Interferon-induced depression: strategies in treatment

Microglial type I interferon signaling mediates chronic stress-induced synapse loss and social behavior deficits

Inflammation and synapse loss have been associated with deficits in social behavior and are involved in pathophysiology of many neuropsychiatric disorders. Synapse loss, characterized by reduction in dendritic spines can significantly disrupt synaptic connectivity and neural circuitry underlying social behavior. Chronic stress is known to induce loss of spines and dendrites in the prefrontal cortex (PFC), a brain region implicated in social behavior. However, the underlying mechanisms are not well understood. In the present study, we investigated the role of type I Interferon (IFN-I) signaling in chronic unpredictable stress (CUS)-induced synapse loss and behavior deficits in mice. We found increased expression of type I IFN receptor (IFNAR) in microglia following CUS. Conditional knockout of microglial IFNAR in adult mice rescued CUS-induced social behavior deficits and synapse loss. Bulk RNA sequencing data show that microglial IFNAR deletion attenuated CUS-mediated changes in the expression of genes such as Keratin 20 (Krt20), Claudin-5 (Cldn5) and Nuclear Receptor Subfamily 4 Group A Member 1 (Nr4a1) in the PFC. Cldn5 and Nr4a1 are known for their roles in synaptic plasticity. Krt20 is an intermediate filament protein responsible for the structural integrity of epithelial cells. The reduction in Krt20 following CUS presents a novel insight into the potential contribution of cytokeratin in stress-induced alterations in neuroplasticity. Overall, these results suggest that microglial IFNAR plays a critical role in regulating synaptic plasticity and social behavior deficits associated with chronic stress conditions.

In sickness and in health-Type I interferon and the brain

Type I interferons (IFN-I) represent a group of pleiotropic cytokines renowned for their antiviral activity and immune regulatory functions. A multitude of studies have unveiled a critical role of IFN-I in the brain, influencing various neurological processes and diseases. In this mini-review, I highlight recent findings on IFN-I's effects on brain aging, Alzheimer's disease (AD) progression, and central nervous system (CNS) homeostasis. The multifaceted influence of IFN-I on brain health and disease sheds light on the complex interplay between immune responses and neurological processes. Of particular interest is the cGAS-STING-IFN-I axis, which extensively participates in brain aging and various forms of neurodegeneration. Understanding the intricate role of IFN-I and its associated pathways in the CNS not only advances our comprehension of brain health and disease but also presents opportunities for developing interventions to modify the process of neurodegeneration and prevent age-related cognitive decline.

Concerted type I interferon signaling in microglia and neural cells promotes memory impairment associated with amyloid β plaques

The principal signals that drive memory and cognitive impairment in Alzheimer's disease (AD) remain elusive. Here, we revealed brain-wide cellular reactions to type I interferon (IFN-I), an innate immune cytokine aberrantly elicited by amyloid β plaques, and examined their role in cognition and neuropathology relevant to AD in a murine amyloidosis model. Using a fate-mapping reporter system to track cellular responses to IFN-I, we detected robust, Aβ-pathology-dependent IFN-I activation in microglia and other cell types. Long-term blockade of IFN-I receptor (IFNAR) rescued both memory and synaptic deficits and resulted in reduced microgliosis, inflammation, and neuritic pathology. Microglia-specific Ifnar1 deletion attenuated the loss of post-synaptic terminals by selective engulfment, whereas neural Ifnar1 deletion restored pre-synaptic terminals and decreased plaque accumulation. Overall, IFN-I signaling represents a critical module within the neuroinflammatory network of AD and prompts concerted cellular states that are detrimental to memory and cognition.

Ergothioneine, a metabolite of the gut bacterium Lactobacillus reuteri, protects against stress-induced sleep disturbances

The relationships between depression and gut microbiota, particularly those involving the immune system, have become a major focus of recent research. Here, we analyzed changes in gut microbiota and their sulfur metabolites in the feces of a depression rat model using the modified 14-day social defeat stress (SDS) paradigm. Our results showed that SDS increased fecal Lactobacillus reuteri in correlation with ergothioneine levels at around day 11, which continued for at least 1 month following SDS administration. In vitro study further revealed that L. reuteri is capable of producing ergothioneine. Although the known anti-inflammatory and anti-oxidative actions of ergothioneine suggested that the increased fecal ergothioneine levels may be related to intestinal anti-inflammatory defense mechanisms, no change was observed in the plasma ergothioneine levels during the same observation period, indicating that the defense mechanisms may not be sufficiently reflected in the body. As ergothioneine is a natural ingredient that is absorbed mainly from the upper gastrointestinal tract, we hypothesized that oral ergothioneine may exert antidepressant effects. As expected, oral administration of ergothioneine prior to and during the SDS paradigm had a preventative effect on SDS-induced depressive behaviors, such as social avoidance and depression-like sleep abnormalities, particularly those of rapid eye movement sleep. These findings indicate that ergothioneine, a metabolite of L. reuteri, may be a common substance in the microbiota-gut-brain axis that prevents stress-induced sleep disturbances, especially those associated with depression.

