Aiding and Abetting Anhedonia: Impact of Inflammation on the Brain and Pharmacological Implications

Transcriptional substrates of cortical thickness alterations in anhedonia of major depressive disorder

BACKGROUND

Anhedonia is a core symptom of major depressive disorder (MDD), which has been shown to be associated with abnormalities in cortical morphology. However, the correlation between cortical thickness (CT) changes with anhedonia in MDD and gene expression remains unclear.

METHODS

We investigated the link between brain-wide gene expression and CT correlates of anhedonia in individuals with MDD, using 7 Tesla neuroimaging and a publicly available transcriptomic dataset. The interest-activity score was used to evaluation MDD with high anhedonia (HA) and low anhedonia (LA). Nineteen patients with HA, nineteen patients with LA, and twenty healthy controls (HC) were enrolled. We investigated CT alterations of anhedonia subgroups relative to HC and related cortical gene expression, enrichment and specific cell types. We further used Neurosynth and von Economo-Koskinas atlas to assess the meta-analytic cognitive functions and cytoarchitectural variation associated with anhedonia-related cortical changes.

RESULTS

Both patient subgroups exhibited widespread CT reduction, with HA manifesting more pronounced changes. Gene expression related to anhedonia had significant spatial correlations with CT differences. Transcriptional signatures related to anhedonia-associated cortical thinning were connected to mitochondrial dysfunction and enriched in adipogenesis, oxidative phosphorylation, mTORC1 signaling pathways, involving neurons, astrocytes, and oligodendrocytes. These CT alterations were significantly correlated with meta-analytic terms involving somatosensory processing and pain perception. HA had reduced CT within the somatomotor and ventral attention networks, and in agranular cortical regions.

LIMITATIONS

These include measuring anhedonia using interest-activity score and employing a cross-sectional design.

CONCLUSIONS

This study sheds light on the molecular basis underlying gene expression associated with anhedonia in MDD, suggesting directions for targeted therapeutic interventions.

The (neuro)inflammatory system in anxiety disorders and PTSD: Potential treatment targets

Targeting the immune system has recently garnered attention in the treatment of stress- associated psychiatric disorders resistant to existing pharmacotherapeutics. While such approaches have been studied in considerable detail in depression, the role of (neuro)inflammation in anxiety-related disorders, or in anxiety as an important transdiagnostic symptom, is much less clear. In this review we first critically review clinical and in part preclinical evidence of central and peripheral immune dysregulation in anxiety disorders and post-traumatic stress disorder (PTSD) and briefly discuss proposed mechanisms of how inflammation can affect anxiety-related symptoms. We then give an overview of existing and potential future targets in inflammation-associated signal transduction pathways and discuss effects of different immune-modulatory drugs in anxiety-related disorders. Finally, we discuss key gaps in current clinical trials such as the lack of prospective studies involving anxiety patient stratification strategies based on inflammatory biomarkers. Overall, although evidence is rather limited so far, there is data to indicate that increased (neuro)inflammation is present in subgroups of anxiety disorder patients. Although exact identification of such immune subtypes of anxiety disorders and PTSD is still challenging, these patients will likely particularly benefit from therapeutic targeting of aspects of the inflammatory system. Different anti-inflammatory treatment approaches (microglia-directed treatments, pro-inflammatory cytokine inhibitors, COX-inhibitors, phytochemicals and a number of novel anti-inflammatory agents) have indeed shown some efficacy even in non-stratified anxiety patient groups and appear promising as novel alternative or complimentary therapeutic options in specific ("inflammatory") subtypes of anxiety disorder and PTSD patients.

The mediating effect of the striatum-based connectivity on the association between high-sensitivity C-reactive protein and anhedonia in adolescents with depressive disorder

BACKGROUND

The potential pairwise connections among high-sensitivity C-reactive protein (hs-CRP), striatum-based circuits, and anhedonia in adolescents with depressive disorder are not clear. This study aimed to explore whether hs-CRP levels in adolescents with depressive disorder influence anhedonia via alterations of striatum-based functional connectivity (FC).

METHODS

A total of 201 adolescents (92 with depressive episodes with anhedonia (anDE), 58 with DE without anhedonia (non-anDE), and 51 healthy controls (HCs)) underwent resting-state functional magnetic resonance imaging (fMRI) and completed the anhedonia subscale of the Children's Depression Inventory (CDI). hs-CRP levels were measured from peripheral blood samples in all DE patients.

RESULTS

Compared with HCs, the anDE and non-anDE groups showed increased FC between the left dorsal caudate putamen (DCP_L) and bilateral cerebellum crus I, and decreased FC between the left ventral rostral putamen (VRP_L) and right parahippocampal cortex (PHC) (all p < 0.05). Only the non-anDE group exhibited increased FC between the right visual cortex (VC_R) and left cerebellum VI, VC_R and right fusiform gyrus (FG), and the left visual cortex (VC_L) and right inferior temporal gyrus (ITG) compared to HCs (all p < 0.05). Compared to the non-anDE group, the anDE group showed reduced FC between the VC_R and left cerebellum VI and between the DCP_L and right superior frontal gyrus (SFG) (all p < 0.05). Multiple regression analysis revealed that the FC between DCP_L and right SFG negatively predicted anhedonia severity (β = -0.288, p = 0.007) in the anDE group. Although hs-CRP levels had no direct effect for anhedonia, FC between the DCP_L and right SFG fully mediated the relationship between hs-CRP and anhedonia in the anDE group (effect = 0.184, Bootstrapping 95 % CI = 0.0156, 0.436).

CONCLUSION

The findings suggest that hs-CRP influences anhedonia through a fully mediated pathway involving alterations in the frontostriatal network, contributing to a greater understanding of the neurobiological mechanisms underlying anhedonia.

Systemic Inflammation and Anhedonic Responses to an Inflammatory Challenge in Adults With Major Depressive Disorder: A Randomized Controlled Trial

OBJECTIVE

The authors sought to determine whether an inflammatory challenge with lipopolysaccharide (LPS) differentially impacts symptoms of anhedonia in participants with major depressive disorder with high (≥3 mg/L) and low (≤1.5 mg/L) serum C-reactive protein (CRP) concentrations.

METHODS

Sixty-eight participants with major depressive disorder were randomly assigned, in a 1:1 ratio, to receive LPS (0.8 ng/kg body weight) or placebo (saline) in a parallel-group double-blind design. Participants were stratified according to baseline CRP concentrations, yielding four groups: high-CRP LPS (N=13), low-CRP LPS (N=19), high-CRP placebo (N=13), and low-CRP placebo (N=19). Blood was sampled at baseline, at 1, 1.5, 3.5, 6, and 24 hours, and 1 week after LPS or saline administration, with concurrent assessment of psychological outcomes. The primary outcome measure was the Snaith-Hamilton Pleasure Scale (SHAPS), and the primary contrast of interest was the change between baseline and 1.5 hours (peak of the inflammatory response) in the high-CRP versus low-CRP groups receiving LPS. Secondary outcomes included the Montgomery-Åsberg Depression Rating Scale (MADRS) and serum levels of three cytokines: interleukin-6 (IL-6), IL-10, and tumor necrosis factor (TNF). Data were analyzed with linear mixed models.

RESULTS

Significantly greater increases in self-reported anhedonia (on the SHAPS) and IL-6 levels were observed between baseline and 1.5 hours in the high-CRP versus low-CRP LPS groups. There were no significant differences for TNF and IL-10. The MADRS was not administered at 1.5 hours; secondary analyses showed a significant group-by-condition-by-time interaction driven by a greater decrease in MADRS scores between baseline and 24 hours in the high-CRP group.

CONCLUSIONS

Depressed individuals with systemic inflammation appeared to be biologically primed to respond more strongly to inflammatory stimuli, and psychologically, this sensitization impacted the symptom of anhedonia, the primary outcome.

Effects of a mild inflammatory challenge on cytokines and sickness behavior: A randomized controlled trial using the influenza vaccine

The influenza vaccine has reliably been associated with mild, within-person increases in inflammation. However, the field lacks rigorous experimental work comparing the effects of the influenza vaccine to a placebo control on changes in plasma inflammatory cytokines and self-reported sickness behavior. In a double-blind, randomized, placebo-controlled trial, 102 participants received either the influenza vaccine or saline placebo. Four cytokines were measured in plasma 24-hours following injection; participants also reported on psychosocial outcomes, specifically sickness behavior, positive/negative affect, sleep, and subjective social disconnection. All cytokines-IL-6, IL-10, TNF-α, IFN-γ-were significantly increased in the influenza vaccine condition compared to placebo. None of the psychosocial outcomes differed by condition. This study fills a gap in the literature by presenting critical causal evidence that the influenza vaccine leads to elevated levels of four inflammatory cytokines, compared to placebo control. However, a more robust increase in inflammation or a larger sample size may be necessary to observe differences in self-reported sickness behavior and other psychosocial outcomes.

Should Inflammation Be a Specifier for Major Depression in the DSM-6?

