Comparison of cytokine levels in depressed, manic and euthymic patients with bipolar disorder

Association Between Mood Disorders and Risk of COVID-19 Infection, Hospitalization, and Death: A Systematic Review and Meta-analysis

IMPORTANCE

Preexisting noncommunicable diseases (eg, diabetes) increase the risk of COVID-19 infection, hospitalization, and death. Mood disorders are associated with impaired immune function and social determinants that increase the risk of COVID-19. Determining whether preexisting mood disorders represent a risk of COVID-19 would inform public health priorities.

OBJECTIVE

To assess whether preexisting mood disorders are associated with a higher risk of COVID-19 susceptibility, hospitalization, severe complications, and death.

DATA SOURCES

Systematic searches were conducted for studies reporting data on COVID-19 outcomes in populations with and without mood disorders on PubMed/MEDLINE, The Cochrane Library, PsycInfo, Embase, Web of Science, Google/Google Scholar, LitCovid, and select reference lists. The search timeline was from database inception to February 1, 2021.

STUDY SELECTION

Primary research articles that reported quantitative COVID-19 outcome data in persons with mood disorders vs persons without mood disorders of any age, sex, and nationality were selected. Of 1950 articles identified through this search strategy, 21 studies were included in the analysis.

DATA EXTRACTION AND SYNTHESIS

The modified Newcastle-Ottawa Scale was used to assess methodological quality and risk of bias of component studies. Reported adjusted odds ratios (ORs) were pooled with unadjusted ORs calculated from summary data to generate 4 random-effects summary ORs, each corresponding to a primary outcome.

MAIN OUTCOMES AND MEASURES

The 4 a priori primary outcomes were COVID-19 susceptibility, COVID-19 hospitalization, COVID-19 severe events, and COVID-19 death. The hypothesis was formulated before study search. Outcome measures between individuals with and without mood disorders were compared.

RESULTS

This review included 21 studies that involved more than 91 million individuals. Significantly higher odds of COVID-19 hospitalization (OR, 1.31; 95% CI, 1.12-1.53; P = .001; n = 26 554 397) and death (OR, 1.51; 95% CI, 1.34-1.69; P < .001; n = 25 808 660) were found in persons with preexisting mood disorders compared with those without mood disorders. There was no association between mood disorders and COVID-19 susceptibility (OR, 1.27; 95% CI, 0.73-2.19; n = 65 514 469) or severe events (OR, 0.94; 95% CI, 0.87-1.03; n = 83 240). Visual inspection of the composite funnel plot for asymmetry indicated the presence of publication bias; however, the Egger regression intercept test result was not statistically significant.

CONCLUSIONS AND RELEVANCE

The results of this systematic review and meta-analysis examining the association between preexisting mood disorders and COVID-19 outcomes suggest that individuals with preexisting mood disorders are at higher risk of COVID-19 hospitalization and death and should be categorized as an at-risk group on the basis of a preexisting condition.

The emerging tale of microglia in psychiatric disorders

As the professional phagocytes of the brain, microglia orchestrate the immunological response and play an increasingly important role in maintaining homeostatic brain functions. Microglia are activated by pathological events or slight alterations in brain homeostasis. This activation is dependent on the context and type of stressor or pathology. Through secretion of cytokines, chemokines and growth factors, microglia can strongly influence the response to a stressor and can, therefore, determine the pathological outcome. Psychopathologies have repeatedly been associated with long-lasting priming and sensitization of cerebral microglia. This review focuses on the diversity of microglial phenotype and function in health and psychiatric disease. We first discuss the diverse homeostatic functions performed by microglia and then elaborate on context-specific spatial and temporal microglial heterogeneity. Subsequently, we summarize microglia involvement in psychopathologies, namely major depressive disorder, schizophrenia and bipolar disorder, with a particular focus on post-mortem studies. Finally, we postulate microglia as a promising novel therapeutic target in psychiatry through antidepressant and antipsychotic treatment.

Lower pro- to anti-inflammatory ratios associated with reduced neurocognitive flexibility in symptomatic adolescents with bipolar disorder

INTRODUCTION

Peripheral inflammatory markers, such as C-reactive protein (CRP), are elevated among adolescents and adults with bipolar disorder (BD), particularly during symptomatic episodes. Neurocognition, predominantly in the domain of executive function, is also impaired among adults and youth with BD. In adults with BD, CRP is negatively associated with neurocognitive functioning. We aim to investigate this relationship in BD adolescents.

METHODS

Serum levels of CRP and five other inflammatory markers (interleukin (IL)-1β, IL-6, IL-10, IL-4 and tumor necrosis factor α (TNF)) were examined in 60 adolescents with BD (34 symptomatic, 26 asymptomatic) age- and sex-matched to 51 healthy controls (HC). Diagnoses were confirmed using semi-structured interviews. Pro- to anti-inflammatory marker ratios were also examined. Neurocognitive flexibility was assessed via the intra/extradimensional shift (IED) task from the CANTAB battery. Multivariate linear regression controlled for age, sex and race.

RESULTS

Within symptomatic BD adolescents, but not asymptomatic BD or HC adolescents, lower IL-6/IL-10 and lower CRP/IL-10 ratios were significantly associated with worse performance on the neurocognitive flexibility task (p = 0.03 and p = 0.04, respectively). Both models accounted for 13.3% of variance in neurocognitive flexibility. No significant CRP by diagnosis interaction effects were observed on neurocognitive flexibility.

LIMITATIONS

Limited sample-size restricted ability to separate the symptomatic BD adolescents into varying mood states.

CONCLUSION

More balanced pro- to anti-inflammatory ratios were associated with better neurocognitive flexibility in symptomatic BD adolescents. Prospective studies are warranted to assess the direction of these findings.

Lithium orotate: A superior option for lithium therapy?

Bipolar disorder (BD) poses a significant public health concern, with roughly one-quarter of sufferers attempting suicide. BD is characterized by manic and depressive mood cycles, the recurrence of which can be effectively curtailed through lithium therapy. Unfortunately, the most frequently employed lithium salt, lithium carbonate (Li₂ CO₃ ), is associated with a host of adverse health outcomes following chronic use: these unwanted effects range from relatively minor inconveniences (e.g., polydipsia and polyuria) to potentially major complications (e.g., hypothyroidism and/or renal impairment). As these undesirable effects can limit patient compliance, an alternative lithium compound with a lesser toxicity profile would dramatically improve treatment efficacy and outcomes. Lithium orotate (LiC₅ H₃ N₂ O₄ ; henceforth referred to as LiOr), a compound largely abandoned since the late 1970s, may represent such an alternative. LiOr is proposed to cross the blood-brain barrier and enter cells more readily than Li₂ CO₃ , which will theoretically allow for reduced dosage requirements and ameliorated toxicity concerns. This review addresses the controversial history of LiOr, complete with discussions of experimental and clinical efficacy, putative mechanisms of action, adverse effects, and its potential future in therapy.

Role of Quercetin in Depressive-Like Behaviors: Findings from Animal Models

Depressive-like behavior is a highly prevalent worldwide neuropsychiatric disorder that owns a complex pathophysiologic mechanism. The available pharmacotherapy is ineffective for most patients and shown several adverse effects. Therefore, it is important to find efficacy and safe antidepressive compounds. Some phytochemicals compounds regulate the same genes and pathways targeted by drugs; therefore, diets rich in fruits and vegetables could be considered novel treatment approaches. Currently, the functional properties of quercetin acquired great interest, due to its beneficial effects on health. Quercetin is a flavonoid ubiquitously present in vegetables and fruits, interestingly for its strong antioxidant properties. The purpose of this review is to summarize the preclinical studies present in the literature, in the last ten years, aimed at illustrating the effects of quercetin pre-treatment in depressive-like behaviors. Quercetin resulted in antidepressant-like actions due to its antioxidant, anti-inflammatory, and neuroprotective effects. This pointed out the usefulness of this flavonoid as a nutraceutical compound against the development of psychological stress-induced behavioral perturbation. Therefore, quercetin or a diet containing it may become a prospective supplementation or an efficient adjuvant therapy for preventing stress-mediated depressive-like behavior.

Inflammatory biomarkers and cognitive functioning in individuals with euthymic bipolar disorder: exploratory study

BACKGROUND

Neurobiological research frequently implicates inflammatory and neurogenic components with core aspects of bipolar disorder. Even in periods of symptom remission (euthymia), individuals with bipolar disorder experience cognitive impairments, which are increasingly being proposed as an outcome for interventions; identifying biomarkers associated with cognitive impairment in people with bipolar disorder could advance progress in this therapeutic field through identifying biological treatment targets.

AIMS

We aimed to identify proteomic biomarker correlates of cognitive impairment in individuals with euthymic bipolar disorder.

METHOD

Forty-four adults with a bipolar disorder diagnosis in euthymia underwent a battery of cognitive assessments and provided blood for biomarkers. We examined a comprehensive panel of inflammatory and trophic proteins as putative cross-sectional predictors of cognition, conceptualised according to recommended definitions of clinically significant cognitive impairment (binary construct) and global cognitive performance (continuous measure).

