Is autoimmune thyroiditis part of the genetic vulnerability (or an endophenotype) for bipolar disorder?

Low-dose interleukin-2 in patients with bipolar depression: A phase 2 randomised double-blind placebo-controlled trial

Immune abnormalities including an insufficiency of regulatory T cells (Treg) and increased blood-based inflammatory markers have been observed in bipolar disorders (BD), particularly during depression. As Tregs are pivotal to control inflammation, Treg stimulation by low-dose IL-2 (IL-2LD) could have a therapeutic impact on bipolar depression. We performed a randomized, double-blind, placebo-controlled (2 active: 1 placebo) proof-of-concept trial of add-on IL-2LD in patients with bipolar depression. Patients received a placebo or IL-2LD (1MIU) once a day for 5 days, and then once a week for 4 weeks starting on week 2. The primary objective was to demonstrate a biological Treg response to IL-2LD assessed by fold increase in Treg percentage of CD4 + cells from baseline to day 5. Secondary objectives included safety assessment and mood improvement throughout the study period. This trial is registered with ClinicalTrials.gov, number NCT04133233. Fourteen patients with bipolar depression were included, with 4 receiving placebo and 10 IL-2LD. Baseline clinical and biological characteristics were balanced between groups. The primary evaluation criterion was met, with IL-2LD expanding 1.17 [95 % CI 1.01-1.34] vs 1.01 [95 % CI 0.90-1.12] (p = 0.0421) and activating Tregs. Secondary evaluation criteria were also met with significant improvements of depressive symptoms and global functioning from day-15 onwards in the IL-2LD treated patients. The treatment was well-tolerated, with no serious adverse events related to treatment. This proof-of-concept trial shows that stimulating Tregs in patients with bipolar depression is safe and associated with clinical improvements. This supports a pathophysiological role of inflammation in BD and warrants pursuing the evaluation of IL-2LD as an adjunct treatment of major mood disorders.

Molecular Mechanisms in Autoimmune Thyroid Disease

The most common cause of acquired thyroid dysfunction is autoimmune thyroid disease, which is an organ-specific autoimmune disease with two presentation phenotypes: hyperthyroidism (Graves-Basedow disease) and hypothyroidism (Hashimoto’s thyroiditis). Hashimoto’s thyroiditis is distinguished by the presence of autoantibodies against thyroid peroxidase and thyroglobulin. Meanwhile, autoantibodies against the TSH receptor have been found in Graves-Basedow disease. Numerous susceptibility genes, as well as epigenetic and environmental factors, contribute to the pathogenesis of both diseases. This review summarizes the most common genetic, epigenetic, and environmental mechanisms involved in autoimmune thyroid disease.

The temporal relationship between severe mental illness diagnosis and chronic physical comorbidity: a UK primary care cohort study of disease burden over 10 years

BACKGROUND

Despite increased rates of physical health problems in people with schizophrenia, bipolar disorder, and other psychotic illnesses, the temporal relationship between physical disease acquisition and diagnosis of a severe mental illness remains unclear. We aimed to determine the cumulative prevalence of 24 chronic physical conditions in people with severe mental illness from 5 years before to 5 years after their diagnosis.

METHODS

In this cohort study, we used the UK Clinical Practice Research Datalink (CPRD) to identify patients aged 18-100 years who were diagnosed with severe mental illness between Jan 1, 2000, and Dec 31, 2018. Each patient with severe mental illness was matched with up to four individuals in the CPRD without severe mental illness by sex, 5-year age band, primary care practice, and year of primary care practice registration. Individuals in the matched cohort were assigned an index date equal to the date of severe mental illness diagnosis in the patient with severe mental illness to whom they were matched. Our primary outcome was the cumulative prevalence of 24 physical health conditions, based on the Charlson and Elixhauser comorbidity indices, at 5 years, 3 years, and 1 year before and after severe mental illness diagnosis and at the time of diagnosis. We used logistic regression to compare people with severe mental illness with the matched cohort, adjusting for key variables such as age, sex, and ethnicity.

FINDINGS

We identified 68 789 patients diagnosed with a severe mental illness between Jan 1, 2000, and Dec 31, 2018, and we matched them to 274 827 patients without a severe mental illness diagnosis. In both cohorts taken together, the median age was 40·90 years (IQR 29·46-56·00), 175 138 (50·97%) people were male, and 168 478 (49·03%) were female. The majority of patients were of White ethnicity (59 867 [87·03%] patients with a severe mental illness and 244 566 [88·99%] people in the matched cohort). The most prevalent conditions at the time of diagnosis in people with severe mental illness were asthma (10 581 [15·38%] of 68 789 patients), hypertension (8696 [12·64%]), diabetes (4897 [7·12%]), neurological disease (3484 [5·06%]), and hypothyroidism (2871 [4·17%]). At diagnosis, people with schizophrenia had increased odds of five of 24 chronic physical conditions compared with matched controls, and nine of 24 conditions were diagnosed less frequently than in matched controls. Individuals with bipolar disorder and other psychoses had increased odds of 15 conditions at diagnosis. At 5 years after severe mental illness diagnosis, these numbers had increased to 13 conditions for schizophrenia, 19 for bipolar disorder, and 16 for other psychoses.

INTERPRETATION

Elevated odds of multiple conditions at the point of severe mental illness diagnosis suggest that early intervention on physical health parameters is necessary to reduce morbidity and premature mortality. Some physical conditions might be under-recorded in patients with schizophrenia relative to patients with other severe mental illness subtypes.

FUNDING

UK Office For Health Improvement and Disparities.

Depression and Autoimmune Hypothyroidism—Their Relationship and the Effects of Treating Psychiatric and Thyroid Disorders on Changes in Clinical and Biochemical Parameters Including BDNF and Other Cytokines—A Systematic Review

Various autoimmune diseases, including autoimmune hypothyroidism (AHT), are associated with a higher risk of developing mood disorders throughout life. Depression is accompanied by the changes in the levels of inflammatory and trophic factors, including interleukins (IL-1beta, IL-2, IL-6), interferon alpha (IFN-alpha), tumor necrosis factor alpha (TNF-alpha), C-reactive protein (CRP), and brain derived neurotrophic factor (BDNF). Disclosure of the relationship between the coexistence of depression and AHT indicates that the pathomechanism of depression may be related to the changes in the immune system, it is also possible that both conditions may be caused by the same immune processes. The above hypothesis is indirectly supported by the observations that the treatment with both antidepressants and levothyroxine leads to a decrease in the levels of proinflammatory cytokines with an increase in BDNF concentrations, simultaneously correlating with an improvement in the clinical parameters. However, so far there are no long-term studies determining the causal relationship between depression, thyroid autoantibodies, and cytokine profile, which could bring us closer to understanding the interrelationships between them and facilitate the use of an adequate pharmacotherapy, not necessarily psychiatric. We consider the above issues to be insufficiently investigated but of great importance. This article is an overview of the available literature as well as an introduction to our research project.

Altered Neuronal Support and Inflammatory Response in Bipolar Disorder Patient-Derived Astrocytes

Bipolar disorder (BD) is characterized by cyclical mood shifts. Studies indicate that BD patients have a peripheral pro-inflammatory state and alterations in glial populations in the brain. We utilized an in vitro model to study inflammation-related phenotypes of astrocytes derived from induced pluripotent stem cells (iPSCs) generated from BD patients and healthy controls. BD astrocytes showed changes in transcriptome and induced a reduction in neuronal activity when co-cultured with neurons. IL-1β-stimulated BD astrocytes displayed a unique inflammatory gene expression signature and increased secretion of IL-6. Conditioned medium from stimulated BD astrocytes reduced neuronal activity, and this effect was partially blocked by IL-6 inactivating antibody. Our results suggest that BD astrocytes are functionally less supportive of neuronal excitability and this effect is partially mediated by IL-6. We confirmed higher IL-6 in blood in a distinct cohort of BD patients, highlighting the potential role of astrocyte-mediated inflammatory signaling in BD neuropathology.

