Psychopharmacology

Background: Adverse drug withdrawal events (ADWEs) are a key safety concern during deprescribing but remain poorly explored in pharmacovigilance systems. Objectives: To identify and compare ADWE signals across drug classes, different drugs within drug classes, and across patient characteristics, countries, and over time. Methods: A case/non-case disproportionality analysis was conducted in FDA-FAERS and EMA-EudraVigilance pharmacovigilance databases, with stratification by age (adults: 18-64, older adults: [≥]65), sex (male/female), reporting time (2004-2023 in 5-year intervals), and country (for EMA data). Disproportionality analysis (quantitative signal detection) was used to detect signals between ADWEs and drugs using the proportional reporting rate (PRR[≥]2), reporting odds ratio (ROR>1), and information component (IC>0) with case count [≥]5. Results: Overall, 158,501 reports (FDA-FAERS 145,514; EMA-EudraVigilance 12,987) included drug-event pairs related to ADWEs. In FDA-FAERS, clobetasone (IC=5.58; PRR=79.18; ROR=176.90) showed the strongest ADWE signals, followed by hydromorphone (4.85; 29.94; 37.37), hydrocodone, and paroxetine. In EMA-EudraVigilance, ethyl loflazepate (IC=6.01; PRR=119.80; ROR=197.53), clobetasone (5.39; 102.73; 155.10), veralipride, and levomethadone had the strongest signals. Most drugs maintained positive ADWE signals in analysis stratified into adults and older adults. However, among the top 10 drugs (based on highest IC values), buprenorphine/naloxone, desvenlafaxine, and baclofen in FDA-FAERS (ICs 4.95-6.05) showed stronger signals in older adults. A sex-based difference was observed, with paroxetine, venlafaxine, and buprenorphine/naloxone showing a stronger positive signal in females in both databases, whereas several opioids had stronger signals in males versus females across both databases. Conclusion: This study suggests ADWE signals for some medications differ by age and sex, potentially indicating different risks for withdrawal effects.

Anxiety-related traits (ARTs) have been linked to altered fear learning, but previous studies have typically examined different experimental phases and response systems, limiting the comparability of findings and the accumulation of consistent evidence. Here, we comprehensively examined associations between ARTs and fear conditioning across acquisition, extinction and renewal and across subjective, physiological and neural response systems in a well-powered sample (N = 267) using a two-day differential conditioning paradigm. ARTs were operationalized as a composite of trait anxiety, neuroticism, and intolerance of uncertainty and conditioned responding was assessed using skin conductance responses, fear-potentiated startle, US expectancy ratings, fear ratings, and functional magnetic resonance imaging. Higher ARTs were consistently associated with elevated subjective fear and US expectancy to both threat and safety cues during extinction and renewal, without corresponding elevations in physiological responding. At the same time, ARTs were not associated with threat-safety discrimination in subjective or physiological measures across phases, while neural associations were limited to reduced dorsal anterior cingulate cortex discrimination during early renewal. These findings suggest that ARTs are characterized by a CS unspecific cognitive bias toward heightened threat expectancy and evaluation rather than altered associative fear learning, highlighting the importance of distinguishing conditioned discrimination from general levels of responding across response systems.

Opioid addiction treatment is often hampered by the severe dysphoria of opioid withdrawal, but withdrawal treatments are limited by incomplete understanding of brain mechanisms involved. One area frequently implicated in withdrawal symptoms is the central amygdala, whose capsular portion (CeC) is particularly strongly activated during withdrawal. Additionally, a ventral posterior striatal region that resides near CeC, the interstitial nucleus of the posterior limb of the anterior commissure (IPACc), is also activated as strikingly as CeC. However, it is still unknown how these regions are activated, nor whether their activation explains the high intensity of withdrawal dysphoria. Using RNAscope, we found that c-fos expression is induced in the parabrachial nucleus (PB), a key glutamatergic afferent of CeC, after precipitated morphine withdrawal. Chemogenetic inhibition of PB glutamatergic neurons (VG2PB) nearly eliminated withdrawal-induced CeC c-Fos, without affecting IPACc c-Fos, indicating these two nuclei are activated by distinct sources. Furthermore, VG2PB inhibition markedly reduced somatic (jumping) and modestly reduced affective (place avoidance) withdrawal behavior. On the other hand, inhibition of CeC-projecting PB neuronal subtypes expressing calcitonin gene-related peptide (CGRP) or mu opioid receptor (MOR) reduced place avoidance without affecting jumping, indicating their specific role in withdrawal aversion. Strikingly, simultaneous inhibition of VG2PB and posterior striatal region containing IPACc robustly reduced withdrawal-induced place avoidance much more than the modest effects of either inhibition alone, suggesting their cooperative action in driving aversion. Our data suggests that PB-CeC circuit and posterior striatal area constitute a cooperative system driving opioid withdrawal aversion.

