poorly understood. BRD1 has emerged as a chromatin-associated regulator with transdiagnostic relevance across psychiatric disorders and a central role in gene regulatory networks enriched for psychiatric risk genes. To investigate the biological consequences of reduced BRD1 function in a translationally relevant system, we generated a minipig model harboring a monoallelic deletion in BRD1 and performed longitudinal neuroimaging together with behavioral and multi-omics profiling. BRD1 haploinsufficient minipigs displayed normal growth and exploratory behavior but exhibited subtle age-dependent differences in motivational behavior. Despite the absence of overt developmental abnormalities, longitudinal neuroimaging revealed genotype-associated structural differences primarily involving the cerebral cortex and caudate nucleus, suggestive of altered neurodevelopmental trajectories. Integrated multi-omics analyses revealed striking convergence across transcriptomic and metabolomic datasets, identifying coordinated perturbations of mitochondrial function, redox regulation, and phospholipid metabolism across multiple brain regions. Notably, these molecular alterations were not restricted to the central nervous system, as peripheral multi-omics profiling revealed systemic metabolic alterations, including altered phospholipid composition and glucose metabolism. Together, these findings indicate that BRD1 haploinsufficiency is associated with coordinated neurodevelopmental and metabolic alterations across brain and peripheral tissues. More broadly, this study provides systems-level insight into how a psychiatric risk gene influences interconnected neurodevelopmental and metabolic processes across multiple levels of biological organization and highlights the value of large-animal multi-omics models for translational neuropsychiatric research.

Importance: Adolescent cannabis use is a growing concern due to its associations with long-term adverse mental health outcomes. However, the distinct, temporal associations of neurodevelopmental factors and childhood adverse life experiences (ALEs) with adolescent substance use in have not yet been fully elucidated. The Adolescent Brain Cognitive Development (ABCD) Study offers an unprecedented opportunity to prospectively examine neurobiological and socioenvironmental predictors of cannabis onset. Objective: To investigate magnetic resonance imaging-derived neurodevelopmental cortical brain Age Gap Estimate (brainAGE) and adverse life events as risk factors of early cannabis initiation. Design, Setting, and Participants: The ABCD Study is a longitudinal study across 22 sites in the United States. Data are collected starting at approximately 10 years old (currently at year-7 follow-up). Our analyses comprised 6688 (48% female) youth after exclusions. Main Outcomes and Measures: Cox proportional hazard models were computed to investigate brainAGE-sex interactions and 10 adversity dimensions at baseline as predictors of time to cannabis initiation up to age 18. Results: Mean age of initiation was 14.8 years (SD=1.43). Global brainAGE was modestly associated with cannabis initiation in females only (Hazard Ratio [HR]=1.05; 95% Confidence Interval [CI]=1.00-1.10, p = .049). Low socioeconomic status, caregiver substance use, family anger and arguments, and caregiver lack of supervision were associated with initiation (HRs = 1.11, 1.56, 1.09, 0.85, respectively; CIs = 1.04-1.19, 1.44-1.69, 1.09-1.19, 0.76-0.91, respectively; p's < .05). Other ALE dimensions and network-specific brainAGEs were not significantly associated with initiation. Conclusions and Relevance: Findings suggest that while cortical brainAGE may be somewhat increase vulnerability to adolescent cannabis use in females, its contributions are modest at best. In contrast, early childhood adversities such as socioeconomic factors and familial characteristics may present more substantive targets for prevention and intervention.