Association between anti-thyroid antibodies and negative symptoms in early psychosis

AIM

In the current cross-sectional study, we aimed to explore whether thyroid function or thyroid autoimmunity are associated with psychopathological symptoms and social functioning in patients with early psychosis. We hypothesized that psychopathological severity is greater in those patients with positive thyroid autoimmunity.

METHODS

We studied 70 outpatients with early psychosis (<3 years of illness) and 37 healthy subjects. Psychopathological symptoms (positive, negative, disorganized, excited and depressive) and social functioning were assessed. Thyroid autoimmunity (antibodies against thyroid peroxidase [TPO-Abs] and thyroglobulin [TG-Abs]) and thyroid function (thyroid-stimulating hormone [TSH] and free thyroxin [FT4]) were determined. Associations of thyroid variables and psychometric measures were assessed with Spearman's correlations. Logistic regression was performed to explore the association between psychopathological symptoms and positive anti-thyroidal antibodies while adjusting for covariates.

RESULTS

When compared to patients without thyroid antibodies, those with positive thyroid antibodies had more negative symptoms and poorer function (P < .05). Titres of TPO-Abs were significantly correlated with negative and depressive PANSS domains and poorer functioning. TG-Abs were also associated with poorer functioning but not with psychopathological symptoms. TSH and FT4 concentrations were not associated with clinical symptoms. In the logistic regression analysis adjusted for age, gender, antipsychotic treatment, lithium, TSH and FT4 concentrations, negative symptoms were associated with thyroid autoimmunity (OR = 1.2, P = .019).

CONCLUSIONS

Our study suggests that anti-thyroid antibodies are associated with a more severe phenotype with increased negative symptoms and poorer functioning in early psychotic patients. Since causality cannot be inferred with cross-sectional data, future longitudinal studies are needed to overcome this limitation.

Neuroimmune Mechanisms and Sex/Gender-Dependent Effects in the Pathophysiology of Mental Disorders

Innate and adaptive immune mechanisms have emerged as critical regulators of CNS homeostasis and mental health. A plethora of immunologic factors have been reported to interact with emotion- and behavior-related neuronal circuits, modulating susceptibility and resilience to mental disorders. However, it remains unclear whether immune dysregulation is a cardinal causal factor or an outcome of the pathologies associated with mental disorders. Emerging variations in immune regulatory pathways based on sex differences provide an additional framework for discussion in these psychiatric disorders. In this review, we present the current literature pertaining to the effects that disrupted immune pathways have in mental disorder pathophysiology, including immune dysregulation in CNS and periphery, microglial activation, and disturbances of the blood-brain barrier. In addition, we present the suggested origins of such immune dysregulation and discuss the gender and sex influence of the neuroimmune substrates that contribute to mental disorders. The findings challenge the conventional view of these disorders and open the window to a diverse spectrum of innovative therapeutic targets that focus on the immune-specific pathophenotypes in neuronal circuits and behavior. SIGNIFICANCE STATEMENT: The involvement of gender-dependent inflammatory mechanisms on the development of mental pathologies is gaining momentum. This review addresses these novel factors and presents the accumulating evidence introducing microglia and proinflammatory elements as critical components and potential targets for the treatment of mental disorders.

Predictive factors of diagnostic conversion from major depressive disorder to bipolar disorder in young adults ages 19-34: A nationwide population study in South Korea

BACKGROUND

Predicting patients who convert to bipolar disorder is important for deciding appropriate treatment for young adults with major depressive disorder (MDD). We focused on the predictive factors of bipolar conversion in a large population of young adults.

METHODS

A nationwide, population-based electronic medical records database from the Health Insurance Review & Assessment service of South was used to investigate adjusted hazard ratio (HR) of each potential predictor of the bipolar converter group compared to the non-converter group using Cox regression analysis including age of onset, medication use, clinical features, comorbid disorders, admission, self-harm, and negative life events in childhood.

RESULTS

Among 291,721 subjects who were initially diagnosed with MDD in young adults, 12,376 subjects experienced diagnostic conversion to bipolar disorder. The cumulative incidence was 6.46% during the average 3.26 years of follow-up. Among the predictive factors during diagnosis of MDD, antipsychotic use (HR 3.12, 95%CI, 2.99-3.26, p < 0.0001) and mood stabilizers (HR 2.45, 95%CI, 2.35-2.55, p < 0.0001) showed the strongest association with diagnostic conversion to bipolar disorder. In addition, female sex, younger age of onset, mood stabilizer use, recurrent depression, psychotic symptoms, and admission to a psychiatric ward during diagnosis of MDD were also associated with diagnostic conversion to bipolar disorder.

CONCLUSION

In young adults with MDD, antipsychotic and mood stabilizer use during diagnosis of MDD were the strongest predictive factors with diagnostic conversion to bipolar disorder during follow-up. If young adults with MDD need antipsychotics or mood stabilizer, patients should be carefully evaluated for possibility of bipolar disorder.

No association between anti-thyroidperoxidase antibodies and bipolar disorder: a study in the Dutch Bipolar Cohort and a meta-analysis

BACKGROUND

Thyroid autoimmunity has been associated with bipolar disorder (BD). However, results from previous studies on the seroprevalence of anti-thyroid peroxidase antibodies (TPO-abs) in BD are inconsistent.

OBJECTIVES

The aim of the present study is to investigate whether the seroprevalence and titer levels of TPO-abs are related to BD.

METHOD

TPO-abs were measured in plasma samples of 760 patients with bipolar disorder, 261 first-degree relatives and 363 controls by enzyme-linked immunosorbent assay (ELISA). To address methodological limitations of previous studies, we assessed clinical characteristics with several (self-reported) questionnaires to investigate whether TPO-abs positivity is related to particular clinical subgroups of BD patients. We performed an additional meta-analysis of seroprevalences of TPO-abs in BD patients including data from present and previous studies.

RESULTS

Seroprevalence or titer levels of TPO-abs did not significantly differ between patients with BD, their first-degree relatives, and controls. In BD patients, the prevalence of TPO-abs was unrelated to specific clinical factors, including lithium use. Our meta-analysis of twelve studies showed an overall odds ratio of 1.3 (CI 95 %: 0.7-2.3; p = 0.30), reaffirming the absence of an association of BD with TPO-abs.

CONCLUSIONS

In the largest study of TPO-abs in BD to date, our findings indicate that TPO-abs are not associated with (the risk for) bipolar disorder.

Physical health in individuals with psychiatric disorders in Austria

INTRODUCTION

The association between severe psychiatric disorders and metabolic syndrome is well documented and goes along with a reduced life expectancy. The prevalence of medical comorbidities in individuals suffering from psychiatric disorders in Austria has not yet been examined; aim of this study was to analyze the prevalence of comorbid somatic disorder in individuals diagnosed with psychiatric disorders in Austria.

METHODS

Patients (n = 600) with a life-time diagnosis of mood and anxiety disorders undergoing a six-week course of intensive treatment in a psychiatric rehabilitation center were recruited. Prevalent somatic and psychological conditions, anamnestic data, medical history, blood samples, clinical and psychological tests as well as medication were examined to determine somatic and psychiatric diagnoses.