This document describes the Statistical Analysis Plan (SAP) for PETRA, a randomised controlled trial in people with generalised anxiety disorder comparing pregabalin plus an antidepressant and standard care, with placebo plus an antidepressant and standard care, with respect to the primary outcome of the GAD-7 score at week 12.

Background: Substance use is common among individuals with depression. Transcranial magnetic stimulation (TMS) is an effective treatment for depression, but current clinical guidelines have discouraged TMS treatment for individuals with depression and co-occurring substance use given concerns for limited efficacy. However, limited data exists on whether substance use affects response to TMS. Methods: Using electronic health record data from patients who received a standard course of TMS for major depressive disorder at an academic medical center, we investigated associations between substance use frequency and response to TMS, defined as change in Patient Health Questionnaire-9 (PHQ-9) scores. Substance use frequency was extracted for alcohol, cannabis, nicotine, stimulants, benzodiazepines, opioids, inhalants, psychedelics, and other drugs. We performed ANCOVA and multiple regression analyses to predict change in PHQ-9 score based on substance use frequency, controlling for pre-TMS PHQ-9 score, age, sex, and number of TMS sessions received. Results: We extracted data from 219 TMS courses. Alcohol was the substance used most commonly (34.2%), followed by prescription benzodiazepines (28.3%), and prescription stimulants (21.0%). Across all substance categories, substance use was not associated with change in PHQ-9 score (all p > 0.05, Cohens d=0.00 to 0.30). In multiple regression models to compare individual levels of substance use frequency (e.g., daily use vs. no use), level of substance use was not associated with change in PHQ-9 score (all p > 0.05). The range of plausible effects of substance use frequency on PHQ-9 change was generally below the minimal clinically important difference for PHQ-9, suggesting substance use was unlikely to have a meaningful clinical effect on antidepressant response to TMS. Conclusions: Low to moderate substance use does not have a clinically significant effect on antidepressant response to TMS. Low-level substance use should not exclude individuals with depression from receiving TMS.

Background: As cannabis policy changes in the United States, secondhand cannabis smoke (SCS) is increasingly common, including within families. However, prevalence of exposure and clinical correlates over time in adolescents are not fully understood. Objectives: (1) To estimate the prevalence of SCS and personal cannabis use in US-based teens exposed to SCS, and (2) examine the cognitive trajectories of adolescents exposed to SCS compared to non-exposed peers. Methods: Data from the Adolescent Brain Cognitive Development (ABCD) Study was used. Participants (n=11,316 of full cohort with follow-up data; n=776 with self-reported family SCS exposure) attended yearly visits from ages 11-17, completing substance use interviews, toxicological testing, and the NIH Toolbox Cognitive battery. Youth with SCS but no personal cannabis use (n=419; 47% female) were matched on prenatal substance exposure, family substance use history, and sociodemographics to non-SCS exposed and non-cannabis-using youth with a 1:2 ratio (Controls n=838). Linear mixed-effects models assessed cognitive performance by SCS*age interactions, accounting for random effects of subject and family. Covariates included sex and alcohol, nicotine, and other substance use. Secondary models analyzed performance by cumulative waves of reported SCS exposure interacting with age. Results: Of the full cohort, 6.9% (n=776) reported exposure to SCS. Of these individuals, 46% endorsed lifetime personal cannabis use by age 17, relative to 20% of non-SCS exposed youth (OR=3.83[95%CI:3.29,4.44]). Within matched participants, SCS*age demonstrated a significant interaction on attention and inhibitory control ({beta}=-0.32, p=.028), with SCS demonstrating reduced improvement over time. More waves of exposure were also associated with worse performance over time ({beta}=-0.39, p=.057). Discussion: Almost half of those who had been exposed to SCS endorsed personal cannabis use. Cognitive findings were domain specific, similar to findings in secondhand tobacco: SCS exposed youth showed restricted improvement in attention and inhibitory control by age 17. Public health and policymakers should make efforts to curb youth SCS exposure, given the potential for risk which has not been fully explored to date.