The gut microbiome regulates the increases in depressive-type behaviors and in inflammatory processes in the ventral hippocampus of stress vulnerable rats

Chronic exposure to stress is associated with increased incidence of depression, generalized anxiety, and PTSD. However, stress induces vulnerability to such disorders only in a sub-population of individuals, as others remain resilient. Inflammation has emerged as a putative mechanism for promoting stress vulnerability. Using a rodent model of social defeat, we have previously shown that rats with short-defeat latencies (SL/vulnerable rats) show increased anxiety- and depression-like behaviors, and these behaviors are mediated by inflammation in the ventral hippocampus. The other half of socially defeated rats show long-latencies to defeat (LL/resilient) and are similar to controls. Because gut microbiota are important activators of inflammatory substances, we assessed the role of the gut microbiome in mediating vulnerability to repeated social defeat stress. We analyzed the fecal microbiome of control, SL/vulnerable, and LL/resilient rats using shotgun metagenome sequencing and observed increased expression of immune-modulating microbiota, such as Clostridia, in SL/vulnerable rats. We then tested the importance of gut microbiota to the SL/vulnerable phenotype. In otherwise naive rats treated with microbiota from SL/vulnerable rats, there was higher microglial density and IL-1β expression in the vHPC, and higher depression-like behaviors relative to rats that received microbiota from LL/resilient rats, non-stressed control rats, or vehicle-treated rats. However, anxiety-like behavior during social interaction was not altered by transplant of the microbiome of SL/vulnerable rats into non-stressed rats. Taken together, the results suggest the gut microbiome contributes to the depression-like behavior and inflammatory processes in the vHPC of stress vulnerable individuals.

Supplementation of Sesamin Alleviates Stress-Induced Behavioral and Psychological Disorders via Reshaping the Gut Microbiota Structure

Sesamin, a lignan from sesame seed, has been reported to attenuate chronic mild stress-induced depressive-like behaviors. Gut microbiota play pivotal roles in mediating psychological behaviors by regulating gut barrier integrity and systemic inflammatory responses. Here, we found that oral sesamin administration (50 mg/kg·bodyweight/day) significantly attenuated depressive, aversive, repetitive, and anxiety-like behaviors in a long-term multiple nonsocial stress-treated mice model. Sesamin inhibited stress-induced gut barrier integrity damage, reduced circulating lipopolysaccharide (LPS) levels, and suppressed neuroinflammatory responses. Moreover, sesamin treatment also restructured the gut microbiome by enhancing the relative abundances of Bacteroidales and S24-7. The correlation analysis indicated that the microbiota composition changes were strongly correlated with behavioral disorders, serotonin, norepinephrine, and LPS levels. In conclusion, sesamin has preventive effects on stress-induced behavioral and psychological disorders, which might be highly related to the reshaped microbiota composition. This study provides a clue for understanding the systemic mechanism of anti-depression effects of sesamin.

Therapeutic spectrum of interferon-β in ischemic stroke

Ischemic stroke is devastating and a major cause of morbidity and mortality worldwide. To date, only clot retrieval devices and/or intravenous tissue plasminogen activators (tPA) have been approved by the US-FDA for the treatment of acute ischemic stroke. Therefore, there is an urgent need to develop an effective treatment for stroke that can have limited shortcomings and broad spectrum of applications. Interferon-beta (IFN-β), an endogenous cytokine and a key anti-inflammatory agent, contributes toward obviating deleterious stroke outcomes. Therefore, exploring the role of IFN-β may be a promising alternative approach for stroke intervention in the future. In the present review, we have discussed about IFN-β along with its different mechanistic roles in ischemic stroke. Furthermore, therapeutic approaches targeting the inflammatory cascade with IFN-β therapy that may be helpful in improving stroke outcome are also discussed.

Interferon-Related Depression: A Primer on Mechanisms, Treatment, and Prevention of a Common Clinical Problem

BACKGROUND

Depression is among the commonest of psychiatric disorders, and inflammatory mechanisms have been suggested to play a role in its pathophysiology. Interferons are a superfamily of proinflammatory cytokines that play a role in host defence mechanisms. Interferons are used in the treatment of a variety of autoimmune (e.g. multiple sclerosis), viral (e.g. chronic hepatitis B and C), and malignant (e.g. malignant melanoma, hairy cell leukemia) disorders; depression, however, is a notable and clinically troublesome adverse effect.

OBJECTIVE

This article seeks to present a simple explanation and update for the reader about what interferons are, how interferons are classified, the clinical conditions in which interferons are used, the occurrence of depression as a clinical adverse effect of interferon therapy, possible mechanisms that explain interferon-related depression, the treatment of interferon-related depression, and the prevention of interferon-related depression.

METHODS

A qualitative literature review is presented.