Neuropsychiatric symptoms are considered the most common feature of long COVID disease. Recent studies have demonstrated structural brain changes and highlighted the importance of neuroinflammation in the development of cognitive deficits as seen in long COVID patients. In addition, peripheral studies have demonstrated heterogeneous molecular subtypes of long COVID pathology. However, it is unknown which peripheral metabolomic alterations occur in patients with neuropsychiatric long COVID syndrome and how these relate to symptom severity. In the present study, we investigated differences in the peripheral serum metabolome profiles of healthy controls and patients with long COVID syndrome with neuropsychiatric symptoms. We found that patients with long COVID showed peripheral alterations in lipid species such as triacylglycerides and acylcarnitines. Furthermore, metabolites altered in patients with long COVID syndrome were also associated with depressive and fatigue symptom burden as well as with differences in cortical thickness in multiple brain regions. Our results demonstrate a metabolic phenotype of long COVID patients that may reflect a dysregulation of lipid metabolism and deficits in mitochondrial energy production as potential contributors to symptom burden and brain structural alterations. These data may serve as a resource and basis for further studies aimed at investigating peripheral molecular alterations in patients with neuropsychiatric long COVID syndrome.

Background: Sleep problems are common in autism, emerge early in life and reduce quality of life, yet the mechanistic link between autism and poor sleep remains unclear. Human and rodent data indicate that difficulty falling asleep is a core feature of autistic insomnia, pointing to impaired responses to sleepiness as the underlying cause. We previously showed that adult mice carrying a mutation in the high-confidence autism gene Shank3 (Shank3{Delta}C) recapitulate this insomnia phenotype and struggle to respond to sleepiness after acute sleep deprivation. Here, we used Shank3{Delta}C mice to examine the molecular basis of sleepiness and how this autism-associated mutation alters it to inform understanding of sleep problems in autistic individuals. Methods: This study used RNA-sequencing and bioinformatics to identify molecular targets underlying the effect of the Shank3{Delta}C mutation on the molecular basis of sleepiness across development in male mice. We first compared cortical genome-wide gene expression following acute sleep deprivation and recovery sleep in adult wild-type (WT) and mutant mice. We then used polysomnography and RNA-sequencing to assess the response to increased sleepiness in WT and mutant mice at postnatal days 24 and 30. Results: The neurotypical response to acute sleep deprivation shifted from upregulating neuronal growth and development pathways at P24/P30 to upregulating DNA damage repair and neuronal activity-dependent transcription in adulthood. The Shank3{Delta}C mutation largely blocked recruitment of these pathways at P24 and in adulthood while paradoxically increasing the magnitude of the mutant response at P30. In addition, mutants consistently upregulated oxidative stress pathways linked to neurodegeneration and protein synthesis regardless of age, whereas WT animals downregulated these functions. Limitations: This study examined gene expression only in male mice, used a single autism rodent model, and averaged signals across mixed cortical cell types. Future work should include females, additional autism models, and single-cell approaches in additional brain regions to further characterize the cellular effects of sleep deprivation and autism-associated mutations. Conclusions: The Shank3{Delta}C mutation impairs the molecular accumulation of and response to sleepiness, both by elevating oxidative stress responses and by blocking the age-typical upregulation of pathways that differ between juveniles and adults.

BackgroundInflammation-associated depression is a subtype of major depressive disorder that is often resistant to conventional pharmacotherapies, which act in a regionally non-specific manner and therefore also produce unwanted side effects. Here we test GPR151, an orphan GPCR associated with inflammation and highly expressed in the habenula--a region linked to negative valence and depression--as a therapeutic target for inflammation-associated depression. MethodsWe integrated mouse and human habenular expression analyses with genetic loss-of-function and adult habenular re-expression approaches in mice. Gpr151 knockout mice and littermate controls were exposed to lipopolysaccharide (LPS) inflammatory challenge and assessed for stress coping and motivated behavior, body weight loss, and peripheral immune activation. To test whether adult habenular GPR151 expression is sufficient to restore inflammation-associated behavioral vulnerability, GPR151 was re-expressed in the habenula of knockout mice. ResultsGPR151 was exceptionally enriched in the habenula and showed conserved topographic organization and similar expression relationships with habenular marker genes in mice and humans. Following LPS challenge, male Gpr151 knockout mice showed reduced passive coping despite body weight loss and immune activation comparable to littermate controls. Adult habenular GPR151 re-expression increased LPS-induced amotivation in male knockout mice without increasing LPS-induced weight loss or immune activation. Female Gpr151 knockout mice also showed reduced passive coping after LPS challenge; however, habenular GPR151 re-expression was insufficient to increase LPS-induced amotivation in females. ConclusionsThese findings identify GPR151 as a conserved, regionally enriched regulator of behavioral sensitivity to inflammatory challenge and support GPR151 as a candidate therapeutic target for inflammation-associated depression.

