International Journal of Neuropsychopharmacology

Importance: Obsessive-Compulsive Disorder (OCD) has a 2% global prevalence, but only about 50% of patients respond to conventional treatment, underscoring the need for additional effective interventions. Objective: To assess the feasibility, safety, and preliminary evidence for efficacy of repeated psilocybin administration in OCD patients who had previously attempted psychotherapy or pharmacotherapy. Design: Waitlist-controlled open label randomized clinical trial. Setting: Data were collected at the Johns Hopkins University School of Medicine. Participants: Data were analyzed from 30 participants (total randomized N=37, by age, sex and OCD severity) with a failed previous attempt at either pharmacotherapy or evidence-based psychotherapies such as exposure response prevention (ERP). Intervention: Participants received two psilocybin doses over two weeks (20 mg followed by 30 mg, if well-tolerated) under supportive conditions. The immediate-treatment arm received the drug within a month following enrollment, and the waitlist-control arm received identical support and dosing after an 8-week waiting period. Main Outcomes: Clinician-administered Y-BOCS scores was collected one week post each drug administration and one month post session 2. Self-assessed reports were collected for acute subjective effects (Mystical Experience Questionnaire (MEQ), Challenging Experience Questionnaire (CEQ), and 11-Dimensional Altered States of Consciousness (11D-ASC)), State-Trait Anxiety Inventory (STAI), Beck Depression Inventory-II (BDI-II), and Quality of Life Enjoyment and Satisfaction Questionnaire (Q-LES-Q). Results: A total of 37 participants were enrolled in the study (age[SD] years:38.4[11.6] years; 21 [56.75%] female), with 30 [81.08%] completing the 1-month follow-up. We show that two successive doses of psilocybin over two weeks were well-tolerated, leading to improvements in OCD symptoms. Compared with the waitlist group (N=14), the immediate-treatment group (N=16) showed a greater reduction in the Y-BOCS scores (F(2,56)=16.17, p<0.001). After crossover, this improvement persisted one month after the second psilocybin dose for both groups (F(3,84)=29.91, p<0.001). Reductions in Y-BOCS score post sessions were correlated with several acute subjective effects measures, including total scores on MEQ, and individual factors on CEQ and 11D-ASC. Conclusions and Relevance: Repeated psilocybin administration is tolerable and potentially efficacious in reducing OCD symptoms. These results support further investigation of multidose psilocybin protocols as a viable therapeutic approach. Trial Registration: ClinicalTrials.gov Identifier NCT05546658

Alcohol use disorder is associated with persistent neuroadaptations and cognitive impairments, particularly during withdrawal, yet the temporal dynamics and interactions between these processes remain poorly understood. In the present study, we investigated time-dependent alterations in the oxytocin receptor (OTR), -opioid receptor (MOPr), metabotropic glutamate receptor 5 (mGlu5R), and translocator protein (TSPO) following chronic ethanol exposure and withdrawal, and their relationship to behavioral impairments. Male C57BL/6J mice were exposed to a 10-day escalating-dose ethanol liquid diet paradigm followed by 1, 4, or 7 days of withdrawal. Motor coordination and recognition memory were assessed using rotarod and novel object recognition tests, and receptor binding was quantified using autoradiography across multiple brain regions. Chronic ethanol exposure induced motor deficits that persisted during early withdrawal, whereas recognition memory impairments emerged after 7 days of withdrawal. Ethanol exposure and withdrawal produced region- and time-dependent alterations across all systems examined, with increased OTR binding in septal regions and transient reductions in basomedial amygdala OTR binding during intermediate withdrawal that normalized following prolonged withdrawal, transient increases in MOPr binding in striatal regions at 4 days of withdrawal, increased mGlu5R binding in the nucleus accumbens core, basolateral amygdala, and hippocampus, and early transient increases in TSPO binding indicative of neuroimmune activation. Notably, mGlu5R binding in the caudate-putamen and amygdala was associated with recognition memory deficits in a withdrawal stage-dependent manner. Bioinformatic analysis of human postmortem hippocampal transcriptomic datasets from individuals with alcohol use disorder revealed no consistent changes in GRM5 expression, suggesting that mGlu5R dysregulation may be driven by post-transcriptional mechanisms. These findings demonstrate that ethanol withdrawal is characterized by temporally distinct neuroadaptations across multiple systems and identify mGlu5R as a key correlate of withdrawal-associated memory impairment, highlighting its potential as a translational therapeutic target.