RESULTS

A total of 48% of the sample met the criteria for cognitive impairment. Adjusting for potentially important covariates, regression analyses identified lower levels of three proteins as significantly and independently associated with cognitive deficits, according to both binary and continuous definitions (interleukin-7, vascular endothelial growth factor C and placental growth factor), and one positively correlated with (continuous) global cognitive performance (basic fibroblast growth factor).

CONCLUSIONS

This study identifies four candidate markers of cognitive impairment in bipolar disorder, none of which have been previously compared with cognitive function in participants with bipolar disorder. Pending replication in larger samples and support from longitudinal studies, these markers could have implications for treating cognitive dysfunction in this patient population.

The lipid paradox in neuroprogressive disorders: Causes and consequences

Chronic systemic inflammation is associated with an increased risk of cardiovascular disease in an environment of low low-density lipoprotein (LDL) and low total cholesterol and with the pathophysiology of neuroprogressive disorders. The causes and consequences of this lipid paradox are explored. Circulating activated neutrophils can release inflammatory molecules such as myeloperoxidase and the pro-inflammatory cytokines interleukin-1 beta, interleukin-6 and tumour necrosis factor-alpha. Since activated neutrophils are associated with atherosclerosis and cardiovascular disease and with major depressive disorder, bipolar disorder and schizophrenia, it seems reasonable to hypothesise that the inflammatory molecules released by them may act as mediators of the link between systemic inflammation and the development of atherosclerosis in neuroprogressive disorders. This hypothesis is tested by considering the association at a molecular level of systemic inflammation with increased LDL oxidation; increased small dense LDL levels; increased lipoprotein (a) concentration; secretory phospholipase A₂ activation; cytosolic phospholipase A₂ activation; increased platelet activation; decreased apolipoprotein A1 levels and function; decreased paroxonase-1 activity; hyperhomocysteinaemia; and metabolic endotoxaemia. These molecular mechanisms suggest potential therapeutic targets.

Evaluating endophenotypes for bipolar disorder

BACKGROUND

Phenotypic heterogeneity is a major impediment to the elucidation of the neurobiology and genetics of bipolar disorder. Endophenotype could help in reducing heterogeneity by defining biological traits that are more direct expressions of gene effects. The aim of this review is to examine the recent literature on clinical, epidemiological, neurobiological, and genetic findings and to select and evaluate candidate endophenotypes for bipolar disorder. Evaluating putative endophenotype could be helpful in better understanding the neurobiology of bipolar disorder by improving the definition of bipolar-related phenotypes in genetic studies. In this manner, research on endophenotypes could be useful to improve psychopathological diagnostics in the long-run by dissecting psychiatric macro phenotypes into biologically valid components.

MAIN BODY

The associations among the psychopathological and biological endophenotypes are discussed with respect to specificity, temporal stability, heritability, familiarity, and clinical and biological plausibility. Numerous findings regarding brain function, brain structure, neuropsychology and altered neurochemical pathways in patients with bipolar disorder and their relatives deserve further investigation. Overall, major findings suggest a developmental origin of this disorder as all the candidate endophenotypes that we have been able to select are present both in the early stages of the disorder as well as in subjects at risk.

CONCLUSIONS

Among the stronger candidate endophenotypes, we suggest circadian rhythm instability, dysmodulation of emotion and reward, altered neuroimmune state, attention and executive dysfunctions, anterior cingulate cortex thickness and early white matter abnormalities. In particular, early white matter abnormalities could be the result of a vulnerable brain on which new stressors are added in young adulthood which favours the onset of the disorder. Possible pathways that lead to a vulnerable brain are discussed starting from the data about molecular and imaging endophenotypes of bipolar disorder.

Insulin Resistance and Blood-Brain Barrier Dysfunction Underlie Neuroprogression in Bipolar Disorder

Bipolar disorder (BD) often progresses to a more chronic and treatment resistant (neuroprogressive) course. Identifying which patients are at risk could allow for early intervention and prevention. Bipolar disorder is highly comorbid with metabolic disorders including type II diabetes mellitus (T2DM), hypertension, obesity, and dyslipidemia. Our studies have shown that insulin resistance (IR) is present in over 50% of patients with BD and that IR might underlie the progression of BD. While no confirmed predictors exist for identifying which patients with BD are likely to develop a more chronic course, emerging evidence including our own studies suggest that IR and related inflammatory pathways lead to impairments in blood-brain barrier (BBB) functioning. For the first time in living psychiatric patients, we have shown that the severity of BBB leakage is proportional to BD severity and is associated with IR. In this hypothesis paper we (i) highlight the evidence for a key role of IR in BD, (ii) show how IR in BD relates to shared inflammatory pathways, and (iii) hypothesize that these modulations result in BBB leakage and worse outcomes in BD. We further hypothesize that (iv) reversing IR through lifestyle changes or the actions of insulin sensitizing medications such as metformin, or optimizing BBB function using vascular protective drugs, such as losartan, could provide novel strategies for the prevention or treatment of neuroprogressive BD.

Inflammation-driven brain and gut barrier dysfunction in stress and mood disorders

Regulation of emotions is generally associated exclusively with the brain. However, there is evidence that peripheral systems are also involved in mood, stress vulnerability vs. resilience, and emotion‐related memory encoding. Prevalence of stress and mood disorders such as major depression, bipolar disorder, and post‐traumatic stress disorder is increasing in our modern societies. Unfortunately, 30%–50% of individuals respond poorly to currently available treatments highlighting the need to further investigate emotion‐related biology to gain mechanistic insights that could lead to innovative therapies. Here, we provide an overview of inflammation‐related mechanisms involved in mood regulation and stress responses discovered using animal models. If clinical studies are available, we discuss translational value of these findings including limitations. Neuroimmune mechanisms of depression and maladaptive stress responses have been receiving increasing attention, and thus, the first part is centered on inflammation and dysregulation of brain and circulating cytokines in stress and mood disorders. Next, recent studies supporting a role for inflammation‐driven leakiness of the blood–brain and gut barriers in emotion regulation and mood are highlighted. Stress‐induced exacerbated inflammation fragilizes these barriers which become hyperpermeable through loss of integrity and altered biology. At the gut level, this could be associated with dysbiosis, an imbalance in microbial communities, and alteration of the gut–brain axis which is central to production of mood‐related neurotransmitter serotonin. Novel therapeutic approaches such as anti‐inflammatory drugs, the fast‐acting antidepressant ketamine, and probiotics could directly act on the mechanisms described here improving mood disorder‐associated symptomatology. Discovery of biomarkers has been a challenging quest in psychiatry, and we end by listing promising targets worth further investigation.

Brain free water alterations in first-episode psychosis: a longitudinal analysis of diagnosis, course of illness, and medication effects

BACKGROUND

Multiple lines of evidence suggest the presence of altered neuroimmune processes in patients with schizophrenia (Sz) and severe mood disorders. Recent studies using a novel free water diffusion tensor imaging (FW DTI) approach, proposed as a putative biomarker of neuroinflammation, atrophy, or edema, have shown significantly increased FW in patients with Sz. However no studies to date have investigated the longitudinal stability of FW alterations during the early course of psychosis, nor have studies focused separately on FE psychosis patients with Sz or bipolar disorder (BD) with psychotic features.

METHODS

The current study included 188 participants who underwent diffusion magnetic resonance imaging scanning at baseline. Sixty-four participants underwent follow-up rescanning after 12 months. DTI-based alterations in patients were calculated using voxelwise tract-based spatial statistics and region of interest analyses.

RESULTS

Patients with FE psychosis, both Sz and BD, exhibited increased FW at illness onset which remained unchanged over the 12-month follow-up period. Preliminary analyses suggested that antipsychotic medication exposure was associated with higher FW in gray matter that reached significance in the BD group. Higher FW in white matter correlated with negative symptom severity.

CONCLUSIONS

Our results support the presence of elevated FW at the onset of psychosis in both Sz and BD, which remains stable during the early course of the illness, with no evidence of either progression or remission.

Periodontal Pathogens and Neuropsychiatric Health

Increasing evidence incriminates low-grade inflammation in cardiovascular, metabolic diseases, and neuropsychiatric clinical conditions, all important causes of morbidity and mortality. One of the upstream and modifiable precipitants and perpetrators of inflammation is chronic periodontitis, a polymicrobial infection with Porphyromonas gingivalis (P. gingivalis) playing a central role in the disease pathogenesis. We review the association between P. gingivalis and cardiovascular, metabolic, and neuropsychiatric illness, and the molecular mechanisms potentially implicated in immune upregulation as well as downregulation induced by the pathogen. In addition to inflammation, translocation of the pathogens to the coronary and peripheral arteries, including brain vasculature, and gut and liver vasculature has important pathophysiological consequences. Distant effects via translocation rely on virulence factors of P. gingivalis such as gingipains, on its synergistic interactions with other pathogens, and on its capability to manipulate the immune system via several mechanisms, including its capacity to induce production of immune-downregulating micro-RNAs. Possible targets for intervention and drug development to manage distal consequences of infection with P. gingivalis are also reviewed.