RESULTS

Metabolic disorders were highly prevalent especially in individuals diagnosed with affective disorders, respectively in bipolar disorder. Furthermore, obesity and thyroid dysfunction were found in about 40% of individuals diagnosed with bipolar disorder in the present study. Significant gender differences were found in CVD and hypertension with higher prevalence in men, while thyroid dysfunction occurred more often in women also compared to the general female population.

CONCLUSIONS

Characterizing somatic comorbidity in individuals with psychiatric disorders can stimulate research to better understand possible shared etiologic factors and has public health implications for improving models of care. This could have a positive effect on the course of mental disorders, and additionally improve social integration and life expectancy. Knowledge about sex differences should be used to further improve individualized treatment of individuals with psychiatric disorders.

Personalized and precision medicine as informants for treatment management of bipolar disorder

DSM-5 diagnostic categories, defined by a set of psychopathological symptoms are heterogeneous conditions that may include different biological entities, with distinct etiopathogenesis, different courses and requiring different treatment management. For bipolar disorder the major evidences for this lack of validity are the long paths before a proper diagnosis, the inconsistence of treatment guidelines, the long phases of pharmacological adjustment and the low average of long-term treatment response rates. Personalized medicine for mental disorders aims to couple established clinical-pathological indexes with new molecular profiling to create diagnostic, prognostic and therapeutic strategies precisely tailored to each patient. Regarding bipolar disorder, the clinical history and presentation are still the most reliable markers in stratifying patients and guiding therapeutic management, despite the research goes to great lengths to develop new neuropsychological or biological markers that can reliably predict individual therapy effectiveness. We provide an overview of the advancements in personalized medicine in bipolar disorder, with particular attention to how psychopathology, age at onset, comorbidity, course and staging, genetic and epigenetic, imaging and biomarkers can influence treatment management and provide an integration to the conventional treatment guidelines. This approach may offer a new and rational path for the development of treatments for targeted subgroups of patients with bipolar disorder.

Thyroid structure and function in long-term lithium-treated and lithium-naïve bipolar patients

OBJECTIVE

The aim of the study was to compare the structure and function of the thyroid in patients with bipolar disorder (BD) receiving long-term lithium treatment, with BD patients never receiving lithium.

METHODS

Ninety-eight patients (68 female and 30 male), aged 62 ± 13 years, receiving lithium for 3-47 years (mean 19 ± 10 years), and 39 patients (27 female and 12 male), aged 57 ± 10 years, receiving other mood-stabilizing drugs but never treated with lithium, were included. The thyroid-stimulating hormone (TSH), free triiodothyronine (fT3), and free thyroxine (fT4) were estimated, and the ultrasonographic study of the thyroid gland was performed.

RESULTS

Compared with patients not receiving lithium, lithium-treated patients had significantly higher concentrations of TSH and fT4 and the lower concentration of fT3. However, the percentage of hypothyroidism was not different in both groups. Lithium-treated patients also had significantly higher thyroid volume, the higher number of focal changes >1 cm, and more frequent goiter. The structural changes were not related to the hormones' concentrations.

CONCLUSIONS

The results show a significant association between long-term lithium treatment and the increase of TSH and fT4, the decrease of fT3, higher thyroid volume, and more frequent goiter and nodular goiter. The effect of lithium on thyroid structure was not associated with its effect on thyroid hormones.

Genetic and environmental influences on circulating NK and T cells and their relation to bipolar disorder

BACKGROUND

In previous studies we found mild deficiencies of circulating T cells in patients with bipolar disorder (BD) and children at risk for BD, correlating to a higher inflammatory state. The genetic and environmental influences on these T cell deficiencies in association with BD development are unknown.

OBJECTIVES

The aim is to quantify genetic and environmental factors that contribute to the association between the liability to develop BD and T cell deficiencies.

METHODS

Participants of a Dutch bipolar twin study (11 monozygotic BD twin pairs, 15 dizygotic BD twin pairs, 15 monozygotic and 12 dizygotic healthy twin pairs) were included. A detailed FACS analysis of frozen stored leukocytes was carried out to determine the percentages of T cells and various other leukocyte and lymphocyte subsets. A bivariate liability threshold twin model was used to determine genetic and environmental (common and unique) influences on the correlation between BD and the various subsets.

RESULTS

Lower percentages of T cells and higher percentages of NK cells were associated with the familial liability to develop BD. Neither genetic nor shared or unique environmental factors could explain the associations. Lithium usage explained part of the association for T cells, smoking in part that for NK cells.

CONCLUSIONS

Our results confirm that BD is the result of a complex interaction between various genetic and environmental risk factors, in which T and NK cells act as important intermediate immune players.

The Link between Thyroid Autoimmunity, Depression and Bipolar Disorder

Depression and bipolar disorder are two major psychiatric illnesses whose pathophysiology remains elusive. Newly emerging data support the hypothesis that the dysfunction of the immune system might be a potential factor contributing to the development of these mental disorders. The most common organ affected by autoimmunity is the thyroid; therefore, the link between autoimmune thyroid disorders and mental illnesses has been studied since the 1930s. The aim of this review is to discuss the associations between thyroid autoimmunity, depression and bipolar disorder.

Immune-based strategies for mood disorders: facts and challenges

INTRODUCTION

Inflammation seems to play a role in the pathophysiology of mood disorders, including major depressive disorder (MDD) and bipolar disorder (BD). In the last years several studies have shown increased levels of inflammatory and/or immune markers in patients with mood disorders. Accordingly, the immune system has become a target of interest for the development of biomarkers and therapeutics for mood disorders. Areas covered: Here, we review the evidence showing low-grade inflammation in mood disorders and the studies evaluating immune-based strategies for the treatment of these conditions. Expert commentary: Clinical trials with non-steroidal anti-inflammatory drugs, polyunsaturated acids, N-acetylcysteine, anti-cytokines, physical activity and probiotics have provided promising results in terms of antidepressant efficacy in patients with MDD and BD. Regarding stem cells, only studies with animal models have been performed so far with interesting pre-clinical results. Due to the preliminary nature of the results, most of the clinical studies need to be replicated and/or confirmed in larger clinical settings, embracing the highly heterogeneous pathophysiology of mood disorders.

Do some anxiety disorders belong to the prodrome of bipolar disorder? A clinical study combining retrospective and prospective methods to analyse the relationship between anxiety disorder and bipolar disorder from the perspective of biorhythms

BACKGROUND

In clinical practice, some patients diagnosed with anxiety disorder (AD) may develop bipolar disorder (BD) many years later, and some cases of AD may be cured by the use of mood stabilizers. However, the relationship between AD and BD should be explored further.

METHOD

To track how many cases of AD turned to BD and to discover the differences between them, we recruited 48 patients diagnosed with BD, who were assigned to the BD group for the retrospective analysis, and we also recruited 186 patients diagnosed with AD at enrolment; this latter group was asked to complete follow-up surveys conducted 3 months, 6 months, 12 months and 18 months after the primary stage of the study. We defined another two groups according to the usage of mood stabilizers, the rates of reduction in scores on the Hamilton Anxiety Scale and Yale-Brown Obsessive Compulsive Scale, and the changes in Clinical Global Impression scores at different follow-up times: the anxiety group and the atypical BD group (who used mood stabilizers to treat AD). All subjects also completed the NEO Five-Factor Inventory and supplied blood samples to be tested for several endocrine indices (TSH, T3, FT3, T4, FT4, ACTH,PTC) and inflammatory cytokines (IL-6, IL-8, IL-10, TNF-α, CRP) at enrolment.

