Basal ganglia hypermetabolism and symptoms of fatigue during interferon-alpha therapy

Associations of depression and perceived physical fatigability with white matter integrity in older adults

BACKGROUNDS

Fatigability is prevalent in older adults. However, it is often associated with depressed mood. We aim to investigate these two psychobehavioral constructs by examining their underpinning of white matter structures in the brain and their associations with different medical conditions.

METHODS

Twenty-seven older adults with late-life depression (LLD) and 34 cognitively normal controls (CN) underwent multi-shell diffusion MRI. Fatigability was measured with the Pittsburgh Fatigability Scale. We examined white matter integrity by measuring the quantitative anisotropy (QA), a fiber tracking parameter with better accuracy than the traditional imaging technique.

RESULTS

We found those with LLD had lower QA in the 2nd branch of the left superior longitudinal fasciculus (SLF-II), and those with more physical fatigability had lower QA in more widespread brain regions. In tracts associated with more physical fatigability, the lower QA in left acoustic radiation and left superior thalamic radiation correlated with higher blood glucose (r = - 0.46 and - 0.49). In tracts associated with depression, lower QA in left SLF-II correlated with higher bilirubin level (r = - 0.58).

DISCUSSION

Depression and fatigability were associated with various white matter integrity changes, which correlated with biochemistry biomarkers all related to inflammation.

Fatigue and perceived energy in a sample of older adults over 10 years: A resting state functional connectivity study of neural correlates

PURPOSE

Declining energy and increasing fatigue, common in older age, predict neurodegenerative conditions, but their neural substrates are not known. We examined brain resting state connectivity in relation to declining self-reported energy levels (SEL) and occurrence of fatigue over time.

METHODS

We examined resting-state functional MRI in 272 community dwelling older adults participating in the Health Aging and Body Composition Study (mean age 83 years; 57.4 % female; 40.8 % Black) with measures of fatigue and SEL collected at regular intervals over the prior ten years. Functional connectivity (FC) between cortex and striatum was examined separately for sensorimotor, executive, and limbic functional subregions. Logistic regression tested the association of FC in each network with prior fatigue state (reporting fatigue at least once or never reporting fatigue), and with SEL decline (divided into stable or declining SEL groups) and adjusted for demographic, physical function, mood, cognition, and comorbidities.

RESULTS

Higher cortico-striatal FC in the right limbic network was associated with lower odds of reporting fatigue (better) at least once during the study period (adjusted odds ratio [95 % confidence interval], p-value: (0.747 [0.582, 0.955], 0.020), independent of SEL. Higher cortico-striatal FC in the right executive network was associated with higher odds of declining SEL (worse) during the study period (adjusted odds ratio [95 % confidence interval], p-value: (1.31 [1.01, 1.69], 0.041), independent of fatigue. Associations with other networks were not significant.

CONCLUSIONS

In this cohort of older adults, the cortico-striatal functional connectivity of declining SEL appears distinct from that underlying fatigue. Studies to further assess the neural correlates of energy and fatigue, and their independent contribution to neurodegenerative conditions are warranted.

Role of cytokines and reactive oxygen species in brain aging

Aging is a complex process that produces profound effects on the brain. Although a number of external factors can promote the initiation and progression of brain aging, peripheral and central changes in the immune cells with time, also play an important role. Immunosenescence, which is an age-associated decline in immune function and Inflammaging, a low-grade inflammatory state in the aging brain contribute to an elevation in cytokine and reactive oxygen species production. In this review, we focus on the pro-inflammatory state that is established in the brain as a consequence of these two phenomena and the resulting detrimental changes in brain structure, function and repair that lead to a decline in central and neuroendocrine function.

Metabolic Brain Changes Can Predict the Underlying Pathology in Neurodegenerative Brain Disorders: A Case Report of Sporadic Creutzfeldt-Jakob Disease with Concomitant Parkinson's Disease

The co-occurrence of multiple proteinopathies is being increasingly recognized in neurodegenerative disorders and poses a challenge in differential diagnosis and patient selection for clinical trials. Changes in brain metabolism captured by positron emission tomography (PET) with 18 F-fluorodeoxyglucose (FDG) allow us to differentiate between different neurodegenerative disorders either by visual exploration or by studying disease-specific metabolic networks in individual patients. However, the impact of multiple proteinopathies on brain metabolism and metabolic networks remains unknown due to the absence of pathological studies. In this case study, we present a 67-year-old patient with rapidly progressing dementia clinically diagnosed with probable sporadic Creutzfeldt-Jakob disease (sCJD). However, in addition to the expected pronounced cortical and subcortical hypometabolism characteristic of sCJD, the brain FDG PET revealed an intriguing finding of unexpected relative hypermetabolism in the bilateral putamina, raising suspicions of coexisting Parkinson's disease (PD). Additional investigation of disease-specific metabolic brain networks revealed elevated expression of both CJD-related pattern (CJDRP) and PD-related pattern (PDRP) networks. The patient eventually developed akinetic mutism and passed away seven weeks after symptom onset. Neuropathological examination confirmed neuropathological changes consistent with sCJD and the presence of Lewy bodies confirming PD pathology. Additionally, hyperphosphorylated tau and TDP-43 pathology were observed, a combination of four proteinopathies that had not been previously reported. Overall, this case provides valuable insights into the complex interplay of neurodegenerative pathologies and their impact on metabolic brain changes, emphasizing the role of metabolic brain imaging in evaluating potential presence of multiple proteinopathies.

Chronic IFNα treatment induces leukopoiesis, increased plasma succinate and immune cell metabolic rewiring

Although clinically effective, the actions of IFNα, either produced endogenously or by therapeutic delivery, remain poorly understood. Emblematic of this research gap is the disparate array of notable side effects that occur in susceptible individuals, such as neuropsychiatric consequences, autoimmune phenomena, and infectious complications. We hypothesised that these complications are driven at least in part by dysregulated cellular metabolism. Male Wistar rats were treated with either 170,000 IU/kg human recombinant IFNα-2a or BSA/saline (0.9% NaCl) three times per week for three weeks. Bone marrow (BM) immune cells were isolated from the excised femurs for glycolytic rate and mitochondrial function assessment using Agilent Seahorse Technology. Frequencies of immune cell populations were assessed by flow cytometry to determine whether leukopoietic changes had occurred in both blood and BM. Plasma levels of lactate and succinate were also determined. BMDMs were metabolically assessed as above, as well as their metabolic response to an antigenic stimulus (iH37Rv). We observed that BM immune cells from IFN-treated rats exhibit a hypermetabolic state (increased basal OCR/GlycoPER) with decreased mitochondrial metabolic respiration and increased non-mitochondrial OCR. Flow cytometry results indicated an increase in immature granulocytes (RP1- SSChi CD45lo) only in the blood, together with increased succinate levels in the plasma. BMDMs from IFN-treated rats retained the hypermetabolic phenotype after differentiation and failed to induce a step-up in glycolysis and mitochondrial respiration after bacterial stimulation. This work provides the first evidence of the effects of IFNα treatment in inducing hypermetabolic immune features that are associated with markers of inflammation, leukopoiesis, and defective responses to bacterial stimulation.

Inflammation, stress and depression: An exploration of ketamine's therapeutic profile

Well-established animal models of depression have described a proximal relationship between stress and central nervous system (CNS) inflammation - a relationship mirrored in the peripheral inflammatory biomarkers of individuals with depression. Evidence also suggests that stress-induced proinflammatory states can contribute to the neurobiology of treatment-resistant depression. Interestingly, ketamine, a rapid-acting antidepressant, can partially exert its therapeutic effects via anti-inflammatory actions on the hypothalamic-pituitary adrenal (HPA) axis, the kynurenine pathway or by cytokine suppression. Further investigations into the relationship between ketamine, inflammation and stress could provide insight into ketamine's unique therapeutic mechanisms and stimulate efforts to develop rapid-acting, anti-inflammatory-based antidepressants.

Structural brain changes in patients with post-COVID fatigue: a prospective observational study

BACKGROUND

Post-COVID syndrome is a severe long-term complication of COVID-19. Although fatigue and cognitive complaints are the most prominent symptoms, it is unclear whether they have structural correlates in the brain. We therefore explored the clinical characteristics of post-COVID fatigue, describe associated structural imaging changes, and determine what influences fatigue severity.

METHODS

We prospectively recruited 50 patients from neurological post-COVID outpatient clinics (age 18-69 years, 39f/8m) and matched non-COVID healthy controls between April 15 and December 31, 2021. Assessments included diffusion and volumetric MR imaging, neuropsychiatric, and cognitive testing. At 7.5 months (median, IQR 6.5-9.2) after the acute SARS-CoV-2 infection, moderate or severe fatigue was identified in 47/50 patients with post-COVID syndrome who were included in the analyses. As a clinical control group, we included 47 matched multiple sclerosis patients with fatigue.