RESULTS AND CONCLUSIONS

Irrespective of the indication for IFN therapy, IFNs are associated with a 30- 70% risk of treatment-emergent depression. This risk could be due to the IFN, or to an interaction between the IFN and the indication for which it was prescribed. Various neurohormonal, neurochemical, neurohistological, and other mechanisms have been put forth to explain IFN-related depression. Prophylactic treatment with antidepressants reduces the risk of IFN-related depression; antidepressants also effectively treat the condition. Recent alternatives to IFNs have shown to decrease the risk of treatment-emergent depression.

Future Directions for Pharmacotherapies for Treatment-resistant Bipolar Disorder

Current pharmacological treatments for bipolar disorder (BD) are limited and efficacy has historically been discovered through serendipity. There is now scope for new drug development, focused on the underlying biology of BD that is not targeted by current therapies. The need for novel treatments is urgent when considering treatment resistant BD, where current therapies have failed. While established drugs targeting the monoamine systems continue to be worthwhile, new biological targets including inflammatory and oxidative an nitrosative pathways, apoptotic and neurotrophic pathways, mitochondrial pathways, the N-methyl-Daspartate (NMDA)-receptor complex, the purinergic system, neuropeptide system, cholinergic system and melatonin pathways are all being identified as potential anchors for the discovery of new agents. Many agents are experimental and efficacy data is limited, however further investigation may provide a new line for drug discovery, previously stalled by lack of corporate interest.

Alterations in leukocyte transcriptional control pathway activity associated with major depressive disorder and antidepressant treatment

Major depressive disorder (MDD) is associated with a significantly elevated risk of developing serious medical illnesses such as cardiovascular disease, immune impairments, infection, dementia and premature death. Previous work has demonstrated immune dysregulation in subjects with MDD. Using genome-wide transcriptional profiling and promoter-based bioinformatic strategies, we assessed leukocyte transcription factor (TF) activity in leukocytes from 20 unmedicated MDD subjects versus 20 age-, sex- and ethnicity-matched healthy controls, before initiation of antidepressant therapy, and in 17 of the MDD subjects after 8 weeks of sertraline treatment. In leukocytes from unmedicated MDD subjects, bioinformatic analysis of transcription control pathway activity indicated an increased transcriptional activity of cAMP response element-binding/activating TF (CREB/ATF) and increased activity of TFs associated with cellular responses to oxidative stress (nuclear factor erythroid-derived 2-like 2, NFE2l2 or NRF2). Eight weeks of antidepressant therapy was associated with significant reductions in Hamilton Depression Rating Scale scores and reduced activity of NRF2, but not in CREB/ATF activity. Several other transcriptional regulation pathways, including the glucocorticoid receptor (GR), nuclear factor kappa-B cells (NF-κB), early growth response proteins 1-4 (EGR1-4) and interferon-responsive TFs, showed either no significant differences as a function of disease or treatment, or activities that were opposite to those previously hypothesized to be involved in the etiology of MDD or effective treatment. Our results suggest that CREB/ATF and NRF2 signaling may contribute to MDD by activating immune cell transcriptome dynamics that ultimately influence central nervous system (CNS) motivational and affective processes via circulating mediators.

Therapeutic implications of the choroid plexus-cerebrospinal fluid interface in neuropsychiatric disorders

The choroid plexus (CP) comprises an epithelial monolayer that forms an important physical, enzymatic and immunologic barrier, called the blood-cerebrospinal fluid barrier (BCSFB). It is a highly vascularized organ located in the brain ventricles that is key in maintaining brain homeostasis as it produces cerebrospinal fluid (CSF) and has other important secretory functions. Furthermore, the CP-CSF interface plays a putative role in neurogenesis and has been implicated in neuropsychiatric diseases such as the neurodevelopmental disorders schizophrenia and autism. A role for this CNS border was also implicated in sleep disturbances and chronic and/or severe stress, which are risk factors for the development of neuropsychiatric conditions. Understanding the mechanisms by which disturbance of the homeostasis at the CP-CSF interface is involved in these different chronic low-grade inflammatory diseases can give new insights into therapeutic strategies. Hence, this review discusses the different roles that have been suggested so far for the CP in these neuropsychiatric disorders, with special attention to potential therapeutic applications.

Bupropion for interferon-alpha-induced depression in patients with hepatitis C viral infection: an open-label study

Interferon (IFN)-α therapy for chronic hepatitis C virus (HCV) infection is frequently associated with major depressive episodes. Bupropion, a commonly used antidepressant agent, has recently found to have strong anti-inflammatory effects in animal models. Despite of the theoretical relevancy, the antidepressant effect of bupropion in IFN-alpha-induced depression has never been studied. Ten HCV patients with IFN-α-induced depression were recruited to receive 8-week bupropion treatment and were assessed every 2 weeks for depressive symptoms by the Hamilton rating scale for depression (HAMD) and somatic symptoms by the Neurotoxicity Rating Scale (NRS). Four of the 10 patients met the criteria for remission (total HAMD scores≤7), and 5 patients met the criteria for response (at least 50% reduction in total HAMD scores). In addition, 5 patients had 50% decreases in NRS for neuropsychiatric symptoms. This preliminary open-label study suggests that bupropion is effective in treating IFN-alpha-induced depressive and somatic symptoms.