Chronic stress is a major risk factor for psychiatric disorders such as depression and anxiety, yet the biological basis of individual differences in stress susceptibility and resilience remains poorly understood. Here, we examined physiological, behavioral, and medial prefrontal cortex (mPFC) transcriptomic responses to chronic restraint stress (CRS) in male BALB/c and C57BL/6J mice. After 21 days of CRS, BALB/c mice exhibited greater stress-related changes than C57BL/6J mice, including greater body weight loss, elevated serum corticosterone, reduced serum antioxidant capacity, and more pronounced depression-like behaviors. RNA sequencing showed largely strain-specific transcriptional changes in the mPFC. Strain x stress interaction analysis, followed by canonical pathway analysis using Ingenuity Pathway Analysis (IPA), identified strain-dependent molecular signatures. The most prominent differences involved extracellular matrix (ECM) organization and remodeling and neuroinflammatory signaling pathways, with greater predicted activation in BALB/c mice. IPA upstream regulator analysis further predicted multiple candidate regulators associated with these pathways, including TGF-{beta}/SMAD, C4a/C4b, and MAPK14. Among genes associated with these pathways, several ECM-related genes were preferentially upregulated in BALB/c mice, whereas activity-dependent immediate early genes were preferentially downregulated in C57BL/6J mice. These findings suggest that the strain-dependent mPFC transcriptional programs identified here may contribute to differential stress susceptibility and resilience.

Background: Altered gamma-aminobutyric acid (GABA) neurotransmission is a proposed mechanism underlying autism spectrum disorder (ASD), prompting evaluation of several GABA-modulating pharmacotherapies. However, it remains unclear whether these interventions improve ASD broadly or preferentially affect specific symptom domains. Methods: We conducted a systematic review and random-effects meta-analysis of randomized controlled trials evaluating GABA-modulating pharmacotherapies in individuals with ASD. PubMed/MEDLINE, Embase, Scopus, and CENTRAL were searched from inception to April 1, 2026. Outcomes were prespecified as global autism severity, social communication, functional communication, restricted and repetitive behaviours (RRBs), adaptive behaviour, and irritability. Risk of bias was assessed using the Cochrane Risk of Bias 2 tool, and certainty of evidence was evaluated using GRADE. Results: Thirteen randomized controlled trials evaluating three GABA-modulating interventions (bumetanide, arbaclofen, and valproate) were included. GABA-modulating therapies were associated with statistically significant improvements in global autism severity (Hedges' g = -0.25, 95% CI -0.46 to -0.03; p = 0.028) and adaptive behaviour (Hedges' g = -0.09, 95% CI -0.15 to -0.02; p = 0.023). No significant pooled effects were observed for social communication (Hedges' g = -0.26, p = 0.077), functional communication (Hedges' g = -0.01, p = 0.869), RRBs (Hedges' g = -0.21, p = 0.126), or irritability (Hedges' g = -0.07, p = 0.543). After Holm-Bonferroni step down procedure, neither global autism severity nor adaptive behaviour remained statistically significant (Holm-adjusted p = .140 and .138, respectively). Adverse events were predominantly gastrointestinal, neurological, metabolic, and appetite-related. Overall risk of bias was variable, and the certainty of evidence ranged from very low to moderate. Conclusions: GABA-modulating pharmacotherapies did not demonstrate a robust, multiplicity-corrected benefit in any of the six prespecified ASD symptom domains. Nominal, unadjusted improvements in global autism severity and adaptive behaviour did not withstand correction for multiple comparisons and should be regarded as hypothesis-generating rather than confirmatory. Larger, adequately powered randomized trials using standardized domain-specific outcome measures are needed to determine whether individual GABA-modulating agents provide clinically meaningful benefit.