FINDINGS

Our diffusion imaging analyses revealed aberrant fractional anisotropy of the thalamus. Diffusion markers correlated with fatigue severity, such as physical fatigue, fatigue-related impairment in everyday life (Bell score) and daytime sleepiness. Moreover, we observed shape deformations and decreased volumes of the left thalamus, putamen, and pallidum. These overlapped with the more extensive subcortical changes in MS and were associated with impaired short-term memory. While fatigue severity was not related to COVID-19 disease courses (6/47 hospitalised, 2/47 with ICU treatment), post-acute sleep quality and depressiveness emerged as associated factors and were accompanied by increased levels of anxiety and daytime sleepiness.

INTERPRETATION

Characteristic structural imaging changes of the thalamus and basal ganglia underlie the persistent fatigue experienced by patients with post-COVID syndrome. Evidence for pathological changes to these subcortical motor and cognitive hubs provides a key to the understanding of post-COVID fatigue and related neuropsychiatric complications.

FUNDING

Deutsche Forschungsgemeinschaft (DFG) and German Ministry of Education and Research (BMBF).

Dopamine Transmission Imbalance in Neuroinflammation: Perspectives on Long-Term COVID-19

Dopamine (DA) is a key neurotransmitter in the basal ganglia, implicated in the control of movement and motivation. Alteration of DA levels is central in Parkinson’s disease (PD), a common neurodegenerative disorder characterized by motor and non-motor manifestations and deposition of alpha-synuclein (α-syn) aggregates. Previous studies have hypothesized a link between PD and viral infections. Indeed, different cases of parkinsonism have been reported following COVID-19. However, whether SARS-CoV-2 may trigger a neurodegenerative process is still a matter of debate. Interestingly, evidence of brain inflammation has been described in postmortem samples of patients infected by SARS-CoV-2, which suggests immune-mediated mechanisms triggering the neurological sequelae. In this review, we discuss the role of proinflammatory molecules such as cytokines, chemokines, and oxygen reactive species in modulating DA homeostasis. Moreover, we review the existing literature on the possible mechanistic interplay between SARS-CoV-2-mediated neuroinflammation and nigrostriatal DAergic impairment, and the cross-talk with aberrant α-syn metabolism.

Effects of an experimentally induced inflammatory stimulus on motivational behavior in remitted depressed patients

BACKGROUND

Acute inflammation is associated with sickness behavior characterized by reduced motivation for pleasurable activities in humans. The current study investigated the effect of an experimentally induced inflammatory stimulus on motivational reward in people who remitted from depression.

METHODS

This randomized, double-blind crossover study involved 12 participants, 5 with remitted major depressive disorder (rMDD) and 7 healthy controls (HC), who received an injection of typhoid vaccine and placebo (or vice-versa) intramuscularly at least one week apart. At baseline and between 4 and 6 h post-injection on both days, participant mood was measured using the profile of mood states (POMS), and injection blood samples were collected for cytokines measurement. All participants completed the Effort Expenditure for Rewards Task (EEfRT), a behavioral paradigm measuring effort-based decision-making before and 4 h post-both injections. Generalized linear mixed modeling was used to evaluate group differences in choosing the hard over easy task to obtain a monetary reward.

RESULTS

Typhoid vaccine increased IL-6 in all participants. On the EEfRT, a significant interaction between treatment condition (typhoid vs. placebo) and participant group (HC vs. rMDD) was found (p = .004). Analyses of simple effects within treatment conditions found that after placebo, HCs were more likely to choose the harder task than rMDD (OR = 3.21; p = .013). However, after the typhoid vaccine, no differences were found between rMDD and HC (p = .397). Analyses within participant groups found that the probability of choosing a hard task was higher after placebo for HC (OR = 1.37; p = .045), but not different within rMDD (p = .241). For HC at baseline, mood was significantly lower following injection with typhoid vaccine, relative to placebo (b = -1.03, p < .001); however, this effect should be considered coincidental, given that mood rating was taken prior to injection. For rMDD patients 4-6 h post-injection, mood was significantly lower following typhoid vaccine, relative to placebo (b = -0.981, p < .001 b = -0.77, p < .001). Finally, for HC receiving placebo, mood was significantly lower 4-6 h post-injection, relative to baseline (b = -1.76, p < .001).

CONCLUSIONS

Our preliminary findings suggest persistent deficits in motivational reward processing function despite clinical improvement in remitted depressed patients.

Inflammation-Related Functional and Structural Dysconnectivity as a Pathway to Psychopathology

Findings from numerous laboratories and across neuroimaging modalities have consistently shown that exogenous administration of cytokines or inflammatory stimuli that induce cytokines disrupts circuits and networks involved in motivation and motor activity, threat detection, anxiety, and interoceptive and emotional processing. While inflammatory effects on neural circuits and relevant behaviors may represent adaptive responses promoting conservation of energy and heightened vigilance during immune activation, chronically elevated inflammation may contribute to symptoms of psychiatric illnesses. Indeed, biomarkers of inflammation such as cytokines and acute phase reactants are reliably elevated in a subset of patients with unipolar or bipolar depression, anxiety-related disorders, and schizophrenia and have been associated with differential treatment responses and poor clinical outcomes. A growing body of literature also describes higher levels of endogenous inflammatory markers and altered, typically lower functional or structural connectivity within these circuits in association with transdiagnostic symptoms such as anhedonia and anxiety in psychiatric and at-risk populations. This review presents recent evidence that inflammation and its effects on the brain may serve as one molecular and cellular mechanism of dysconnectivity within anatomically and/or functionally connected cortical and subcortical regions in association with transdiagnostic symptoms. We also discuss the need to establish reproducible methods to assess inflammation-associated dysconnectivity in relation to behavior for use in translational studies or biomarker-driven clinical trials for novel pharmacological or behavioral interventions targeting inflammation or its effects on the brain.

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.

Cerebral glucose changes after chemotherapy and their relation to long-term cognitive complaints and fatigue

Purpose

To investigate the short-term cerebral metabolic effects of intravenous chemotherapy and their association with long-term fatigue/cognitive complaints.

Experimental design

Using [¹⁸F]-FDG-PET/CT whole-body scans, we retrospectively quantified relative cerebral glucose metabolism before and after neoadjuvant chemotherapy in a cohort of patients treated for non-metastatic breast cancer (2009-2019). Self-report of cognitive complaints and fatigue were prospectively assessed 7 ± 3 years after therapy. Metabolic changes were estimated with i) robust mixed-effects modelling in regions-of-interest (frontal, parietal, temporal, occipital, and insular cortex) and ii) general-linear modelling of whole-brain voxel-wise outcomes. iii) The association between metabolic changes and self-reported outcomes was evaluated using linear regression-analysis.

Results

Of the 667 screened patients, 263 underwent PET/CT before and after chemotherapy and 183 (48 ± 9 years) met the inclusion criteria. After chemotherapy, decreased frontal and increased parietal and insular metabolism were observed (|ß|>0.273, p_FDR<0.008). Separately, additional increased occipital metabolism after epiribucin+ cyclophosphamide (EC) and temporal metabolism after EC+ fluorouracil chemotherapy were observed (ß>0.244, p_FDR≤0.048). Voxel-based analysis (p_cluster-FWE<0.001) showed decreased metabolism in the paracingulate gyrus (-3.2 ± 3.9%) and putamen (3.1 ± 4.1%) and increased metabolism in the lateral cortex (L=2.9 ± 3.1%) and pericentral gyri (3.0 ± 4.4%). Except for the central sulcus, the same regions showed changes in EC, but not in FEC patients. Of the 97 self-reported responders, 23% and 27% experienced extreme fatigue and long-term cognitive complaints, respectively, which were not associated with metabolic changes.

Conclusion

Both hyper- and hypometabolism were observed after chemotherapy for breast cancer. Combined with earlier findings, this study could support inflammatory mechanisms resulting in relative hypermetabolism, mainly in the parietal/occipital cortices. As early metabolic changes did not precede long-term complaints, further research is necessary to identify vulnerable patients.

Behavioral activation therapy for depression is associated with a reduction in the concentration of circulating quinolinic acid

BACKGROUND

An inflammation-induced imbalance in the kynurenine pathway (KP) has been reported in major depressive disorder but the utility of these metabolites as predictive or therapeutic biomarkers of behavioral activation (BA) therapy is unknown.

METHODS

Serum samples were provided by 56 depressed individuals before BA therapy and 29 of these individuals also provided samples after 10 weeks of therapy to measure cytokines and KP metabolites. The PROMIS Depression Scale (PROMIS-D) and the Sheehan Disability Scale were administered weekly and the Beck depression inventory was administered pre- and post-therapy. Data were analyzed with linear mixed-effect, general linear, and logistic regression models. The primary outcome for the biomarker analyses was the ratio of kynurenic acid to quinolinic acid (KynA/QA).