Prefrontal dopamine D1 receptor manipulation influences anxiety behavior and induces neuroinflammation within the hippocampus

Background

Prefrontal dopamine D1 receptor (D1R) mediates behavior related to anxiety, reward and memory, and is involved in inflammatory processes, all of which are affected in bipolar disorder. Interleukin-6 (IL-6), a pro-inflammatory cytokine, is increased in patients with bipolar disorder in plasma samples, imaging studies and postmortem tissue and is an indicator for an inflammatory state. We could previously show that lentiviral overexpression of D1R in the medial prefrontal cortex (mPFC) of male adult rats and its termination induces bipolar disorder-like behavior. The purpose of this study was to investigate anxiety and the role of the immune system, specifically IL-6 positive neurons in this animal model. Due to its high density of inflammatory mediator receptors and therewith sensibility to immune activation, the hippocampus was investigated.

Methods

Expression of the gene for D1R in glutamatergic neurons within the mPFC of male, adult rats was manipulated through an inducible lentiviral vector. Animals over-expressing the gene (mania-like state), after termination of the expression (depressive-like) and their respective control groups were investigated. Anxiety behavior was studied in the elevated plus maze and marble burying test. Furthermore, IL-6-positive cells were counted within several subregions of the hippocampus.

Results

D1R manipulation in the mPFC had only mild effects on anxiety behavior in the elevated plus maze. However, subjects after termination buried more marbles compared to D1R over-expressing animals and their respective control animals indicating elevated anxiety behavior. In addition, animals in the depressive-like state showed higher numbers of IL-6 positive cells reflecting an elevated pro-inflammatory state in the hippocampus, in the CA3 and dentate gyrus. Consistently, inflammatory state in the whole hippocampus and anxiety behavior correlated positively, indicating a connection between anxiety and inflammatory state of the hippocampus.

Conclusions

Behavioral and neurobiological findings support the association of manipulation of the D1R in the mPFC on anxiety and inflammation in the hippocampus. In addition, by confirming changes in the inflammatory state, the proposed animal model for bipolar disorder has been further validated.

Transcriptional analysis of sodium valproate in a serotonergic cell line reveals gene regulation through both HDAC inhibition-dependent and independent mechanisms

Sodium valproate (VPA) is a histone deacetylase (HDAC) inhibitor, widely prescribed in the treatment of bipolar disorder, and yet the precise modes of therapeutic action for this drug are not fully understood. After exposure of the rat serotonergic cell line RN46A to VPA, RNA-sequencing (RNA-Seq) analysis showed widespread changes in gene expression. Analysis by four bioinformatic pipelines revealed as many as 230 genes were significantly upregulated and 72 genes were significantly downregulated. A subset of 23 differentially expressed genes was selected for validation using the nCounter® platform, and of these we obtained robust validation for ADAM23, LSP1, MAOB, MMP13, PAK3, SERPINB2, SNAP91, WNT6, and ZCCHC12. We investigated the effect of lithium on this subset and found four genes, CDKN1C, LSP1, SERPINB2, and WNT6 co-regulated by lithium and VPA. We also explored the effects of other HDAC inhibitors and the VPA analogue valpromide on the subset of 23 selected genes. Expression of eight of these genes, CDKN1C, MAOB, MMP13, NGFR, SHANK3, VGF, WNT6 and ZCCHC12, was modified by HDAC inhibition, whereas others did not appear to respond to several HDAC inhibitors tested. These results suggest VPA may regulate genes through both HDAC-dependent and independent mechanisms. Understanding the broader gene regulatory effects of VPA in this serotonergic cell model should provide insights into how this drug works and whether other HDAC inhibitor compounds may have similar gene regulatory effects, as well as highlighting molecular processes that may underlie regulation of mood.

Inflammatory and metabolic markers in patients with mood disorders

OBJECTIVES

An increasing bulk of data underlined that mood disorders show alterations that are not confined to the brain, but involve several other systems. The aim of this retrospective study was to explore metabolic/inflammatory profiles, blood pressure, and BMI in patients affected by bipolar disorders (BDs) to better understand the role of peripheral biomarkers in mood disorders.

METHODS

Different metabolic/inflammatory parameters and clinical characteristics were evaluated in 97 BD inpatients from Sicily, a southern Italian region, and compared with normative values from the same area.

RESULTS

No difference was detected between the assessed parameters and the normative values, or between treated and untreated patients. Interestingly, the mean acid uric levels were at the lowest extreme of the normative values, with men showing higher concentrations than women.

CONCLUSIONS

No metabolic nor inflammatory alterations emerged in BD patients, even if when obese. A possible explanation might be due to their geographical origin, with culinary traditions based on the Mediterranean diet. Therefore, it would be interesting to ascertain whether such a diet might improve the metabolic impairment often associated with mood disorders. Again, the routine assessment of different clinical/chemistry parameters might be helpful to improve the diagnostic stratification and the personalised treatment.

The role of high-density lipoprotein cholesterol, apolipoprotein A and paraoxonase-1 in the pathophysiology of neuroprogressive disorders

Lowered high-density lipoprotein (HDL) cholesterol has been reported in major depressive disorder, bipolar disorder, first episode of psychosis, and schizophrenia. HDL, its major apolipoprotein component, ApoA1, and the antioxidant enzyme paraoxonase (PON)1 (which is normally bound to ApoA1) all have anti-atherogenic, antioxidant, anti-inflammatory, and immunomodulatory roles, which are discussed in this paper. The paper details the pathways mediating the anti-inflammatory effects of HDL, ApoA1 and PON1 and describes the mechanisms leading to compromised HDL and PON1 levels and function in an environment of chronic inflammation. The molecular mechanisms by which changes in HDL, ApoA1 and PON1 might contribute to the pathophysiology of the neuroprogressive disorders are explained. Moreover, the anti-inflammatory actions of ApoM-mediated sphingosine 1-phosphate (S1P) signalling are reviewed as well as the deleterious effects of chronic inflammation and oxidative stress on ApoM/S1P signalling. Finally, therapeutic interventions specifically aimed at improving the levels and function of HDL and PON1 while reducing levels of inflammation and oxidative stress are considered. These include the so-called Mediterranean diet, extra virgin olive oil, polyphenols, flavonoids, isoflavones, pomegranate juice, melatonin and the Mediterranean diet combined with the ketogenic diet.

Concepts of Neuroinflammation and Their Relationship With Impaired Mitochondrial Functions in Bipolar Disorder

Bipolar disorder (BD) is a chronic psychiatric disease, characterized by frequent behavioral episodes of depression and mania, and neurologically by dysregulated neurotransmission, neuroplasticity, growth factor signaling, and metabolism, as well as oxidative stress, and neuronal apoptosis, contributing to chronic neuroinflammation. These abnormalities result from complex interactions between multiple susceptibility genes and environmental factors such as stress. The neurocellular abnormalities of BD can result in gross morphological changes, such as reduced prefrontal and hippocampal volume, and circuit reorganization resulting in cognitive and emotional deficits. The term "neuroprogression" is used to denote the progressive changes from early to late stages, as BD severity and loss of treatment response correlate with the number of past episodes. In addition to circuit and cellular abnormalities, BD is associated with dysfunctional mitochondria, leading to severe metabolic disruption in high energy-demanding neurons and glia. Indeed, mitochondrial dysfunction involving electron transport chain (ETC) disruption is considered the primary cause of chronic oxidative stress in BD. The ensuing damage to membrane lipids, proteins, and DNA further perpetuates oxidative stress and neuroinflammation, creating a perpetuating pathogenic cycle. A deeper understanding of BD pathophysiology and identification of associated biomarkers of neuroinflammation are needed to facilitate early diagnosis and treatment of this debilitating disorder.

Inflammation is correlated with abnormal functional connectivity in unmedicated bipolar depression: an independent component analysis study of resting-state fMRI

BACKGROUND

Inflammation might play a role in bipolar disorder (BD), but it remains unclear the relationship between inflammation and brain structural and functional abnormalities in patients with BD. In this study, we focused on the alterations of functional connectivity (FC), peripheral pro-inflammatory cytokines and their correlations to investigate the role of inflammation in FC in BD depression.

METHODS

In this study, 42 unmedicated patients with BD II depression and 62 healthy controls (HCs) were enrolled. Resting-state-functional magnetic resonance imaging was performed in all participants and independent component analysis was used. Serum levels of Interleukin-6 (IL-6) and Interleukin-8 (IL-8) were measured in all participants. Correlation between FC values and IL-6 and IL-8 levels in BD was calculated.