This Viewpoint discusses the opportunity to include inflammatory biomarkers as specifiers for major depression in the upcoming Sixth Edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-6).

Anhedonia as a Core Symptom of Depression and a Construct for Biological Research

Anhedonia is a key psychiatric symptom that has seen significant advances in its understanding in both clinical practice and research over the past few decades. Once considered primarily a feature of depression, recent studies have shown that anhedonia is also a core element of other psychiatric disorders and contributes to considerable morbidity, mortality, and suicidality. Emerging models of psychopathology and illness emphasize the transdiagnostic relevance of anhedonia. At the same time, neuroimaging research has provided deeper insights into its underlying pathophysiology, and several assessment scales with strong psychometric properties have been developed. Various treatment strategies-including psychopharmacology, neuromodulation, and psychotherapy-have demonstrated varying degrees of effectiveness. This review discusses the evolving understanding of anhedonia, its significance as both a symptom and a diagnostic marker, its prevalence, and its pathophysiological underpinnings. Additionally, the authors provide an overview of key assessment tools and explore the range of treatment approaches studied to date.

A randomized proof-of-mechanism trial of TNF antagonism for motivational deficits and related corticostriatal circuitry in depressed patients with high inflammation

Chronic, low-grade inflammation has been associated with motivational deficits in patients with major depression (MD). In turn, impaired motivation has been linked to poor quality of life across psychiatric disorders. We thus determined effects of the anti-inflammatory drug infliximab-a potent tumor necrosis factor (TNF) antagonist-on behavioral and neural measures of motivation in 42 medically stable, unmedicated MD patients with a C-reactive protein >3 mg/L. All patients underwent a double-blind, placebo-controlled, single-dose, randomized clinical trial with infliximab (5 mg/kg) versus placebo. Behavioral performance on an effort-based decision-making task, self-report questionnaires, and neural responses during event-related functional magnetic resonance imaging were assessed at baseline and 2 weeks following infusion. We found that relative to placebo, patients receiving infliximab were more willing to expend effort for rewards. Moreover, increase in effortful choices was associated with reduced TNF signaling as indexed by decreased soluble TNF receptor type 2 (sTNFR2). Changes in effort-based decision-making and sTNFR2 were also associated with changes in task-related activity in a network of brain areas, including dorsomedial prefrontal cortex (dmPFC), ventral striatum, and putamen, as well as the functional connectivity between these regions. Changes in sTNFR2 also mediated the relationships between drug condition and behavioral and neuroimaging measures. Finally, changes in self-reported anhedonia symptoms and effort-discounting behavior were associated with greater responses of an independently validated whole-brain predictive model (aka "neural signature") sensitive to monetary rewards. Taken together, these data support the use of anti-inflammatory treatment to improve effort-based decision-making and associated brain circuitry in depressed patients with high inflammation.

Medial prefrontal glutamate response to acute stress is associated with social subordination in female rhesus macaques

Chronic psychosocial stress is associated with increased risk of psychiatric disorders. Magnetic resonance spectroscopy (MRS) in humans has been used to show that glutamate levels in medial prefrontal cortex (mPFC) following acute stress exposure adapt to recent chronic stress levels. Here, we sought to determine the presence of this glutamate stress response adaptation in rhesus macaques, whose societies are maintained by dominance relationships that are enforced by agonistic interactions and result in chronic stress phenotypes seen in humans. We tested the hypothesis that change in mPFC glutamate after an acute stressor would be moderated by behavioral factors related to social subordination in a manner similar to that previously observed in humans. Seventeen adult female rhesus monkeys (Macaca mulatta, 13-23 yrs.) were observed over ten weeks to collect behavioral data and then received two MRS scans. The first scan occurred after acute stress manipulation involving relocation and isolation. The second control scan occurred after acclimation to the new location. As expected, we found that a behavioral measure of social subordination predicted an adaptive glutamate response such that animals experiencing more submissive behavior asymmetry (a behavioral measure related to social subordination) exhibited an attenuated glutamate response to the acute stressor. These data establish the use of MRS to measure the adaptive glutamate stress in non-human primates and will help further our understanding of the neurobiology of stress adaptation.

The characteristics of anhedonia in depression: a review from a clinically oriented perspective

Anhedonia, as one of the core symptoms of major depressive disorder (MDD), has been regarded as a potential endophenotype of the disease. Multiple studies have evaluated the potential mechanisms of anhedonia in MDD, and found that MDD patients with anhedonia showed different functions in clinical features. In this review, we focus on the clinical research to explore the differences between MDD patients with and without anhedonia in the clinical manifestations and biological alterations, and elaborate the treatments and prognosis of anhedonia. It is demonstrated that anhedonia is associated with adverse outcomes including more severe depressive episode and suicidality, and poor prognosis in patients with MDD. At the biological level, MDD patients with anhedonia seem to present higher levels of inflammatory factors, abnormal metabolic function and hypermetabolism of BDNF. In brain imaging studies, there are some structural and/ or functional changes in multiple brain regions of subcortical and cortical areas, as well as the limbic system in MDD patients with anhedonia. Meanwhile, preliminary research findings have also indicated that there are associations between intestinal flora imbalance and anhedonia. Moreover, evidence indicated the benefit of some selective serotonin reuptake inhibitors seemed limited on anhedonia, and other treatments including psychotherapy, physical therapy and probiotic interventions has remained to be explored but has interesting potential. Therefore, increased awareness of the anhedonic symptoms and the unique clinical features would benefit improved early diagnosis and therapeutic effects in MDD.

Advancing precision psychiatry and targeted treatments: Insights from immunopsychiatry

Despite tremendous advancements in neuroscience, there has been limited impact on patient care. Current psychiatric treatments are largely non-specific, and drug development is hindered by outdated, overinclusive diagnostic categories and a "one-size-fits-all" approach. Additionally, mechanisms underlying psychiatric illnesses and their treatments with conventional medications remain poorly understood. Precision psychiatry is a strategy that holds great promise for novel therapies targeting specific pathophysiologic mechanisms in selected patients, ultimately contributing to more effective, personalized treatments. Immunopsychiatry, which focuses on the immune system's role in psychiatric disorders, exemplifies the challenges and potential solutions for precision psychiatry. Despite understanding how inflammation contributes to psychiatric illness, results of clinical trials with anti-inflammatory drugs have been inconsistent and underwhelming. Shortcomings of these trials include a lack of focus on subgroups of patients with increased inflammation, the use of non-specific outcome variables (e.g., not specific to inflammation's impact on the brain and behavior), and failure to establish target engagement of the inflammatory response. To advance anti-inflammatory treatments, clinical trials should: 1) enrich for patients using predictive biomarkers; 2) use clinical outcome assessments that align with inflammation's effects on the brain; 3) consider novel diagnostic constructs linked to inflammation; and 4) verify target engagement. Moreover, greater attention should be paid to efforts to repurpose available anti-inflammatory drugs while awaiting development of novel treatments targeting more specific immune pathways. Taken together, a collaborative approach involving academia, industry, funding agencies, patients, payors, and policymakers is required to advance Immunopsychiatry and ultimately provide a roadmap for successful implementation of precision psychiatry.

Depressive and Negative Symptoms in the Early and Established Stages of Schizophrenia: Integrating Structural Brain Alterations, Cognitive Performance, and Plasma Interleukin 6 Levels

Background

Depressive and negative symptoms are related to poor functional outcomes in schizophrenia. Cognitive deficits, reduced brain cortical thickness and volumes, and inflammation may contribute to depressive and negative symptoms, but pharmacological treatment and disease progression may confound the associations.

Methods

We evaluated whether higher plasma interleukin 6 (IL-6) levels would be associated with more severe negative or depressive symptoms in schizophrenia and explored illness stage utilizing early (BeneMin [Benefit of Minocycline on Negative Symptoms of Psychosis: Extent and Mechanism], n = 201, 72.8% male) and established (iRELATE [Immune Response & Social Cognition in Schizophrenia], n = 94, 67.3% male) schizophrenia cohorts. Using structural equation modeling in a subsample (iRELATE: n = 42, 69.0% male; BeneMin: n = 102, 76.5% male) with data on structural brain metrics (cortical thickness and volume), general cognitive performance, and plasma IL-6 levels, we assessed the interrelationships between these variables on depressive and negative symptom severity in early and established schizophrenia samples combined and in early schizophrenia only. All analyses were adjusted for sex, age, and chlorpromazine equivalent dose.

Results

Higher plasma IL-6 levels were related to more severe depressive symptoms in early schizophrenia (p < .05) and negative symptoms in established schizophrenia (p < .05). Structural equation modeling findings in early and established schizophrenia samples combined and early schizophrenia only showed that the interrelationship between higher plasma IL-6 levels, structural brain metrics, and general cognitive performance did not predict the severity of depressive and negative symptoms (p > .05). Higher plasma IL-6 levels and lower general cognitive performance were associated with reduced brain metrics (p < .05).

Conclusions

Our results indicate that higher plasma IL-6 levels may be differently associated with the severity of depressive and negative symptoms dependent on the illness stage. Future work identifying elevated levels of inflammation in larger samples may allow stratification and personalized intervention by subgroups who are at risk of poor outcomes.