RESULTS

In total, 14 subjects developed BD by the end of the study. One hundred eleven subjects were included in the anxiety group. Sixty-three subjects were assigned to the atypical BD group, and they had similar features to the 48 subjects in the BD group in terms of personality traits, abnormality rates of endocrine indices and levels of inflammatory cytokines. From the anxiety group to the atypical BD group and then the BD group, the age of first onset gradually decreased, while the frequency of onset and the score of suicidal ideation gradually increased. Furthermore, the atypical BD group showed markedly higher levels of TSH, IL-6, TNF-α and CRP than the other two groups.

CONCLUSIONS

Some ADs with unique features might belong to the prodromal stage or the atypical presentation of BD, and recognizing these ADs early will economize many medical resources.

Thyroid autoimmunity in bipolar disorder: A systematic review

BACKGROUND

Accumulating evidence points to the pathophysiological relevance between immune dysfunction and mood disorders. High rates of thyroid dysfunction have been found in patients with bipolar disorder (BD), compared to the general population. A systematic review of the relationship between BD and thyroid autoimmunity was performed.

METHODS

Pubmed, EMBASE and PsycINFO databases were searched up till January 28th, 2017. This review has been conducted according to the PRISMA statements. Observational studies clearly reporting data among BD patients and the frequency of autoimmune thyroid pathologies were included.

RESULTS

11 original studies met inclusion criteria out of 340 titles first returned from the global search. There is evidence of increased prevalence of circulating thyroid autoantibodies in depressed and mixed BD patients, while there is no evidence showing a positive relationship between BD and specific autoimmune thyroid diseases. There is a controversy about the influence of lithium exposure on circulating thyroid autoantibodies, even if most of studies seem not to support this association. A study conducted on bipolar twins suggests that autoimmune thyroiditis is related to the genetic vulnerability to develop BD rather than to the disease process itself. Females are more likely to develop thyroid autoimmunity.

LIMITATIONS

The samples, study design and outcomes were heterogeneous.

CONCLUSION

Thyroid autoimmunity has been suggested to be an independent risk factor for bipolar disorder with no clear association with lithium exposure and it might serve as an endophenotype for BD.

The seroprevalence of antithyroid peroxidase antibodies in bipolar families and bipolar twins: results from two longitudinal studies

Background

Previous studies of our group among bipolar offspring and bipolar twins showed significant higher prevalence’s and levels of antithyroid peroxidase antibodies (TPO-Abs) in offspring and co-twins (without a mood disorder) compared to controls, suggesting that TPO-Abs might be considered as vulnerability factor (trait marker) for BD development.

Objectives

Here we elucidate, in the same cohorts, but now after 12- and 6-year follow-up, whether TPO-abs should be considered as a ‘trait’ marker for BD. The present study aims to investigate whether TPO-Abs (1) are stable over time, (2) are associated with lithium-exposure, (3) share a common genetic background with BD and are related to psychopathology.

Results

In bipolar offspring and twins, the prevalence of TPO-Abs is stable over time (r_s = .72 p < .001 resp. r_s = .82, p < .001) and not associated with lithium use. At follow-up, an increased prevalence of TPO-abs was again observed in bipolar offspring (10,4% versus 4%) and higher TPO-abs titers were still present in co-twins of bipolar cases compared to control twins [mean 1.06 IU/ml (SD .82) versus mean .82 IU/ml (SD .67)], although statistical significance was lost.

Conclusions

Although our results show a trend toward an increased inherited risk of the co-occurrence of BD and thyroid autoimmunity, large-scale studies can only draw final conclusions. Nationwide epidemiological and GWAS studies reach such numbers and support the view of a possible common (autoimmune) etiology of severe mood disorders and chronic recurrent infections and autoimmunity, including thyroid autoimmunity.

Neuropathology of mood disorders: do we see the stigmata of inflammation?

A proportion of cases with mood disorders have elevated inflammatory markers in the blood that conceivably may result from stress, infection and/or autoimmunity. However, it is not yet clear whether depression is a neuroinflammatory disease. Multiple histopathological and molecular abnormalities have been found postmortem but the etiology of these abnormalities is unknown. Here, we take an immunological perspective of this literature. Increases in activated microglia or perivascular macrophages in suicide victims have been reported in the parenchyma. In contrast, astrocytic markers generally are downregulated in mood disorders. Impairment of astrocytic function likely compromises the reuptake of glutamate potentially leading to excitotoxicity. Inflammatory cytokines and microglia/macrophage-derived quinolinic acid (QA) downregulate the excitatory amino acid transporters responsible for this reuptake, while QA has the additional effect of inhibiting astroglial glutamine synthetase, which converts glutamate to glutamine. Given that oligodendroglia are particularly vulnerable to inflammation, it is noteworthy that reductions in numbers or density of oligodendrocyte cells are one of the most prominent findings in depression. Structural and/or functional changes to GABAergic interneurons also are salient in postmortem brain samples, and may conceivably be related to early inflammatory insults. Although the postmortem data are consistent with a neuroimmune etiology in a subgroup of depressed individuals, we do not argue that all depression-associated abnormalities are reflective of a neuroinflammatory process or even that all immunological activity in the brain is deleterious. Rather, we highlight the pervasive role of immune signaling pathways in brain function and provide an alternative perspective on the current postmortem literature.

Delirious Mania Associated with Autoimmune Gastrothyroidal Syndrome of a Mid-Life Female: The Role of Hashimoto Encephalopathy and a 3-Year Follow-Up including Serum Autoantibody Levels

We report the case study of a 57-year-old Caucasian female with steroid-responsive encephalopathy associated with autoimmune thyroiditis (SREAT), commonly termed Hashimoto encephalopathy (HE). This presentation includes one of the longest lasting follow-up studies of HE considering the neuropsychiatric symptoms (here delirium, mania, and EEG-slowing) and their relation to serum autoantibody levels. Antithyroid-peroxidase autoantibodies, the hallmark of autoimmune thyroiditis, were found in the serum and also in the cerebrospinal fluid. Diagnostic analyses found no evidence of limbic encephalopathies characterized by serum antibodies against intracellular, synaptic, or further cell surface antigenic targets, neoplasm, and connective tissue or vasculitis diseases. A potential contribution of bipolar disorder and metabolic encephalopathies due to severe hypothyroidism, glucocorticoid treatment, accelerated thyroid hormone replacement therapy, or vitamin B deficiency is critically discussed. Another special feature of this case report is the linkage of HE to an autoimmune polyendocrine syndrome (type 3B) affecting the gastroduodenum in addition to the thyroid gland.

Volume, metabolites and neuroinflammation of the hippocampus in bipolar disorder - A combined magnetic resonance imaging and positron emission tomography study

BACKGROUND

The hippocampus is one of the brain regions that is involved in several pathophysiological theories about bipolar disorder (BD), such as the neuroinflammation theory and the corticolimbic metabolic dysregulation theory. We compared hippocampal volume and hippocampal metabolites in bipolar I disorder (BD-I) patients versus healthy controls (HCs) with magnetic resonance imaging (MRI) and spectroscopy (MRS). We post hoc investigated whether hippocampal volume and hippocampal metabolites were associated with microglial activation and explored if potential illness modifying factors affected these hippocampal measurements and whether these were associated with experienced mood and functioning.