BackgroundPsilocybin, a classic psychedelic, produces acute alterations in brain function, and has shown sustained therapeutic effects in psychiatric disorders. However, most studies focus on acute brain imaging readouts (e.g., fMRI) and rarely assess longer-term molecular changes. MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression, are enriched in the brain, and can be released into blood, potentially indexing brain-relevant molecular processes. We hypothesised that a single psilocybin dose would show acute changes in miRNAs with predicted relevance to neuroplasticity related signalling and immune/inflammatory regulation in healthy adults. MethodsIn a randomised, double-blind, placebo-controlled study (N=62; 31 psilocybin, 31 placebo), volunteers received psilocybin (0.17 mg/kg) or placebo. Blood was collected at baseline, 360 minutes, and 7 days after dosing. Plasma miRNAs were quantified by small RNA sequencing. Elastic net regression was used for feature selection, followed by differential expression analysis and validation with linear mixed models. Pathway enrichment used Reactome and Gene Ontology. ResultsTwo circulating miRNAs (let-7g-5p and miR-150-5p) met criteria for differentially expressed at 360 minutes following psilocybin administration, with no significant differences detected at 7 days or in the placebo condition under the statistical thresholds used. Over representation analysis suggested enrichment of molecular processes involved in neuroplasticity (e.g., TrkA, MAPK), inflammation (e.g., IL-6, TGF-{beta}), and transcriptional regulation (e.g., RNA polymerase II, SMAD2/3/4). ConclusionsA single oral dose of psilocybin was associated with transient alterations in circulating miRNA expression, consistent with an acute shift in circulating gene-regulatory miRNA signals, without sustained miRNA changes at 7 days. These findings provide initial evidence that circulating miRNA changes after psilocybin may reflect acute molecular process responses and support further investigation of circulating miRNAs as potential biomarkers of psychedelic-induced molecular responses.

Recent large-scale studies have enabled new knowledge about genetic underpinnings of morphological and electrophysiological alterations of the retina. Variation in retinal traits, often of neurodevelopmental origin, have been linked to major psychiatric disorders (MPDs). Here, we investigate the genetic overlap between MPDs and key retinal traits to identify underlying molecular mechanisms. We obtained genome-wide associations studies data for bipolar disorder (BD), major depression (MD), schizophrenia (SCZ), and the retinal traits retinal nerve fibre layer thickness (RNFL), ganglion cell inner plexiform layer thickness (GCIPL), and vertical cup-disc ratio (VCDR). We estimated the number of trait-influencing variants shared between traits with MiXeR and identified shared genetic loci with condFDR. Subsequently, we examined the biological pathways of the genes mapped to shared loci. This revealed that GCIPL shared the most genetic variants with MPDs (~60%), followed by RNFL (~40%), and VCDR (~20%). The genetic variants shared between retinal traits and MPDs showed disorder-specific patterns with more pronounced overlaps of SCZ and BD with RNFL, and MD negatively correlated with GCIPL. Gene-pathway analysis highlighted the importance of GABAergic neurotransmission and a two-stage neurodevelopmental process in SCZ, whereas the role of mitochondria and a weaker developmental component were observed in BD. The results also implicated synaptic functioning and gene-expression processes in MD. Furthermore, polygenic analysis suggested that the genetic architecture of retinal traits can distinguish between MPDs. Our findings indicate shared genetic underpinnings between retinal traits and SCZ, BD, and MD, implicating altered neurodevelopment and neurotransmission underlying the retinal link to major psychiatric disorders.