RESULTS

BA decreased depression and disability scores (p's < 0.001, Cohen's d's > 0.5). KynA/QA significantly increased at post-therapy relative to baseline (p < 0.001, d = 2.2), an effect driven by a decrease in QA post-therapy (p < 0.001, uncorrected, d = 3.39). A trend towards a decrease in the ratio of kynurenine to tryptophan (KYN/TRP) was also observed (p = 0.054, uncorrected, d = 0.78). Neither the change in KynA/QA, nor baseline KynA/QA were associated with response to BA therapy.

CONCLUSION

The current findings together with previous research show that electronconvulsive therapy, escitalopram, and ketamine decrease concentrations of the neurotoxin, QA, raise the possibility that a common therapeutic mechanism underlies diverse forms of anti-depressant treatment but future controlled studies are needed to test this hypothesis.

Tetrahydrobiopterin modulates the behavioral neuroinflammatory response to an LPS challenge in mice

Tetrahydrobiopterin (BH4) is a necessary cofactor for the synthesis of monoamines from essential amino-acids, phenylalanine, tyrosine and tryptophan. The BH4 synthesis pathway is induced by inflammatory factors but highly regulated processes maintain levels in a physiological range. However, BH4 activity can be durably altered in inflammation-related pathologies, such as certain types of depression, potentially involving impairment of dopaminergic neurotransmission. The purpose of this study was to investigate the response of the brain BH4 pathway to the inflammatory stimulus induced by lipopolysaccharide (LPS) in mice. Brain expression of genes related to BH4 synthesis, levels of BH4, changes in L-aromatic amino acid precursors of monoamines and dopamine levels were determined. As secondary aim, the effect of acute BH4 supply under the inflammatory challenge was tested on these parameters and on the expression of inflammatory cytokines. Mice were also submitted to the sucrose preference test and to the open-field in order to asses hedonic and locomotor responses to LPS, in addition to their modulation by BH4 supply. The LPS challenge resulted in decreased striatal DA levels and increased Phenylalanine/Tyrosine ratio, suggesting reduced BH4 activity. BH4 supply was effective to increase striatal BH4 levels, to restore the LPS-induced decreased in DA levels in striatum and to dampen the LPS-induced expression of inflammatory cytokines. At the behavioral level, BH4 supply was able to restore the loss of locomotor response to amphetamine in the LPS treated mice, suggesting a modulation of the dopaminergic neurotransmission. These data suggest that BH4 can be considered as a potential add-on molecule, helping to maintain or restore dopaminergic neurotransmission in neuroinflammatory conditions..

Cognitive dysfunction in SLE: An understudied clinical manifestation

Neuropsychiatric lupus (NPSLE) is a debilitating manifestation of SLE which occurs in a majority of SLE patients and has a variety of clinical manifestations. In the central nervous system, NPSLE may result from ischemia or penetration of inflammatory mediators and neurotoxic antibodies through the blood brain barrier (BBB). Here we focus on cognitive dysfunction (CD) as an NPSLE manifestation; it is common, underdiagnosed, and without specific therapy. For a very long time, clinicians ignored cognitive dysfunction and researchers who might be interested in the question struggled to find an approach to understanding mechanisms for this manifestation. Recent years, however, propelled by a more patient-centric approach to disease, have seen remarkable progress in our understanding of CD pathogenesis. This has been enabled through the use of novel imaging modalities and numerous mouse models. Overall, these studies point to a pivotal role of an impaired BBB and microglial activation in leading to neuronal injury. These insights suggest potential therapeutic modalities and make possible clinical trials for cognitive impairment.

Influences of dopaminergic system dysfunction on late-life depression

Deficits in cognition, reward processing, and motor function are clinical features relevant to both aging and depression. Individuals with late-life depression often show impairment across these domains, all of which are moderated by the functioning of dopaminergic circuits. As dopaminergic function declines with normal aging and increased inflammatory burden, the role of dopamine may be particularly salient for late-life depression. We review the literature examining the role of dopamine in the pathogenesis of depression, as well as how dopamine function changes with aging and is influenced by inflammation. Applying a Research Domain Criteria (RDoC) Initiative perspective, we then review work examining how dopaminergic signaling affects these domains, specifically focusing on Cognitive, Positive Valence, and Sensorimotor Systems. We propose a unified model incorporating the effects of aging and low-grade inflammation on dopaminergic functioning, with a resulting negative effect on cognition, reward processing, and motor function. Interplay between these systems may influence development of a depressive phenotype, with an initial deficit in one domain reinforcing decline in others. This model extends RDoC concepts into late-life depression while also providing opportunities for novel and personalized interventions.

Inflammation as a Pathophysiologic Pathway to Anhedonia: Mechanisms and Therapeutic Implications

Anhedonia, characterized by a lack of motivation, interest, or ability to experience pleasure, is a prominent symptom of depression and other psychiatric disorders and has been associated with poor response to standard therapies. One pathophysiologic pathway receiving increased attention for its potential role in anhedonia is inflammation and its effects on the brain. Exogenous administration of inflammatory stimuli to humans and laboratory animals has reliably been found to affect neurotransmitters and neurocircuits involved in reward processing, including the ventral striatum and ventromedial prefrontal cortex, in association with reduced motivation. Moreover, a rich literature including meta-analyses describes increased inflammation in a significant proportion of patients with depression and other psychiatric illnesses involving anhedonia, as evident by elevated inflammatory cytokines, acute phase proteins, chemokines, and adhesion molecules in both the periphery and central nervous system. This endogenous inflammation may arise from numerous sources including stress, obesity or metabolic dysfunction, genetics, and lifestyle factors, many of which are also risk factors for psychiatric illness. Consistent with laboratory studies involving exogenous administration of peripheral inflammatory stimuli, neuroimaging studies have further confirmed that increased endogenous inflammation in depression is associated with decreased activation of and reduced functional connectivity within reward circuits involving ventral striatum and ventromedial prefrontal cortex in association with anhedonia. Here, we review recent evidence of relationships between inflammation and anhedonia, while highlighting translational and mechanistic work describing the impact of inflammation on synthesis, release, and reuptake of neurotransmitters like dopamine and glutamate that affects circuits to drive motivational deficits. We will then present insight into novel pharmacological strategies that target either inflammation or its downstream effects on the brain and behavior. The meaningful translation of these concepts through appropriately designed trials targeting therapies for psychiatric patients with high inflammation and transdiagnostic symptoms of anhedonia is also discussed.

Depressive Disorders in HIV/AIDS: A Clinically Focused Narrative Review

After participating in this activity, learners should be better able to:• Assess strategies for diagnosing depressive disorders in patients with human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS)• Identify factors that contribute to the development of depressive disorders in HIV/AIDS• Evaluate strategies for managing depressive disorders in HIV/AIDS ABSTRACT: Depressive disorders and human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) are associated with major socioeconomic burdens. The negative impact of depressive disorders on HIV/AIDS is well known, including on treatment outcomes. Unfortunately, depressive disorders are underdiagnosed and undertreated in seropositive persons. This review summarizes clinically useful information on depressive disorders in HIV/AIDS. More specifically, we address assessment, differential diagnosis, contributing factors, management, and common challenges in the treatment of depressive disorders in seropositive individuals. Assessment and diagnosis of depression may be challenging in seropositive persons because of several biopsychosocial particularities associated with HIV/AIDS. One of the difficulties is the overlap between depression and HIV/AIDS symptoms, particularly in individuals with advanced AIDS, requiring consideration of a broad differential diagnosis. Several factors related to HIV/AIDS status contribute to the higher rates of depressive disorders, including infectious-immunological, psychosocial, and exogenous factors. The treatment of depressive disorders in HIV/AIDS involves three groups of interventions: (1) pharmacological interventions, (2) psychotherapeutic interventions, and (3) management of other contributing factors. Challenges in management include poor adherence to treatment and the risk of suicide. We provide evidence-based recommendations to improve assessment and management of depressive disorders in seropositive persons.

Multimodal Investigations of Reward Circuitry and Anhedonia in Adolescent Depression

Depression is a highly prevalent condition with devastating personal and public health consequences that often first manifests during adolescence. Though extensively studied, the pathogenesis of depression remains poorly understood, and efforts to stratify risks and identify optimal interventions have proceeded slowly. A major impediment has been the reliance on an all-or-nothing categorical diagnostic scheme based solely on whether a patient endorses an arbitrary number of common symptoms for a sufficiently long period. This approach masks the well-documented heterogeneity of depression, a disorder that is highly variable in presentation, severity, and course between individuals and is frequently comorbid with other psychiatric conditions. In this targeted review, we outline the limitations of traditional diagnosis-based research and instead advocate an alternative approach centered around symptoms as unique dimensions of clinical dysfunction that span across disorders and more closely reflect underlying neurobiological abnormalities. In particular, we highlight anhedonia-the reduced ability to anticipate and experience pleasure-as a specific, quantifiable index of reward dysfunction and an ideal candidate for dimensional investigation. Anhedonia is a core symptom of depression but also a salient feature of numerous other conditions, and its severity varies widely within clinical and even healthy populations. Similarly, reward dysfunction is a hallmark of depression but is evident across many psychiatric conditions. Reward function is especially relevant in adolescence, a period characterized by exaggerated reward-seeking behaviors and rapid maturation of neural reward circuitry. We detail extensive work by our research group and others to investigate the neural and systemic factors contributing to reward dysfunction in youth, including our cumulative findings using multiple neuroimaging and immunological measures to study depressed adolescents but also trans-diagnostic cohorts with diverse psychiatric symptoms. We describe convergent evidence that reward dysfunction: (a) predicts worse clinical outcomes, (b) is associated with functional and chemical abnormalities within and beyond the neural reward circuitry, (c) is linked to elevated peripheral levels of inflammatory biomarkers, and (d) manifests early in the course of illness. Emphasis is placed on high-resolution neuroimaging techniques, comprehensive immunological assays, and data-driven analyses to fully capture and characterize the complex, interconnected nature of these systems and their contributions to adolescent reward dysfunction.