Background: Social difficulties in alcohol use disorder (AUD) have been linked to alterations in social cognition, including increased egocentric bias. Psychedelics such as psilocybin have been proposed to modulate self-related processing, but their effects on specific socio-cognitive mechanisms remain unclear. Methods: In this randomized controlled pilot study, recently detoxified individuals with AUD with persistent depressive symptoms completed a visual perspective-taking task before and after a psilocybin session (25 mg dose vs active placebo 1 mg psilocybin). Results: The 25 mg psilocybin group showed a significant reduction in egocentric bias and egocentric superiority on reaction times, with no effect on altercentric bias nor on accuracy. Between-group comparisons confirmed greater reductions in the high-dose relative to the low-dose group. The high-dose group reported more intense subjective psychedelic experiences, and greater subjective intensity was associated with lower egocentric superiority in accuracy. Conclusions: These findings provide preliminary evidence that psilocybin may selectively reduce egocentric interference in individuals with AUD, suggesting a decrease in egocentricity rather than enhanced sensitivity to others. Although replication in larger samples is needed, reduced egocentricity may represent one mechanism through which psilocybin influences social cognition in AUD. Clinical trial registration: ClinicalTrials.gov, https://clinicaltrials.gov/study/NCT06235411, NCT06235411.

Background: ADHD is characterized by inattention and impulsivity. Stimulants such as amphetamine are the first line treatments for ADHD. Amphetamine (AMPH) works by increasing extracellular levels of dopamine and noradrenaline. Such stimulants are used to test predictive validity of animal tasks, where it has been reported that amphetamine improves rat 5-CSRTT accuracy when the session length is increased to 250 trials. This improvement in accuracy was observed later in the session as control performance declined. Proving that amphetamine can improve 5C-CPT task performance adds to the predictive validity of the task. No previous works has demonstrated the pro-attentional effects of amphetamine on sustained attention in rat 5C-CPT. We have previously shown that pharmacological manipulations of dopaminergic system improve waiting impulsivity in a rate dependent manner and the importance of analysing the data using Oldham method. The present study extends this work to investigate the effect of amphetamine on attentional processes. Objective: to investigate effects of amphetamine on attentional processes as measured by 5C-CPT task using correlational analysis and group performance. Methods: Trained female Lister hooded rats were tested with AMPH (0.1, 0.2 and 0.4 mg/kg) under reduced stimulus duration schedule (0.25,0.5,1,1.5 and 2s SD) over normal length session (120 trials). Correlational analysis (Oldham method) was used to understand the relationship between baseline performance measures and the change following administration of AMPH. Results: The highest dose of AMPH impaired attentional performance in the 5C-CPT under reduced SD challenge (0.5s,1s,1.5s and 2s). This impairment was due to increase in FAR. Previous studies in 5-CSRTT suggest that reducing the SD increases attentional demand in the form of reducing accuracy without affecting waiting impulsivity. However, the 5-CSRTT does not include non-target trials, therefore, it cannot be used to measure sustained attention (SI) and responsivity index. The 5C-CPT requires greater attentional resources than the 5-CSRTT.This study is the first to report that reducing the SD changes responsivity index (bias) rather than measures of sustained attention (sensitivity index) in the 5C-CPT. Control sensitivity index did not change until the SD was reduced to less than 0.5s and this change was due to a change in baseline responsivity index (bias). Performance under each reduced SD revealed that the highest dose of AMPH (0.4 mg/kg) showed a tendency toward reducing sensitivity index at 0.5, 1.0 and 1.5s SDs. Under 1.0s SD, the highest dose of AMPH changed sustained attention (SI, HR and FAR) and omission in a rate-dependent manner without changing responsivity index. Performance across the session revealed that the impairment in sustained attention was observed at the beginning of the session. In the third trial block, Oldham method revealed an inverse relationship between baseline accuracy and the change following administration of 0.2 mg/kg AMPH, indicative of a rate-dependent effect. Conclusions: This study successfully demonstrates rate-dependent effects of AMPH on measures of attentional performance in the 5C-CPT. This experiment also demonstrates that responsivity index is sensitive to reduced SD challenge. To our knowledge this is the first study to report the presence of a direct relationship between baseline sustained attention and magnitude of improvement following administration of 0.4 mg/kg AMPH and an inverse relationship between baseline accuracy and the change following administration of 0.2 mg/kg AMPH in 5C-CPT task. Future studies should test lower doses of amphetamine (0.05 and 0.1 mg/kg) over extended session length (250 trials) to reveal the pro-attentional effects of this drug on 5C-CPT performance measures.