Emerging Medications for Treatment-Resistant Depression: A Review with Perspective on Mechanisms and Challenges

Background/Objectives: Non-response to initial treatment options for major depressive disorder (MDD) is a common clinical challenge with profound deleterious impacts for affected patients. Few treatments have received regulatory approval for treatment-resistant depression (TRD). Methods: A systematic search of United States and European Union clinical trials registries was conducted to identify Phase II, III, or IV clinical trials, with a last update posted on or after 1 January 2020, that were evaluating medications for TRD. For both the US and EU registries, the condition term "treatment resistant depression" and associated lower-level terms (per registry search protocol) were used. For the US registry, a secondary search using the condition term "depressive disorders" and the modifying term "inadequate" was also performed to capture registrations not tagged as TRD. Two additional searches were also conducted in the US registry for the terms "suicide" and "anhedonia" as transdiagnostic targets of investigational medications. Trials were categorized based on the primary mechanism of action of the trial's investigational medication. Results: Fifty clinical trials for TRD, 20 for anhedonia, and 25 for suicide were identified. Glutamate system modulation was the mechanism currently with the most compounds in development, including antagonists and allosteric modulators of NMDA receptors, AMPA receptors, metabotropic type 2/3 glutamate receptors, and intracellular effector molecules downstream of glutamate signaling. Psychedelics have seen the greatest surge among mechanistic targets in the past 5 years, however, with psilocybin in particular garnering significant attention. Other mechanisms included GABA modulators, monoamine modulators, anti-inflammatory/immune-modulating agents, and an orexin type 2 receptor antagonist. Conclusions: These investigations offer substantial promise for more efficacious and potentially personalized medication approaches for TRD. Challenges for detecting efficacy in TRD include the heterogeneity within the TRD population stemming from the presumed variety of biological dysfunctions underlying the disorder, comorbid disorders, chronic psychosocial stressors, and enduring effects of prior serotonergic antidepressant medication treatments.

Lipids and C-reactive protein predict anhedonia and reward circuit functional connectivity responses to anti-cytokine and dopaminergic therapies in patients with depression

Increased inflammation and associated metabolic disturbances have been shown to affect neurotransmitters and brain circuits, contributing to an immunometabolic phenotype of anhedonic depression. To extend our previous findings on relationships between plasma lipids and antidepressant response to anti-cytokine therapy, we explored in secondary analyses whether lipid-related biomarkers similarly predicted change in anhedonia or functional connectivity (FC) in dopamine-rich corticostriatal reward circuitry in medically-stable, depressed patients with a range of inflammation levels (indexed by plasma C-reactive protein [CRP]) who were administered inflammation-targeted therapies. Relationships were examined between baseline lipids (plasma cholesterols, triglycerides and non-esterified fatty acids) and reduction of anhedonia symptoms in Study 1 (n = 60) after three infusions of infliximab or placebo and change in resting-state FC in Study 2 (n = 31) after acute, within-subject challenge with levodopa (L-DOPA) and placebo. A treatment by inflammation interaction revealed lower anhedonia after infliximab versus placebo (F[1,49] = 5.5, p < 0.05) in patients with, but not without, CRP>3 mg/L (n = 27). A composite score of lipid-related biomarkers (with increasing values reflecting higher concentrations) also precited anhedonia response (post-treatment minus baseline) to infliximab (r = -0.46, p < 0.05) but not placebo (r = 0.14, p = 0.56). Lipid scores similarly predicted CRP-related increases in reward circuit FC after L-DOPA (r = 0.53, p < 0.01) but not placebo (r = 0.20, p = 0.34). Responses to infliximab and L-DOPA were strongest in patients with versus without clinically elevated CRP (>3 mg/L) and/or cholesterol (>150 mg/dL)(p < 0.05). Results highlight a role for dyslipidemia in immunometabolic depression, biomarkers of which, together with CRP, have potential to classify patients indicated for therapies that block inflammation or its effects on neurotransmitters like dopamine.

Facets of mindfulness are associated with inflammation biomarkers in a sample of sexual minority men with HIV

Sexual minority men (SMM) are disproportionately impacted by HIV and thus, HIV related-health complications. HIV has been linked to earlier onset of multi-morbid chronic diseases and declines in physical and cognitive functioning attributable to chronic HIV immune activation and resulting inflammation. Inflammation has been targeted with mindfulness-based interventions (MBIs); however, hypothesized negative associations between mindfulness and inflammation need to be confirmed in SMM with HIV. This is a secondary data analysis of baseline data from a randomized clinical trial (RCT) of SMM living with HIV with biologically confirmed recent methamphetamine use (ARTEMIS). Mindfulness was assessed with the Five Factor Mindfulness Questionnaire (FFMQ). Inflammation was assessed via cytokines interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α). Separate adjusted (for age, viral load, CD4 count, and methamphetamine use) regression models evaluated associations between four facets of mindfulness (description, awareness, non-judgement, and non-reactivity) with IL-6 and TNF-α. The average age of the participants was 43.86 (SD = 8.95). Both description (b = .54, se = .24) and awareness (b = .50, se=.23) were positively associated with IL-6. All other associations between mindfulness and inflammation were non-significant in adjusted models. There was also some evidence to suggest that engagement in care moderated associations between description and non-reactivity with IL-6 (ΔR2 = .03, F = 3.64), such that description and non-reactivity were each positively associated with inflammation among those who attended <100% of primary care appointments (b = 1.04, se=.34 and b = 1.23, se=.39, respectively), but was not associated with inflammation among those who attended 100% of appointments (b =.16, se=.32 and b=-.17, se=.40, respectively). There was also a significant interaction between 12-step program attendance and awareness with IL-6 (ΔR2= .03, F = 4.26), such that awareness was positively associated with inflammation among those who attended 12-step programming (b = 1.25, se = .41), but not associated with inflammation among those who did not (b = .22, se = .28). Further research is needed to understand how and under what circumstances mindfulness is associated with pro- versus anti-inflammatory processes.Trial Registration: NCT01926184.

Trajectory of peripheral inflammation during index ECT in association with clinical outcomes in treatment-resistant depression

Background

Electroconvulsive therapy (ECT) is a highly efficacious intervention for severe and intractable depression. Evidence suggests ECT provokes an initial acute inflammatory response that subsequently decreases with repeated administration. However, relationships between inflammatory changes and clinical effects are unclear. Improved understanding of these processes may provide critical insight into effective intervention for treatment-resistant depression (TRD).

Methods

Plasma inflammatory markers were assessed at pre-treatment (T1), after the second ECT session (T2), and after ECT index series completion (post-treatment/T3) in TRD (n = 40). Changes were examined over time and in association with post-treatment Responder/Non-responder status (≥50% reduction in global depression severity) and percent change in affective, cognitive and neurovegetative depressive symptom domains.

Results

C-reactive protein (CRP) and interleukin-6 (IL-6) increased from pre-treatment to T2, and decreased from T2 to post-treatment. Neither early (%T2-T1) nor total (%T1-T3) change in inflammation predicted clinical outcomes, however, the interaction between early/acute inflammatory response and post-treatment inflammation (relative to baseline) was associated with clinical outcomes. Larger initial increases in IL-6 predicted greater reductions in both affective and cognitive symptoms in subjects with higher post-treatment IL-6; those with lower post-treatment IL-6 trended toward the opposite. The same was found between changes in CRP and neurovegetative symptoms.

Conclusions

Though preliminary, these results demonstrate how processes involved in the acute inflammatory response to ECT may differentially influence clinical outcomes depending on overall trajectory of inflammation following ECT. Findings also highlight the importance of examining symptom-specific changes in depression when studying treatment mechanisms, rather than relying solely on global measures of severity.

Prevalence of anhedonia in women with deep endometriosis

Anhedonia, characterized by diminished motivation and pleasure sensitivity, is increasingly recognized as prevalent among patients with chronic pain. Deep Endometriosis (DE), the most severe endophenotype of the disease, is commonly presented with chronic pelvic pain. This cross-sectional study reports, for the first time, the prevalence of anhedonia in a sample comprised by 212 premenopausal women with suspected DE referred to a tertiary hospital. Our findings show that 27,8% [95% CI 22.1, 26.5] of DE patients experience abnormal hedonic tone. Severity of DE pain-related symptoms significantly correlated with anhedonia, consistent with previous findings. Chronic pelvic pain emerged as a significant predictor of anhedonia (OR 1.5, 95% CI 1.0-1.22, p < 0.05) with the odds increasing to 2.28 [95% CI 1.12, 4.23] when pain was severe. The most affected areas in DE patients were interests, social interaction and food pleasure. The present results are representative of DE patients under multimodal treatment, limiting generalizability. Overall, our study highlights the impact of chronic pain on hedonic functioning in DE. Therapeutic approaches targeting hedonic capacity in DE patients are crucial for restoring health and well-being.