MATERIALS AND METHODS

Twenty-two BD-I patients and twenty-four HCs were included in the analyses. All subjects underwent psychiatric interviews as well as an MRI scan, including a T1 scan and PRESS magnetic resonance spectroscopy (MRS). Volumetric analysis was performed with Freesurfer. MRS quantification was performed with LC Model. A subgroup of 14 patients and 11 HCs also underwent a successful [(11)C]-(R)-PK11195 neuroinflammation positron emission tomography scan.

RESULTS

In contrast to our hypothesis, hippocampal volumes were not decreased in patients compared to HC after correcting for individual whole-brain volume variations. We demonstrated decreased N-acetylaspartate (NAA)+N-acetyl-aspartyl-glutamate (NAAG) and creatine (Cr)+phosphocreatine (PCr) concentrations in the left hippocampus. In the explorative analyses in the left hippocampus we identified positive associations between microglial activation and the NAA+NAAG concentration, between alcohol use and NAA+NAAG concentration, between microglial activation and the depression score and a negative relation between Cr+PCr concentration and experienced occupational disability. Duration of illness associated positively with volume bilaterally.

CONCLUSION

Compared to HCs, the decreased NAA+NAAG concentration in the left hippocampus of BD-I patients suggests a decreased neuronal integrity in this region. In addition we found a positive relation between microglial activation and neuronal integrity in vivo, corresponding to a differentiated microglial function where some microglia induce apoptosis while others stimulate neurogenesis.

Hypothyroidism risk compared among nine common bipolar disorder therapies in a large US cohort

OBJECTIVES

Thyroid abnormalities in patients with bipolar disorder (BD) have been linked to lithium treatment for decades, yet other drugs have been less well studied. Our objective was to compare hypothyroidism risk for lithium versus the anticonvulsants and second-generation antipsychotics commonly prescribed for BD.

METHODS

Administrative claims data on 24,574 patients with BD were analyzed with competing risk survival analysis. Inclusion criteria were (i) one year of no prior hypothyroid diagnosis nor BD drug treatment, (ii) followed by at least one thyroid test during BD monotherapy on lithium carbonate, mood-stabilizing anticonvulsants (lamotrigine, valproate, oxcarbazepine, or carbamazepine) or antipsychotics (aripiprazole, olanzapine, risperidone, or quetiapine). The outcome was cumulative incidence of hypothyroidism per drug, in the presence of the competing risk of ending monotherapy, adjusted for age, sex, physician visits, and thyroid tests.

RESULTS

Adjusting for covariates, the four-year cumulative risk of hypothyroidism for lithium (8.8%) was 1.39-fold that of the lowest risk therapy, oxcarbazepine (6.3%). Lithium was non-statistically significantly different from quetiapine. While lithium conferred a higher risk when compared to all other treatments combined as a group, hypothyroidism risk error bars overlapped for all drugs. Treatment (p = 3.86e-3), age (p = 6.91e-10), sex (p = 3.93e-7), and thyroid testing (p = 2.79e-87) affected risk. Patients taking lithium were tested for hypothyroidism 2.26-3.05 times more frequently than those on other treatments.

CONCLUSIONS

Thyroid abnormalities occur frequently in patients with BD regardless of treatment. Therefore, patients should be regularly tested for clinical or subclinical thyroid abnormalities on all therapies and treated as indicated to prevent adverse effects of hormone imbalances on mood.

Aberrant Levels of Hematopoietic/Neuronal Growth and Differentiation Factors in Euthyroid Women at Risk for Autoimmune Thyroid Disease

Background

Subjects at risk for major mood disorders have a higher risk to develop autoimmune thyroid disease (AITD) and vice-versa, implying a shared pathogenesis. In mood disorder patients, an abnormal profile of hematopoietic/neuronal growth factors is observed, suggesting that growth/differentiation abnormalities of these cell lineages may predispose to mood disorders. The first objective of our study was to investigate whether an aberrant profile of these hematopoietic/neuronal growth factors is also detectable in subjects at risk for AITD. A second objective was to study the inter relationship of these factors with previously determined and published growth factors/cytokines in the same subjects.

Methods

We studied 64 TPO-Ab-negative females with at least 1 first- or second-degree relative with AITD, 32 of whom did and 32 who did not seroconvert to TPO-Ab positivity in 5-year follow-up. Subjects were compared with 32 healthy controls (HCs). We measured serum levels of brain-derived neurotrophic factor (BDNF), Stem Cell Factor (SCF), Insulin-like Growth Factor-Binding Protein 2 (IGFBP-2), Epidermal Growth Factor (EGF) and IL-7 at baseline.

Results

BDNF was significantly lower (8.2 vs 18.9 ng/ml, P<0.001), while EGF (506.9 vs 307.6 pg/ml, P = 0.003) and IGFBP-2 (388.3 vs 188.5 ng/ml, P = 0.028) were significantly higher in relatives than in HCs. Relatives who seroconverted in the next 5 years had significantly higher levels of SCF than non-seroconverters (26.5 vs 16.7 pg/ml, P = 0.017). In a cluster analysis with the previously published growth factors/cytokines SCF clustered together with IL-1β, IL-6 and CCL-3, of which high levels also preceded seroconversion.

Conclusion

Relatives of AITD patients show aberrant serum levels of 4 hematopoietic/neuronal growth factors similar to the aberrancies found in mood disorder patients, suggesting that shared growth and differentiation defects in both the hematopoietic and neuronal system may underlie thyroid autoimmunity and mood disorders. A distinct pattern of four inter correlating immune factors in the relatives preceded TPO-Ab seroconversion in the next 5 years.

Bipolar disorder and antithyroid antibodies: review and case series

Mood disorders and circulating thyroid antibodies are very prevalent in the population and their concomitant occurrence may be due to chance. However, thyroid antibodies have been repeatedly hypothesized to play a role in specific forms of mood disorders. Potentially related forms include treatment-refractory cases, severe or atypical depression, and depression at specific phases of a woman’s life (early gestation, postpartum depression, perimenopausal). With regard to bipolar disorder, studies of specific subgroups (rapid cycling, mixed, or depressive bipolar) have reported associations with thyroid antibodies. Offspring of bipolar subjects were found more vulnerable to develop thyroid antibodies independently from the vulnerability to develop psychiatric disorders. A twin study suggested thyroid antibodies among possible endophenotypes for bipolar disorder. Severe encephalopathies have been reported in association with Hashimoto’s thyroiditis. Cases with pure psychiatric presentation are being reported, the antithyroid antibodies being probably markers of some other autoimmune disorders affecting the brain. Vasculitis resulting in abnormalities in cortical perfusion is one of the possible mechanisms.

Exaggerated Increases in Microglia Proliferation, Brain Inflammatory Response and Sickness Behaviour upon Lipopolysaccharide Stimulation in Non-Obese Diabetic Mice

The non-obese diabetic (NOD) mouse, an established model for autoimmune diabetes, shows an exaggerated reaction of pancreas macrophages to inflammatory stimuli. NOD mice also display anxiety when immune-stimulated. Chronic mild brain inflammation and a pro-inflammatory microglial activation is critical in psychiatric behaviour.

OBJECTIVE

To explore brain/microglial activation and behaviour in NOD mice at steady state and after systemic lipopolysaccharide (LPS) injection.