Influence of psychiatric diagnosis on treatment uptake and interferon side effects in patients with hepatitis C

BACKGROUND AND AIM

Pegylated-interferon-α/ribavirin (PEG-IFN/RBV) treatment can cure hepatitis C virus (HCV) infection but has frequent neuropsychiatric side-effects. Patients with pre-existing psychiatric illness may not be offered therapy. We established prevalence of self-reported psychiatric comorbidity among HCV-infected patients in a hospital-liver clinic, and determined the impact of such diagnoses on uptake and tolerance to PEG-IFN/RBV.

METHODS

All HCV cases referred for assessment in Australian Capital Territory/surrounding regions April 2004-March 2012 were entered into a clinical database. We conducted univariate and multivariate analyses of variables correlating with uptake of antiviral therapy and frequency of treatment-related side-effects.

RESULTS

Of 773 referred patients, 235 (30%) described pre-existing psychiatric illness. Among these, 26% received antiviral therapy, compared with 30% of 538 without psychiatric comorbidity. History of depression (usually validated by liaison psychiatry) was associated with higher incidence of treatment-related neuropsychiatric side-effects (odds ratio 2.79 [1.35-5.70], P < 0.05) but did not affect treatment outcome. Twenty-seven patients reported schizophrenia: three (11%) received antiviral therapy, compared with 30% admitting depression and 20% with bipolar affective disorder (all assessed by psychiatrist). In most schizophrenia cases, the reason for not offering antiviral treatment was psychological illness, yet none of five treated (these three plus two others in a psychiatric rehabilitation facility) experienced worsening psychiatric symptoms.

CONCLUSIONS

A history of depression is common with hepatitis C but does not affect initiation of antiviral treatment, despite substantially increased risk of psychiatric side-effects. In contrast, pre-existing schizophrenia appears to influence treatment decisions, despite little evidence that PEG-IFN/RBV exacerbates the psychiatric condition, and well-supervised antiviral therapy can have good outcomes.

The roles of BDNF, S100B, and oxidative stress in interferon-induced depression and the effect of antidepressant treatment in patients with chronic viral hepatitis: a prospective study

OBJECTIVE

The aim of the study was to research the relationship between interferon (IFN) induced depression and sociodemographic characteristics, neurotrophic factors and oxidative stress.

METHODS

Sixty four cases, 34 with Chronic Hepatitis B (CHB) and 30 with Chronic Hepatitis C (CHC), were included in the study. The patients were assessed with Structured Clinical Interview for DSM-IV (SCID-I), Hamilton Anxiety Rating Scale (HARS) and Hamilton Depression Rating Scale (HDRS) at baseline on the 2nd and 6th weeks of treatment. S100 calcium binding protein B (S100B), brain-derived neurotrophic factor (BDNF), total antioxidant status (TAS) and total oxidative stress (TOS) levels were measured at the same visits.

RESULTS

In total, 20 patients were diagnosed with major depression (MD) on the sixth week. A significant relationship was found between depression developed after IFN therapy and baseline HARS scores and the type of IFN-α. When the pretreatment levels of HDRS, HARS, S100B, BDNF, TAS, and TOS were compared to those after treatment on the 2nd week, there was a significant increase in HDRS and HARS levels and a significant decrease in the levels of S100B and BDNF. No significant change was determined for TAS and TOS levels.

CONCLUSIONS

Our study suggests that the pathogenesis of IFN induced depression may involve neurotrophic factors.

Management of depression induced by interferon hepatitis therapies

OBJECTIVE

Treatment with interferon therapy for hepatitis can induce depression and/or recurrence of affective illness, which could result in cessation of interferon treatment. This article reviews treatment for interferon-induced depression, including antidepressant drugs that may diminish associated symptoms.

DATA SOURCES

English-language literature with no date restrictions on the treatment of interferon-induced depression was reviewed via PubMed and MEDLINE using the key words hepatitis, interferon, hepatitis C, interferon-induced depression, pharmacotherapy of interferon-induced depression, and depression prevention. Fourteen of the most pertinent references are cited.

DATA EXTRACTION

Escitalopram is the most prominently noted pharmaceutical prescribed for treating mood symptoms in hepatitis patients with interferon-induced depression. Other antidepressant medicines may have utility as well.

RESULTS

Antidepressant drugs can be efficacious in diminishing mood disorders during hepatitis therapies. It remains controversial as to whether antidepressant medications can provide prophylaxis against newly developing interferon-induced depressions in individuals with no past history of a mood disorder.