Background: Major depressive disorder (MDD) is a severe mental illness associated with severe clinical consequences and substantial societal burden. It's characterized by immune-inflammatory dysregulation and immune sensitization. Objective: To determine whether in vitro ketamine attenuates phytohemagglutinin (PHA)/lipopolysaccharide (LPS)-induced immune sensitization in patients with MDD and healthy controls (HCs). Methods: Whole blood from 18 patients with MDD and 18 HCs was stimulated with PHA/LPS and exposed to ketamine (0.3 M, 0.6 M, and 6 M) for 72 hours. Cytokines, chemokines, growth factors, and composite immune profiles, including M1/M2 macrophages, T helper (Th)1/2/17, the immune-inflammatory response system (IRS), and compensatory immunoregulatory system (CIRS), were synthesized and determined. Results: Under PHA and LPS stimulation in vitro, the MDD group exhibited markedly elevated immune profiles, including M1, M2, Th1, Th2, Th17, IRS, CIRS, chemokines, and growth factors, consistent with immune sensitization. Significant group-by-treatment interactions were observed for Th1-Th2, M2, growth factors, IL-12(p70), M1, and chemokines. Ketamine produced minimal changes in HCs but broader suppression in MDD, particularly at the highest concentration, without normalizing the sensitized immune phenotype. Among the immune markers with no notable group-by-treatment interactions, ketamine exerted diagnosis-independent effects, decreasing MIP-1{beta}, IL-1&{beta}, Th1, TNF-{beta} IRS, IFN-{gamma}, and IL-2 compared to the control condition. Conclusions: Ketamine exhibited two distinct immunoregulatory patterns: selective, disease-dependent attenuation of sensitized immune pathways and broader, diagnosis-independent suppression of the stimulated immune response, predominantly at higher concentrations. However, these effects were insufficient to normalize the immune-sensitized phenotype of MDD.

Introduction: Nicotine Pouches are increasingly used as a smokeless alternative to cigarettes and other nicotine products, yet their acute cardiovascular effects remain poorly documented. While nicotine's impact on heart rate and electrocardiogram (ECG) parameters is well-documented in smoking, no trials have evaluated these effects specifically for nicotine pouches. Methods: This study is a single-center, double-blind, placebo-controlled, crossover trial which will include 20 healthy adult nicotine users. Participants will undergo three sessions, receiving either a placebo, 6 mg, or 14 mg nicotine pouch in random order. Heart rate obtained by an ECG and various other ECG parameters, vital signs, and subjective symptoms will be measured at baseline, and multiple time points over 30 minutes. Conclusions: This study aims to determine whether nicotine pouches cause acute changes in heart rate, ECG parameters, vital signs, and self-reported symptoms. We hypothesize that higher nicotine pouch does will lead to measurable increases in heart rate and other autonomic effects compared to placebo.

Excitatory synaptic plasticity within the nucleus accumbens (NAc) drives motivated behaviors, and dysregulation is implicated in several psychiatric disorders marked by impaired reward processing. The NAc integrates glutamatergic input, which conveys information about reward, context, and behavioral goals, with local GABAergic signaling that regulates excitatory transmission and medium spiny neuron (MSNs) output. However, little is known regarding GABA-dependent modulation of activity-dependent excitatory synaptic plasticity. Here, we investigated GABAB receptor (GABABR) regulation of plasticity at hippocampus (Hipp)-NAc synapses, at which plasticity is a key mediator of reward-related behaviors. Using whole-cell electrophysiological recordings in mouse brain slices, we found that pharmacological inhibition of GABABRs converts long-term potentiation (LTP) into long-term depression (LTD) selectively in females, identifying a sex-specific role for GABABRs in modulating long-term plasticity of Hipp-MSN synapses. This LTD required mGluR5 activation and estrogen receptor alpha (ER) in both D1- and D2-expressing MSN subtypes, while only D1-MSNs suggested that LTD was expressed presynaptically through a CB1 receptor-dependent mechanism. Notably, GABABR inhibition did not alter basal synaptic transmission, indicating a specific role for these receptors in gating plasticity beyond regulation of basal excitatory drive. Together, these findings identify a novel, sex-specific mechanism by which GABABRs control the direction of synaptic plasticity.