METHODS

Affymetrix analysis on purified microglia of pre-diabetic NOD mice (8-10 weeks) and control mice (C57BL/6 and CD1 mice, the parental non-autoimmune strain) at steady state and after systemic LPS (100 μg/kg) administration. Quantitative PCR was performed on the hypothalamus for immune activation markers (IL-1β, IFNγ and TNFα) and growth factors (BDNF and PDGF). Behavioural profiling of NOD, CD1, BALB/c and C57BL/6 mice at steady state was conducted and sickness behaviour/anxiety in NOD and CD1 mice was monitored before and after LPS injection.

RESULTS

Genome analysis revealed cell cycle/cell death and survival aberrancies of NOD microglia, substantiated as higher proliferation on BrdU staining. Inflammation signs were absent. NOD mice had a hyper-reactive response to novel environments with some signs of anxiety. LPS injection induced a higher expression of microglial activation markers, a higher brain pro-inflammatory set point (IFNγ, IDO) and a reduced expression of BDNF and PDGF after immune stimulation in NOD mice. NOD mice displayed exaggerated and prolonged sickness behaviour after LPS administration.

CONCLUSION

After stimulation with LPS, NOD mice display an increased microglial proliferation and an exaggerated inflammatory brain response with reduced BDNF and PDGF expression and increased sickness behaviour as compared to controls.

Quality of life in patients with primary hypothyroidism related to BMI

OBJECTIVE

Many patients treated for primary hypothyroidism have an unexplained reduced quality of life (QOL). We studied the relation between QOL and various parameters in treated hypothyroid patients.

DESIGN AND METHODS

QOL analysis was done in 90 consecutive patients (77.8% females) treated for primary hypothyroidism. QOL was measured by the questionnaires Short-Form 36, Hospital Anxiety and Depression Scale and MFI20. Post hoc analysis was performed on the relation of QOL at baseline and BMI, thyroid hormones and other serum values. QOL in patients was also compared to the general population.

RESULTS

QOL was decreased compared to the general population. We found an inverse relationship between QOL and BMI. A relationship between QOL and serum thyroid parameters or auto-antibodies could not be found. Higher sex hormone binding globulin (SHBG) levels corresponded with a better QOL, which is explained by the negative association of SHBG with body weight and BMI.

CONCLUSIONS

A decreased QOL in hypothyroid patients on thyroxine treatment is related to a higher body weight (BMI). Weight gain needs more attention in the treatment of hypothyroidism.

Maternal history of autoimmune disease and later development of tourette syndrome in offspring

OBJECTIVE

In a nationwide prospective cohort study, we examined the possible association between maternal autoimmune disease (AD) and later diagnosis of Tourette syndrome (TS) in offspring.

METHOD

Data from national Danish health registers identified a cohort consisting of all children born in Denmark between 1990 and 2007 (n = 1,116,255), followed prospectively from birth until 2011, date of TS diagnosis, death, or emigration/disappearance, whichever came first. The incidence rate ratio (IRR) of TS, dependent on whether or not the mother had a prior diagnosis of AD, was estimated by Poisson regression with 95% CIs and adjusted for age, calendar time, place of birth, maternal and paternal age, parental psychiatric diagnoses other than TS, and parental TS.

RESULTS

The cohort contributed a total of 13,000,162 person years and 2,442 participants with a diagnosis of TS (414 females and 2,028 males). Prior maternal AD was found in 110 of the 2,442 children with TS, corresponding to an increased risk of TS, with an adjusted IRR of 1.22 (95% CI = 1.01-1.48). Maternal history of a prior AD increased the risk of TS in males, with an adjusted IRR of 1.29 (95% CI = 1.05-1.58), but not in females, with an adjusted IRR of 0.89 (95% CI = 0.52-1.52).

CONCLUSION

Maternal AD was associated with a 29% increased incidence rate of TS in male offspring. This finding supports the hypothesis that neuroimmunological disorders may act as a component in the etiology of a subset of TS.

A cross-sectional study of thyroid function in 66 patients with bipolar disorder receiving lithium for 10-44 years

OBJECTIVES

An important side effect of lithium therapy is an influence on thyroid function. It is unclear whether there is a significant association between thyroid function and duration of lithium administration. The aim of the present cross-sectional study was to measure levels of thyroid hormones and antibodies in patients with bipolar disorder receiving lithium for more than ten years.

METHODS

The study was performed in 66 patients (21 males, 45 females) with bipolar mood disorder, receiving lithium for 10-44 (21 ± 9; mean ± standard deviation) years. Thyroid-stimulating hormone (TSH), free thyroxine (fT3), and free triiodothyronine (fT4) were measured by the microparticle enzyme immunoassay. Thyroid peroxidase (TPO) antibodies, thyroglobulin (TG) antibodies, and TSH receptor (TSH-R) antibodies were measured by the radioimmunoassay.

RESULTS

Some features of hypothyroidism were found in ten (22%) female patients (seven received levothyroxine and three had increased TSH). No abnormality in thyroid hormones was found in male patients. A significant percentage of patients had abnormally high levels of anti-TPO, and anti-TG antibodies, which correlated with TSH and fT3 concentrations. There were no differences in thyroid function between patients receiving lithium for 10-20 years and those taking the drug for more than 20 years.

CONCLUSIONS

These results confirm the greater susceptibility of female subjects for disturbances of thyroid hormones during lithium therapy, with one-fifth of them showing some features of hypothyroidism. Abnormally high levels of anti-TPO and anti-TG antibodies were shown in a significant proportion of patients. However, in contrast to the effect of lithium on kidney function, our results do not show an association between the duration of lithium therapy and thyroid dysfunction.

The trajectory of neuropsychological dysfunctions in bipolar disorders: a critical examination of a hypothesis

OBJECTIVE

The hypothesis of a progressive nature of neuropsychological deficits in bipolar disorders is often accepted as an axiom by many clinicians and researchers in the field. However, contradictory pieces of data and a number of methodological concerns put it under debate.

METHOD

We reviewed findings from three different approaches to the study of the trajectory of cognitive features in bipolar disorders: longitudinal evaluation of cognition in affected subjects, cross-sectional neuropsychological assessment of patients belonging to different age groups, and exploration of the risk of dementia in bipolar subjects.

RESULTS

An increased risk of developing dementia was found in bipolar subjects. However, evidence from cross-sectional studies did not show more severe cognitive deficits in patients with longer illness duration. Furthermore, longitudinal studies revealed that bipolar subjects׳ cognitive performance did not change between different points in time.

CONCLUSIONS

After a thorough discussion of these findings and the limitations of the different approaches, we argue that, at present, there is no consistent evidence supporting that bipolar disorders, as a group, have a progressively deteriorating course of cognitive functions. Furthermore, we highlight the possible influence of psychotropic agents and metabolic factors on neuropsychological outcomes. Finally, we discuss the clinical implications of these findings and propose targets for forthcoming research.

The influence of life events on first and recurrent admissions in bipolar disorder

Background

Life events play an important role in the onset and course of bipolar disorder. We will test the influence of life events on first and recurrent admissions in bipolar disorder and their interaction to test the kindling hypothesis.

Methods

We collected information about life events and admissions across the life span in 51 bipolar patients. We constructed four models to explore the decay of life event effects on admissions. To test their interaction, we used the Andersen-Gill model.

Results

The relationship between life events and admissions was best described with a model in which the effects of life events gradually decayed by 25% per year. Both life event load and recurrent admissions significantly increased the risk of both first and subsequent admissions. No significant interaction between life event load and number of admissions was found.

Conclusions

Life events increase the risk of both first and recurrent admissions in bipolar disorder. We found no significant interaction between life events and admissions, but the effect of life events on admissions decreases after the first admission which is in line with the kindling hypothesis.