Negative emotional bias, including reduced processing of positive information and negative interpretation of ambiguous stimuli, is a core feature of depression. Esketamine, an N-methyl-D-aspartate (NMDA) receptor antagonist with rapid antidepressant effects in treatment-resistant depression (TRD), reduces depressive symptoms, but its effects on distinct components of emotional processing remain unclear. Fifty-three patients with TRD and 53 healthy controls performed an Emotional Facial Expression Morphing task. Patients were assessed at baseline, 24 hours after the first esketamine administration, and after 4 weeks of treatment. Statistical models examined detection thresholds for happy and sad faces, negative categorisation of neutral faces, and signal detection indices separating emotion-neutral discrimination sensitivity (d') from response criterion (c), indexing the evidence required to report the presence of an emotion. At baseline, patients required greater happy-face intensity for emotion detection and were more likely to categorise detected neutral faces as negative. They also showed a more conservative response criterion without group difference in discrimination sensitivity. Responders showed an early increase in d'; and, by week 4, less negative categorisation of neutral faces than non-responders. A lower baseline response criterion was associated with responder status and, in secondary continuous analyses, with greater subsequent MADRS improvement. These findings indicate that TRD involves abnormalities across detection-related, valence-related, and decisional aspects of facial-emotion processing that are differently associated with esketamine response: baseline response criterion emerged as a candidate prognostic marker, whereas negative categorisation of neutral faces tracked clinical response. Assessing these domains may inform clinical evaluation, pending independent replication.

Home-based 2 mA transcranial direct current stimulation (tDCS) was recently approved by the US Food and Drug Administration for depression, but tDCS amplitude has been limited largely by skin tolerance, and higher-intensity, accelerated dosing may be more efficacious or faster-acting. Using a novel high-capacity tDCS (HC-tDCS) stimulator and hydrogel electrodes, we evaluated the safety, tolerability and feasibility of accelerated HC-tDCS (20-minute bifrontal 6 mA sessions, twice daily for five days) in 20 patients with major depressive disorder. A Safety Review Committee reviewed data from the first three participants, who completed a within-day escalation to 6 mA, before the remaining 17 were enrolled. Retention and adherence were 100% (203 of 203 sessions), and 19/20 tolerated the full 6 mA amplitude without dose reduction. There were no serious adverse events. The most common symptoms were fatigue (49% of sessions), burning (46%) and tingling (43%) at the electrode, and difficulty concentrating (40%). Electrode-site erythema occurred in all participants, with no severe reaction or skin breakdown. At 1 week, 7 of 20 reported a residual skin change, mostly peeling or redness, none painful; at 1 month, hyperpigmentation at the electrode site persisted in 2 participants, both Black. At the end of the five-day course, PHQ-9 scores decreased from 15.8 to 7.2 (Hedges g = 1.62); 50% of participants responded, 45% remitted, and improvement was maintained at 1-month follow-up. Accelerated HC-tDCS was feasible, well tolerated, and warrants a sham-controlled trial.