RESULTS

Compared with the HCs, BD II patients showed decreased FC in the left orbitofrontal cortex (OFC) implicating the limbic network and the right precentral gyrus implicating the somatomotor network. BD II showed increased IL-6 (p = 0.039), IL-8 (p = 0.002) levels. Moreover, abnormal FC in the right precentral gyrus were inversely correlated with the IL-8 (r = -0.458, p = 0.004) levels in BD II. No significant correlation was found between FC in the left OFC and cytokines levels.

CONCLUSIONS

Our findings that serum IL-8 levels are associated with impaired FC in the right precentral gyrus in BD II patients suggest that inflammation might play a crucial role in brain functional abnormalities in BD.

Proinflammatory Cytokine Dysregulation and Cognitive Dysfunction Among Patients with Remitted Bipolar I and II Disorders

BACKGROUND

Euthymic patients with bipolar disorder reportedly demonstrated increased levels of proinflammatory cytokines and cognitive function deficits. Because uncertain differences exist in cognitive function and proinflammatory cytokines between remitted bipolar I (BD1) and bipolar II (BD2) disorders, we performed this study to further investigate these differences.

METHOD

We enrolled 58 patients with remitted BD1 and 27 with remitted BD2, and matched them for age and sex with 51 controls. Proinflammatory cytokines, including soluble interleukin-6 receptor (sIL-6R), C-reactive protein, and soluble tumor necrosis factor receptor 1 (sTNFR1) were measured, and performance in the Word List Memory Task (WLMT) and Wisconsin Card Sorting Task (WCST) was assessed.

RESULTS

Significantly elevated levels of sTNFR1 were observed among patients with BD1 (p < .001) and BD2 (p = .038) compared with the controls; however, they did not differ between patients with BD1 and BD2 (p =.130). Working memory deficit measured by the WLMT was significantly greater in patients with BD1 (p < .001) and BD2 (p < .05) compared with controls, but did not differ between patients with BD1 and BD2 (p > 0.1). Furthermore, sTNFR1 levels were negatively correlated with cognitive function measured using the WLMT and WCST (all p < .05).

DISCUSSION

Our results showed that euthymic patients with BD1 and BD2 showed similar levels of sTNFR1 and cognitive function (especially working memory) impairments. Further investigation is required to explore whether a common pathophysiology may contribute to the shared inflammatory and cognitive alterations between BD1 and BD2.

Changes in inflammation are related to depression and amount of aerobic exercise in first episode schizophrenia

INTRODUCTION

Elevated levels of pro-inflammatory cytokines have been reported in meta-analyses of multi-episode schizophrenia patients when compared to controls. However, little is known about whether these same relationships are present in the early course of schizophrenia.

OBJECTIVE

To assess first episode schizophrenia patients for depression and to assay blood samples collected at baseline and at 6 months for interleukin-6 (IL-6).

MATERIALS AND METHODS

Trained raters used the Brief Psychiatric Rating Scale to assess depressive symptoms and a standard lab assay kit to assess for IL-6 levels in plasma.

CONCLUSIONS

Decreases in pro-inflammatory IL-6 levels were significantly related to decreases in depressive symptoms. Within a subset of patients in a 6-month aerobic exercise protocol, the number of exercise sessions completed was significantly correlated with the amount of decrease in IL-6. The reductions observed in IL-6 with aerobic exercise suggest exercise is a promising intervention to reduce brain inflammation effects in schizophrenia patients.

Neutrophil-to-Lymphocyte, Platelet-to-Lymphocyte and Monocyte-to-Lymphocyte Ratio in Bipolar Disorder

Background: Several inflammatory hypotheses have been suggested to explain the etiopathogenesis of bipolar disorder (BD) and its different phases. Neutrophil-to-lymphocyte (NLR), platelet-to-lymphocyte (PLR), and monocyte-to-lymphocyte (MLR) ratios have been proposed as potential peripheral biomarkers of mood episodes. Methods: We recruited 294 patients affected by BD, of which 143 were experiencing a (hypo)manic episode and 151 were in a depressive phase. A blood sample was drawn to perform a complete blood count. NLR, PLR, and MLR were subsequently calculated. A t-test was performed to evaluate differences in blood cell counts between depressed and (hypo)manic patients and a regression model was then computed. Results: Mean values of neutrophils, platelets, mean platelet volume, NLR, PLR, and MLR were significantly higher in (hypo)manic than depressed individuals. Logistic regression showed that PLR may represent an independent predictor of (hypo)mania. Conclusions: Altered inflammatory indexes, particularly PLR, may explain the onset and recurrence of (hypo)manic episodes in patients with BD. As inflammatory ratios represent economical and accessible markers of inflammation, further studies should be implemented to better elucidate their role as peripheral biomarkers of BD mood episodes.

Phenomenology, Epidemiology and Aetiology of Postpartum Psychosis: A Review

Postpartum psychoses are a severe form of postnatal mood disorders, affecting 1–2 in every 1000 deliveries. These episodes typically present as acute mania or depression with psychosis within the first few weeks of childbirth, which, as life-threatening psychiatric emergencies, can have a significant adverse impact on the mother, baby and wider family. The nosological status of postpartum psychosis remains contentious; however, evidence indicates most episodes to be manifestations of bipolar disorder and a vulnerability to a puerperal trigger. While childbirth appears to be a potent trigger of severe mood disorders, the precise mechanisms by which postpartum psychosis occurs are poorly understood. This review examines the current evidence with respect to potential aetiology and childbirth-related triggers of postpartum psychosis. Findings to date have implicated neurobiological factors, such as hormones, immunological dysregulation, circadian rhythm disruption and genetics, to be important in the pathogenesis of this disorder. Prediction models, informed by prospective cohort studies of high-risk women, are required to identify those at greatest risk of postpartum psychosis.

The role of vitamin D in bipolar disorder: Epidemiology and influence on disease activity

BACKGROUND

Although many studies found an association between psychiatric disorders, especially major depressive disorder, and vitamin D deficiency, little is still known about the association between vitamin D and bipolar disorder (BD). Therefore, the present review aims at providing an overview of the available literature exploring the role of vitamin D in BD patients in different phases of the disease.

METHODS

From a bibliographic research in PubMed until April 2020, we collected ten original studies that fulfilled our inclusion criteria.

RESULTS

No significant differences in vitamin D levels between BD patients and other psychiatric disorders were found by most of the studies. In the majority of the studies, the average values of vitamin D in BD population were sub-threshold for vitamin D deficiency. Moreover, although an association between vitamin D levels and clinical symptomatology was observed in BD patients, it cannot be considered a specific marker of this disorder but a common characteristic shared with other psychiatric disorders, including schizophrenia and major depressive disorder. Finally, vitamin D supplementation was associated with a reduction in both depressive and manic symptoms.

LIMITATIONS

Few studies with small and heterogeneous populations. Methodological heterogeneity in terms of vitamin D measurement and threshold.

CONCLUSIONS

The results showed that vitamin D status does not differ between BD and other psychiatric conditions. However, given the correlation between vitamin D levels and depressive or manic symptoms, we could hypothesize that an adequate vitamin D status could positively affect the mood balance thanks to its immunomodulatory activity.

STAT3 in the dorsal raphe gates behavioural reactivity and regulates gene networks associated with psychopathology

The signal transducer and activator of transcription 3 (STAT3) signalling pathway is activated through phosphorylation by Janus kinases in response to a diverse set of immunogenic and non-immunogenic triggers. Several distinct lines of evidence propose an intricate involvement of STAT3 in neural function relevant to behaviour in health and disease. However, in part due to the pleiotropic effects resulting from its DNA binding activity and the consequent regulation of expression of a variety of genes with context-dependent cellular consequences, the precise nature of STAT3 involvement in the neural mechanisms underlying psychopathology remains incompletely understood. Here, we focused on the midbrain serotonergic system, a central hub for the regulation of emotions, to examine the relevance of STAT3 signalling for emotional behaviour in mice by selectively knocking down raphe STAT3 expression using germline genetic (STAT3 KO) and viral-mediated approaches. Mice lacking serotonergic STAT3 presented with reduced negative behavioural reactivity and a blunted response to the sensitising effects of amphetamine, alongside alterations in midbrain neuronal firing activity of serotonergic neurons and transcriptional control of gene networks relevant for neuropsychiatric disorders. Viral knockdown of dorsal raphe (DR) STAT3 phenocopied the behavioural alterations of STAT3 KO mice, excluding a developmentally determined effect and suggesting that disruption of STAT3 signalling in the DR of adult mice is sufficient for the manifestation of behavioural traits relevant to psychopathology. Collectively, these results suggest DR STAT3 as a molecular gate for the control of behavioural reactivity, constituting a mechanistic link between the upstream activators of STAT3, serotonergic neurotransmission and psychopathology.

Interleukin-6 and total antioxidant capacity levels following N-acetylcysteine and a combination nutraceutical intervention in a randomised controlled trial for bipolar disorder

OBJECTIVE

The aims of this study were to evaluate changes in inflammatory and oxidative stress levels following treatment with N-acetylcysteine (NAC) or mitochondrial-enhancing agents (CT), and to assess the how these changes may predict and/or moderate clinical outcomes primarily the Montgomery-Åsberg Depression Rating Scale (MADRS).