Dissecting depression symptoms: Multi-omics clustering uncovers immune-related subgroups and cell-type specific dysregulation

In a subset of patients with mental disorders, such as depression, low-grade inflammation and altered immune marker concentrations are observed. However, these immune alterations are often assessed by only one data type and small marker panels. Here, we used a transdiagnostic approach and combined data from two cohorts to define subgroups of depression symptoms across the diagnostic spectrum through a large-scale multi-omics clustering approach in 237 individuals. The method incorporated age, body mass index (BMI), 43 plasma immune markers and RNA-seq data from peripheral mononuclear blood cells (PBMCs). Our initial clustering revealed four clusters, including two immune-related depression symptom clusters characterized by elevated BMI, higher depression severity and elevated levels of immune markers such as interleukin-1 receptor antagonist (IL-1RA), C-reactive protein (CRP) and C-C motif chemokine 2 (CCL2 or MCP-1). In contrast, the RNA-seq data mostly differentiated a cluster with low depression severity, enriched in brain related gene sets. This cluster was also distinguished by electrocardiography data, while structural imaging data revealed differences in ventricle volumes across the clusters. Incorporating predicted cell type proportions into the clustering resulted in three clusters, with one showing elevated immune marker concentrations. The cell type proportion and genes related to cell types were most pronounced in an intermediate depression symptoms cluster, suggesting that RNA-seq and immune markers measure different aspects of immune dysregulation. Lastly, we found a dysregulation of the SERPINF1/VEGF-A pathway that was specific to dendritic cells by integrating immune marker and RNA-seq data. This shows the advantages of combining different data modalities and highlights possible markers for further stratification research of depression symptoms.

Neural and immune interactions linking early life stress and anhedonia

Early experiences of stress and adversity are associated with blunted reward sensitivity and altered reward learning. Meanwhile, anhedonia is characterized by impairments in reward processing, including motivation, effort, and pleasure. Early life stress (ELS) and anhedonia share psychological, behavioral, and neurobiological correlates, and the system-level interactions that give rise to anhedonia have yet to be fully appreciated. The proposed framework uses a multilevel, multisystem approach to aid in understanding neural-immune interactions that link ELS and anhedonia. The interactions linking anhedonia and ELS presented here include reduced reward sensitivity, alterations in hypothalamic-pituitary-adrenal (HPA) axis response, elevated inflammatory cytokines or physiological markers of stress, and blunted reward circuitry functioning along the mesocorticolimbic pathway. The clinical implications and areas for future research are also discussed. Ultimately, this research may inform the development of more specific and individualized treatments for anhedonia.

Applying the Research Domain Criteria to Rodent Studies of Sex Differences in Chronic Stress Susceptibility

Women have a 2-fold increased rate of stress-associated psychiatric disorders such as depression and anxiety, but the mechanisms that underlie this increased susceptibility remain incompletely understood. Historically, female subjects were excluded from preclinical studies and clinical trials. Additionally, chronic stress paradigms used to study psychiatric pathology in animal models were developed for use in males. However, recent changes in National Institutes of Health policy encourage inclusion of female subjects, and considerable work has been performed in recent years to understand biological sex differences that may underlie differences in susceptibility to chronic stress-associated psychiatric conditions. Here, we review the utility as well as current challenges of using the framework of the National Institute of Mental Health's Research Domain Criteria as a transdiagnostic approach to study sex differences in rodent models of chronic stress including recent progress in the study of sex differences in the neurobehavioral domains of negative valence, positive valence, cognition, social processes, and arousal.

Increased white blood cell in young adults with family histories of alcohol and other substance use disorders

Individuals with a family history of alcohol or other substance use disorders (FH+) are at increased risk for developing alcohol and other substance use disorders (AUD/SUD) compared to individuals with no such family histories (FH-). FH+ young adults have blunted stress reactivity, lower cognitive performance and altered frontal white matter microstructure compared to FH- controls. We hypothesized that family history of AUD/SUD disrupts neuroendocrine regulation of the immune system in FH+ individuals, resulting in altered blood immune cell composition, inflammation and neurocognitive alterations that, ultimately, increases risk for AUD/SUD and associated psychopathology. We examined white blood cell (WBC) parameters derived from complete blood counts in FH+ (n = 37) and FH- (n = 77) young adults without AUD/SUD to test if immune system dysregulation is present in FH+ individuals. The total WBC count, number of neutrophils and number of monocytes and associated systemic inflammatory response index (SIRI) were significantly increased in the FH+ group. Further, WBC, neutrophil, monocyte counts and SIRI values were all positively correlated with FH density (number of biological parents and grandparents with AUD/SUD). These novel data are the first to identify an association between family history of AUD/SUD and increased circulating leukocytes, which is likely indicative of immune dysregulation in FH+ young adults prior to onset of AUD/SUD. Additional studies are warranted to characterize the functional relevance of the observed immune cell composition in FH+ individuals, but the notion that inexpensive and widely available blood tests may help identify addiction risk could be transformative.

HIV, inflammation, and initiation of methamphetamine use in sexual and gender minorities assigned male at birth

Methamphetamine use and HIV disproportionately affect sexual and gender minority (SGM) people assigned male at birth. Identifying risk factors for methamphetamine use is crucial to inform preventive interventions. In this cohort study with 1,296 SGM people assigned male at birth, ages 16 to 29, and who resided in Chicago, Poisson regression analyses indicated the prevalence of methamphetamine use increased from 2015 to 2023 [Incidence Rate Ratio (IRR) = 1.07; 95% CI = 1.01 to 1.13; P = 0.02]. This increase was most pronounced among those ages 25 or older at baseline (IRR = 2.20; 95% CI = 1.33 to 3.63; P = 0.002), and 23.9 [Interquartile Range (IQR) = 22.1 to 26.9] was the median age of first-time methamphetamine use. In 826 participants with a prior HIV diagnosis or previous inflammatory measurements, Cox proportional-hazards models examined risk factors for incident, first-time methamphetamine use. Adjusting for other substance use, the rate of incident, first-time methamphetamine use was two-fold greater after HIV diagnosis [adjusted hazard ratio (aHR) = 2.02; 95% CI = 1.27 to 3.23; P = 0.003]. For each SD higher C-reactive protein, the rate of incident, first-time methamphetamine use was 18% greater (aHR = 1.18; 95% CI, 1.05 to 1.34; P = 0.008). HIV seroconversion and inflammation could increase the risk of initiating methamphetamine use in SGM people assigned male at birth.

Glycolytic metabolism: Food for immune cells, fuel for depression?

Inflammation is one biological pathway thought to impact the brain to contribute to major depressive disorder (MDD) and is reliably associated with resistance to standard antidepressant treatments. While peripheral immune cells, particularly monocytes, have been associated with aspects of increased inflammation in MDD and symptom severity, significant gaps in knowledge exist regarding the mechanisms by which these cells are activated to contribute to behavioral symptoms in MDD. One concept that has gained recent appreciation is that metabolic rewiring to glycolysis in activated myeloid cells plays a crucial role in facilitating these cells' pro-inflammatory functions, which may underlie myeloid contribution to systemic inflammation and its effects on the brain. Given emerging evidence from translational studies of depression that peripheral monocytes exhibit signs of glycolytic activation, better understanding the immunometabolic phenotypes of monocytes which are known to be elevated in MDD with high inflammation is a critical step toward comprehending and treating the impact of inflammation on the brain. This narrative review examines the extant literature on glycolytic metabolism of circulating monocytes in depression and discusses the functional implications of immunometabolic shifts at both cellular and systemic levels. Additionally, it proposes potential therapeutic applications of existing immunomodulators that target glycolysis and related metabolic pathways in order to reverse the impact of elevated inflammation on the brain and depressive symptoms.

Recent Advances in Anti-Inflammatory Compounds from Marine Microorganisms

Marine microbial secondary metabolites with diversified structures have been found as promising sources of anti-inflammatory lead compounds. This review summarizes the sources, chemical structures, and pharmacological properties of anti-inflammatory natural products reported from marine microorganisms in the past three years (2021-2023). Approximately 252 anti-inflammatory compounds, including 129 new ones, were predominantly obtained from marine fungi and they are structurally divided into polyketides (51.2%), terpenoids (21.0%), alkaloids (18.7%), amides or peptides (4.8%), and steroids (4.3%). This review will shed light on the development of marine microbial secondary metabolites as potential anti-inflammatory lead compounds with promising clinical applications in human health.

The effects of psychotherapy for anhedonia on subcortical brain volumes measured with ultra-high field MRI

BACKGROUND

Anhedonia is a transdiagnostic symptom often resistant to treatment. The identification of biomarkers sensitive to anhedonia treatment will aid in the evaluation of novel anhedonia interventions.

METHODS

This is an exploratory analysis of changes in subcortical brain volumes accompanying psychotherapy in a transdiagnostic anhedonic sample using ultra-high field (7-Tesla) MRI. Outpatients with clinically impairing anhedonia (n = 116) received Behavioral Activation Treatment for Anhedonia, a novel psychotherapy, or Mindfulness-Based Cognitive Therapy (ClinicalTrials.gov Identifiers NCT02874534 and NCT04036136). Subcortical brain volumes were estimated via the MultisegPipeline, and regions of interest were the amygdala, caudate nucleus, hippocampus, pallidum, putamen, and thalamus. Bivariate mixed effects models estimated pre-treatment relations between anhedonia severity and subcortical brain volumes, change over time in subcortical brain volumes, and associations between changes in subcortical brain volumes and changes in anhedonia symptoms.