It is estimated that approximately fifty percent of the population will encounter at least one traumatic event during their lifetime; however, only six percent develop Posttraumatic Stress Disorder (PTSD), a trauma-related disorder characterized by persistent alterations in affect and cognition, including an exaggerated fear response. It is well established that females (9.7%) are more than twice as likely as males (3.6%) to be diagnosed with PTSD. Nevertheless, a significant challenge remains in understanding how the severity of traumas experienced in childhood versus adulthood influences PTSD development across sexes. To address this challenge effectively, the adoption of preclinical animal models that accurately reflect these key characteristics is crucial. The Stress Enhanced Fear Learning (SEFL) paradigm in rodents encapsulates some of these complexities associated with PTSD, such as persistent fear sensitization following exposure to acute trauma. This study investigates how stress severity and developmental timing affect the long-term maintenance of SEFL in male and female rats. Juvenile and adult rats were initially subjected to no stress (control, context only), low stress (1 footshock), moderate stress (3 footshocks), or high stress (15 footshocks), followed by an extinction session either one day (recent) or sixty days (remote) later. Subsequently, to evaluate SEFL in a new context, all subjects received a single footshock and were tested the following day. Shortly after stress induction, all groups displayed SEFL. Although the effects persisted for sixty days in adult males and juvenile females, even at the lowest stress level, they were significantly reduced in juvenile males and adult females. These findings offer novel insights into sex-related differences in the persistence of SEFL and introduce new considerations regarding how the timing of developmental stressors influences future threat encoding and fear responses.

Background and Purpose High novelty-seeking is an endophenotype associated with greater vulnerability to drug addiction, marked by a hyperdopaminergic state and reduced dopamine D2 receptor (D2R) levels in the dorsal striatum (DS). G protein-coupled receptor kinases (GRKs) regulate desensitization, internalization, and recycling of these receptors, including the D2R. This study investigated the relevance of GRK2 and 3 (GRK2/3) in novelty-seeking behavior and striatal dopamine dynamics. Experimental Approach Individual novelty-seeking trait was assessed in Sprague Dawley rats using an open-field test. D2R, GRK2, and GRK5 protein levels were measured in synaptosomal DS samples using Western Blot. Pharmacological inhibition of GRK2/3 was assessed using Cmpd101. We tested the effect of systemic Cmpd101 administration on contextual novelty discrimination and local Cmpd101 perfusion on baseline and stimulus-evoked extracellular dopamine (DA) levels in the DS. Key Results Locomotor activity in a novel environment inversely correlated with the synaptosomal GRK2 and D2R protein levels in the DS. Systemic Cmpd101 treatment modulated the locomotor discrimination index in a novelty phenotype-dependent manner. Moreover, local Cmpd101 perfusion in the DS elicited a sustained elevation in basal extracellular dopamine levels and significantly blunted subsequent stimulus-evoked DA release, both effects independent of novelty-seeking phenotype. Conclusion and Implications Together, our findings link GRK2/3 signaling to individual differences in novelty-seeking and striatal dopaminergic function. These results suggest a potential relevance to drug addiction vulnerability.

Following cocaine self-administration, male and female rats received daily semaglutide during a 30-day abstinence period before cue- and cocaine-induced reinstatement tests. Semaglutide attenuated cue-induced reinstatement and cocaine-induced stereotypy, although operant responding was elevated following cocaine priming. These findings support further investigation of semaglutide as a treatment for cocaine use disorder.