METHODS

This study involved secondary analysis of a placebo-controlled randomised trial (n = 163). Serum samples were collected at baseline and week 16 of the clinical trial to determine changes in Interleukin-6 (IL-6) and total antioxidant capacity (TAC) following adjunctive CT and/or NAC treatment, and to explore the predictability of the outcome or moderator effects of these markers.

RESULTS

In the NAC-treated group, no difference was observed in serum IL-6 and TAC levels after 16 weeks of treatment with NAC or CT. However, results from a moderator analysis showed that in the CT group, lower IL-6 levels at baseline was a significant moderator of MADRS χ2 (df) = 4.90, p = 0.027) and Clinical Global Impression-Improvement (CGI-I, χ2 (df) = 6.28 p = 0.012). In addition, IL-6 was a non-specific but significant predictor of functioning (based on the Social and Occupational Functioning Assessment Scale (SOFAS)), indicating that individuals with higher IL-6 levels at baseline had a greater improvement on SOFAS regardless of their treatment (p = 0.023).

CONCLUSION

Participants with lower IL-6 levels at baseline had a better response to the adjunctive treatment with the mitochondrial-enhancing agents in terms of improvements in MADRS and CGI-I outcomes.

Association of pro-inflammatory cytokines with clinical features in euthymic patients with Bipolar-I-Disorder

BACKGROUND

A chronic low-grade inflammatory state appears to be a relevant mechanism in the pathophysiology of bipolar disorder. Pro-inflammatory cytokines may influence disease course and individual symptomatology; and biological markers correlating with illness features may be of utility in clinical decision making during euthymia.

METHODS

51 euthymic outpatients with Bipolar-I-Disorder (BD-I) and 93 healthy controls (HC) were investigated. Comparisons between groups, and correlations with clinical features were performed. Serum concentrations of interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and soluble interleukin-6 receptor (sIL-6R) were evaluated by ELISA under highly standardized conditions. Clinical features included duration of illness, number of previous suicide attempts and mood episodes (manic, hypomanic, depressive), scores of the Young Mania Rating Scale (YMRS), the Inventory of Depressive Symptoms (IDS-30), the Pittsburg Sleep Quality Index (PSQI), and the Global Assessment of Functioning (GAF).

RESULTS

No significant difference in serum concentrations of IL-1β, TNF-α, and sIL-6R between BD-I euthymic patients and HC could be identified. Among euthymic BD-I patients, a positive correlation of r_s = 0.47 (p = 0.004) between levels of IL-1β and IDS-30 score was identified.

LIMITATIONS

The design was cross-sectional, most patients were receiving medication, only 3 cytokines were assessed, only euthymic BD-I patients were evaluated.

CONCLUSIONS

The findings suggest that elevated pro-inflammatory cytokine concentrations are likely state rather than trait markers of BD-I. It also seems unlikely that cytokine concentrations are clinically informative interepisode. An inflammatory component might possibly be involved in the pathophysiology of subsyndromic depression in BD-I, and conceivably of bipolar depression per se.

The dual-system theory of bipolar spectrum disorders: A meta-analysis

Bipolar spectrum disorders are characterized by alternating intervals of extreme positive and negative affect. We performed a meta-analysis to test the hypothesis that such disorders would be related to dysregulated reinforcement sensitivity. First, we reviewed 23 studies that reported the correlation between self-report measures of (hypo)manic personality and measures of reinforcement sensitivity. A large relationship was found between (hypo)manic personality and BAS sensitivity (g = .74), but not with BIS sensitivity (g = -.08). This stands in contrast to self-reported depression which has a small, negative relationship with BAS sensitivity and a large positive one with BIS sensitivity (Katz et al., 2020). Next, we reviewed 33 studies that compared reinforcement sensitivity between euthymic, bipolar participants and healthy controls. There, bipolar disorder had a small, positive relationship with BAS sensitivity (g = .20) and a medium, positive relationship with BIS sensitivity (g = .64). These findings support a dualsystem theory of bipolar disorders, wherein BAS sensitivity is more closely related to mania and BIS sensitivity more closely to bipolar depression. Bipolar disorders show diatheses for both states with euthymic participants being BAS- and BIS- hypersensitive. Implications for further theory and research practice are expounded upon in the discussion.

Endothelial dysfunction in neuroprogressive disorders-causes and suggested treatments

BACKGROUND

Potential routes whereby systemic inflammation, oxidative stress and mitochondrial dysfunction may drive the development of endothelial dysfunction and atherosclerosis, even in an environment of low cholesterol, are examined.

MAIN TEXT

Key molecular players involved in the regulation of endothelial cell function are described, including PECAM-1, VE-cadherin, VEGFRs, SFK, Rho GEF TRIO, RAC-1, ITAM, SHP-2, MAPK/ERK, STAT-3, NF-κB, PI3K/AKT, eNOS, nitric oxide, miRNAs, KLF-4 and KLF-2. The key roles of platelet activation, xanthene oxidase and myeloperoxidase in the genesis of endothelial cell dysfunction and activation are detailed. The following roles of circulating reactive oxygen species (ROS), reactive nitrogen species and pro-inflammatory cytokines in the development of endothelial cell dysfunction are then described: paracrine signalling by circulating hydrogen peroxide, inhibition of eNOS and increased levels of mitochondrial ROS, including compromised mitochondrial dynamics, loss of calcium ion homeostasis and inactivation of SIRT-1-mediated signalling pathways. Next, loss of cellular redox homeostasis is considered, including further aspects of the roles of hydrogen peroxide signalling, the pathological consequences of elevated NF-κB, compromised S-nitrosylation and the development of hypernitrosylation and increased transcription of atherogenic miRNAs. These molecular aspects are then applied to neuroprogressive disorders by considering the following potential generators of endothelial dysfunction and activation in major depressive disorder, bipolar disorder and schizophrenia: NF-κB; platelet activation; atherogenic miRs; myeloperoxidase; xanthene oxidase and uric acid; and inflammation, oxidative stress, nitrosative stress and mitochondrial dysfunction.

CONCLUSIONS

Finally, on the basis of the above molecular mechanisms, details are given of potential treatment options for mitigating endothelial cell dysfunction and activation in neuroprogressive disorders.

Enduring neuroimmunological consequences of developmental experiences: From vulnerability to resilience

The immune system is crucial for normal neuronal development and function (neuroimmune system). Both immune and neuronal systems undergo significant postnatal development and are sensitive to developmental programming by environmental experiences. Negative experiences from infection to psychological stress at a range of different time points (in utero to adolescence) can permanently alter the function of the neuroimmune system: given its prominent role in normal brain development and function this dysregulation may increase vulnerability to psychiatric illness. In contrast, positive experiences such as exercise and environmental enrichment are protective and can promote resilience, even restoring the detrimental effects of negative experiences on the neuroimmune system. This suggests the neuroimmune system is a viable therapeutic target for treatment and prevention of psychiatric illnesses, especially those related to stress. In this review we will summarise the main cells, molecules and functions of the immune system in general and with specific reference to central nervous system development and function. We will then discuss the effects of negative and positive environmental experiences, especially during development, in programming the long-term functioning of the neuroimmune system. Finally, we will review the sparse but growing literature on sex differences in neuroimmune development and response to environmental experiences.

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The immune system is essential for development and function of the central nervous system (neuroimmune system)

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Environmental experiences can permanently alter neuroimmune function and associated brain development

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Altered neuroimmune function following negative developmental experiences may play a role in psychiatric illnesses

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Positive experiences can promote resilience and rescue the effects of negative experiences on the neuroimmune system

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The neuroimmune system is therefore a viable therapeutic target for preventing and treating psychiatric illnesses

Chronobiology Revisited in Psychiatric Disorders: From a Translational Perspective

OBJECTIVE

Several lines of evidence support a relationship between circadian rhythms disruption in the onset, course, and maintenance of mental disorders. Despite the study of circadian phenotypes promising a decent understanding of the pathophysiologic or etiologic mechanisms of psychiatric entities, several questions still need to be addressed. In this review, we aimed to synthesize the literature investigating chronobiologic theories and their associations with psychiatric entities.

METHODS

The Medline, Embase, PsycInfo, and Scopus databases were comprehensively and systematically searched and articles published between January 1990 and October 2019 were reviewed. Different combinations of the relevant keywords were polled. We first introduced molecular elements and mechanisms of the circadian system to promote a better understanding of the chronobiologic implications of mental disorders. Then, we comprehensively and systematically reviewed circadian system studies in mood disorders, schizophrenia, and anxiety disorders.

RESULTS

Although subject characteristics and study designs vary across studies, current research has demonstrated that circadian pathologies, including genetic and neurohumoral alterations, represent the neural substrates of the pathophysiology of many psychiatric disorders. Impaired HPA-axis function-related glucocorticoid rhythm and disrupted melatonin homeostasis have been prominently demonstrated in schizophrenia and other psychotic disorders, while alterations of molecular expressions of circadian rhythm genes including CLOCK, PER, and CRY have been reported to be involved in the pathogenesis of mood disorders.