Association between autoimmune thyroiditis and depressive disorder in psychiatric outpatients

Thyroid diseases are often associated with psychiatric disorders. The prevalence of autoimmune thyroiditis in the general population is estimated to be at about 5-14 %. A clinical study was conducted to evaluate the association between autoimmune thyroiditis and depression in psychiatric outpatients. Fifty-two patients with depression and nineteen patients with schizophrenia (serving as control group), attending a psychiatric outpatient unit, were included. In addition to the measurement of thyroid-stimulating hormone (TSH), free triiodothyronine, free thyroxine, antithyroid peroxidase (anti-TPO) antibodies, and anti-thyroglobulin antibodies, ultrasound examination of the thyroid gland was performed. The proportion of pathologically increased anti-TPO levels in patients with depression was high. Furthermore, the distribution of pathologically increased anti-TPO levels was significantly (χ (2) = 5.5; p = 0.019) different between patients with depression (32.7 %) and patients with schizophrenia (5.3 %). In a gender- and age-adjusted logistic regression, the odds ratio of uni- or bipolar patients with depression for an autoimmune thyroiditis was ten times higher (95 % CI = 1.2-85.3) when compared with schizophrenia patients. TSH basal level did not differ between patients with depression and patients with schizophrenia. Our study demonstrates a strong association between anti-TPO levels, which are considered to be of diagnostic value for autoimmune thyroiditis (in combination with a hypoechoic thyroid in ultrasonography) with uni- or bipolar depression. It should be noted that the routinely measured TSH level is not sufficient in itself to diagnose this relevant autoimmune comorbidity.

Lack of confirmation of thyroid endophenotype in Bipolar Disorder Type I and their first-degree relatives

BACKGROUND

Among the biological factors associated with the development and outcomes in Bipolar Disorder Type I (BD-I), previous studies have highlighted the involvement of both thyroid function and/or auto-immunity, proposing a thyroid endophenotype. The objective of this study was to determine the presence of thyroid alterations in BD-I and their first-degree relatives (FDR).

METHODOLOGY

Unselected, cross-sectional case-control study with parallel analysis of individuals affected by BD-I (239), their FD-R (131), and 108 healthy controls. Thyroidal functional abnormalities (TSH and free T4) and thyroidal antibodies (thyroglobulin and thyroperoxidase antibodies) were studied. Assessments were carried out in parallel. The sample was described using arithmetic means, standard deviations, percentages and ranges. Chi-square, Student-t tests, ANOVA and Pearson correlation coefficients were used when indicated.

RESULTS

BD-I on actual and/or ever treated with lithium showed significant thyroidal functional abnormalities as compared to their FD-R and healthy controls. This BD-I subgroup showed a significant greater proportion of subjects suffering from subclinical hypothyroidism (22%). The role of gender/lithium interactions was relevant. The groups did not show differences in terms of positivization of thyroidal antibodies.

LIMITATIONS

The crosssectional design and the lack of determination of dietary iodine deficiencies and/or thyroidal ecographical controls may be a drawback.

CONCLUSIONS

The present study supports previous findings on the effect of lithium treatment on thyroidal functional, but did not support previous findings related to a familial association or endophenotype. In addition, the present study did not support a familial aggregation of thyroidal antibodies positivization in pedegrees of BD-I.

The Role of Infections and Autoimmune Diseases for Schizophrenia and Depression: Findings from Large-Scale Epidemiological Studies

An immunologic component to schizophrenia and depression has been increasingly recognized, which has led to extensive research into the associations with infections and autoimmune diseases. Large-scale nationwide epidemiological studies have displayed an increased prevalence of both autoimmune diseases and infections among persons with schizophrenia and depression. Autoimmune diseases, and especially the number of infections requiring hospitalization, increase the risk of schizophrenia and depression in a dose–response relationship. Infections are a common exposure and a broad spectrum of infections are associated with schizophrenia and depression. Particularly the autoimmune diseases with a potential presence of brain-reactive antibodies were associated with psychiatric disorders. However, the associations seem to be bidirectional, since the risk of autoimmune diseases and infections is also increased after diagnosis with schizophrenia and depression. The risk of autoimmune diseases was particularly increased in individuals with prior hospital contacts for infections.

It has been suggested that inflammation and autoimmunity could be involved in the etiology and pathogenesis of some patients with symptoms of schizophrenia and depression. The psychiatric symptoms can be directly triggered by immune components, such as brain-reactive antibodies and cytokines, or infections reaching the central nervous system (CNS), or be secondary to systemic inflammation indirectly affecting the brain. However, the associations could also be caused by shared genetic factors, other environmental factors, or common etiological components. Nonetheless, autoimmune diseases and infections should be considered by clinicians in the treatment of individuals with psychiatric symptoms, since treatment would probably improve the psychiatric symptoms, quality of life, and the survival of the individuals.

Cognitive and affective dysfunctions in autoimmune thyroiditis

Hashimoto's thyroiditis (HT) is the most frequent cause of hypothyroidism in areas with sufficient iodine intake. While the impact of thyroid function on mood and cognition is well known, only in the recent years, an increasing number of studies report on the association of HT with cognitive and affective disturbances also in the euthyroid state. Recent imaging studies have shown that these impairments are accompanied by altered brain perfusion, in particular, in the frontal lobe and a reduced gray matter density in the left inferior gyrus frontalis. Brain function abnormalities in euthyroid patients with HT may be subtle and only detected by specific testing or even severe as it is the case in the rare neuropsychiatric disorder Hashimoto's encephalopathy (HE). The good response to glucocorticoids in patients with HE indicates an autoimmune origin. In line with this, the cognitive deficits and the high psycho-social burden in euthyroid HT patients without apparent signs of encephalopathy appear to be associated with anti-thyroid peroxidase auto-antibody (TPO Abs) levels. Though in vitro studies showing binding of TPO Abs to human cerebellar astrocytes point to a potential direct role of TPO Abs in the pathogenesis of brain abnormalities in HT patients, TPO Abs may function only as a marker of an autoimmune disorder of the central nervous system. In line with this, anti-central nervous system auto-antibodies (CNS Abs) which are markedly increased in patients with HT disturb myelinogenesis in vitro and, therefore, may impair myelin sheath integrity. In addition, in HT patients, production of monocyte- and T-lymphocyte-derived cytokines is also markedly increased which may negatively affect multiple neurotransmitters and, consequently, diverse brain neurocircuits.

Thyroglobulin antibodies and risk of readmission at one year in subjects with bipolar disorder

Thyroid autoimmunity has been proposed as an endophenotype for Bipolar Disorder (BD), although its relationship with clinical outcomes remains unclear. We aimed to determine whether thyroid autoimmune status (thyroperoxidase antibodies [TPO-Abs] and thyroglobulin antibodies [TG-Abs]) in BD is associated with a greater risk for readmission at one year. We studied 77 inpatients with BD admitted for an index manic or mixed episode. Serum thyroid antibodies (TPO-Abs and TG-Abs) were determined at admission. We compared the readmission risk at 1 year, based on patients׳ thyroid autoimmunity profile using survival analyses. Cox regression was used to control covariates. TG-Abs+ but not TPO-Abs+ was associated with a lower risk of relapse. The Kaplan-Meier mean estimated survival times were 341.6 days (CI95% 316.4-366.8) for the TG-Abs+ group and 261.9 days (CI95%: 221.8 to 302.0) for the TG-Abs- group. Cox proportional hazards regression indicated that subjects with TG-Abs+ were 3.7 (1/OR=1/0.27) times less likely to get admitted during the follow-up period than those with TG-Abs-. Our study suggests that an autoimmune biomarker in patients with BD (i.e., the presence of TG-Abs) is associated with a lower risk of psychiatric readmission after an index hospitalization for a manic or mixed episode.