Background: Suicide is a major public health concern and a highly complex, heterogeneous phenotype. Increasing evidence implicates epigenetic mechanisms, particularly DNA methylation (DNAm), in suicidal behavior. Methods: Building on previous epigenome-wide association studies (EWASs), we conducted the largest EWAS to date in postmortem dorsolateral prefrontal cortex (Brodmann area 9), analyzing DNAm and epigenetic aging (EA) in 199 suicide decedents (SD) and 190 age- and sex-matched non-psychiatric controls (NPC) using the Infinium MethylationEPIC BeadChip Array v2.0. Results: Bulk tissue analysis identified no significant differentially methylated positions or regions. In contrast, cell type-specific analysis using DNAm-deconvoluted cell proportions identified 605 differentially methylated cytosines in individual cell types (DMCTs) in excitatory neurons, 10 in inhibitory neurons, and 28 in oligodendrocyte precursor cells. Sex-stratified analyses identified mainly male-specific DMCTs, most of which were found in excitatory neurons, while comparison of violent and non-violent suicide identified additional DMCTs in glial cell types. Excitatory neuron DMCTs were enriched for synaptic, small GTPase signaling, and neurodevelopmental pathways, and overlapped genes previously associated with suicidal behavior, including MAD1L1. No significant differences in EA acceleration were observed overall or by sex or suicide mechanism. Conclusions: These findings indicate that suicide-associated DNAm patterns are primarily neuron-specific and may remain undetectable in bulk tissue, highlighting the importance of cell type-specific approaches to elucidate biological mechanisms underlying suicide.

Autism Spectrum Disorder (ASD) is a heterogeneous neurodevelopmental condition defined by differences in social communication and restricted, repetitive behaviours. As diagnostic criteria have broadened, ASD is now recognised across a wider range of individuals, raising key questions about its structure: does ASD have discrete sub-types, or is it better conceptualised as a continuous, possibly multidimensional, condition? We aim to explore whether a multidimensional continuum model more accurately captures the variability within ASD. We analysed a large SPARK phenotypic dataset of medical history and diagnostic surveys (background history, SCQ, RBS-R; n=36,710 individuals). We apply and compare two traditional statistical approaches, Factor Analysis and Gaussian Mixture Models, with a modern machine learning technique, the Variational Autoencoder (VAE). VAEs reconstructed unseen test data with ~4-fold better accuracy than Factor Analysis, and ~8-fold better accuracy than Gaussian Mixture Models. We identified four stable latent factors across 100 independently trained VAEs. These four dimensions provide an individual behavioural profile that can be visualized using radar-plots, offering a compact way to compare profiles at the person level. Through further analysis, we found evidence for 3 overlapping clusters or subtypes of ASD identified within the 4D latent space. This work aims to inform new ways of modelling ASD using a VAE that will be able to discern between a continuum or a clustered output and that go beyond binary diagnosis, instead reflecting the complex range of trait profiles, with implications for personalised diagnosis and intervention.

The social anxiety disorder (SAD) is one of the most common mental health disorders, often developing in adolescence. It can severely impair educational achievement, career progression, and social functioning. Certain individuals within the Chinese Kunming dog (CKD) population display spontaneous, SAD-like behaviors towards strangers, offering a valuable model for genetic investigation. Using whole-genome sequencing data, we conducted a genome-wide association study on this SAD-like behavior in 100 CKDs, identifying several genes previously linked to human psychiatric disorders. Notably, SLC6A3 reached genome-wide significance, whereas CADPS2 exceeded only the suggestive threshold and is therefore considered a network-supported candidate locus. By integrating weighted gene co-expression network analysis with public RNA-seq data from the VTA of 38 mice (after quality control), we further showed that Slc6a3 and Cadps2 are part of a co-expression network module associated with the dopamine system. These findings suggest that this specific module may play a functional role in the stranger-directed anxiety-related behaviours in CKDs. Furthermore, we identified Nrip3 as a key candidate transcriptional coregulator in this specific module. Subsequent virus-mediated overexpression and behavioural experiments showed that Nrip3 regulates gene expression within this network and induces a spectrum of behavioural alterations in mice, including social avoidance, anhedonia, and increased locomotor activity. Collectively, this study highlights the involvement of dopamine system genes in canine social anxiety and suggests Nrip3 as an upstream regulator of Slc6a3 associated with anxiety. The identification of conserved anxiety-related signatures between humans and dogs further supports the dog as a valuable translational model for psychiatric research.