Background Alcohol use disorder (AUD) is highly prevalent in schizophrenia, yet the neurobiological basis of this vulnerability remains poorly understood. Neurodevelopmental models suggest that pre-existing brain dysconnectivity may increase vulnerability to AUD. We therefore tested whether schizophrenia-like neurodevelopmental pathology alters how alcohol-related experience is incorporated into large-scale brain networks. Methods Resting-state functional connectivity was assessed in male Sprague-Dawley rats (n = 18-21/group) with neonatal ventral hippocampal lesions (NVHL), a neurodevelopmental model of schizophrenia, and sham-operated controls, with or without voluntary adolescent alcohol exposure. Functional connectivity was assessed using seed-to-voxel and seed-to-seed analyses within a cortico-striato-limbic network. We additionally examined whether individual alcohol intake during adolescence predicted adult functional connectivity according to neurodevelopmental status. Results NVHL and adolescent alcohol exposure independently produced predominantly hypoconnected cortico-striato-limbic networks. However, alcohol exposure did not exacerbate NVHL-associated dysconnectivity but instead induced a distinct network reorganization characterized by functional hyperconnectivity. Although alcohol intake was comparable between groups, dose-dependent relationships between adolescent alcohol consumption and adult functional connectivity were observed in sham animals but were absent or markedly attenuated in NVHL rats. These effects were primarily centered on prelimbic cortex connectivity with the amygdala, hippocampus, and dorsal striatum, highlighting this circuitry as a major locus of altered experience-dependent remodeling. Conclusions These findings suggest that vulnerability to AUD associated with schizophrenia-like neurodevelopment may arise less from additive network dysfunction than from an altered capacity of large-scale brain networks for experience-dependent functional remodeling. Schizophrenia-like neurodevelopmental pathology may therefore change how alcohol-related experience is translated into persistent brain network organization.

Abstract Introduction: Despite advances in pain management, effective analgesics in pain situations remain elusive. Opioids and non-opioids carry risks of neurotoxic and psychedelic effects with adverse physiological outcomes. Indian instrumental music (IIM) mitigates subacute pain by rewiring neurochemical synergy as an evidence-based, non-invasive, non-pharmacological system to mitigate pain. Objective: Investigating therapeutic efficacy of IIM in mitigating subacute pain by analyzing behavioral, peripheral, and central neurochemical re-tuning. Methods: Mice were divided into Control, Pain, Pain+Music, and Music groups. Pre-treatment behavioral parameters were compared with those observed after 14 days IIM exposure. Evaluations included nociceptive latencies (hot-plate/tail-flick), locomotion (Open Field Test), and anxiety (Elevated Plus Maze). Molecular analyses quantified peripheral neuropeptides (SP, NK-1R, CGRP), serum cortisol, spinal neurotrophic factor, neurotransmitters (glutamate, GABA, dopamine (DA), 5-HT), BDNF, and mRNA expression of BDNF, Ntrk1R/2R, and D1R in cortex, thalamus, hippocampus and hypothalamus. All procedures adhered to IAEC guidelines. Results: IIM yielded 3.9-4.4-fold antinociceptive improvements, 3.3-fold locomotor restoration, and 3.6-4.9-fold anxiolysis. 14 days IIM exposure reduced peripheral nociceptive-neuropeptides 1.3-2.0-fold (SP, NK-1R, CGRP), serum cortisol 1.3-fold, and spinal glutamate, serotonin levels 1.5- and 1.3-fold. An enhanced expression of spinal GABA, DA about 1.5-fold, and BDNF by 1.3-fold was observed after music listening. Brain-region-specific differential mRNA-expression at cortex, thalamus, hypothalamus and hippocampus revealed the neuromodulatory impact of rhythmic music in a formalin-induced murine pain-model. Conclusion: Gross reduction of pain parameters demonstrates therapeutic potential of IIM as multilevel neuromodulator to suppress the multidimensional stressor, pain, via peripheral desensitization, spinal E-I balance, and differential calibration of BDNF/Trk/D1R plasticity at specific brain-regions. Keywords: Pain, Non-Pharmacological Method, Indian Instrumental Music (IIM), Behavior, Neurotransmitters, Neuroplasticity, mRNA Expression.