RESULTS

As reported previously (Cernasov et al., 2023), both forms of psychotherapy resulted in equivalent and significant reductions in anhedonia symptoms. Pre-treatment anhedonia severity and subcortical brain volumes were not related. No changes in subcortical brain volumes were observed over the course of treatment. Additionally, no relations were observed between changes in subcortical brain volumes and changes in anhedonia severity over the course of treatment.

LIMITATIONS

This trial included a modest sample size and did not have a waitlist-control condition or a non-anhedonic comparison group.

CONCLUSIONS

In this exploratory analysis, psychotherapy for anhedonia was not accompanied by changes in subcortical brain volumes, suggesting that subcortical brain volumes may not be a candidate biomarker sensitive to response to psychotherapy.

Effects of Lycium barbarum polysaccharide on cytokines in adolescents with subthreshold depression: a randomized controlled study

JOURNAL/nrgr/04.03/01300535-202409000-00036/figure1/v/2024-01-16T170235Z/r/image-tiff Strong evidence has accumulated to show a correlation between depression symptoms and inflammatory responses. Moreover, anti-inflammatory treatment has shown partial effectiveness in alleviating depression symptoms. Lycium barbarum polysaccharide (LBP), derived from Goji berries, exhibits notable antioxidative and anti-inflammatory properties. In our recent double-blinded randomized placebo-controlled trial, we found that LBP significantly reduced depressive symptoms in adolescents with subthreshold depression. It is presumed that the antidepressant effect of LBP may be associated with its influence on inflammatory cytokines. In the double-blinded randomized controlled trial, we enrolled 29 adolescents with subthreshold depression and randomly divided them into an LBP group and a placebo group. In the LBP group, adolescents were given 300 mg/d LBP. A 6-week follow up was completed by 24 adolescents, comprising 14 adolescents from the LBP group (15.36 ± 2.06 years, 3 men and 11 women) and 10 adolescents from the placebo group (14.9 ± 1.6 years, 2 men and 8 women). Our results showed that after 6 weeks of treatment, the interleukin-17A level in the LBP group was lower than that in the placebo group. Network analysis showed that LBP reduced the correlations and connectivity between inflammatory factors, which were associated with the improvement in depressive symptoms. These findings suggest that 6-week administration of LBP suppresses the immune response by reducing interleukin-17A level, thereby exerting an antidepressant effect.

Association of Depression With the Progression of Multimorbidity in Older Adults: A Population-Based Cohort Study

BACKGROUND

The relationship between depression and the risk of multimorbidity progression has rarely been studied in older adults. This study was aimed to determine whether depression is associated with progression in the severity and complexity of multimorbidity, considering the influence of depression's severity and subtype.

METHODS

As a part of the Korean Longitudinal Study on Cognitive Aging and Dementia, this population-based cohort study followed a random sample of community-dwelling Koreans aged 60 and older for 8 years at 2-year intervals starting in 2010. Participants included those who completed mood and multimorbidity assessments and did not exhibit complex multimorbidity at the study's outset. Depression was assessed using the Geriatric Depression Scale, while multimorbidity was evaluated using the Cumulative Illness Rating Scale. The study quantified multimorbidity complexity by counting affected body systems and measured multimorbidity severity by averaging scores across 14 body systems.

FINDINGS

The 2,486 participants (age = 69.1 ± 6.5 years, 57.6% women) were followed for 5.9 ± 2.4 years. Linear mixed models revealed that participants with depression had a faster increase in multimorbidity complexity score (β = .065, SE = 0.019, p = 0.001) than those without depression, but a comparable increase in multimorbidity severity score (β = .001, SE = .009, p = 0.870) to those without depression. Cox proportional hazard models revealed that depression was associated with the risk of developing highly complex multimorbidity affecting five or more body systems, particularly in severe or anhedonic depression.

INTERPRETATION

Depression was associated with the worsening of multimorbidity in Korean older adults, particularly when severe or anhedonic. Early screening and management of depression may help to reduce the burden of multimorbidity in older adults.

Treating Depression to Improve Survival in Coronary Heart Disease: What Have We Learned?

Major depressive disorder is a well-established risk factor for cardiac events in patients with coronary heart disease, but clinical trials have produced little evidence that treating depression reliably improves cardiac event-free survival in these patients. In this review, we offer evidence that certain symptoms that commonly remain after otherwise successful treatment of depression-insomnia, fatigue, and anhedonia-independently predict cardiac events. This may help to explain the failure of previous depression treatment trials to improve cardiac event-free survival even when other symptoms of depression improve. We thus propose that adverse cardiovascular effects that have long been attributed to syndromal depression may be instead caused by persistent fatigue, insomnia, and anhedonia, regardless of whether other symptoms of depression are present. We also identify interventions for these symptoms and call for more research to evaluate their effectiveness in depressed patients with coronary heart disease.

Inflammatory depression is associated with selective glomerular hypofiltration

BACKGROUND

Systemic low-grade inflammation may be a pathophysiological mechanism in a subtype of depression. In this study we investigate a novel candidate mechanism of inflammatory depression - Selective Glomerular Hypofiltration Syndromes (SGHS) - which are characterized by a reduced estimated glomerular filtration rate (eGFR) based on cystatin C (cysC) relative to eGFR based on creatinine (crea). SGHS have been associated with increased blood levels of pro-inflammatory markers, but have never been investigated in a sample of depressed individuals.

METHOD

The prevalence of SGHS was compared between 313 patients with difficult-to-treat depression and 73 controls. Since there is no single established eGFRcysC/eGFRcrea-ratio cut-off to define SGHS, several cut-offs were investigated in relation to a depression diagnosis, inflammation, and symptom severity. Plasma inflammatory markers tumor necrosis factor alpha (TNF-α), interferon gamma (IFN-γ), interleukin (IL)-6, IL-8, and IL-10 were available from 276 depressed patients. We examined mediation effects of IL-6 on the relationship between SGHS and depression.

RESULTS

Depressed patients were more likely to have SGHS compared to controls defining SGHS as either eGFRcysC/eGFRcrea-ratio < 0.9 (33.2 % vs 20.5 %, p = 0.035) or < 0.8 (15.7 % vs 5.5 %, p = 0.023). Lower eGFRcysC/eGFRcrea-ratio was associated with higher levels of inflammatory markers in depressed patients. IL-6 partly mediated the relationship between SGHS and depression.

CONCLUSION

This is the first study to demonstrate a link between SGHS and inflammatory depression. If replicated in independent and longitudinal cohorts, this may prove to be a relevant pathophysiological mechanism in some cases of depression that could be targeted in future intervention and prevention studies.

Chronic inflammation is associated with worsening working memory performance: Preliminary evidence from a diverse, longitudinal cohort of adolescents and young adults

Many depressed individuals experience cognitive difficulties that persist when depression is in remission. Inflammation is hypothesized to play a role in cognitive dysfunction in depression; however, many aspects of this relationship are not well characterized. The current study examined whether inflammation is associated with specific cognitive deficits in individuals with a history of depression and with progressively worsening working memory over time. Adolescents who participated in a prospective, longitudinal study of adolescent-onset depression were recruited to complete a follow-up cognitive assessment. The sample was comprised of 82 participants (52.4% female; 37.8% white; 42.7% low socioeconomic status) who were aged 22.61 years (SD = 1.50) at the time of the follow-up cognitive assessment. Prior to the follow-up cognitive assessment, they had completed an average of 6.24 (SD = 1.80) prior annual assessments over 6.24 years (SD = 2.08) as part of the parent longitudinal study in which C-reactive protein (CRP), depressive symptoms, and working memory were assessed repeatedly. First, using linear regression, we tested whether individuals exhibiting inflammation (CRP ≥3 mg/L) at multiple timepoints and a history of likely depression (Children's Depression Inventory ≥19) exhibited differentially worse executive functioning, episodic memory, or psychomotor speed. Second, using hierarchical linear modeling, we tested whether the combination of inflammation and likely past depression was associated with poorer working memory over time. Chronic inflammation was associated with worsening working memory over time, but no significant associations were observed in cross-sectional analyses. These preliminary data indicate that chronic inflammation may lead to progressive decline in working memory over time.