CONCLUSIONS

Antidepressant medicines can be effective at improving mood in patients undergoing interferon treatment for hepatitis.

Sleep architecture variation: a mediator of metabolic disturbance in individuals with major depressive disorder

Remarkable proportions of individuals diagnosed with major depressive disorder (MDD) have comorbid metabolic disturbances (i.e., obesity, type 2 diabetes mellitus (T2DM), hypertension, dyslipidemia), and vice versa. Accumulating evidence suggests that common pathophysiologic pathways such as a chronic, low-grade, proinflammatory state mediate this frequent co-occurrence. However, it remains unclear what traits precede the onset and increase the risk for these pathologic states. The aim of our review was to evaluate the evidentiary base supporting the hypothesis that the increased hazard for metabolic disturbance in MDD subpopulations (and vice versa) is mediated in part by endophenotypic variations in sleep architecture. We conducted a PubMed search of all English-language literature with the following search terms: sleep disturbance, circadian rhythm, inflammation, metabolic syndrome, obesity, MDD, mood disorder, prodrome, T2DM, cytokine, interleukin, hypertension, dyslipidemia, and hypercholesterolemia. Longitudinal and meta-analysis data indicate that specific variations in sleep architecture (i.e., decreased slow-wave sleep [SWS], increased rapid eye movement [REM] density) precede the onset of depressive symptomatology for a subpopulation of individuals. The same sleep architecture variations also are associated with obesity, T2DM, and hypertension. Decreased SWS and increased REM density is correlated with an increase in proinflammatory cytokines (e.g., IL-6, tumor necrosis factor, etc.). This proinflammatory state has been independently shown to be associated with MDD and metabolic disturbances. Taken together, our review suggests that sleep architecture variation of increased REM density and decreased SWS may be an endophenotypic trait, which serves to identify a subpopulation at increased risk for depressive symptoms and metabolic disturbances. Future research is needed to discern the predictive value, sensitivity, and specificity of using sleep architecture variation as a biomarker for MDD and metabolic disturbances. Validation of this marker would have broad clinical implications, such as primary, secondary, and tertiary preventative health strategies.

Symptomatic treatment of interferon-α-induced depression in hepatitis C: a systematic review

Despite its efficacy in treating hepatitis C, interferon-α (IFN-α) can cause depression. The purpose of this systematic review is to summarize and discuss the available and effective therapies in treating IFN-α-induced depression. Using PubMed, The Cochrane Library, Scopus, Embase, Ovid of Medline, PsycINFO, and ISI Web of Knowledge, we selected 64 articles concerning IFN-α-induced depression treatment in hepatitis C patients. Selective serotonin reuptake inhibitors can be considered the first choice for the treatment of IFN-α-induced depression, as demonstrated in open-label studies, case reports, and a randomized, double-blind, placebo-controlled trial. Also 5-hydroxytryptophan and tryptophan have been suggested to be effective as monotherapy or as augmentation of selective serotonin reuptake inhibitors. Clinical cases that show positive effects of tricyclic antidepressants, however, do not provide sufficient evidence for the use of these drugs. Two cohort studies have reported the effectiveness of amisulpride, but not of levosulpiride. Mirtazapine has been suggested to be a better choice of treatment in cases where insomnia or anorexia develop. Milnacipram can be useful in cases of concomitant medications, for the unlikely occurrence of drug-drug interactions. Psychostimulants represent an empirical treatment without controlled data to support their use. Two case reports have shown the favorable use of bupropion, particularly if sexual dysfunction or cravings for illicit drugs are present. A single case report suggests electroconvulsive therapy to be a possible choice when antidepressants are ineffective or poorly tolerated. The main limitation of our review is that the quality of the findings varied across the reviewed studies. Our observations may help clinicians with managing IFN-α-induced depression.

Depressive symptoms following interferon-α therapy: mediated by immune-induced reductions in brain-derived neurotrophic factor?

Interferon-α (IFN-α) therapy for the treatment of hepatitis C is known to induce depressive symptoms and major depression in a substantial proportion of patients. While immune activation and disturbances in peripheral tryptophan catabolism have been implicated, the exact underlying mechanism remains unknown. A role for brain-derived neurotrophic factor (BDNF) in the pathophysiology of mood disorders has recently emerged. This study examined whether depressive symptoms over time are associated with changes in serum BDNF concentration in hepatitis C patients treated with IFN-α, and whether BDNF mediates the effects of IFN-α-induced immune activation on depressive symptoms. For this purpose, 17 hepatitis C patients received IFN-α treatment with ribavirin. Patients were assessed before and at 1, 2, 4, 8, 12 and 24 wk after start of treatment. Depressive symptoms were assessed using the Montgomery-Asberg Depression Rating Scale (MADRS). In addition, cytokine concentrations and serum BDNF levels were measured at all time-points. Serum levels of BDNF decreased during the course of treatment, and were significantly and inversely associated with total MADRS score. Furthermore, pro-inflammatory cytokine levels predicted lower subsequent BDNF levels, whereas low BDNF levels, as well as increased cytokine levels, were independently associated with the development of depressive symptoms during IFN-α treatment. These findings suggest that the effect of IFN-α-induced immune activation on depression may be explained in part by alterations in neuroprotective capacity, reflected by decreases in serum BDNF following IFN-α treatment.