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

Exogenous administration of inflammatory stimuli to humans and laboratory animals and chronic endogenous inflammatory states lead to motivational deficits and ultimately anhedonia, a core and disabling symptom of depression present in multiple other psychiatric disorders. Inflammation impacts neurotransmitter systems and neurocircuits in subcortical brain regions including the ventral striatum, which serves as an integration point for reward processing and motivational decision-making. Many mechanisms contribute to these effects of inflammation, including decreased synthesis, release and reuptake of dopamine, increased synaptic and extrasynaptic glutamate, and activation of kynurenine pathway metabolites including quinolinic acid. Neuroimaging data indicate that these inflammation-induced neurotransmitter effects manifest as decreased activation of ventral striatum and decreased functional connectivity in reward circuitry involving ventral striatum and ventromedial prefrontal cortex. Neurocircuitry changes in turn mediate nuanced effects on motivation that include decreased willingness to expend effort for reward while maintaining the ability to experience reward. Taken together, the data reveal an inflammation-induced pathophysiologic phenotype that is agnostic to diagnosis. Given the many mechanisms involved, this phenotype represents an opportunity for development of novel and/or repurposed pharmacological strategies that target inflammation and associated cellular and systemic immunometabolic changes and their downstream effects on the brain. To date, clinical trials have failed to capitalize on the unique nature of this transdiagnostic phenotype, leaving the field bereft of interpretable data for meaningful clinical application. However, novel trial designs incorporating established targets in the brain and/or periphery using relevant outcome variables (e.g., anhedonia) are the future of targeted therapy in psychiatry. SIGNIFICANCE STATEMENT: Emerging understanding of mechanisms by which peripheral inflammation can affect the brain and behavior has created unprecedented opportunities for development of pharmacological strategies to treat deficits in motivation including anhedonia, a core and disabling symptom of depression well represented in multiple psychiatric disorders. Mechanisms include inflammation and cellular and systemic immunometabolism and alterations in dopamine, glutamate, and kynurenine metabolites, revealing a target-rich environment that nevertheless has yet to be fully exploited by current clinical trial designs and drugs employed.

HIV Infection and Related Mental Disorders

Over the more than thirty-year period of the human immunodeficiency virus type 1 (HIV-1) epidemic, many data have been accumulated indicating that HIV infection predisposes one to the development of mental pathologies. It has been proven that cognitive disorders in HIV-positive individuals are the result of the direct exposure of the virus to central nervous system (CNS) cells. The use of antiretroviral therapy has significantly reduced the number of cases of mental disorders among people infected with HIV. However, the incidence of moderate to mild cognitive impairment at all stages of HIV infection is still quite high. This review describes the most common forms of mental pathology that occur in people living with HIV and presents the current concepts on the possible pathogenetic mechanisms of the influence of human immunodeficiency virus (HIV-1) and its viral proteins on the cells of the CNS and the CNS’s functions. This review also provides the current state of knowledge on the impact of the antiretroviral therapy on the development of mental pathologies in people living with HIV, as well as current knowledge on the interactions between antiretroviral and psychotropic drugs that occur under their simultaneous administration.

Paraquat-activated BV-2 microglia induces neuroinflammatory responses in the neuron model through NF-κB signaling pathway

Paraquat (PQ), a non-selective contact herbicide, has been generally accepted as one of the environmental neurotoxicants. Despite the direct evidence that PQ could induce inflammation responses in microglia, little is known about the effects of the inflammatory microglia on neurons. Thus in the present study, mouse primary cortical neurons and PC12 cells, widely-used in vitro neuron models for neurotoxicity research were applied to investigate the neuroinflammatory effects of PQ-activated microglia on neurons. We observed that the secretion levels of TNF-α and IL-6 in PC12 cells were markedly increased upon treatment with the supernatants of inflammatory BV2 microglia, and NF-κB p65 protein expression was also elevated. Specific inhibition of NF-κB by PDTC dramatically attenuated the increase of TNF-α and IL-6 release. These results suggested that PQ-induced inflammatory microglia exerts secondary inflammatory effects on neurons through activation of NF-κB pathway.

Appetite Regulation of TLR4-Induced Inflammatory Signaling

Appetite is the basis for obtaining food and maintaining normal metabolism. Toll-like receptor 4 (TLR4) is an important receptor expressed in the brain that induces inflammatory signaling after activation. Inflammation is considered to affect the homeostatic and non-homeostatic systems of appetite, which are dominated by hypothalamic and mesolimbic dopamine signaling. Although the pathological features of many types of inflammation are known, their physiological functions in appetite are largely unknown. This review mainly addresses several key issues, including the structures of the homeostatic and non-homeostatic systems. In addition, the mechanism by which TLR4-induced inflammatory signaling contributes to these two systems to regulate appetite is also discussed. This review will provide potential opportunities to develop new therapeutic interventions that control appetite under inflammatory conditions.

Positive association between serum quinolinic acid and functional connectivity following concussion

The molecular mechanisms underlying the diverse psychiatric and neuropathological sequalae documented in subsets of athletes with concussion have not been identified. We have previously reported elevated quinolinic acid (QuinA), a neurotoxic kynurenine pathway metabolite, acutely following concussion in football players with prior concussion. Similarly, work from our group and others has shown that increased functional connectivity strength, assessed using resting state fMRI, occurs following concussion and is associated with worse concussion-related symptoms and outcome. Moreover, other work has shown that repetitive concussion may have cumulative effects on functional connectivity and is a risk factor for adverse outcomes. Understanding the molecular mechanisms underlying these cumulative effects may ultimately be important for therapeutic interventions or the development of prognostic biomarkers. Thus, in this work, we tested the hypothesis that the relationship between QuinA in serum and functional connectivity following concussion would depend on the presence of a prior concussion. Concussed football players with prior concussion (N = 21) and without prior concussion (N = 16) completed a MRI session and provided a blood sample at approximately 1 days, 8 days, 15 days, and 45 days post-injury. Matched, uninjured football players with (N = 18) and without prior concussion (N = 24) completed similar visits. The association between QuinA and global connectivity strength differed based on group (F(3, 127) = 3.46, p = 0.019); post-hoc analyses showed a positive association between QuinA and connectivity strength in concussed athletes with prior concussion (B = 16.05, SE = 5.06, p = 0.002, 95%CI[6.06, 26.03]), but no relationship in concussed athletes without prior concussion or controls. Region-specific analyses showed that this association was strongest in bilateral orbitofrontal cortices, insulae, and basal ganglia. Finally, exploratory analyses found elevated global connectivity strength in concussed athletes with prior concussion who reported depressive symptoms at the 1-day visit compared to those who did not report depressive symptoms (t(15) = 2.37, mean difference = 13.50, SE = 5.69, p = 0.032, 95%CI[1.36, 25.63], Cohen's d = 1.15.). The results highlight a potential role of kynurenine pathway (KP) metabolites in altered functional connectivity following concussion and raise the possibility that repeated concussion has a "priming" effect on KP metabolism.