Annual Research Review: Neuroimmune network model of depression: a developmental perspective

Depression is a serious public health problem, and adolescence is an 'age of risk' for the onset of Major Depressive Disorder. Recently, we and others have proposed neuroimmune network models that highlight bidirectional communication between the brain and the immune system in both mental and physical health, including depression. These models draw on research indicating that the cellular actors (particularly monocytes) and signaling molecules (particularly cytokines) that orchestrate inflammation in the periphery can directly modulate the structure and function of the brain. In the brain, inflammatory activity heightens sensitivity to threats in the cortico-amygdala circuit, lowers sensitivity to rewards in the cortico-striatal circuit, and alters executive control and emotion regulation in the prefrontal cortex. When dysregulated, and particularly under conditions of chronic stress, inflammation can generate feelings of dysphoria, distress, and anhedonia. This is proposed to initiate unhealthy, self-medicating behaviors (e.g. substance use, poor diet) to manage the dysphoria, which further heighten inflammation. Over time, dysregulation in these brain circuits and the inflammatory response may compound each other to form a positive feedback loop, whereby dysregulation in one organ system exacerbates the other. We and others suggest that this neuroimmune dysregulation is a dynamic joint vulnerability for depression, particularly during adolescence. We have three goals for the present paper. First, we extend neuroimmune network models of mental and physical health to generate a developmental framework of risk for the onset of depression during adolescence. Second, we examine how a neuroimmune network perspective can help explain the high rates of comorbidity between depression and other psychiatric disorders across development, and multimorbidity between depression and stress-related medical illnesses. Finally, we consider how identifying neuroimmune pathways to depression can facilitate a 'next generation' of behavioral and biological interventions that target neuroimmune signaling to treat, and ideally prevent, depression in youth and adolescents.

Annual Research Review: Puberty and the development of anhedonia - considering childhood adversity and inflammation

Anhedonia, or diminished pleasure and motivation, is a symptom of severe mental illness (e.g., depressive disorder, bipolar disorder, schizophrenia) that emerges during adolescence. Anhedonia is a pernicious symptom that is related to social impairments, treatment resistance, and suicide. As the mechanisms of anhedonia are postulated to include the frontostriatal circuitry and the dopamine neuromodulatory system, the development and plasticity of these systems during the vulnerable period of adolescence, as well as their sensitivity to pubertal hormones, suggest that pubertal maturation could play a role in the development of anhedonia. This review takes a developmental perspective, considering the possibility that anhedonia emerges in the context of pubertal maturation and adolescent development, with childhood adversity and chronic inflammation influencing neural reward systems to accelerate anhedonia's progression. Here, we review the relevant extant literature on the components of this model and suggest directions for future research.

Struggling Can Also Show on the Inside: Current Knowledge of the Impact of Childhood Maltreatment on Biomarkers in Mood Disorders

The link between childhood maltreatment and mood disorders is complex and involves multiple bio-psycho-social factors that affect multiple molecular pathways. The present narrative review aims to clarify the current understanding of the impact of childhood maltreatment on biomarkers in patients with mood disorders and their first-degree relatives. Neurotransmitters, such as serotonin, dopamine, norepinephrine, and hormones (eg the stress hormone cortisol), play a crucial role in regulating mood and emotion. Childhood maltreatment can alter and affect the levels and functioning of these neurotransmitters in the brain; further, childhood maltreatment can lead to structural and connectivity changes in the brain, hence contributing to the development of mood disorders and moderating illness presentation and modifying response to treatments. Childhood maltreatment information, therefore, appears mandatory in treatment planning and is a critical factor in therapeutic algorithms. Further research is needed to fully understand these pathways and develop new treatment modalities for individuals with mood disorders who have experienced childhood maltreatment and effective preventive interventions for individuals at risk of developing mood disorders.

A randomized proof-of-mechanism trial of TNF antagonism for motivational anhedonia and related corticostriatal circuitry in depressed patients with high inflammation

Chronic, low-grade inflammation has been associated with motivational deficits in patients with major depression (MD). In turn, impaired motivation has been linked to poor quality of life across psychiatric disorders. We thus determined effects of the anti-inflammatory drug infliximab-a potent tumor necrosis factor (TNF) antagonist-on behavioral and neural measures of motivation in 42 medically stable, unmedicated MD patients with a C-reactive protein > 3mg/L. All patients underwent a double-blind, placebo-controlled, single-dose, randomized clinical trial with infliximab (5mg/kg) versus placebo. Behavioral performance on an effort-based decision-making task, self-report questionnaires, and neural responses during event-related functional magnetic resonance imaging were assessed at baseline and 2 weeks following infusion. We found that relative to placebo, patients receiving infliximab were more willing to expend effort for rewards. Moreover, increase in effortful choices was associated with reduced TNF signaling as indexed by decreased soluble TNF receptor type 2 (sTNFR2). Changes in effort-based decision-making and sTNFR2 were also associated with changes in task-related activity in a network of brain areas, including dmPFC, ventral striatum, and putamen, as well as the functional connectivity between these regions. Changes in sTNFR2 also mediated the relationships between drug condition and behavioral and neuroimaging measures. Finally, changes in self-reported anhedonia symptoms and effort-discounting behavior were associated with greater responses of an independently validated whole-brain predictive model (aka "neural signature") sensitive to monetary rewards. Taken together, these data support the use of anti-inflammatory treatment to improve effort-based decision-making and associated brain circuitry in depressed patients with high inflammation.

The presence of anhedonia in individuals with subacute and chronic stroke: an exploratory cohort study

Background

Anhedonia refers to the diminished capacity to experience pleasure. It has been described both as a symptom of depression and an enduring behavioral trait that contributes its development. Specifically, in stroke patients, anhedonia has been closely linked to depression, resulting in reduced sensitivity to everyday pleasures and intrinsic motivation to engage in rehabilitation programs and maintain a healthy active lifestyle. This condition may hinder patients' recovery, diminishing their autonomy, functioning, and quality of life.

Objective

We aimed to explore the prevalence and level of anhedonia and those variables that might be associated in patients with both ischemic and hemorrhagic stroke at subacute and chronic phases of the disease.

Methods

We conducted an exploratory cohort study with a sample of 125 patients with subacute and chronic stroke presenting upper-limb motor deficits. We measured participants' level of anhedonia with four items from the Beck Depression Inventory-II that describe the symptoms of this condition: loss of pleasure, loss of interest, loss of energy, and loss of interest in sex. We also collected demographic and clinical information and evaluated motor and cognitive functions as well as levels of depression, apathy, and various mood states. The results were compared to a sample of 71 healthy participants of similar age, sex, and level of education.

Results

Stroke patients demonstrated a significantly higher prevalence (18.5-19.7%) and level of anhedonia compared to the healthy controls (4.3%), regardless of stroke phase, level of motor impairment, and other clinical variables. Furthermore, post-stroke anhedonia was associated with lower levels of motivation and higher levels of negative mood states such as fatigue and anger in the long term. Importantly, anhedonia level was superior in stroke patients than in healthy controls while controlling for confounding effects of related emotional conditions.

Conclusion

This study provides novel evidence on the prevalence, level and factors related to anhedonia post-stroke. We emphasize the importance of assessing and treating anhedonia in this population, as well as conducting large-scale cohort and longitudinal studies to test its influence on long-term functional and emotional recovery.

A feasibility study of goal-directed network-based real-time fMRI neurofeedback for anhedonic depression

Anhedonia is a hallmark symptom of depression that often lacks adequate interventions. The translational gap remains in clinical treatments based on neural substrates of anhedonia. Our pilot study found that depressed individuals depended less on goal-directed (GD) reward learning (RL), with reduced reward prediction error (RPE) BOLD signal. Previous studies have found that anhedonia is related to abnormal activities and/or functional connectivities of the central executive network (CEN) and salience network (SN), both of which belong to the goal-directed system. In addition, it was found that real-time functional magnetic resonance imaging (rt-fMRI) neurofeedback (NF) could improve the balance between CEN and SN in healthy individuals. Therefore, we speculate that rt-fMRI NF of the CEN and SN associated with the GD system may improve depressive and/or anhedonic symptoms. Therefore, this study (1) will examine individuals with anhedonic depression using GD-RL behavioral task, combined with functional magnetic resonance imaging and computational modeling to explore the role of CEN/SN deficits in anhedonic depression; and (2) will utilize network-based rt-fMRI NF to investigate whether it is feasible to regulate the differential signals of brain CEN/SN of GD system through rt-fMRI NF to alleviate depressive and/or anhedonic symptoms. This study highlights the need to elucidate the intervention effects of rt-fMRI NF and the underlying computational network neural mechanisms.

Add-on pramipexole for anhedonic depression: study protocol for a randomised controlled trial and open-label follow-up in Lund, Sweden

INTRODUCTION

Many depressed patients do not achieve remission with available treatments. Anhedonia is a common residual symptom associated with treatment resistance as well as low function and quality of life. There are currently no specific and effective treatments for anhedonia. Some trials have shown that dopamine agonist pramipexole is efficacious for treating depression, but more data is needed before it could become ready for clinical prime time. Given its mechanism of action, pramipexole might be a useful treatment for a depression subtype characterised by significant anhedonia and lack of motivation-symptoms associated with dopaminergic hypofunction. We recently showed, in an open-label pilot study, that add-on pramipexole is a feasible treatment for depression with significant anhedonia, and that pramipexole increases reward-related activity in the ventral striatum. We will now confirm or refute these preliminary results in a randomised controlled trial (RCT) and an open-label follow-up study.