Mood disorders and obesity: understanding inflammation as a pathophysiological nexus

The aim of this review is to evaluate the evidentiary base supporting the hypothesis that the increased hazard for obesity in mood disorder populations (and vice versa) is a consequence of shared pathophysiological pathways. We conducted a PubMed search of all English-language articles with the following search terms: obesity, inflammation, hypothalamic-pituitary-adrenal axis, insulin, cognition, CNS, and neurotransmitters, cross-referenced with major depressive disorder and bipolar disorder. The frequent co-occurrence of mood disorders and obesity may be characterized by interconnected pathophysiology. Both conditions are marked by structural and functional abnormalities in multiple cortical and subcortical brain regions that subserve cognitive and/or affective processing. Abnormalities in several interacting biological networks (e.g. immuno-inflammatory, insulin signaling, and counterregulatory hormones) contribute to the co-occurence of mood disorders and obesity. Unequivocal evidence now indicates that obesity and mood disorders are chronic low-grade pro-inflammatory states that result in a gradual accumulation of allostatic load. Abnormalities in key effector proteins of the pro-inflammatory cascade include, but are not limited to, cytokines/adipokines such as adiponectin, leptin, and resistin as well as tumor necrosis factor alpha and interleukin-6. Taken together, the bidirectional relationship between obesity and mood disorders may represent an exophenotypic manifestation of aberrant neural and inflammatory networks. The clinical implications of these observations are that, practitioners should screen individuals with obesity for the presence of clinically significant depressive symptoms (and vice versa). This clinical recommendation is amplified in individuals presenting with biochemical indicators of insulin resistance and other concurrent conditions associated with abnormal inflammatory signaling (e.g. cardiovascular disease).

Neural substrates of psychostimulant withdrawal-induced anhedonia

Psychostimulant drugs have powerful reinforcing and hedonic properties and are frequently abused. Cessation of psychostimulant administration results in a withdrawal syndrome characterized by anhedonia (i.e., an inability to experience pleasure). In humans, psychostimulant withdrawal-induced anhedonia can be debilitating and has been hypothesized to play an important role in relapse to drug use. Hence, understanding the neural substrates involved in psychostimulant withdrawal-induced anhedonia is essential. In this review, we first summarize the theoretical perspectives of psychostimulant withdrawal-induced anhedonia. Experimental procedures and measures used to assess anhedonia in experimental animals are also discussed. The review then focuses on neural substrates hypothesized to play an important role in anhedonia experienced after termination of psychostimulant administration, such as with cocaine, amphetamine-like drugs, and nicotine. Both neural substrates that have been extensively investigated and some that need further evaluation with respect to psychostimulant withdrawal-induced anhedonia are reviewed. In the context of reviewing the various neurosubstrates of psychostimulant withdrawal, we also discuss pharmacological medications that have been used to treat psychostimulant withdrawal in humans. This literature review indicates that great progress has been made in understanding the neural substrates of anhedonia associated with psychostimulant withdrawal. These advances in our understanding of the neurobiology of anhedonia may also shed light on the neurobiology of nondrug-induced anhedonia, such as that seen as a core symptom of depression and a negative symptom of schizophrenia.

Interferon-gamma deficiency modifies the motor and co-morbid behavioral pathology and neurochemical changes provoked by the pesticide paraquat

In addition to nigrostriatal pathology and corresponding motor disturbances, Parkinson's disease (PD) is often characterized by co-morbid neuropsychiatric symptoms, most notably anxiety and depression. Separate lines of evidence indicate that inflammatory processes associated with microglial activation and cytokine release may be fundamental to the progression of both PD and its co-morbid psychiatric pathology. Accordingly, we assessed the contribution of the pro-inflammatory cytokine, interferon-gamma (IFN-gamma), to a range of PD-like pathology provoked by the ecologically relevant herbicide and dopamine (DA) toxin, paraquat. To this end, paraquat provoked overt motor impairment (reduced home-cage activity and impaired vertical climbing) and signs of anxiety-like behavior (reduced open field exploration) in wild-type but not IFN-gamma-deficient mice. Correspondingly, paraquat promoted somewhat divergent variations in neurochemical activity among wild-type and IFN-gamma null mice at brain sites important for both motor (striatum) and co-morbid affective pathologies (dorsal hippocampus, medial prefrontal cortex, and locus coeruleus). Specifically, the herbicide provoked a dosing regimen-dependent reduction in striatal DA levels that was prevented by IFN-gamma deficiency. In addition, the herbicide influenced serotonergic and noradrenergic activity within the dorsal hippocampus and medial prefrontal cortex; and elevated noradrenergic activity within the locus coeruleus. Although genetic ablation of IFN-gamma had relatively few effects on monoamine variations within the locus coeruleus and prefrontal cortex, loss of the pro-inflammatory cytokine did normalize the paraquat-induced noradrenergic alterations within the hippocampus. These findings further elucidate the functional implications of paraquat intoxication and suggest an important role for IFN-gamma in the striatal and motor pathology, as well as the co-morbid behavioral and hippocampal changes induced by paraquat.