Chronic pain is frequently accompanied by negative affect and motivational deficits due to dysregulated mesocorticolimbic dopamine and kappa opioid receptor (KOR) signalling. Although intracranial KOR antagonism prevents pain-induced negative affect in preclinical models, systemic KOR antagonists can produce adverse off-target effects in the periphery, thereby limiting its clinical utility. Consistent with this, we found that systemic administration of KOR antagonist norbinaltorphimine (NorBNI), exacerbated motivational deficits in rats with persistent inflammatory pain. We hypothesized that maximizing central and minimizing peripheral KOR antagonism could overcome these limitations. To test this, we engineered an intranasal liposomal NorBNI formulation incorporated into an in-situ forming mucoadhesive hydrogel to enable selective nose-to-brain delivery (Nor-BNILV-HG). We characterized its physicochemical properties and functional efficacy in rats with inflammatory pain produced by Complete Freund's Adjuvant (CFA). NorBNI-loaded liposomes exhibited high drug entrapment efficiency, nanometric size, and suitable surface charge for intranasal administration. The selected thermosensitive hydrogel demonstrated appropriate gelation properties and sustained drug release. Intranasal administration of NorBNI-LV-HG produced negligible systemic NorBNI levels compared with intraperitoneal delivery. In vivo microdialysis showed that NorBNI-LV-HG prevented KOR agonist-induced reductions in nucleus accumbens (NAc) dopamine release, confirming functional central KOR blockade. Behaviourally, intranasal NorBNI-LV-HG attenuated pain-induced impairments in sucrose motivation. Importantly, unlike systemic NorBNI, repeated intranasal NorBNI-LV-HG did not alter mechanical nociceptive thresholds in pain-naive animals, suggesting this strategy mitigates unwanted peripheral nociceptive effects. Together, these findings demonstrate that intranasal NorBNI-LV-HG achieves functional brain KOR antagonism while minimizing systemic exposure and off-target effects. Selective nose-to-brain delivery of KOR antagonists therefore represents a promising therapeutic strategy to prevent and potentially reverse the affective and motivational consequences of pain and may overcome key translational barriers associated with systemic KOR treatments.

Gabapentin (GBP) and pregabalin (PGB) are widely used gabapentinoids. Previously, we have demonstrated, for the first time, that GBP and PGB modulate the nociceptive response to noxious heat in C. elegans at an optimal concentration. In the current study, we use C. elegans and paired thermal nociception assays with direct internal drug concentration measurements to characterize the pharmacokinetic (PK)/pharmacodynamic (PD) relationship of both compounds. Neither drug altered baseline mobility or quadrant preference, confirming that behavioral effects reflected genuine antinociceptive action. Both GBP and PGB produced dose- and time-dependent reductions in thermal avoidance, with 500 uM exposures generating a biphasic, V-shaped time course in which suppression of thermal sensitivity deepened before partially reversing. This partial reversal occurred later with PGB than with GBP. Internal concentrations confirmed dose-dependent absorption and retention for both drugs, yet at 500 uM, internal drug levels remained elevated through 360 min even as behavioral avoidance recovered, indicating that the recovery limb reflects active counter-regulation rather than passive clearance, consistent with previously reported transcriptional and proteomic signatures. Exposure-response profiles were notably flat, suggesting a saturable pharmacodynamic ceiling. Molecular modeling revealed conserved electronic pharmacophores supporting shared alpha-2-delta engagement, alongside shape-descriptor differences that may contribute to divergent absorption kinetics. These findings position C. elegans as a valuable model for dissecting gabapentinoid PK/PD relationships. Beyond mechanistic insight, these findings support the continued investigation of C. elegans as a screening platform whose validation could help address the 3R (Replacement, Reduction, Refinement) principles guiding animal research.