Background: Dissociative identity disorder (DID) is associated with frequent psychiatric comorbidity. Its complex and overlapping symptom profile can complicate recognition of both DID and co-occurring psychiatric conditions, contributing to diagnostic uncertainty. Evidence regarding psychiatric comorbidity is limited and prevalence estimates vary across studies. Aims: This meta-analysis aimed to examine the prevalence of psychiatric comorbidities in DID and factors associated with variation in prevalence estimates. Methods: Eligible studies were identified through PubMed, Scopus, Embase, PsycINFO, and MEDLINE from 1980 to 25 April 2026 (PROSPERO, no. CRD420261335819). Studies reporting psychiatric comorbidity in adults with DID were independently screened by two reviewers. Risk of bias was assessed. Random-effects meta-analyses using logit-transformed prevalence estimates were conducted. Meta-regressions examined moderators, whilst influence and sensitivity analyses assessed robustness. Certainty was evaluated using the GRADE approach. Results: Twenty-four studies (N = 858) contributed to the meta-analysis across 23 psychiatric comorbidities. Among individuals with DID, posttraumatic stress disorder had the highest pooled prevalence (87.44%, 95% CI 71.79-94.96), followed by major depressive disorder (62.64%, 95% CI 33.45-84.84), and borderline personality disorder (47.05%, 95% CI 34.21-60.32). Substantial heterogeneity was noted across most estimates. Meta-regressions identified significant associations with participant characteristics, recruitment, study quality, and diagnostic method. Risk of bias and certainty of evidence were heterogenous. Conclusions: Psychiatric comorbidity in DID is substantial and spans multiple diagnostic categories, although considerable heterogeneity and methodological variation limit confidence in prevalence estimates. Standardised diagnostic assessment, more representative sampling, and longitudinal research are needed to clarify the extent and clinical significance of comorbidity in DID.

Individuals with major depressive disorder (MDD) show an attentional bias toward negatively valenced stimuli and thoughts. In this study, we applied a closed-loop neurofeedback procedure designed to reduce this bias. Participants were shown composite negative faces and neutral scenes with variable opacity and were instructed to attend to the neutral scene while ignoring the negative face. Internal attentional states were decoded in real time from functional magnetic resonance imaging (fMRI) data. When a participant's decoded attentional state indicated a failure to ignore the negative faces, the faces became more visible (higher opacity), thus externalizing the brain's attentional lapse in that moment. Forty-eight individuals with MDD were randomly assigned to a real neurofeedback training group (N = 24) or a sham control group (N = 24); the control group received feedback yoked to a participant in the real group. All participants completed three fMRI neurofeedback sessions. The main outcome quantified the extent to which participants got ``stuck'' in the most negative attentional state of focusing strongly on the negative faces. We hypothesized that the real neurofeedback group would learn to escape that state by the end of training, relative to the sham control group. Consistent with our hypothesis, neurofeedback training reduced the probability of getting stuck in the most negative attentional state. In offline analyses, training reduced fMRI activity in the precuneus/posterior cingulate and the medial prefrontal cortex when participants successfully attended to scenes and ignored faces. These results demonstrate the efficacy of remediating the negative attentional bias in depression with closed-loop neurofeedback from real-time fMRI.

Background: Stimulant and non-stimulant medications increase fronto-striato-thalamic activation in youth with Attention-Deficit/Hyperactivity Disorder (ADHD). However, comparative effects of the more recently licensed stimulant lisdexamfetamine and non-stimulant guanfacine on functional magnetic resonance imaging (fMRI) correlates in ADHD are unknown. Methods: This exploratory randomised, placebo-controlled, double-blind, crossover study compared fMRI activation in youth with ADHD during a tracking stop-signal task (SST; N = 12), a working memory task (N-back; N = 11) and a sustained attention task (SAT; N = 10), after single clinical doses of either guanfacine extended-release, lisdexamfetamine, or placebo, with one-week washouts. Twenty-one demographically matched typically developing controls (TD) were assessed once to test for potential normalisation of case-control activation differences. Results: Region of interest analysis showed increased right caudate and putamen activation for lisdexamfetamine versus placebo during N-back and SAT, respectively. Both drugs shared an increase in left superior temporal activation versus placebo during N-back. In whole-brain analyses only lisdexamfetamine increased precuneus/posterior cingulate activation during SST versus guanfacine, and during N-back in pre- and postcentral and occipital cortices versus placebo. During SST, placebo-treated ADHD versus TD showed reduced putamen, insula, parietal and occipital activation that was potentially attenuated/normalised under lisdexamfetamine, while under guanfacine lingual gyrus underactivation remained, with additional precuneus and middle temporal underactivation. Also, only lisdexamfetamine improved and normalised SST performance. Conclusion: Lisdexamfetamine appears to have stronger and drug-exclusive upregulation and potential attenuation/normalisation effects than guanfacine on basal ganglia, posterior parieto-occipital and sensorimotor activations during ADHD-relevant executive function tasks with some shared putamen and superior temporal effects.