Differences in depressive thoughts between major depressive disorder, IFN-alpha-induced depression, and depressive disorders among cancer patients

OBJECTIVE

The objective of this study is to test the hypothesis that there are differences in the distribution of negative thoughts among major depressive disorders (MDD), depressive disorders among cancer patients, and IFN-alpha-induced depression.

METHODS

Twenty-three patients affected by MDD, 25 cancer patients affected by depressive disorders (20 MDD), and 19 patients affected by IFN-alpha-induced depression satisfying MDD criteria were evaluated using the 17-item Hamilton Depression Rating Scale and the 13-item Beck Depression Inventory.

RESULTS

Sense of guilt was higher among MDD patients (56.5%) and was lower among cancer patients (4%) (P<.0001). Sense of failure, dissatisfaction, and self-dislike were higher among MDD patients than among IFN-alpha patients (P<.0001).

CONCLUSIONS

In our study, patients affected by MDD present a different pattern of symptoms in comparison with patients affected by IFN-alpha-induced depression and depressive disorders. In particular, core depressive thoughts were less frequent in the last two conditions.

The successful use of electroconvulsive therapy in a patient with interferon-induced psychotic depression

We report the successful use of electroconvulsive therapy in a patient who developed major depression with psychotic features while being treated with interferon alfa-2b for hepatitis C. We reviewed the literature of similar cases and discuss treatment options for interferon-induced depression and psychosis.

Hypomanic mood in a child patient treated with interferon-alpha 2a: case report

We report on a male child born in Rumania, adopted by an Italian family, and who at 10 years of age was submitted to interferon-alpha 2a therapy for chronic hepatitis B. About 30 days after the beginning of the treatment he developed hypomanic mood and psychogenic seizures. Psychological evaluation showed hyperactivity, distractibility, excessive talkativeness, grandiosity and racing thoughts. Temperamental traits were characterized by an elevated emotionality. The patient was successfully administered risperidone and cognitive-behavioral therapy; six months of treatment with interferon led to positive outcome of hepatitis B. Since affective symptoms may occur in children treated with IFN, a careful evaluation of psychiatric disturbances and adequate intervention are needed.

Interferon-induced depression in hepatitis C: an update

Hepatitis C is a global epidemic, and its costs in both lives and health care expenditures continue to rise. The only approved treatment for this disease, interferon-alpha (IFN), causes treatment-emergent depression in more than one quarter of all patients who take it. Newer preparations of IFN have been developed to increase its antiviral efficacy, but the incidence of treatment-emergent depression has not decreased. The data on the epidemiology and risk factors for interferon-induced depression are reviewed in an effort to delineate its standing as a unique psychiatric disorder. In addition, evidence-based treatment approaches are outlined, including the potential efficacy of preinterferon prophylactic treatment with antidepressants.

The effects of HCV infection and management on health-related quality of life

Infection with HCV leads to an array of symptoms that compromise health-related quality of life (HRQL). Chronic hepatitis C is treated primarily with pegylated interferon (peg-IFN) and an inosine 5' monophosphate dehydrogenase inhibitor, ribavirin (RBV), with the goal of achieving a sustained virologic response (SVR). SVR reduces the rate of hepatic fibrosis and other disease-related complications and, in turn, increases HRQL. Although combination therapy with peg-IFN and RBV produces SVRs in more than 50% of treated patients, it is associated with side effects that can reduce short-term HRQL, can lead to dose reductions and discontinuations, and may impair treatment response. Fatigue and depression are common symptoms of chronic HCV infection that may also be caused by IFN-based therapy. Hemolytic anemia and IFN-mediated bone marrow suppression are well-known consequences of IFN/RBV therapy, often resulting in dose reductions or discontinuations, and have the potential to affect SVR rates. Management of these symptoms is vital to successful outcomes and generally relies on therapy that is adjunctive to the primary treatment of the viral infection itself. Several new drugs with the potential to increase SVR rates without compromising HRQL are in development.

CONCLUSION

The relationship of chronic HCV infection, treatment, and HRQL is complex. Successful treatment of chronic hepatitis C requires an understanding of the intricacies of this relationship and appropriate management of treatment-related symptoms.