Interferon and anti-TNF therapies differentially modulate amygdala reactivity which predicts associated bidirectional changes in depressive symptoms

A third of patients receiving Interferon-α (IFN-α) treatment for Hepatitis-C develop major depressive disorder (MDD). Conversely, anti-Tumor Necrosis Factor (TNF) therapies improve depression providing key empirical support for the "inflammatory theory" of depression. Heightened amygdala reactivity (particularly to negatively valanced stimuli) is a consistent finding within MDD; can predict treatment efficacy and reverses following successful treatment. However, whether IFN-α and anti-TNF enhance/attenuate depressive symptoms through modulation of amygdala emotional reactivity is unknown. Utilizing a prospective study design, we recruited 30 patients (mean 48.0 ± 10.5 years, 21 male) initiating IFN-α treatment for Hepatitis-C and 30 (mean 50.4 ± 15.7 years, 10 male) anti-TNF therapy for inflammatory arthritis. All completed an emotional face-processing task during fMRI and blood sampling before and after their first IFN-α (4-h) or anti-TNF (24-h) injection and follow-up psychiatric assessments for 3 months of treatment. IFN-α significantly increased depression symptoms (Hamilton Depression Rating Scale HAM-D) at 4 weeks (p < 0.001) but not 4-h after first dose (p > 0.1). Conversely, anti-TNF significantly improved depressive symptoms (Hospital Anxiety and Depression Rating Scale HADS) at both 24-h (P = 0.015) and 12 weeks (p = 0.018). In support of our a-priori hypothesis, both IFN-α and anti-TNF significantly modulated amygdala reactivity with IFN-α acutely enhancing right amygdala responses to sad (compared with neutral) faces (p = 0.032) and anti-TNF conversely decreasing right amygdala reactivity (across emotional valence) (p = 0.033). Furthermore, these changes predicted IFN-induced increases in HAM-D 4 weeks later (R² = 0.17, p = 0.022) and anti-TNF-associated decreases in HADS at 24-h (R² = 0.23, p = 0.01) suggesting that actions of systemic inflammation on amygdala emotional reactivity play a mechanistic role in inflammation-associated depressive symptoms.

Correlates of C-reactive protein with neural reward circuitry in adolescents with psychiatric symptoms

INTRODUCTION

Increased inflammation has been implicated in many psychiatric conditions across ages. We previously reported relationships between blood cytokine levels and anhedonia, the decreased capacity to experience pleasure, as well as with reward brain activation in adolescents with psychiatric symptoms. Here, we sought to extend this work in a larger cohort of adolescents with psychiatric symptoms and assess the relationships of C-Reactive Protein (CRP, inflammation biomarker) with clinical symptoms and reward-related brain activation.

METHODS

Subjects were 64 psychotropic-medication-free adolescents with psychiatric symptoms (ages: 15.17 ± 2.10, 44 female). All had psychiatric evaluations and dimensional assessments for anxiety, depression, anhedonia, and suicidality. Neuroimaging included the Reward Flanker fMRI Task examining brain activation during reward anticipation, attainment and positive prediction error. Both whole-brain and ROI analyses focusing on reward circuitry were performed. All analyses were controlled for BMI, age, and sex at pFWE < 0.05.

RESULTS

No relationships were identified between CRP and clinical symptom severity. CRP was positively associated with brain activation during reward attainment in regions of the visual and dorsal attention networks, as well as during positive prediction error in the cerebellum. In ROI analyses, CRP was negatively correlated with brain activation during reward anticipation in dorsal anterior cingulate cortex. When subject with high CRP was excluded, CRP was also positively correlated with positive predication error activation in nucleus accumbens.

CONCLUSION

Despite lack of associations of CRP with clinical symptomatology, our fMRI findings suggest a relationship between inflammation and brain function early course of psychiatric conditions.

Inflammation, reward circuitry and symptoms of anhedonia and PTSD in trauma-exposed women

Trauma exposure is associated with increased inflammatory biomarkers (e.g. C-reactive protein [CRP] and cytokines), and inflammation has been shown to impact corticostriatal reward circuitry and increase anhedonia-related symptoms. We examined resting-state functional MRI in a high-trauma inner-city population of African-American women (n = 56), who reported on average five different types of trauma exposures, to investigate whether inflammation correlated with functional connectivity (FC) in corticostriatal reward circuitry in association with symptoms of anhedonia and PTSD. Plasma CRP negatively correlated with bilateral ventral striatum (VS) to ventromedial prefrontal cortex (vmPFC) FC (P < 0.01). In participants where plasma was available to also measure cytokines and their soluble receptors, left (L)VS-vmPFC FC negatively correlated with an inflammatory composite score (previously shown to be increased in plasma and cerebrospinal fluid of depressed patients with high CRP) only in women with significant PTSD symptoms (n = 14; r = -0.582, P = 0.029) and those who experienced moderate-severe childhood trauma (r = -0.595, P = 0.009). Exploratory analyses indicated that LVS-vmPFC FC correlated with anhedonia-related subscales from the Beck Depression Inventory (r = -0.691, P = 0.004) and PTSD Symptom Scale (avoidance/numbness; r = -0.514, P = 0.042) in participants with an inflammatory score over the median (n = 16). Results suggest that inflammation contributes to compromised reward circuitry and symptoms of anhedonia and PTSD in trauma-exposed women.

Comparative analysis of clinical, physiological, temperamental and personality characteristics of elderly subjects and young subjects with asthma

BACKGROUND

Asthma is a heterogeneous disease of a complex etiology in which genetic, environmental and personality variables are important factors determining the development of complicated strategies related to coping with stress and temperament traits. Our thesis is that coping styles in asthmatic patients are modified by the environment (chronic inflammation and stress) which affects individual temperament traits in the course of time. Thus, patient age is one of factors which determine the clinical image of asthma and its natural history.

AIM

The aim of the study was to evaluate the variables describing stress coping styles and temperament in young (18 to 35 years old) and elderly asthmatics (aged ≥60 years).

MATERIAL AND METHODS

A total of 200 patients, 104 elderly and 96 young asthmatics were enrolled in the study. Apart from medical examination, the following tests were performed in all subjects: the Formal Characteristics of Behavior- Temperament Inventory (FCB-TI), Coping Inventory for Stressful Situations (CISS), Beck Depression Inventory, State-Trait Anxiety Inventory, and Borg Rating of Perceived Exertion (RPE) Scale.

RESULTS

Elderly patients with asthma exhibited higher intensity of anxiety as a trait, a higher level of depression and experienced dyspnea, as well as higher levels of stress coping strategies such as Avoidance-Oriented Coping (AOC), Distraction Seeking (DS) and Social Diversion (SD) compared to young asthmatics. In elderly patients, Perseverance and Sensory Sensitivity traits have been observed to decline with the duration and development of asthma at later life stages as opposed to young asthmatics, in whom these temperament characteristics are elevated.

CONCLUSIONS

Asthma is a heterogeneous disease of a complex etiopathogenesis that has a complex interplay with mental health. The present study confirms a relationship between age and stress coping strategies as well as temperament traits.

Inflammatory Biomarkers, Hematopoietic Stem Cells, and Symptoms in Breast Cancer Patients Undergoing Adjuvant Radiation Therapy

Background

Fatigue and insomnia are common symptoms experienced by breast cancer patients undergoing adjuvant radiation therapy (RT), yet the underlying mechanisms of these symptoms are unclear. In particular, the roles of hematopoietic stem cells (HSCs) and inflammatory cytokines remain to be elucidated.

Methods

Breast cancer patients (n = 147) completed questionnaires to longitudinally assess symptoms before, during, and after adjuvant RT. Phlebotomies were performed prior to RT, at the second and fifth treatment fractions, end of treatment (EOT), and 1 month after completing RT, assessing for CD34⁺, CD45⁺, full hematology, and 17 inflammatory cytokines. The associations between symptoms and all biomarkers were evaluated. All statistical tests were 2-sided.

Results

General fatigue and insomnia worsened with RT, with peak levels observed at EOT, which remained statistically significant even after controlling for anxiety and depression (P < .05 for all). CD34⁺, CD45⁺, white blood cell, and lymphocyte counts decreased, with the lowest levels also observed at EOT (P < .001). Fatigue and insomnia were associated with changes in both interferon γ-induced protein 10 (IP-10) - (P = .03 and P = .01, respectively) and tumor necrosis factor receptor II (TNF-RII) (P = .02 and P = .006, respectively), while mental fatigue was associated with increased matrix metalloproteinases-2 (MMP-2) levels (P = .03). Patients who received prior chemotherapy demonstrated statistically significantly greater severity in all symptoms, with lower baseline HSC levels.

Conclusions

This is the first longitudinal study to examine linkages between symptoms, HSCs, and cytokines, demonstrating that fatigue and insomnia shared associations with increasing serum levels of IP-10 and TNF-RII, and mental fatigue was associated with increasing serum levels of MMP-2. Our findings highlight opportunities for further research into mechanisms and potential interventions for these symptoms.

Nucleus accumbens cytoarchitecture predicts weight gain in children

The prevalence of obesity in children and adolescents worldwide has quadrupled since 1975 and is a key predictor of obesity later in life. Previous work has consistently observed relationships between macroscale measures of reward-related brain regions (e.g., the nucleus accumbens [NAcc]) and unhealthy eating behaviors and outcomes; however, the mechanisms underlying these associations remain unclear. Recent work has highlighted a potential role of neuroinflammation in the NAcc in animal models of diet-induced obesity. Here, we leverage a diffusion MRI technique, restriction spectrum imaging, to probe the microstructure (cellular density) of subcortical brain regions. More specifically, we test the hypothesis that the cell density of reward-related regions is associated with obesity-related metrics and early weight gain. In a large cohort of nine- and ten-year-olds enrolled in the Adolescent Brain Cognitive Development (ABCD) study, we demonstrate that cellular density in the NAcc is related to individual differences in waist circumference at baseline and is predictive of increases in waist circumference after 1 y. These findings suggest a neurobiological mechanism for pediatric obesity consistent with rodent work showing that high saturated fat diets increase gliosis and neuroinflammation in reward-related brain regions, which in turn lead to further unhealthy eating and obesity.