Background: Bipolar disorder is associated with persistent social, cognitive, and functional impairment during euthymia, yet the neural mechanisms underlying these deficits remain unclear. Alterations to self-referential processing are a candidate mechanism, but existing electrophysiological studies rely on emotionally valenced paradigms that potentially confound self-processing with emotional biases. Methods: We analysed electroencephalography from 28 patients with bipolar disorder (type I or II) and 28 age- and sex-matched healthy controls during an emotionally neutral colour judgment task with self-related (preference) and non-self-related (similarity) conditions. Late positive potentials, temporal generalisation decoding, and frequency band decoding (theta, alpha, beta) were used to characterise the temporal dynamics and oscillatory correlates of self versus non-self processing. Results: Controls showed higher overall event-related potential amplitudes and greater self versus non-self differentiation than patients (condition by group interaction, 337 to 946 ms). Broadband temporal generalisation decoding revealed extensive cross-temporal generalisation of the self versus non-self representation in controls, spanning most of the trial, but no significant generalisation in patients. Frequency analyses showed that alpha and beta carried self versus non-self information in both groups, with broader extent in controls, and that anterior theta carried this information in patients but not controls. Exploratory correlations linked decoding measures to rumination and anxiety but not to manic symptoms. Conclusions: The neural representation distinguishing self-referential from externally guided processing was both smaller in amplitude and less temporally sustained in bipolar disorder. Reduced persistence is not detectable by conventional amplitude analyses, and may bear on the self-related and social cognitive difficulties reported in this population.

Adolescent substance use is a major public health concern due to increased risk of future physical and mental health conditions. Fronto-striatal functioning - particularly regarding inhibition and reward processing - may increase vulnerability to high-risk substance use. However, it remains unclear if these neurobiological differences precede substance use or are consequences of it. The ongoing Adolescent Brain Cognitive Development (ABCD) Study follows over 10000 youth, offering an unprecedented opportunity to longitudinally examine substance use patterns throughout development. We utilized family-clustered time-varying Cox proportional hazard models to prospectively examine main and interaction effects of right Inferior Frontal Gyrus (IFG) inhibitory control and bilateral nucleus accumbens (NAc) reward response, alongside early life adversity and peer substance use as predictors of alcohol and cannabis onset in the ABCD Study. We identified a significant crossover interaction such that left NAc activity had a slight positive association with first full alcoholic drink in the context of higher right IFG activity but a negative association in the context of lower right IFG activity. However, peer alcohol and cannabis use emerged as the strongest predictors of outcomes. Alcohol onset was also more common in females, and early life adversity was associated only with cannabis onset. Findings indicate that interactions between inhibition- and reward-related brain regions may impact risk for early substance use onset, but these effects may be modest relative to socioenvironmental factors. Additionally, divergent alcohol and cannabis findings suggest that risk profiles are substance specific. Peer-focused strategies should be considered in preventive efforts.

BACKGROUND: An individual's adaptation to threatening environments under uncertainty is reflected in stress responses. Predictability (the ability to anticipate events) and controllability (the ability to control outcomes) are central to how one adapts, yet their joint influence on aversive learning remains unclear. METHODS: Thirty healthy adults completed a probabilistic aversive learning task in which cue-outcome contingencies varied across levels of predictability and controllability, i.e. whether shock intensity depended on prediction accuracy. Prediction accuracy, reaction time, subjective stress ratings, and skin conductance responses were recorded throughout. Trial-wise learning dynamics were estimated using the Volatile Kalman Filter. RESULTS: Prediction accuracy reduced as environments became less predictable and negatively associated with higher learning rates across predictability levels, with the strongest relationship observed in highly predictable blocks. Skin conductance responses showed that moderately predictable environments elicited responses like those in highly predictable environments when accurate predictions reduced shock intensity, but resembled responses in unpredictable environments when shock intensity was uncontrollable. Model comparison revealed a double dissociation between subjective stress ratings and skin conductance responses. Subjective ratings were best explained by model-derived volatility when prediction accuracy determined shock intensity and by belief uncertainty when it was independent of prediction accuracy, whereas skin conductance responses showed the reverse pattern. Reaction times were best explained by belief uncertainty when predictions influenced shock intensity. Higher anxiety was associated with elevated learning rates in highly and moderately predictable blocks when predictions did not control shock intensity.