Anhedonia emerges in adolescence, has putative substrates in neural reward and dopamine systems, and is a hallmark of poor course in depression. Psychoneuroimmunology models suggest altered immune and reward systems may jointly underlie its development. When dopamine availability (rather than function) is considered, immune activation may be understood as a moderator amplifying how lower dopamine levels translate into motivational deficits. This cross-sectional study analyzed data from 55 youth with current depression (Mage=21.4 years; Female=75%). Plasma was assayed for relative quantification of 92 immune proteins, followed by dimensionality reduction via principal component (PC) analysis, forming five PC scores. Dopamine availability was indexed by basal ganglia tissue iron, quantified by MRI R2', a measure detectable in youth. Anhedonia was assessed using the Snaith-Hamilton Pleasure Scale (SHAPS), thought to capture overall anhedonia, and Positive Valence Systems Scale (PVSS), which provides overall, anticipatory, and consummatory anhedonia scores. PC1 scores--whose loadings indicated broad inflammatory activity, including cytokines, chemokines, and tissue remodeling/angiogenic markers--moderated the relationship between basal ganglia dopamine availability and anhedonia: At higher PC1 levels, lower dopamine availability was linked to greater overall anhedonia (as measured by SHAPS) and anticipatory anhedonia, but not to consummatory anhedonia. Exploratory analyses showed comparable effect patterns for PC4, reflecting T cell-related effector/apoptotic signaling. Analyses of individual basal ganglia regions suggest potential differences in dopaminergic-immune interactions across these regions, with effects most consistently observed in the putamen. Findings highlight nuanced neuroimmune pathways underlying anhedonia components in youth and support inflammation-based models of depression emphasizing dopaminergic-immune interplay.

Stressful experiences are a major risk factor for the development of neuropsychiatric disorders in vulnerable individuals. Identifying features that can distinguish stress-susceptible from resilient individuals remains a central goal in stress neurobiology. Due to the routine exclusion of female subjects from stress research or the use of male-defined criteria in behavioral characterization of subjects post-stress, female stress responses and vulnerability profiles remain poorly understood. This work aimed to gain a better understanding of sex-specific stress responses to social defeat stress. Here, we used a novel paired male-female social defeat paradigm and tracked subjects longitudinally in a ''two-hit'' design to evaluate responses to both acute social defeat stress (ASDS) and chronic social defeat stress (CSDS), and to determine how prior stress exposure influences subsequent vulnerability. We found that both ASDS and CSDS induces changes in social avoidance/approach behavior in males but not females, as measured by a classic social interaction ratio. Prior ASDS exposure enhanced susceptibility to subsequent CSDS most clearly in males, with females displaying specific changes in corner zone occupancy. Furthermore, we observed divergent anxiety profiles between males and females in a post-stress behavioral battery. Finally, females exhibited specific stress-related locomotor responses following ASDS. Together, these findings suggest that females may adopt distinct behavioral strategies following social defeat stress.