METHODS AND ANALYSIS

Eighty patients with major depression (bipolar or unipolar) or dysthymia and significant anhedonia according to the Snaith Hamilton Pleasure Scale (SHAPS) are randomised to either add-on pramipexole or placebo for 9 weeks. Change in anhedonia symptoms per the SHAPS is the primary outcome, and secondary outcomes include change in core depressive symptoms, apathy, sleep problems, life quality, anxiety and side effects. Accelerometers are used to assess treatment-associated changes in physical activity and sleep patterns. Blood and brain biomarkers are investigated as treatment predictors and to establish target engagement. After the RCT phase, patients continue with open-label treatment in a 6-month follow-up study aiming to assess long-term efficacy and tolerability of pramipexole.

ETHICS AND DISSEMINATION

The study has been approved by the Swedish Ethical Review Authority and the Swedish Medical Products Agency. The study is externally monitored according to Good Clinical Practice guidelines. Results will be disseminated via conference presentations and peer-reviewed publications.

TRIAL REGISTRATION NUMBER

NCT05355337 and NCT05825235.

Proinflammatory phenotype in major depressive disorder with adulthood adversity: In line with social signal transduction theory of depression

BACKGROUND

The social signal transduction theory of depression proposes that life stress can be transformed into inflammatory signals, and ultimately lead to the development of major depressive disorder (MDD). The hypotheses of this study were: (1) The pro-inflammatory effect of life stress was only seen in patients with MDD, but not in healthy controls (HCs); (2) Inflammation can mediate the relationship between life stress and depressive symptoms.

METHODS

This study included 170 MDD patients and 196 HCs, and 13 immune-inflammatory biomarkers closely related to MDD were measured, principal component analysis (PCA) was adopted to extract the inflammatory index. Life stress was assessed by Life Event Scale (LES), a total score of >32 points on the LES was considered as adulthood adversity (AA). Path analyses were used to explore the relationship among adulthood stress, inflammatory index, and severity of depression.

RESULTS

Among MDD patients, α2M, CXCL-1, IL-1β, and TLR-1 levels were higher in patients with AA than non-AA group (all FDR-adjusted P values <0.05), meanwhile, the levels of CCL-2 and IL-18 were lower. Path analyses suggested that pro- and anti-inflammatory index could mediate the association between AA and severity of depression in MDD patients.

CONCLUSION

This study found that inflammatory signals can mediate the relationship between adulthood adversity and depression, however, the causal relationship need to be further confirmed. These findings shed light on further understanding the theory of social signal transduction in MDD and provide clues for stress management and controlling inflammation strategies in depression.

CLINICAL TRIALS

NCT02023567.

The sex differences in anhedonia in major depressive disorder: A resting-state fMRI study

OBJECTIVE

The external behavioural manifestations and internal neural mechanisms of anhedonia are sexually dimorphic. This study aimed to explore the sex differences in the regional brain neuroimaging features of anhedonia in the context of major depressive disorder (MDD).

METHOD

The resting-fMRI by applying amplitude of low-frequency fluctuation (ALFF) method was estimated in 414 patients with MDD (281 high anhedonia [HA], 133 low anhedonia [LA]) and 213 healthy controls (HC). The effects of two factors in patients with MDD were analysed using a 2 (sex: male, female) × 2 (group: HA, LA) ANOVA concerning the brain regions in which statistical differences were identified between patients with MDD and HC. We followed up with patients with HA at baseline, and 43 patients completed a second fMRI scan in remission. Paired t-test was performed to compare the ALFF values of anhedonia-related brain regions between the baseline and remission periods.

RESULTS

For the sex-by-group interaction, the bilateral insula, right hippocampus, right post cingulum cortex, and left putamen showed significant differences. Furthermore, the abnormally elevated ALFF values in anhedonia-related brain regions at baseline decreased in remission.

CONCLUSION

Our findings point to the fact that the females showed unique patterns of anhedonia-related brain activity compared to males, which may have clinical implications for interfering with the anhedonia symptoms in MDD. Using task fMRI, we can further examine the distinct characteristics between consumption anhedonia and anticipation anhedonia in MDD.

Predictors of successful anti-inflammatory drug trials in patients with schizophrenia: A meta-regression and critical commentary

Given evidence pointing toward a role for immune dysregulation in the pathogenesis of schizophrenia, anti-inflammatory agents are promising adjunctive treatments that have potential to support a causal relationship for inflammation and psychopathology and lead to novel treatments for individuals. Indeed, previous meta-analyses have demonstrated small-to-medium effect sizes (ES) in favor of various anti-inflammatory agents, though there is significant heterogeneity and challenges in the interpretation of this literature. Identifying predictors, including sociodemographic variables, trial duration, and/or symptoms themselves, of successful anti-inflammatory trials may help identify which patients who might benefit from these compounds. We performed a meta-regression analysis of 63 adjunctive anti-inflammatory trial arms (2232 patients randomized to adjunctive anti-inflammatory agents and 2207 patients randomized to placebo).Potential predictors of effect size estimates for changes in psychopathology scores from baseline to endpoint included geography, trial duration, sample size, age, sex, race, smoking, body mass index, illness duration, age of onset of psychosis, study quality score and psychopathology scores (total and subscale) at baseline. Geography (β = 0.31, p = 0.011), smaller sample size (β = 0.33, p = 0.009), and higher study quality score (β = 0.44, p < 0.001) were significant predictors of larger ES estimates for change in total psychopathology in favor of anti-inflammatory agents. Smaller sample size (β = 0.37, p = 0.034) and higher study quality score (β = 0.55, p = 0.003) were significant predictors of larger ES estimates for change in negative psychopathology in favor of anti-inflammatory agents. Higher study quality score (β = 0.46, p = 0.019) was a significant predictor of larger ES estimates for change in general psychopathology in favor of anti-inflammatory agents. These findings should be interpreted with caution given concerns of publication bias regarding the geographic differences and small study effects. The lack of an association with other demographic variables should be seen as a primary limitation of the literature that needs to be considered in future studies. The association with study quality score suggests that future anti-inflammatory trials must consider demographic variables known to be associated with inflammation (e.g., BMI and smoking) and evidence of increased baseline inflammation should be incorporated in study design. Moreover, evidence of target engagement and endpoints thoughts to be associated with increased inflammation should be considered as well.

Inflammation, Dopaminergic Brain and Bilirubin

Dopamine is a well-known neurotransmitter due to its involvement in Parkinson's disease (PD). Dopamine is not only involved in PD but also controls multiple mental and physical activities, such as the pleasure of food, friends and loved ones, music, art, mood, cognition, motivation, fear, affective disorders, addiction, attention deficit disorder, depression, and schizophrenia. Dopaminergic neurons (DOPAn) are susceptible to stressors, and inflammation is a recognized risk for neuronal malfunctioning and cell death in major neurodegenerative diseases. Less is known for non-neurodegenerative conditions. Among the endogenous defenses, bilirubin, a heme metabolite, has been shown to possess important anti-inflammatory activity and, most importantly, to prevent DOPAn demise in an ex vivo model of PD by acting on the tumor necrosis factor-alpha (TNFα). This review summarizes the evidence linking DOPAn, inflammation (when possible, specifically TNFα), and bilirubin as an anti-inflammatory in order to understand what is known, the gaps that need filling, and the hypotheses of anti-inflammatory strategies to preserve dopamine homeostasis with bilirubin included.

Alterations in inflammasome-related immunometabolites in individuals with severe psychiatric disorders

INTRODUCTION

Psychiatric disorders are common and significantly impact the quality of life. Inflammatory processes are proposed to contribute to the emergence of psychiatric disorders. In addition to inflammation, disturbances in metabolic pathways have been observed in individuals with different psychiatric disorders. A suggested key player in the interaction between inflammation and metabolism is the Nod-like receptor 3 (NLRP3) inflammasome, and NLRP3 is known to react to a number of specific metabolites. However, little is known about the interplay between these immunometabolites and the NLRP3 inflammasome in mental health disorders.

AIM

To assess the interplay between immunometabolites and inflammasome function in a transdiagnostic cohort of individuals with severe mental disorders.

METHODS

Mass spectrometry-based analysis of selected immunometabolites, previously known to affect inflammasome function, were performed in plasma from low-functioning individuals with severe mental disorders (n = 39) and sex and aged-matched healthy controls (n = 39) using a transdiagnostic approach. Mann Whitney U test was used to test differences in immunometabolites between psychiatric patients and controls. To assess the relationship between inflammasome parameters, disease severity, and the immunometabolites, Spearman's rank-order correlation test was used. Conditional logistic regression was used to control for potential confounding variables. Principal component analysis was performed to explore immunometabolic patterns.

RESULTS

Among the selected immunometabolites (n = 9), serine, glutamine, and lactic acid were significantly higher in the patient group compared to the controls. After adjusting for confounders, the differences remained significant for all three immunometabolites. No significant correlations were found between immunometabolites and disease severity.