Methodological approaches in the assessment of interferon-alfa-induced depression in patients with chronic hepatitis C - a critical review

In recent years, research on interferon (IFN)-induced depressive symptoms in antivirally treated patients suffering from chronic hepatitis C (CHC) has considerably intensified. Profound scientific knowledge of this complication is of great relevance with regard to adherence, compliance, and premature therapy discontinuation. Presently, there is considerable variability of both, the frequency and extent of IFN-induced depression reported in different cohorts of patients. The aim of the presented study was to systematically review recent literature of research within this field; and particularly (1) to identify to what extent methodological bias contributed to inconsistent results in different studies, (2) to critically appraise methods and results of studies published so far, and (3) to suggest directions for future work, especially with respect to alternative and improved methodological approaches. The results of this critical review suggest that the variability of findings seem to be largely due to different study populations, treatment regimens, methodological approaches, and sometimes arbitrary or at least poorly defined choice of screening instruments for depression, particularly criteria for clinically relevant depression (cut-off criteria). Study designs and methodological approaches to investigate IFN-alfa-induced depression in patients with CHC have been incoherent. Future research in this field needs agreement on the use of standardized assessment of IFN-induced depression in CHC. Furthermore, objective criteria and guidelines for the treatment of IFN-induced depression in these patients are needed in clinical practice.

Depressive behavior in mice due to immune stimulation is accompanied by reduced neural activity in brain regions involved in positively motivated behavior

BACKGROUND

Immune stimulation inhibits positively motivated behavior and induces depressive illness. To help clarify the mechanism of these effects, neural activity in response to a positive stimulus was examined in brain regions associated with positively motivated activity defined on the basis of prior behavioral studies of central alpha1-adrenoceptor action.

METHODS

Mice pretreated with either lipopolysaccharide or, for comparison, reserpine were exposed to a motivating stimulus (fresh cage) and subsequently assayed for fos expression and mitogen-activated protein kinase (MAPK) phosphorylation, two measures associated with alpha1-adrenoceptor-dependent neural activity, in several positive-activity-related (motor, piriform, cingulate cortex, nucleus accumbens, locus coeruleus) and stress-related brain regions (paraventricular hypothalamus, bed nucleus stria terminalis).

RESULTS

Both lipopolysaccharide and reserpine pretreatment abolished fresh cage-induced fos expression and MAPK activation in the positive activity-related brain regions but enhanced these measures in the stress-related areas.

CONCLUSIONS

The results support the hypothesis that immune activation reduces alpha1-adrenoceptor-related signaling and neural activity in brain regions associated with positive activity while it increases these functions in stress-associated areas. It is suggested that neural activities of these two types of brain regions are mutually antagonistic and that a reciprocal shift toward the stress regions is a factor in the loss of positively motivated behaviors in sickness behavior and depressive illness.

Methylphenidate for alpha-interferon induced depression

Interferon-Alpha (IFN) has been effective in the treatment of chronic viral infections and cancer albeit the added risk of severe depression. The literature has reported effectiveness in the use of antidepressants for interferon-induced depression. We report a case of severe protracted depression induced by IFN in a patient diagnosed with melanoma who responded rapidly to a course of methylphenidate using the Hamilton Depressive Rating Scale. Methylphenidate appeared to be effective in the treatment of neurovegetative symptoms of major depression induced by IFN. This report provides further clinical evidence that the neurovegetative symptoms of depression might respond better to a norepinephrine uptake inhibitor or psycho-stimulants.

Chronic hepatitis C: treatment of pegylated interferon/ribavirin nonresponders

Patients with chronic hepatitis C virus (HCV) who were nonresponders to previous treatment with pegylated interferon and ribavirin are a growing population. The vast majority have genotype 1, a high viral load, advanced fibrosis or cirrhosis, and are of African-American race. The evaluation of these patients should include a thorough review of the previous treatment record and characterization of the previous nonresponse. Patients with prior null response are likely resistant to the effects of interferon. In contrast, patients with partial virologic response, breakthrough, and relapse could potentially achieve sustained virologic response if one or more correctable factors that contributed to the prior nonresponse are identified and addressed before and during retreatment. Many HCV nonresponders, especially those with no fibrosis or mild fibrosis, have an excellent prognosis, are at low risk to develop cirrhosis, and should simply be monitored at periodic intervals until more effective therapy has been developed.

Endotoxin- or pro-inflammatory cytokine-induced sickness behavior as an animal model of depression: focus on anhedonia

In humans, exposure to endotoxins or pro-inflammatory cytokines induces a number of neuropsychological symptoms collectively referred to as 'flu-like syndrome'. The degree of overlap between flu-like syndrome and major depressive disorder is considerable and a close linkage between these has been predicted to arise due to hypersecretion of endogenous pro-inflammatory cytokines and activation of the hypothalamic pituitary adrenal axis. In animals, exposure to pro-inflammatory cytokines or endotoxins induces a 'sickness behavior' syndrome that is analogous to flu-like symptoms observed in human patients. The goal of the current paper is to review evidence implicating endotoxin- or cytokine-induced sickness behavior as an animal model of depression, with an emphasis on reduced consumption of highly palatable substances as a defining feature.