CONCLUSION

Further translational work is needed to identify the causal relationship between circadian physiology abnormalities and mental disorders and related psychopathology, and to develop sound pharmacologic interventions.

Call to action regarding the vascular-bipolar link: A report from the Vascular Task Force of the International Society for Bipolar Disorders

OBJECTIVES

The association of bipolar disorder with early and excessive cardiovascular disease was identified over a century ago. Nonetheless, the vascular-bipolar link remains underrecognized, particularly with regard to how this link can contribute to our understanding of pathogenesis and treatment.

METHODS

An international group of experts completed a selective review of the literature, distilling core themes, identifying limitations and gaps in the literature, and highlighting future directions to bridge these gaps.

RESULTS

The association between bipolar disorder and vascular disease is large in magnitude, consistent across studies, and independent of confounding variables where assessed. The vascular-bipolar link is multifactorial and is difficult to study given the latency between the onset of bipolar disorder, often in adolescence or early adulthood, and subsequent vascular disease, which usually occurs decades later. As a result, studies have often focused on risk factors for vascular disease or intermediate phenotypes, such as structural and functional vascular imaging measures. There is interest in identifying the most relevant mediators of this relationship, including lifestyle (eg, smoking, diet, exercise), medications, and systemic biological mediators (eg, inflammation). Nonetheless, there is a paucity of treatment studies that deliberately engage these mediators, and thus far no treatment studies have focused on engaging vascular imaging targets.

CONCLUSIONS

Further research focused on the vascular-bipolar link holds promise for gleaning insights regarding the underlying causes of bipolar disorder, identifying novel treatment approaches, and mitigating disparities in cardiovascular outcomes for people with bipolar disorder.

Role of gut microbiota in the GBR12909 model of mania-like behavior in mice

Growing evidence suggests a role for brain-gut-microbiota axis in affective disorders including major depression and bipolar disorder (BD). Herein, we aim to explore, by employing germ-free (GF) mice, the effect of the indigenous microbiota in the development of mania-like behavior. Conventional and GF mice were evaluated for the hyperlocomotion induced by the dopamine transporter inhibitor GBR12909 (15 mg/Kg), a validated model for mania-like behavior. Inflammatory mediators and neurotrophic factors were quantified in the prefrontal cortex, hippocampus and striatum. Mice lacking indigenous microbiota were less susceptible to the mania-like behavior induced by GBR12909. This effect was associated with decreased levels of inflammatory cytokines such as IL-6 and TNF-α, along with increased concentrations of anti- inflammatory cytokines (IL-10) and of neurotrophins (BDNF and NGF). We provided the first evidence that gut-microbiota-brain axis participates in the development of mania-like behavior in rodents, possibly through neuroimmunepathways.

State-of-the-Art: Inflammatory and Metabolic Markers in Mood Disorders

Mounting evidence highlights the involvement of inflammatory/immune systems and their relationships with neurotransmitters and different metabolic processes in mood disorders. Nevertheless, there is a general agreement that available findings are still inconclusive. Therefore, further investigations are required, aimed at deepening the role of possible alterations of biomarkers in the pathophysiology of mood disorders that might lead to more focused and tailored treatments. The present study is a comprehensive review on these topics that seem to represent intriguing avenues for the development of real innovative therapeutic strategies of mood disorders.

Risk of bipolar disorder in patients with endometriosis: A nationwide population-based cohort study

BACKGROUND

Women with endometriosis (EM) have increased vulnerability to certain psychiatric disorders, including depression and anxiety, as well as bipolar disorder (BD). This study investigates the risk of BD development in EM patients. Also, the impact of EM treatment on the risk of developing BD is examined.

METHODS

A total of 17,832 EM patients and 17,832 non-EM controls matched by age, index year, and Charlson Comorbidity Index (CCI) score were included between 2000-2012 and followed to the end of 2013. Participants newly diagnosed as BD by board-certified psychiatrist were defined as incidents. Cox regression analysis was used to calculate the hazard ratio (HR) with 95% confidence interval (CI) of the BD incidence rate between two studied groups.

RESULTS

EM patients were associated with an increased risk of BD development compared with non-EM controls after adjusting for age, CCI score, and different treatment options (1.04 versus 0.56 per 1,000 person-years, HR: 2.34, 95% CI: 1.75-3.12). Also, there was no significant difference in the risk estimate between different hormonal or surgical treatment groups, suggesting a limited impact of EM treatment on the risk of BD development.

LIMITATIONS

This study deals with the duration of hormonal treatment, whether operated or not, which reduces the chances of showing the effect of individual EM treatment on the risk of BD development.

CONCLUSION

This study shows that EM patients are associated with an increased risk of BD development. Further studies would be needed to elucidate the mechanism linking the EM and BD.

Differences in Kynurenine Metabolism During Depressive, Manic, and Euthymic Phases of Bipolar Affective Disorder

Background & Objectives:

The kynurenine pathway is involved in inflammatory diseases. Alterations of this pathway were shown in psychiatric entities as well. The aim of this study was to determine whether specific changes in kynurenine metabolism are associated with current mood symptoms in bipolar disorder.

Methods:

Sum scores of the Hamilton Depression Scale, Beck Depression Inventory, and Young Mania Rating Scale were collected from 156 bipolar individuals to build groups of depressive, manic and euthymic subjects according to predefined cut-off scores. Severity of current mood symptoms was correlated with activities of the enzymes kynurenine 3-monooxygenase (ratio of 3-hydroxykynurenine/ kynurenine), kynurenine aminotransferase (ratio of kynurenic acid/ kynurenine) and kynureninase (ratio of 3-hydroxyanthranilic acid/ 3-hydroxykynurenine), proxied by ratios of serum concentrations.

Results:

Individuals with manic symptoms showed a shift towards higher kynurenine 3-monooxygenase activity (χ2 = 7.14, Df = 2, p = .028), compared to euthymic as well as depressed individuals. There were no differences between groups regarding activity of kynurenine aminotransferase and kynureninase. Within the group of depressed patients, Hamilton Depression Scale and kynurenine aminotransferase showed a significant negative correlation (r = -0.41, p = .036), displaying lower metabolism in the direction of kynurenic acid.

Conclusion:

Depression severity in bipolar disorder seems to be associated with a decreased synthesis of putative neuroprotective kynurenic acid. Furthermore, higher kynurenine 3-monooxygenase activity in currently manic individuals indicates an increased inflammatory state within bipolar disorder with more severe inflammation during manic episodes. The underlying pathophysiological mechanisms of the different affective episodes could represent parallel mechanisms rather than opposed processes.

Chronic Periodontitis Is Associated with the Risk of Bipolar Disorder: A Population-Based Cohort Study

Bipolar disorder (BD) is a psychiatric mood disturbance manifested by manic, hypomanic, or major depressive periods. Chronic inflammation was evidenced as an important etiologic factor of BD. Chronic periodontitis (CP) is an inflammatory disease triggered by bacterial products, leading to the destruction of periodontium. The relationship between BD and CP is of interest to investigate. Therefore, a nationwide population-based cohort study was used to investigate the risk of BD and CP exposure from 2001 to 2012. We identified 61,608 patients with CP from the Taiwanese National Health Insurance Research Database (NHIRD). The 123,216 controls were randomly captured and matched by age, sex, index year, and co-morbidities. The association between CP exposure and BD risk was examined by Cox proportional hazards regression models. In this study, 61,608 CP patients and 123,216 controls were followed up for 7.45 and 7.36 years, respectively. In total, 138 BD patients were identified in the CP cohort and 187 BD cases were found in the non-CP cohort. The incidence rate of BD was significantly higher in the CP cohort than in the non-CP cohort (adjusted HR: 1.46, 95% CI: 1.17–1.81) according to the multivariate Cox regression analysis. Females had a 1.47-fold increased risk (95% CI: 1.16–1.86) for BD compared to males. Taken together, CP may be associated with an increased risk of subsequent BD in Taiwan.

Psychiatric Adverse Events Associated With Infliximab: A Cohort Study From the French Nationwide Discharge Abstract Database

Introduction

Infliximab (IFX) was the first anti-tumor necrosis factor (TNFα) antibody to be used in the treatment of severe chronic inflammatory diseases, such as Crohn’s disease and rheumatoid arthritis. A number of serious adverse drug reactions are known to be associated with IFX use; they include infections, malignancies, and injection site reactions. Although a few case reports have described potential psychiatric adverse events (including suicide attempts and manic episodes), the latter are barely mentioned in IFX’s summary of product characteristics. The objective of the present retrospective study was to detect potential psychiatric adverse events associated with IFX treatment by analyzing a national discharge abstract database.

Materials and Methods

We performed an historical cohort study by analyzing data from the French national hospital discharge abstract database (PMSI) between 2008 and 2014. All patients admitted with one of the five diseases treated with IFX were included.