CONCLUSION

Previous research on metabolic changes in mental disorders has not been conclusive. This study shows that severely ill patients have common metabolic perturbations. The changes in serine, glutamine, and lactic acid could constitute a direct contribution to the low-grade inflammation observed in severe psychiatric disorders.

An inflamed subtype of difficult-to-treat depression

BACKGROUND

Chronic low-grade inflammation may play a role in the pathophysiology of depression, at least in a subset of patients. High-sensitivity C-reactive protein (hs-CRP) has been used to define an inflamed subgroup of depression with specific clinical characteristics and symptoms. In this study we investigated biochemical and clinical characteristics in patients with difficult-to-treat depression with and without chronic low-grade inflammation.

METHOD

We assayed plasma levels of interferon-gamma, tumor necrosis factor-alpha, Interleukin (IL)-10, IL-6, IL-8, and vitamin D in a clinically well-characterized sample of patients with difficult-to-treat depression (n = 263) and healthy controls (n = 46). Serum hs-CRP levels were available in the patient group and were used to define "inflamed depression" (hs-CRP > 3 mg/L). Based on previous studies correlating specific depressive symptoms to inflammatory markers, we calculated a composite score of inflammatory depressive symptoms (Infl-Dep score). A principal component analysis (PCA) was performed to identify patterns of variance in cytokines and vitamin D among patients.

RESULTS

Mean levels of IL-6 and IL-8 were significantly higher in depressed patients compared to controls, also after adjusting for sex, smoking, BMI, and age. None of the other inflammatory markers differed significantly between depressed patients and controls. Two components were extracted using PCA; one showed general cytokine elevations and one represented a pattern where IL-6 and IL-8 were inversely related to vitamin D (IL6-IL8-VitD component). The inflamed subgroup (hs-CRP > 3, n = 51) exhibited significantly higher BMI, higher Infl-Dep scores and higher IL6-IL8-VitD component scores than uninflamed patients (hs-CRP ≤ 3, n = 212). There were no significant differences in overall depression severity or suicidality between the inflamed and uninflamed groups.

CONCLUSION

Our results support the hypothesis of an inflamed subgroup of depression as a meaningful construct. This subgroup may have certain biological and clinical characteristics and more studies are needed to determine potential clinical implications.

New and emerging approaches to treat psychiatric disorders

Psychiatric disorders are highly prevalent, often devastating diseases that negatively impact the lives of millions of people worldwide. Although their etiological and diagnostic heterogeneity has long challenged drug discovery, an emerging circuit-based understanding of psychiatric illness is offering an important alternative to the current reliance on trial and error, both in the development and in the clinical application of treatments. Here we review new and emerging treatment approaches, with a particular emphasis on the revolutionary potential of brain-circuit-based interventions for precision psychiatry. Limitations of circuit models, challenges of bringing precision therapeutics to market and the crucial advances needed to overcome these obstacles are presented.

A role of gut-microbiota-brain axis via subdiaphragmatic vagus nerve in depression-like phenotypes in Chrna7 knock-out mice

The α7 subtype of the nicotinic acetylcholine receptor (α7 nAChR: coded by Chrna7) is known to regulate the cholinergic ascending anti-inflammatory pathway. We previously reported that Chrna7 knock-out (KO) mice show depression-like behaviors through abnormal composition of gut microbiota and systemic inflammation. Given the role of subdiaphragmatic vagus nerve in gut-microbiota-brain axis, we investigated whether subdiaphragmatic vagotomy (SDV) could affect depression-like behaviors, abnormal composition of gut microbiota, and microbes-derived metabolites in Chrna7 KO mice. SDV blocked depression-like behaviors and reduced expression of synaptic proteins in the medial prefrontal cortex (mPFC) of Chrna7 KO mice. LEfSe (linear discriminant analysis effect size) analysis revealed that the species Lactobacillus sp. BL302, the species Lactobacillus hominis, and the species Lactobacillus reuteri, were identified as potential microbial markers in the KO + SDV group. There were several genus and species altered among the three groups [wild-type (WT) + sham group, KO + sham group, KO + SDV group]. Furthermore, there were several plasma metabolites altered among the three groups. Moreover, there were correlations between relative abundance of several microbiome and behavioral data (or synaptic proteins). Network analysis showed correlations between relative abundance of several microbiome and plasma metabolites (or behavioral data). These data suggest that Chrna7 KO mice produce depression-like behaviors and reduced expression of synaptic proteins in the mPFC through gut-microbiota-brain axis via subdiaphragmatic vagus nerve.

Burning down the house: reinventing drug discovery in psychiatry for the development of targeted therapies

Despite advances in neuroscience, limited progress has been made in developing new and better medications for psychiatric disorders. Available treatments in psychiatry rely on a few classes of drugs that have a broad spectrum of activity across disorders with limited understanding of mechanism of action. While the added value of more targeted therapies is apparent, a dearth of pathophysiologic mechanisms exists to support targeted treatments, and where mechanisms have been identified and drugs developed, results have been disappointing. Based on serendipity and early successes that led to the current drug armamentarium, a haunting legacy endures that new drugs should align with outdated and overinclusive diagnostic categories, consistent with the idea that "one size fits all". This legacy has fostered clinical trial designs focused on heterogenous populations of patients with a single diagnosis and non-specific outcome variables. Disturbingly, this approach likely contributed to missed opportunities for drugs targeting the hypothalamic-pituitary-adrenal axis and now inflammation. Indeed, cause-and-effect data support the role of inflammatory processes in neurotransmitter alterations that disrupt specific neurocircuits and related behaviors. This pathway to pathology occurs across disorders and warrants clinical trial designs that enrich for patients with increased inflammation and use primary outcome variables associated with specific effects of inflammation on brain and behavior. Nevertheless, such trial designs have not been routinely employed, and results of anti-inflammatory treatments have been underwhelming. Thus, to accelerate development of targeted therapeutics including in the area of inflammation, regulatory agencies and the pharmaceutical industry must embrace treatments and trials focused on pathophysiologic pathways that impact specific symptom domains in subsets of patients, agnostic to diagnosis. Moreover, closer collaboration among basic and clinical investigators is needed to apply neuroscience knowledge to reveal disease mechanisms that drive psychiatric symptoms. Together, these efforts will support targeted treatments, ultimately leading to new and better therapeutics in psychiatry.

Dopamine, Immunity, and Disease

The neurotransmitter dopamine is a key factor in central nervous system (CNS) function, regulating many processes including reward, movement, and cognition. Dopamine also regulates critical functions in peripheral organs, such as blood pressure, renal activity, and intestinal motility. Beyond these functions, a growing body of evidence indicates that dopamine is an important immunoregulatory factor. Most types of immune cells express dopamine receptors and other dopaminergic proteins, and many immune cells take up, produce, store, and/or release dopamine, suggesting that dopaminergic immunomodulation is important for immune function. Targeting these pathways could be a promising avenue for the treatment of inflammation and disease, but despite increasing research in this area, data on the specific effects of dopamine on many immune cells and disease processes remain inconsistent and poorly understood. Therefore, this review integrates the current knowledge of the role of dopamine in immune cell function and inflammatory signaling across systems. We also discuss the current understanding of dopaminergic regulation of immune signaling in the CNS and peripheral tissues, highlighting the role of dopaminergic immunomodulation in diseases such as Parkinson's disease, several neuropsychiatric conditions, neurologic human immunodeficiency virus, inflammatory bowel disease, rheumatoid arthritis, and others. Careful consideration is given to the influence of experimental design on results, and we note a number of areas in need of further research. Overall, this review integrates our knowledge of dopaminergic immunology at the cellular, tissue, and disease level and prompts the development of therapeutics and strategies targeted toward ameliorating disease through dopaminergic regulation of immunity. SIGNIFICANCE STATEMENT: Canonically, dopamine is recognized as a neurotransmitter involved in the regulation of movement, cognition, and reward. However, dopamine also acts as an immune modulator in the central nervous system and periphery. This review comprehensively assesses the current knowledge of dopaminergic immunomodulation and the role of dopamine in disease pathogenesis at the cellular and tissue level. This will provide broad access to this information across fields, identify areas in need of further investigation, and drive the development of dopaminergic therapeutic strategies.

Increased Inflammation and Treatment of Depression: From Resistance to Reuse, Repurposing, and Redesign

Based on mounting clinical and translational evidence demonstrating the impact of exogenously administered inflammatory stimuli on the brain and behavior, increased endogenous inflammation has received attention as one pathophysiologic process contributing to psychiatric illnesses and particularly depression. Increased endogenous inflammation is observed in a significant proportion of depressed patients and has been associated with reduced responsiveness to standard antidepressant therapies. This chapter presents recent evidence that inflammation affects neurotransmitters and neurocircuits to contribute to specific depressive symptoms including anhedonia, motor slowing, and anxiety, which may preferentially improve after anti-cytokine therapies in patients with evidence of increased inflammation. Existing and novel pharmacological strategies that target inflammation or its downstream effects on the brain and behavior will be discussed in the context of a need for intelligent trial design in order to meaningfully translate these concepts and develop more precise therapies for depressed patients with increased inflammation.