Laboratory stress tasks are widely used to assess individual differences in acute stress reactivity, yet it remains unclear how these responses correspond to stress experienced in everyday life. Here, we combined the Montreal imaging stress task (MIST) with ecological momentary assessment (EMA) over three months to assess acute and everyday stress in 67 healthy women. Greater within-person variability in everyday stress, but not average stress levels, were associated with stronger overall stress-related brain responses (b = 0.73, p = .039), with a whole-brain association particularly evident in the bilateral caudate (rROI = .32, pcluster.FWE < .001). Greater everyday stress variability was also associated with stronger stress-related functional connectivity between the ventromedial prefrontal cortex (vmPFC) and parietal and posterior medial regions (pcluster.FWE < .001). We conclude that acute neural stress responses relate more closely to fluctuations in perceived stress than to how stressed an individual feels on average. This suggests that laboratory stress tasks capture acute stress responsivity that is distinct from average stress exposure, highlighting the importance of considering what these tasks measure when interpreting individual differences in acute stress responses.

Despite its strong link to neuropsychiatric conditions, frustration remains critically understudied in humans and animals alike. Therefore, there is an urgent need to develop tools to understand and therapeutically target frustration-related functions. Interestingly, humans and rats respond similarly during frustrative nonreward by increasing barpress durations. We previously validated barpress duration in rat operant tasks as a reliable measure of frustration-related behavior; however, it is wellknown that in addition to duration of responding, emotional states such as frustration alter other aspects of responding such as force of pressing. One-dimensional, static measures such as maximum force could miss rich information contained within operant data. Thus, the objective of this study is to apply machine learning (ML) to force/time profiles to discriminate frustration-related barpresses from non-frustration-related barpresses. Results showed an AUROC for FR1 (i.e., non-frustrated) vs. extinction (frustrated condition) for individual barpresses of 0.65 that improved to 0.84 with a chunk size of 10. The model generalized well to progressive ratio responding, a different kind of frustration procedure. We conclude that force/time profiling does provide utility beyond one dimensional measures of duration or force separately, meaning that we can indeed infer the internal state of frustration from behavior using ML techniques. Importantly, this project will also serve as proof-of-concept for applying ML to predict other internal states from barpress data.

The olfactory and intranasal trigeminal systems interact closely, influencing chemosensory perception, yet the mechanisms underlying their interaction remain poorly understood and have been studied mainly in young adults. We aimed to characterize olfactory-trigeminal interactions in aging by comparing electrophysiological and behavioral responses under ipsilateral and contralateral olfactory-trigeminal co-stimulation, to determine the relative contributions of peripheral and central mechanisms. Using chemosensory event-related potentials and a localization task, 44 healthy older adults (66.3 {+/-} 4.6 years; 29 women) were tested under four conditions: pure trigeminal (carbon dioxide; CO2), pure olfactory (2-phenylethanol; PEA), ipsilateral co-stimulation (PEA+CO2 in the same nostril), and contralateral co-stimulation (PEA+CO2 in opposite nostrils). Ipsilateral, but not contralateral olfactory-trigeminal co-stimulation, improved trigeminal localization performance and induced larger late positive component amplitudes. Together, these findings suggest that olfactory-trigeminal interactions are driven primarily by peripheral rather than central mechanisms. This study also provides normative CSERP data for healthy older adults.

Background The prevalence and pattern of secondary causes of first-onset psychosis (FEP) in Asian populations are understudied. Our objectives are to investigate the prevalence and pattern of secondary causes of FEP presenting in an acute medical setting in a metropolitan, Chinese-predominant population, and to investigate the prevalence and pattern of undiagnosed conditions presenting as psychosis. Method This is a retrospective observational study. We reviewed medical records of patients referred to the consultation psychiatry team at a tertiary acute teaching hospital in Hong Kong from January 2015 to Apr 2025. The inclusion criteria of the study are 1) age 18-64 at the time of the assessment, and 2) FEP confirmed by the consultation liaison team. Patients diagnosed with delirium were excluded. Result Among the 384 patients included in the study (mean age = 40.0 {+/-}13.7 years, 69% female), secondary causes of psychosis were found in 9.6% (n=37) of the cohort. Substance use is the most common secondary cause found (n=11, 2.9% of all FEPs) overall. Among those with secondary psychoses, patients' underlying conditions were revealed only by the workup in relation to the FEP in 16 of them, of which definitive or probable autoimmune encephalitis (n=5) and early-onset dementia (n=4) were the most common conditions uncovered. Conclusion The prevalence of secondary psychoses in our FEP cohort is lower than published international figures. Clinicians need to be aware of the suspicious clinical features suggestive of autoimmune encephalitis and early-onset dementia in FEP patients with otherwise unremarkable past history and toxicology test.