Results

Of the 325,319 patients included in the study, 7,600 had been treated with IFX. The proportion of hospital admissions for one or more psychiatric events was higher among IFX-exposed patients (750 out of 7,600; 9.87%) than among non-exposed patients (17,456 out of 317,719; 5.49%). After taking account of potential confounders in the cohort as a whole, a semi-parametric Cox regression analysis gave an overall hazard ratio (HR) [95% confidence interval] (CI) of 4.5 [3.95; 5.13] for a hospital admission with a psychiatric adverse event during treatment with IFX. The HR (95%CI) for a depressive disorder was 4.97 (7.35; 6.68). Even higher risks were observed for certain pairs of adverse events and underlying pathologies: psychotic disorders in patients treated for ulcerative colitis (HR = 5.43 [2.01; 14.6]), manic episodes in patients treated for severe psoriasis (HR = 12.6 [4.65; 34.2]), and suicide attempts in patients treated for rheumatoid arthritis (HR = 4.45 [1.11; 17.9]).

Discussion

The present retrospective, observational study confirmed that IFX treatment is associated with an elevated risk of psychiatric adverse events. Depending on the disease treated, physicians should be aware of these potential adverse events.

A Population-Based, Nationwide Longitudinal Study of Bipolar Disorder With Incident Dementia in Taiwan

OBJECTIVE

Affective disorders are associated with increased risk of dementia, yet most studies focus on the association of major depressive disorder or depressive episodes of bipolar disorder with increased dementia risk. The association of manic/mixed episodes of bipolar disorder with increased dementia risk is unclear.

PARTICIPANTS

Between January 1, 2001 and December 31, 2009, 20,535 individuals aged 45-80 years with bipolar disorder and 82,140 age- and sex-matched comparisons were enrolled and followed up to December 2011 in Taiwan. Those who developed dementia (ICD-9-CM codes: 290.0-290.4, 294.1-294.2, and 331.0-331.2) during the follow-up period were identified.

DESIGN AND METHODS

Cox proportional hazards models were used to examine the relationship between manic/mixed/depressive episodes of bipolar disorder and incident dementia. We also assessed the association between the frequency of psychiatric admissions (total, manic/mixed, and depressive episodes per year) for bipolar disorder and dementia risk.

RESULTS

Bipolar disorder was associated with increased risk of incident dementia (hazard ratio [HR]: 7.52, 95% confidence interval [CI]: 6.86-8.25). Greater frequency of manic/mixed (>2/year: HR: 4.50, 3.50-5.79; 1-2/year: HR: 3.17, 2.31-4.36) and depressive episodes (>2/year: HR: 7.84, 5.93-10.36; 1-2/year: HR: 2.93, 2.05-4.19) were associated with increased risk of incident dementia.

CONCLUSIONS

Not only depressive episode of bipolar disorder, but manic/mixed episodes of bipolar play a role as a risk factor of incident dementia, especially for those patients with more than two manic/mixed episodes per year. These findings remind the clinicians the importance of preventing the relapse of bipolar disorder for the potential subsequent cognitive decline and disease.

Leptin in bipolar disorder: A systematic review and meta-analysis

Background

Bipolar disorder (BD) is a psychiatric disorder associated with increased rates of obesity and inflammation. Leptin is an adipokine that is mainly produced by the white adipose tissue in response to insulin. It stimulates the immune system, increasing the production of pro-inflammatory cytokines. There is currently uncertainty regarding possible alterations in peripheral leptin levels across the mood states in BD.

Methods

This study comprises a between-group meta-analysis comparing serum and plasma leptin levels in people with BD in mania, depression or euthymia and healthy controls. We conducted a systematic search for all possibly eligible-English and non-English peer-reviewed articles. We calculated the effect size (ES) utilizing Hedges’ adjusted g using random effects.

Results

Eleven studies were included in the meta-analyses, providing data on 1118 participants. Serum and plasma leptin levels were not altered in subjects with BD when compared to healthy controls in mania (g = −0.99, 95% CI −2.43 to 0.43, P = 0.171), in depression (g = 0.17, 95% CI −0.45 to 0.79, P = 0.584), or in euthymia (g = 0.03, 95% CI −0.39 to 0.46, P = 0.882). However, we did observe a stronger association between leptin levels and both age and BMI in patients with BD in euthymia compared to healthy controls, such that the greater the age of the individuals, the greater the difference in leptin levels between BD and controls; and the higher the BMI, the greater the difference in leptin levels between BD and controls.

Conclusions

Our meta-analysis provides evidence that leptin levels are not altered in BD across the mood spectrum compared to healthy controls. The disproportionate increase of leptin levels with increase in BMI in BD speaks in favour of a potential inflammatory role of white adipose tissue in BD and a disproportionate increase of leptin levels with increase in age.

The impact of sample processing on inflammatory markers in serum: Lessons learned

Objectives: To investigate the effect of sample handling on inflammatory cytokines in serum and highlight challenges with using samples pre-collected from biobanks for biomarker research.Methods: Cytokine concentrations (IL-1β, IL-2, IL-6, IL-8, IL-10, TNFα, and IFNγ) were measured in serum samples of 205 patients with bipoldar disorder (BD) from the Mayo Clinic Bipolar Disorder Biobank and 205 non-psychiatric controls from the Mayo Clinic Biobank. As cytokine concentrations varied by recruitment site, post-hoc models were used to test the effect of clinical variables and pre-processing time on cytokines. To evaluate the effect of pre-processing time experimentally, cytokines were assayed in serum and plasma from 6 healthy volunteers processed at different time points.Results: Cytokine levels were significantly higher in the BD group. However, both cytokine levels and pre-processing times differed by recruitment site, and post-hoc analyses revealed that pre-processing time was significantly associated with several cytokines. An experiment using samples from healthy volunteers confirmed that concentrations for most cytokines increased with longer pre-processing times.Conclusions: Delays in processing influence cytokine concentrations in blood samples. Given the increasing use of biobanks in research, this study highlights the need to carefully evaluate sample collection and handling methods when designing biomarker studies.

Inflammation as a Mechanism of Bipolar Disorder Neuroprogression

Bipolar disorder (BD) is a severe, debilitating psychiatric condition with onset in adolescence or young adulthood and often follows a relapsing and remitting course throughout life. The concept of neuroprogression in BD refers to the progressive path with an identifiable trajectory that takes place with recurrent mood episodes, which eventually leads to cognitive, functional, and clinical deterioration in the course of BD. Understanding the biological basis of neuroprogression helps to explain the subset of BD patients who experience worsening of their disorder over time. Additionally, the study of the neurobiological mechanisms underpinning neuroprogression will help BD staging based on systems biology. Replicated epidemiological studies have suggested inflammatory mechanisms as primary contributors to the neuroprogression of mood disorders. It is known that dysregulated inflammatory/immune pathways are often associated with BD pathophysiology. Hence, in this chapter, we focus on the evidence for the involvement of inflammation and immune regulated pathways in the neurobiological consequences of BD neuroprogression. Herein we put forth the evidence of immune markers from autoimmune disorders, chronic infections, and gut-brain axis that lead to BD neuroprogression. Further, we highlighted the peripheral and central inflammatory components measured along with BD progression.

Neuroinflammation in Bipolar Depression

Bipolar disorder (BD) is a leading cause of worldwide disability among mood disorders. Pathological mechanisms are still vastly unclear, and current treatments with conventional medications are often unsatisfactory in maintaining symptoms control and an adequate quality of life. Consequently, current research is focusing on shedding new light on disease pathogenesis, to improve therapeutic effectiveness. Recent evidence has suggested a prominent role of inflammation in mood disorders. Elevated levels of peripheral proinflammatory mediators have been reported in BD, as well as in other mood disorders, and people with systemic autoimmune diseases have an increased risk of developing BD. These immunological alterations are stable, and current medications are unable to alter peripheral concentrations even when clinical improvement is evident. These findings have also been replicated in the central nervous system (CNS) milieu, whereas genetic studies have shown that these immune alterations are not due to the disorder itself, being detectable before the illness onset. Moreover, these inflammatory modifications seem to be affected by and linked to other biomarkers of the disorder, such as alterations of white matter (WM) microstructure, metabolism, kynurenine pathway, and circadian rhythmicity. Finally, these immune variations seem to be useful as predictors of therapeutic responsiveness to medications, and in discriminating between clinically different outcomes. The objective of this review is to summarize available evidence on the connection between inflammation and BD, focusing on peripheral inflammatory markers and recent findings on their connection with other typical features of BD, to outline a general overview of the disorder. Moreover, it is meant to analyze the issues with data gathering and interpretation, given the partially contradictory and inconsistent nature of results.