NODDI in clinical research

Diffusion MRI (dMRI) has proven to be a useful imaging approach for both clinical diagnosis and research investigating the microstructures of nervous tissues, and it has helped us to better understand the neurophysiological mechanisms of many diseases. Though diffusion tensor imaging (DTI) has long been the default tool to analyze dMRI data in clinical research, acquisition with stronger diffusion weightings beyond the DTI regimen is now possible with modern clinical scanners, potentially enabling even more detailed characterization of tissue microstructures. To take advantage of such data, neurite orientation dispersion and density imaging (NODDI) has been proposed as a way to relate the dMRI signal to tissue features via biophysically inspired modeling. The number of reports demonstrating the potential clinical utility of NODDI is rapidly increasing. At the same time, the pitfalls and limitations of NODDI, and general challenges in microstructure modeling, are becoming increasingly recognized by clinicians. dMRI microstructure modeling is a rapidly evolving field with great promise, where people from different scientific backgrounds, such as physics, medicine, biology, neuroscience, and statistics, are collaborating to build novel tools that contribute to improving human healthcare. Here, we review the applications of NODDI in clinical research and discuss future perspectives for investigations toward the implementation of dMRI microstructure imaging in clinical practice.

Pro- and anti-inflammatory properties of interleukin (IL6) in vitro: relevance for major depression and for human hippocampal neurogenesis

BACKGROUND

Although the pro-inflammatory cytokine, interleukin (IL)6, has been generally regarded as "depressogenic", recent research has started to question this assumption, in light of the fact that this cytokine can also have anti-inflammatory properties. This bimodal action seems to be dependent on its concentration levels, and on the concomitant presence of other pro-inflammatory cytokines.

METHODS

We exposed a human hippocampal progenitor cell line HPC0A07/03C to cytokine levels described in depressed patients (IL6 5pg/ml with IL1β 10pg/ml or Macrophage Migration Inhibitory Factor (MIF) 300pg/ml), in healthy subjects (IL6 with IL1β, 1pg/ml or MIF 10pg/ml), as well as to the potentially anti-inflammatory, much higher concentrations of IL6 (50000pg/ml).

RESULTS

Treatment with high concentrations of IL6 with IL1β or MIF (resembling depressed patients) decreases neurogenesis when compared with low concentrations of the same cytokines (healthy subjects), and that this is mediated via production of, respectively, IL8 and IL1β in cell supernatant. Instead, treatment with the very high, anti-inflammatory concentration of IL6 (50000pg/ml) together with high IL1β or MIF prevents the decrease in neurogenesis and reduces both IL8 and IL1β. When the high concentrations of both IL1β and MIF were used in co-treatment, as a model of treatment resistant depression, we also demonstrate a reduction in neurogenesis, and that this is mediated via a decrease in IL4; moreover, co-treatment with high IL1β and MIF and the very high concentration of IL6 prevents the reduction in neurogenesis, and increases IL4.

CONCLUSIONS

Our results demonstrate that IL6 can exert both pro- and anti-inflammatory (potentially antidepressant) properties, depending on its concentrations and combinations with other inflammatory cytokines.

Whole-blood expression of inflammasome- and glucocorticoid-related mRNAs correctly separates treatment-resistant depressed patients from drug-free and responsive patients in the BIODEP study

The mRNA expression signatures associated with the 'pro-inflammatory' phenotype of depression, and the differential signatures associated with depression subtypes and the effects of antidepressants, are still unknown. We examined 130 depressed patients (58 treatment-resistant, 36 antidepressant-responsive and 36 currently untreated) and 40 healthy controls from the BIODEP study, and used whole-blood mRNA qPCR to measure the expression of 16 candidate mRNAs, some never measured before: interleukin (IL)-1-beta, IL-6, TNF-alpha, macrophage inhibiting factor (MIF), glucocorticoid receptor (GR), SGK1, FKBP5, the purinergic receptor P2RX7, CCL2, CXCL12, c-reactive protein (CRP), alpha-2-macroglobulin (A2M), acquaporin-4 (AQP4), ISG15, STAT1 and USP-18. All genes but AQP4, ISG15 and USP-18 were differentially regulated. Treatment-resistant and drug-free depressed patients had both increased inflammasome activation (higher P2RX7 and proinflammatory cytokines/chemokines mRNAs expression) and glucocorticoid resistance (lower GR and higher FKBP5 mRNAs expression), while responsive patients had an intermediate phenotype with, additionally, lower CXCL12. Most interestingly, using binomial logistics models we found that a signature of six mRNAs (P2RX7, IL-1-beta, IL-6, TNF-alpha, CXCL12 and GR) distinguished treatment-resistant from responsive patients, even after adjusting for other variables that were different between groups, such as a trait- and state-anxiety, history of childhood maltreatment and serum CRP. Future studies should replicate these findings in larger, longitudinal cohorts, and test whether this mRNA signature can identify patients that are more likely to respond to adjuvant strategies for treatment-resistant depression, including combinations with anti-inflammatory medications.

Longitudinal changes of inflammatory biomarkers moderate the relationship between recent stressful life events and prospective symptoms of depression in a diverse sample of urban adolescents

This study investigated whether longitudinal changes in inflammatory physiology moderated the relationship between recent stressful life events and subsequent depressive symptoms in adolescence. A diverse sample of adolescents representative of an urban community (N = 129; Age at baseline = 12.5 years; 48.8% female; 55.0% African American) completed measures of stressful life events, depressive symptoms, and two annual blood draws (BD1 and BD2). Controlling for inflammatory activity at BD1, depression at BD1, demographics and the time between assessments, increases in interleukin-6 (IL-6; b = 0.878, p = .007) and C-reactive protein (CRP; b = 0.252, p = .024) from BD1 to BD2 interacted with recent stressful life events before BD1 to predict severity of depressive symptoms at BD2. Similar associations were evident for IL-6 (b = 2.074, p = .040) and CRP (b = 0.919, p = .050) when considering acute stressful life events that had occurred within the two weeks before the first blood collection. More frequent stressful life events before BD1 predicted significantly more severe depressive symptoms at BD2, but only for adolescents with moderate (50th percentile) and high (84th percentile) levels of IL-6 and CRP at BD2. In conclusion, adolescents who experienced both recent stressful life events and larger increases in inflammatory activity following these stressors were at increased risk for more severe depressive symptoms after approximately one year. The findings indicate that the interaction of stress and larger changes in inflammatory activity following these stressors are prognostic risk factors for depression severity in adolescents.

Inflammatory markers are associated with psychomotor slowing in patients with schizophrenia compared to healthy controls

Patients with schizophrenia exhibit psychomotor deficits that are associated with poor functional outcomes. One pathway that may be associated with psychomotor slowing is inflammation. Inflammatory markers have been shown to be elevated in patients with schizophrenia and are associated with psychomotor deficits in both animal and human studies. Forty-three patients with schizophrenia and 29 healthy controls were recruited and underwent a battery of psychomotor tasks. The following immune measures in peripheral blood were assayed: IL-6, IL-1 beta, IL-10, TNF, MCP-1, IL-6sr, IL-1RA, and TNFR2. Generalized linear models were used to determine which immune markers, in addition to their interaction with diagnosis, were associated with performance on the psychomotor tasks. As expected, patients with schizophrenia demonstrated slower performance compared with healthy controls on the finger tapping test (FTT, tested on dominant and non-dominant hands), trail making test (TMT), and symbol coding test (SC). Interactive effects with diagnosis were found for TNF, IL-10, IL-6sr, and TNFR2 for the FTT (dominant), IL-10 and IL-6sr for FTT (non-dominant), TNF and IL-10 for TMT and TNF, IL-10, IL-6sr, TNFR2, and IL-1RA for SC. The results of this study provide evidence that peripheral inflammatory markers contribute to psychomotor slowing in patients with schizophrenia. These data are consistent with a growing literature, demonstrating that inflammation may target the basal ganglia to contribute to psychomotor deficits as is seen in other psychiatric disorders such as depression. These data also indicate that psychomotor speed may be a relevant construct to target in studies of the immune system in schizophrenia.

Effects of combined exercise training on the inflammatory profile of older cancer patients treated with systemic therapy

Cancer-related fatigue (CRF) is a major issue in older cancer patients as it is associated with functional decline and a lower quality of life, and an increased inflammatory activity during cancer therapy is suspected to play a key role in CRF etiology. Combined aerobic and resistance exercise training is known to reduce CRF, and this could be mediated by a protective effect against this increased inflammatory activity. Hence, the main objective was to measure the effect of a 12-week combined exercise training on the inflammatory profile of older cancer patients undergoing systemic therapy. A secondary objective was to verify if there was an association between inflammatory profile and CRF.