Stressors experienced during the postnatal period may increase vulnerability to mental health disorders, including postpartum depression and anxiety. In rodents, maternal separation (MS) has been shown to alter behaviours in dams, but these observations have been made almost exclusively in rats and thus robust mouse models of postpartum mental health disorders using this stressor remain limited. Here we first examined, in mice, the effects of MS on maternal caregiving and on anxiety- and depressive-like behaviours. As stress-induced inflammatory activation in the gut-brain axis has been associated with behavioural alterations in non-postpartum contexts, changes in pro-inflammatory cytokines and tight junction proteins in the brain and intestinal tract were also examined. Female C57BL/6N mice were assigned to a No Separation (NS) or a MS condition that consisted of 3-hour daily separation sessions from postnatal days (P) 2 to 14. Maternal care behaviours were assessed on P3 and P7, followed by anxiety- and depressive-like behaviours on P22 and P23, and the collection of the medial prefrontal cortex (mPFC) and colon on P24 to determine the expression of selected genes. Caregiving patterns in MS dams fluctuated throughout the early postnatal period. Although behaviours and gene expression outcomes remained unchanged by MS, grooming time in the splash test was correlated with the expression of different genes in the mPFC. These findings suggest that C57BL/6 mouse dams may be less sensitive to the actions of MS on behaviour and on brain and intestinal markers of inflammation and barrier permeability, at least when examined shortly after weaning.

Pavlovian bias, a motor bias driven by emotionally-valenced context, has long been considered a proxy for emotion-action processing, which may become aberrant in affective disorders and suicidality. The orthogonal valenced Go/NoGo paradigm was developed to isolate this bias and has been widely adopted in translational psychiatry research under this interpretation. However, several unresolved theoretical inconsistencies highlight the need to dissociate potential confounding factors within this paradigm before assigning mechanistic and clinical interpretations to its findings. Using a novel paradigm that fully orthogonalized valence, action, and aimed transition in a normative sample of 25 individuals, we found that the "active escape bias" previously observed in aversive contexts--and interpreted as reflecting suicidality in the clinical population--was reproduced in appetitive contexts using trials with the same transition structure. Furthermore, computational modeling indicated that the bias patterns isolated by the orthogonal paradigm are primarily explained by the combined effects of aimed transition and cue salience, without requiring emotional-valence modulation. These findings call for a fundamental reconsideration of how orthogonal Go/NoGo paradigms are interpreted in translational psychiatry, particularly how the behavior they isolate is mechanistically linked to affective symptoms.

GABAergic inhibitory neurons play a central role in shaping network dynamics, and accordingly, their dysfunction is implicated in the pathophysiology of various psychiatric, neurodevelopmental, and neurological disorders. In the past decade, studies on vasoactive intestinal polypeptide-expressing inhibitory neurons (VIP+ neurons) have positioned them as critical components of this circuitry. In particular, VIP+ neurons have been proposed to function within a canonical disinhibitory circuit motif, preferentially inhibiting other interneuron subtypes, to ultimately modulate the gain and activity of local pyramidal neurons. However, their contribution to psychiatrically relevant behavioral endophenotypes is still not fully understood, limiting our ability to target these neurons for therapeutic purposes. In the present study, we systematically assessed the functional contribution of VIP+ neurons to affective and social behaviors. To this end, we used a chemogenetic approach to manipulate the activity of VIP+ neurons in core corticolimbic regions, including the medial prefrontal cortex (mPFC), basolateral amygdala (BLA), and ventral hippocampus (vHPC). The consequences of either activating or inhibiting VIP+ neurons in these regions were observed while mice underwent a battery of behavioral tasks assessing anxiety-related avoidance behaviors, social interest and recognition, and associative fear learning. While sustained modulation of VIP+ neurons had no significant effect on anxiety-related or social behaviors in any of the brain regions assessed, it produced a robust reduction in associative fear learning specifically in the mPFC. These findings demonstrate that the consequences of sustained VIP+ neuron modulation depend on both anatomical location and behavioural context. Moreover, they identify VIP+ neurons in the mPFC as potentially clinically relevant targets for interventions aimed at modulating fear-related circuits.