The Innate Immune System and Inflammatory Priming: Potential Mechanistic Factors in Mood Disorders and Gulf War Illness

Gulf War Illness is a chronic multisystem disorder affecting approximately a third of the Veterans of the Gulf War, manifesting with physical and mental health symptoms such as cognitive impairment, neurological abnormalities, and dysregulation of mood. Among the leading theories into the etiology of this multisystem disorder is environmental exposure to the various neurotoxins encountered in the Gulf Theatre, including organophosphates, nerve agents, pyridostigmine bromide, smoke from oil well fires, and depleted uranium. The relationship of toxin exposure and the pathogenesis of Gulf War Illness converges on the innate immune system: a nonspecific form of immunity ubiquitous in nature that acts to respond to both exogenous and endogenous insults. Activation of the innate immune system results in inflammation mediated by the release of cytokines. Cytokine mediated neuroinflammation has been demonstrated in a number of psychiatric conditions and may help explain the larger than expected population of Gulf War Veterans afflicted with a mood disorder. Several of the environmental toxins encountered by soldiers during the first Gulf War have been shown to cause upregulation of inflammatory mediators after chronic exposure, even at low levels. This act of inflammatory priming, by which repeated exposure to chronic subthreshold insults elicits robust responses, even after an extended period of latency, is integral in the connection of Gulf War Illness and comorbid mood disorders. Further developing the understanding of the relationship between environmental toxin exposure, innate immune activation, and pathogenesis of disease in the Gulf War Veterans population, may yield novel therapeutic targets, and a greater understanding of disease pathology and subsequently prevention.

Neuroimmunological effects of early life experiences

Exposure to adverse experiences during development increases the risk of psychiatric illness later in life. Growing evidence suggests a role for the neuroimmune system in this relationship. There is now substantial evidence that the immune system is critical for normal brain development and behaviour, and responds to environmental perturbations experienced early in life. Severe or chronic stress results in dysregulated neuroimmune function, concomitant with abnormal brain morphology and function. Positive experiences including environmental enrichment and exercise exert the opposite effect, promoting normal brain and immune function even in the face of early life stress. The neuroimmune system may therefore provide a viable target for prevention and treatment of psychiatric illness. This review will briefly summarise the neuroimmune system in brain development and function, and review the effects of stress and positive environmental experiences during development on neuroimmune function. There are also significant sex differences in how the neuroimmune system responds to environmental experiences early in life, which we will briefly review.

Peripheral blood metabolome predicts mood change-related activity in mouse model of bipolar disorder

Bipolar disorder is a major mental illness characterized by severe swings in mood and activity levels which occur with variable amplitude and frequency. Attempts have been made to identify mood states and biological features associated with mood changes to compensate for current clinical diagnosis, which is mainly based on patients' subjective reports. Here, we used infradian (a cycle > 24 h) cyclic locomotor activity in a mouse model useful for the study of bipolar disorder as a proxy for mood changes. We show that metabolome patterns in peripheral blood could retrospectively predict the locomotor activity levels. We longitudinally monitored locomotor activity in the home cage, and subsequently collected peripheral blood and performed metabolomic analyses. We then constructed cross-validated linear regression models based on blood metabolome patterns to predict locomotor activity levels of individual mice. Our analysis revealed a significant correlation between actual and predicted activity levels, indicative of successful predictions. Pathway analysis of metabolites used for successful predictions showed enrichment in mitochondria metabolism-related terms, such as "Warburg effect" and "citric acid cycle." In addition, we found that peripheral blood metabolome patterns predicted expression levels of genes implicated in bipolar disorder in the hippocampus, a brain region responsible for mood regulation, suggesting that the brain-periphery axis is related to mood-change-associated behaviors. Our results may serve as a basis for predicting individual mood states through blood metabolomics in bipolar disorder and other mood disorders and may provide potential insight into systemic metabolic activity in relation to mood changes.

The immunobiology of autoimmune encephalitides

Autoimmune encephalitides, with an estimated incidence of 1.5 per million population per year, although described only 15 years ago, have already had a remarkable impact in neurology and paved the field to autoimmune neuropsychiatry. Many patients traditionally presented with aberrant behavior, especially of acute or subacute onset, and treated with anti-psychotic therapies, turn out to have a CNS autoimmune disease with pathogenic autoantibodies against synaptic antigens responding to immunotherapies. The review describes the clinical spectrum of these disorders, and the pathogenetic role of key autoantibodies directed against: a) cell surface synaptic antigens and receptors, including NMDAR, GABAa, GABAb, AMPA and glycine receptors; b) channels such as AQP4 water-permeable channel or voltage-gated potassium channels; c) proteins that stabilize voltage-gated potassium channel complex into the membrane, like the LGI1 and CASPR2; and d) enzymes that catalyze the formation of neurotransmitters such as Glutamic Acid Decarboxylase (GAD). These antibodies, effectively target excitatory or inhibitory synapses in the limbic system, basal ganglia or brainstem altering synaptic function and resulting in uncontrolled neurological excitability disorder clinically manifested with psychosis, agitation, behavioral alterations, depression, sleep disturbances, seizure-like phenomena, movement disorders such as ataxia, chorea and dystonia, memory changes or coma. Some of the identified triggering factors include: viruses, especially herpes simplex, accounting for the majority of relapses occurring after viral encephalitis, which respond to immunotherapy rather than antiviral agents; tumors especially teratoma, SCLC and thymomas; and biological cancer therapies (immune-check-point inhibitors). As anti-synaptic antibodies persist after viral infections or tumor removal, augmentation of autoreactive B cells which release autoantigens to draining lymph nodes, molecular mimicry and infection-induced bystander immune activation products play a role in autoimmunization process or perpetuating autoimmune neuroinflammation. The review stresses the importance of early detection, clinical recognition, proper antibody testing and early therapy initiation as these disorders, regardless of a known or not trigger, are potentially treatable responding to systemic immunotherapy with intravenous steroids, IVIg, rituximab or even bortezomid.

Targeting the immune system in the treatment of bipolar disorder

RATIONALE

Immune dysfunction has been strongly implicated in the pathophysiology of bipolar disorder (BD). As such, numerous clinical trials have investigated the effects of anti-inflammatory agents in the treatment of BD.

OBJECTIVES

Review clinical studies evaluating the effects of anti-inflammatory agents in the treatment of BD during all illness phases (e.g., depression, mania, and euthymia).

METHODS

Relevant databases were searched from inception to August 27, 2018 for clinical studies evaluating the effects of anti-inflammatory agents in BD.

RESULTS

The majority of identified clinical trials evaluated adjunctive anti-inflammatory agents in the acute treatment of bipolar depression, demonstrating antidepressant effects with N-acetylcysteine (NAC), pioglitazone, minocycline, and coenzyme Q10, along with mixed evidence for omega-3s, and non-steroidal anti-inflammatory drugs (NSAIDs). The anti-manic effects of adjunctive anti-inflammatory agents have been minimally studied, with some promising preliminary results supporting potential anti-manic effects of adjunctive celecoxib and NAC. Maintenance studies are also limited, with inadequate evidence to support mood stabilizing effects of anti-inflammatories while euthymic. Regardless of illness phase, early results suggest that anti-inflammatory agents are likely most beneficial in the subgroup of BD with immune dysregulation.

CONCLUSIONS

Several proof-of-concept clinical trials have shown promising results for anti-inflammatory agents in the treatment of bipolar depression with moderate effect sizes and good tolerability. The effects of anti-inflammatory agents during manic and euthymic periods remains uncertain. Future larger studies, using stratified samples, enriched for participants with immune dysfunction, are required to determine the role of immune modulating agents in the treatment of BD.

A microfluidic antibody bioarray for fast detection of human interleukins in low sample volumes

The antibody bioarray is a promising tool for the detection of proteins, which can be used as disease biomarkers. Therefore, we have developed a sandwich immunoassay-type bioarray using a microfluidic method to detect human interleukins that have diagnostic values. In the method development, we studied the effect of different factors that affect capture antibody immobilization, antibody–antigen interactions, and detection methods on the bioarray surface. The fluorescence signal obtained from different detection strategies was compared based on the signal fold-increase. This comparison showed that the use of covalent immobilization of capture antibodies, as opposed to their physical adsorption on the bioarray surface, increases the signal by 1.5 fold. Moreover, the use of protein G to achieve a better oriented immobilized capture antibody has resulted in a more than 3-fold signal enhancement.

Schizophrenia and bipolar disorders: The Toxoplasma connection

The infectious etiology of psychiatric illnesses has remained an unexplored area till recently. During the past two decades, numerous studies from multiple angles have tried to link chronic toxoplasmosis with schizophrenia and bipolar disorders, among others. Most of the evidence has come from serological studies in the patient population, but other facets have also been explored. This review examines the various areas from which a causal link has been deduced and includes: (a) serological studies, (b) effect of maternal toxoplasmosis on children, (c) neurotransmitter studies, (d) parasite localization in the brain, (e) role of cytokines, and (f) psychotherapy and its effect on Toxoplasma. However, multiple factors may play a role in the etiopathogenesis of psychiatric illnesses, and chronic Toxoplasma infection may be considered an important risk factor for the genesis and symptomatology of schizophrenia and bipolar disorders.