Methods

Twenty older non-metastatic cancer patients initiating chemotherapy and/or hormone therapy were randomly assigned to 12 weeks of supervised, combined exercise or a control group (static stretching). Primary outcomes were the inflammatory profile, Indoleamine 2,3-deoxygenase activity (KYN/TRP ratio), and CRF (FACIT-F questionnaire). Control outcomes were the fasting nutritional and hormonal blood profiles, body composition (iDXA), physical activity habits (PASE questionnaire), nutritional habits (3-day log), and treatment-related variables.

Results

No worsening of the inflammatory profile was observed in both arms of the study after the intervention. No significant change in CRF was observed, although there was a trend for a reduction in the experimental group (p ​= ​0.10). Significant correlations were found at both timepoints between the KYN/TRP ratio and the delay with the previous treatment received (p ​≤ ​0.03).

Conclusion

These results suggest that exercise might have elicited a positive effect on CRF, which was not mediated by the modulation of the pro-inflammatory cytokine profile. However, the decrease in IL-6/IL-10 ratio in the exercise group might reflect a possible anti-inflammatory effect of exercise. Moreover, exploratory analyses suggest that an acute effect of chemotherapy treatments influenced the inflammatory profile measurements, which could explain the absence of change in the fasting inflammatory profile.

Inflammation and the dimensions of depression: A review

Patients with depressive disorders show a wide range of clinical manifestations including cognitive and neurovegetative symptoms. Importantly, these symptoms can differ in terms of biological etiology, and deconstructing depression into specific symptoms may provide valuable insight into the underlying neurobiology. Little research has examined inflammation in the context of depressive dimensions. Here we conduct a narrative review of the existing literature (21 studies) to elucidate whether the depression-inflammation link is symptom specific. Overall, there is evidence that an association exists between neurovegetative symptoms of depression and inflammation, independent of cognitive symptoms. The same cannot be said of cognitive symptoms and inflammation. There is also some evidence of gender differences in the directionality of the relationship between depression and inflammation. Potential explanations for these findings, limitations of the existing literature and recommendations for future research design are discussed.

Interferon-beta-induced changes in neuroimaging phenotypes of appetitive motivation and reactivity to emotional salience

Treatment with interferon (IFN) has been associated with depressive side effects. Previous neuroimaging studies have provided information about changes in brain activation patterns in patients under treatment with IFN-alpha, but the effect of other IFNs, or the role of the underlying disease, has yet to be clarified. In the present fMRI study, we looked at brain changes after 8 days of IFN-beta treatment in N = =17 healthy volunteers, thus avoiding the possible confound of the effects of underlying pathology in studies of IFN-treated patients with neurological or other medical disorders. We followed a symptom dimensional approach by simultaneously investigating two distinct symptom domains of depressiveness: negative affect (amygdala) and appetitive motivation (ventral striatum). In these early phases of IFN treatment we detected a selective change in neural substrates of appetitive motivation, consistent with the predominant symptomatic change recorded in psychopathology ratings. In contrast, the fMRI phenotype of negative affect, which is known to characterize disorders of affect involving anxiety and depressiveness as well as individual vulnerability to depression, was unchanged after treatment. These findings suggest that IFN may induce an affective syndrome through a mechanism involving down-regulation of appetitive motivation.

Association of chronic inflammation and perceived stress with abnormal functional connectivity in brain areas involved with interoception in hepatitis C patients

BACKGROUND

Sickness behavioral changes elicited by inflammation may become prolonged and dysfunctional in patients with chronic disease, such as chronic hepatitis C (CHC). Neuroimaging studies show that the basal ganglia and insula are sensitive to systemic inflammation.

AIM

To elucidate the clinical and neurobiological aspects of prolonged illnesses in patients with CHC.

METHODS

Thirty-five CHC patients not treated with interferon-α or other antiviral therapy, and 30 control subjects matched for age and sex, were evaluated for perceived stress (perceived stress scale; PSS), depression (PHQ-9), fatigue and irritability through a visual analog scale (VAS), as well as serum levels of interleukin-6 (IL-6), prostaglandin E₂ (PGE₂) and oxidative stress markers. Functional MRI was performed, measuring resting-state functional connectivity using a region-of-interest (seed)-based approach focusing on the bilateral insula, subgenual anterior cingulate cortex and bilateral putamen. Between-group differences in functional connectivity patterns were assessed with two-sample t-tests, while the associations between symptoms, inflammatory markers and functional connectivity patterns were analyzed with multiple regression analyses.

RESULTS

CHC patients had higher PSS, PHQ-9 and VAS scores for fatigue and irritability, as well as increased IL-6 levels, PGE₂ concentrations and antioxidant system activation compared to controls. PSS scores positively correlated with functional connectivity between the right anterior insula and right putamen, whereas PHQ-9 scores correlated with functional connectivity between most of the seeds and the right anterior insula. PGE₂ (positively) and IL-6 (negatively) correlated with functional connectivity between the right anterior insula and right caudate nucleus and between the right ventral putamen and right putamen/globus pallidus. PGE₂ and PSS scores accounted for 46% of the variance in functional connectivity between the anterior insula and putamen.

CONCLUSIONS

CHC patients exhibited increased perceived stress and depressive symptoms, which were associated with changes in inflammatory marker levels and in functional connectivity between the insula and putamen, areas involved in interoceptive integration, emotional awareness, and orientation of motivational state.

Can't or Won't? Immunometabolic Constraints on Dopaminergic Drive

Inflammatory cytokines have been shown to have a direct effect on mesolimbic dopamine (DA) that is associated with a reduced willingness to expend effort for reward. To date, however, the broader implications of this communication between inflammation and mesolimbic DA have yet to be explored. Here, we suggest that the metabolic demands of chronic low-grade inflammation induce a reduction of striatal DA that in turn leads to a steeper effort-discounting curve because of reduced perceived ability (can't) versus preference (won't) for reward. This theoretical framework can inform how the mesolimbic DA system responds to increased immunometabolic demands during chronic inflammation, ultimately contributing to motivational impairments in psychiatric and other medical disorders.

A potential mechanistic role for neuroinflammation in reward processing impairments in autism spectrum disorder

Accumulating evidence suggests that autism spectrum disorder (ASD) may be conceptualized within a framework of reward processing impairments. The Social Motivation Theory of Autism posits that reduced motivation to interact with people and decreased pleasure derived from social interactions may derail typical social development and contribute to the emergence of core social communication deficits in ASD. Neuroinflammation may disrupt the development of mesolimbic dopaminergic systems that are critical for optimal functioning of social reward processing systems. This neuroinflammation-induced disturbance of mesolimbic dopaminergic functioning has been substantiated using maternal immune activation rodent models whose offspring show aberrant dopaminergic corticostriatal function, as well as behavioral characteristics of ASD model systems. Preclinical findings are in turn supported by clinical evidence of increased mesolimbic neuroinflammatory responses in individuals with ASD. This review summarizes evidence for reward processing deficits and neuroinflammatory impairments in ASD and examines how immune inflammatory dysregulation may impair the development of dopaminergic mesolimbic circuitry in ASD. Finally, future research directions examining neuroinflammatory effects on reward processing in ASD are proposed.

Cytokine Research in Depression: Principles, Challenges, and Open Questions

Cytokines have been implicated in the pathology of depression. Currently, the evidence is based on cross-sectional studies and meta-analytic research comparing blood concentrations of T helper type 1 (TH1), T helper type 2 (TH2), pro-inflammatory or anti-inflammatory cytokines of patients with a depressive disorder to those of healthy controls. Additionally, multiple longitudinal studies have investigated cytokine levels during antidepressant treatment. According to the current literature, it seems that peripheral levels of interleukin (IL)-6, IL-10, IL-12, IL-13, and tumor necrosis factor (TNF)-α are elevated and that interferon (IFN)-γ levels are lower in patients with depression compared to healthy controls. However, the overlap of cytokine values between acutely depressed patients, remitted and recovered patients and healthy controls is considerable. Thus, the discriminative power of cytokine concentrations between depressed and non-depressed people is likely weak. Treatment with certain antidepressants appears to decrease peripheral levels of IL-6, IL-10, and TNF-α. However, weight gain-inducing psychopharmacological substances, such as the antidepressant mirtazapine, have been reported to potentially increase the production of pro-inflammatory cytokines. Even though cytokines are often discussed as biomarkers for depression, they have also been shown to be altered in other psychiatric disorders. Moreover, many environmental, social, psychological, biological, and medical factors are also associated with cytokine changes. Thus, cytokine alterations seem extremely unspecific. The interpretation of the results of these studies remains a challenge because it is unknown which type of cells are most responsible for cytokine changes measured in the blood nor have the main target cells or target tissues been identified. The same cytokine can be produced by multiple cell types, and the same cell can produce various cytokines. Additionally, redundancy, synergy, antagonism, and signaling cascades of cytokine signaling must be considered. Cytokines might not be associated with the diagnosis of depression according to the currently used diagnostic manuals, but rather with specific subtypes of depression, or with depressive symptoms across different psychiatric diagnoses. Therefore, the currently available diagnostic systems may not be the ideal starting point for psychiatric cytokine research.