Postpartum depression (PPD) impacts nearly 20% of mothers and a much larger percentage (up to 75%) suffer from postpartum blues. Despite this high incidence, we still have an incomplete understanding of the underlying neurobiology of PPD. Deficits in neurosteroid signaling has been implicated in the vulnerability to postpartum behavioral deficits and mice with reduced expression of {delta} subunit-containing GABAA receptors (GABAARs) (Gabrd -/- or Gabrd +/-), the predominant site of action for 5-reduced neurosteroids, exhibit behavioral deficits restricted to the postpartum period. Allopregnanolone and allopregnanolone analogs (SGE-516) can improve postpartum behavioral outcomes and their ability to modulate oscillations in the basolateral amygdala (BLA) involved in emotional processing has been proposed to contribute to their antidepressant effects. Here we demonstrate that the behavioral differences in postpartum wild type, Gabrd+/-, and SGE-516-treated Gabrd+/- dams is largely driven by theta oscillations in the BLA. Previous studies have linked theta oscillations in the BLA to altered behavioral responding in response to stress or threat. Interestingly, here we demonstrate that Gabrd+/- dams exhibit a failure to properly respond to their own pup calls, with reduced theta oscillations that correlates with deficits in maternal approach behavior both of which are restored with SGE-516 treatment. Further, unbiased MoSeq analysis identified altered behavioral syllable expression in Gabrd+/- dams in response to their pup calls compared to wild type dams that are restored with SGE-516 treatment. These findings demonstrate network and behavioral signatures of postpartum behavioral deficits and characterize the effects associated with neurosteroid-based treatment response.

In Ethiopia, khat (Catha edulis) leaves, containing amphetamine-like alkaloids, are chewed for their psycho-stimulating effects. Khat use has been associated with psychosis. In a psychosis etiology framework, we investigated whether season, fluctuations of khat availability and khat use are associated with khat-induced psychotic experiences and whether trauma load moderates this association. In Southwestern Ethiopia, a cohort of 685 men aged 18-40 years were interviewed twice, during dry and after rainy season (low vs. high khat availability). Khat use was assessed by urine immunoassay and self-report. Trauma load and psychotic experiences were assessed by trained local interviewers. Khat use increased after the rainy season (p < 0.0001). Khat use and seasonality predicted khat-induced psychotic experiences. Main findings comprise increased odds of psychotic experiences among immunoassay-positive individuals with high trauma load. A potential additional interaction with recent trauma emerged. Findings support sensitization-related mechanisms but require replication in larger samples with longer follow-up.

Background: Antidepressant selection in major depressive disorder remains trial-and-error, and no biomarker identifies which drug will work for an individual patient. Because neuroplasticity is a convergent mechanism of antidepressant response, we tested whether it could serve as a drug-specific biomarker in patient-derived neurons. Methods: We developed the Neuroplasticity Score (NPS), integrating structural and synaptic features from high-content imaging of patient-derived cortical neurons, and validated it against graded brain-derived neurotrophic factor (BDNF) exposure in neurons from 16 healthy donors. NPS was then applied unmodified to 75 antidepressant treatment episodes from 44 patients across two independent retrospective cohorts: 40 episodes from 20 STAR*D participants (Cohort 1; USA multi-site) and 35 episodes from 24 participants at Sheba Medical Center and Geha Mental Health Center (Cohort 2; Israel). Results: NPS increased with escalating BDNF dose (Spearman rho=0.83; P<.001). Response rate rose monotonically across NPS tertiles in both cohorts (trend P=.001 and P<.001). Across all 75 episodes, 84.6% of episodes in the highest NPS tertile responded, compared to 48.0% overall. NPS discriminated responding from non-responding episodes with an area under the receiver operating characteristic curve of 0.81 in both cohorts. The pooled odds ratio per 1-SD increase was 6.05 (95% CI, 2.80-13.05; I-squared=26%). Within patients contributing both a responding and a non-responding episode, the highest-scoring drug was the one that worked in 86% of patients (P<.001). Conclusions: Higher antidepressant-induced neuroplasticity in a patient's own neurons corresponded to a higher likelihood of response to that specific drug across two independent cohorts.