Rheumatoid arthritis and depression: an inflammatory perspective

The coexistence of immune-mediated inflammatory diseases with depression has long been recognised. Data that illustrate the intimate associations between peripheral and brain immune responses raise the possibility of shared pathophysiological mechanisms. These associations include the negative effects of proinflammatory cytokines on monoaminergic neurotransmission, neurotrophic factors, and measures of synaptic plasticity. The evidence supporting this association is accumulating and includes findings from clinical trials of immunomodulatory therapy, indicating that these interventions can provide benefits to mental health independent of improvements in physical disease scores. In this Review, we assess this evidence in relation to rheumatoid arthritis and depression, with a focus on innate immune and molecular responses to inflammation, and discuss the challenges of assessing causation in this population, acknowledging the difficulty of assessing the confounding and contributory effects of pain and fatigue. We also discuss how future clinical and preclinical research might improve diagnosis of depression in people with rheumatoid arthritis and shed light on mechanisms that could be substrates for therapeutic interventions.

The Psychopharmacology of Effort-Related Decision Making: Dopamine, Adenosine, and Insights into the Neurochemistry of Motivation

Effort-based decision making is studied using tasks that offer choices between high-effort options leading to more highly valued reinforcers versus low-effort/low-reward options. These tasks have been used to study the involvement of neural systems, including mesolimbic dopamine and related circuits, in effort-related aspects of motivation. Moreover, such tasks are useful as animal models of some of the motivational symptoms that are seen in people with depression, schizophrenia, Parkinson's disease, and other disorders. The present review will discuss the pharmacology of effort-related decision making and will focus on the use of these tasks for the development of drug treatments for motivational dysfunction. Research has identified pharmacological conditions that can alter effort-based choice and serve as models for depression-related symptoms (e.g., the vesicular monoamine transport-2 inhibitor tetrabenazine and proinflammatory cytokines). Furthermore, tests of effort-based choice have identified compounds that are particularly useful for stimulating high-effort work output and reversing the deficits induced by tetrabenazine and cytokines. These studies indicate that drugs that act by facilitating dopamine transmission, as well as adenosine A_2A antagonists, are relatively effective at reversing effort-related impairments. Studies of effort-based choice may lead to the identification of drug targets that could be useful for treating motivational treatments that are resistant to commonly used antidepressants such as serotonin transport inhibitors.

The role of neuro-immune interactions in cancer-related fatigue: Biobehavioral risk factors and mechanisms

Fatigue is a common and distressing symptom in both patients with cancer and cancer survivors. There is substantial variation in the severity and persistence of cancer-related fatigue that may be driven by individual differences in host factors, including characteristics that predate the cancer experience as well as responses to cancer and its treatment. This review examines biobehavioral risk factors linked to fatigue and the mechanisms through which they influence fatigue across the cancer continuum, with a focus on neuro-immune processes. Among psychosocial risk factors, childhood adversity is a strong and consistent predictor of cancer-related fatigue; other risk factors include history of depression, catastrophizing, lack of physical activity, and sleep disturbance, with compelling preliminary evidence for loneliness and trait anxiety. Among biologic systems, initial work suggests that alterations in immune, neuroendocrine, and neural processes are associated with fatigue. The identification of key risk factors and underlying mechanisms is critical for the development and deployment of targeted interventions to reduce the burden of fatigue in the growing population of cancer survivors. Given the multidimensional nature of fatigue, interventions that influence multiple systems may be most effective.

Role of Inflammation in Depression and Treatment Implications

Approximately one third of depressed patients fail to respond to currently available antidepressant therapies. Therefore, new conceptual frameworks are needed to identify pathophysiologic pathways and neurobiological targets for the development of novel treatment strategies. In this regard, recent evidence suggests that inflammation may contribute to symptoms relevant to a number of psychiatric disorders and particularly depression. Numerous studies (including meta-analyses) have found elevated peripheral and central inflammatory cytokines and acute phase proteins in depression. Chronic exposure to increased inflammation is thought to drive changes in neurotransmitters and neurocircuits that lead to depressive symptoms and that may also interfere with or circumvent the efficacy of antidepressants. Indeed, patients with high inflammation have been shown to exhibit poor response to conventional antidepressant therapies. Recent developments in our ability to understand and measure the effects of inflammation on the brain in patients have opened new doors for the testing of novel treatment strategies that target the immune system or its consequences on neurotransmitter systems. Such recent developments in the field of behavioral immunology and their translational implications for the treatment of depression are discussed herein.

Regional neuronal activity in patients with relapsing remitting multiple sclerosis

OBJECTIVES

Although interferon-beta is an established drug for relapsing remitting multiple sclerosis (RRMS), its impact on neuronal activity is not well understood.

METHODS

We investigated 15 patients with RRMS by [¹⁸ F]fluorodeoxyglucose positron emission tomography (FDG-PET) to assess cerebral metabolic rate of glucose (CMR_glc ) before interferon-beta therapy. Further, we performed clinical and neuropsychological investigations. In nine patients, these investigations were repeated after 6 months of therapy. Ten healthy controls were also studied.

RESULTS

We found no significant differences in absolute CMR_glc between patients and controls, or in patients before and during treatment. However, during treatment, relative regional glucose metabolism (rCMRl_glc ) was decreased in cerebellum and increased in parts of left inferior parietal, temporo-occipital, frontal cortical areas, left striatum and right insula. In untreated patients, higher fatigue was associated with lower rCMRl_glc in portions of left posterior cingulate cortex, and higher depression was associated with lower rCMRl_glc within the left superior temporal sulcus. In the pooled sample, higher depression was associated with higher rCMRl_glc in parts of the right precuneus.

CONCLUSIONS

Our results indicate effects of IFN-beta treatment on cerebellar, cortical and subcortical neuronal function. Moreover, more severe fatigue and depression in untreated patients seem to be associated with reduced neuronal activity in left posterior cingulate cortex and left superior temporal cortex, respectively.

The role of inflammation in core features of depression: Insights from paradigms using exogenously-induced inflammation

A wealth of evidence has implicated inflammation in the development of depression. Yet, the heterogeneous nature of depression has impeded efforts to understand, prevent, and treat the disease. The purpose of this integrative review is to summarize the connections between inflammation and established core features of depression that exhibit more homogeneity than the syndrome itself: exaggerated reactivity to negative information, altered reward processing, decreased cognitive control, and somatic syndrome. For each core feature, we first provide a brief overview of its relevance to depression and neurobiological underpinnings, and then review evidence investigating a potential role of inflammation. We focus primarily on findings from experimental paradigms of exogenously-induced inflammation. We conclude that inflammation likely plays a role in exaggerated reactivity to negative information, altered reward reactivity, and somatic symptoms. There is less evidence supporting an effect of inflammation on cognitive control as assessed by standard neuropsychological measures. Finally, we discuss implications for future research and recommendationsfor how to test the role of inflammation in the pathogenesis of heterogeneous psychiatric disorders.

Imaging the Role of Inflammation in Mood and Anxiety-related Disorders

Background

Studies investigating the impact of a variety of inflammatory stimuli on the brain and behavior have reported evidence that inflammation and release of inflammatory cytokines affect circuitry relevant to both reward and threat sensitivity to contribute to behavioral change. Of relevance to mood and anxiety-related disorders, biomarkers of inflammation such as inflammatory cytokines and acute-phase proteins are reliably elevated in a significant proportion of patients with major depressive disorder (MDD), bipolar disorder, anxiety disorders and post-traumatic stress disorder (PTSD).

Methods

This review summarized clinical and translational work demonstrating the impact of peripheral inflammation on brain regions and neurotransmitter systems relevant to both reward and threat sensitivity, with a focus on neuroimaging studies involving administration of inflammatory stimuli. Recent translation of these findings to further understand the role of inflammation in mood and anxiety-related disorders is also discussed.

Results

Inflammation was consistently found to affect basal ganglia and cortical reward and motor circuits to drive reduced motivation and motor activity, as well as anxiety-related brain regions including amygdala, insula and anterior cingulate cortex, which may result from cytokine effects on monoamines and glutamate. Similar relationships between inflammation and altered neurocircuitry have been observed in MDD patients with increased peripheral inflammatory markers, and such work is on the horizon for anxiety disorders and PTSD.

Conclusion

Neuroimaging effects of inflammation on reward and threat circuitry may be used as biomarkers of inflammation for future development of novel therapeutic strategies to better treat mood and anxiety-related disorders in patients with high inflammation.