Discordant twins as a tool to unravel the aetiology of bipolar disorder

This editorial focuses on discordant twins as a valuable epidemiological design for psychiatric aetiological research. First, we summarise the advantages and strengths of this design over the classical matched case-control study. Then, we draw attention to the use of this method in bipolar disorder, revising previous discordant-twin studies. A future greater use of discordant twins is desirable to gain further relevant insights in the aetiology of bipolar disorder.

Seroreactive marker for inflammatory bowel disease and associations with antibodies to dietary proteins in bipolar disorder

OBJECTIVES

Immune sensitivity to wheat glutens and bovine milk caseins may affect a subset of individuals with bipolar disorder. Digested byproducts of these foods are exorphins that have the potential to impact brain physiology through action at opioid receptors. Inflammation in the gastrointestinal (GI) tract might accelerate exposure of food antigens to systemic circulation and help explain elevated gluten and casein antibody levels in individuals with bipolar disorder.

METHODS

We measured a marker of GI inflammation, anti-Saccharomyces cerevisiae antibodies (ASCA), in non-psychiatric controls (n = 207), in patients with bipolar disorder without a recent onset of psychosis (n = 226), and in patients with bipolar disorder with a recent onset of psychosis (n = 38). We compared ASCA levels to antibodies against gluten, casein, Epstein-Barr virus (EBV), herpes simplex virus 1 (HSV-1), influenza A, influenza B, measles, and Toxoplasma gondii.

RESULTS

Elevated ASCA conferred a 3.5-4.4-fold increased odds ratio of disease association (age-, race-, and gender-corrected multinomial logistic regressions, p ≤ 0.00001) that was independent of type of medication received. ASCA correlated with food antibodies in both bipolar disorder groups (R(2)  = 0.29-0.59, p ≤ 0.0005), and with measles and T. gondii immunoglobulin G (IgG) in the recent onset psychosis bipolar disorder group (R(2)  = 0.31-0.36, p ≤ 0.004-0.01).

CONCLUSIONS

Elevated seropositivity of a GI-related marker and its association with antibodies to food-derived proteins and self-reported GI symptoms suggest a GI comorbidity in at least a subgroup of individuals with bipolar disorder. Marker seroreactivity may also represent part of an overall heightened activated immune state inherent to this mood disorder.

Hypothyroidism and bipolar affective disorder: is there a connection?

CONTEXT

Hypothalamic-pituitary-thyroid axis dysfunction in the pathophysiology of bipolar disorder has received less attention as compared with that in depressive disorder.

AIMS

To study the prevalence of hypothyroidism in patients diagnosed with bipolar disorder and compare it with a population norm.

SETTINGS AND DESIGN

The setting was the psychiatry inpatient unit of a tertiary care hospital. The design was retrospective and observational.

SUBJECTS AND METHODS

A retrospective observational study was performed, referring to the case records of 84 cases of bipolar disorder admitted to the Department of Psychiatry in a Tertiary Referral Center during the year 2010-2012. The prevalence of hypothyroidism both subclinical as demonstrated by elevated thyroid stimulating hormone (TSH) levels (cut-off value 4.2 μU/ml) and overt hypothyroidism (fasting T4 <0.92 ng/dl and TSH >4.2 μU/ml) was calculated. This was compared with the population prevalence of hypothyroidism as determined by an epidemiological study carried out in the year 2009, in the same region. The correlation between hypothyroidism, gender, lithium prophylaxis and family history of mood disorder was computed.

STATISTICAL ANALYSIS

Percentage prevalence of hypothyroidism in the sample was calculated and compared to a population norm. The correlation between hypothyroidism, gender, lithium prophylaxis and family history of mood disorder was computed using the odds ratio (OR).

RESULTS

The total prevalence of hypothyroidism in both males and females in the bipolar group was comparable with that in the general population. There is a significant association between family history of mood disorder in first degree relatives and patients having hypothyroidism (OR 5.504 and P = 0.012). There were no statistically significant associations between thyroid abnormalities and age, duration of illness and lithium prophylaxis.

CONCLUSIONS

There is no significant association between hypothyroidism and bipolar disorder. Family history of mood disorder and hypothyroidism show significant association. (OR -5.504 AND P = 0.012).

Antibodies in autoimmune thyroiditis affect glucose metabolism of anterior cingulate

BACKGROUND

Hypothyroidism induced by an autoimmune process is associated with neuropsychiatric symptoms and metabolic abnormalities in the brain. The aim of this study was to examine the relationship between autoimmune thyroiditis and regional brain function in hypothyroid patients.

METHODS

Cerebral glucose metabolism, as an index of brain function, was assessed in regional whole-brain analyses using positron emission tomography (PET) and [18F]fluorodeoxyglucose in thirteen hypothyroid patients with autoimmune thyroiditis suffering from neuropsychiatric symptoms. The primary biological measures were radioactivity in pre-selected brain regions, relative to whole-brain radioactivity, as a surrogate index of glucose metabolism, and serum levels of thyroglobulin (TG) and thyroid peroxidase (TPO) antibodies as endocrine markers of autoimmune thyroiditis.

RESULTS

Serum levels of anti-TG antibodies in hypothyroid patients were significantly correlated with glucose metabolism in the perigenual anterior cingulate cortex, a brain region previously shown to regulate affect and emotional homeostasis.

CONCLUSION

Thyroid autoimmune processes may play an important role in the still poorly defined pathogenic correlates of disturbed function in brain regions critically involved in emotional processing in hypothyroid conditions.

Relationship between clinical features and inflammation-related monocyte gene expression in bipolar disorder - towards a better understanding of psychoimmunological interactions

OBJECTIVES

Existing and previously published datasets were examined for associations between illness and treatment characteristics and monocyte pro-inflammatory gene expression in patients with bipolar disorder (BD). We hypothesized a priori that increased monocyte pro-inflammatory gene expression would be found more frequently in patients with a lifetime history of psychotic symptoms.

METHODS

Monocyte quantitative polymerase chain reaction and symptom data from 64 patients with BD were collected from three Dutch studies. Regression analyses were performed to analyze the various associations between pro-inflammatory gene expression and clinical features, from which feature-expression heat maps were drawn.

RESULTS

No associations were found between pro-inflammatory gene expression and lifetime psychotic symptoms, whereas a positive association was identified between subcluster 2 genes and manic symptoms. For several subcluster 1a genes, a negative association was found with age at onset. For most subcluster 2 genes, a positive association was found with the duration of illness. Current use of antidepressants and of anti-epileptic agents was associated with subcluster 2 gene expression, and current use of lithium and antipsychotic agents with subcluster 1a gene expression.

CONCLUSIONS

Our hypothesis that lifetime psychotic features would be associated with pro-inflammatory monocyte gene expression was not confirmed. In an explorative analysis we found: (i) a possible relationship between pro-inflammatory gene expression and manic symptomatology; (ii) a differential immune activation related to age at onset and duration of illness; and (iii) support for the concept of an immune suppressive action of some of the mood-regulating medications.

Autoimmunity, inflammation, and psychosis: a search for peripheral markers

Accumulating evidence supports the view that deregulation of the immune system represents an important vulnerability factor for psychosis. In a subgroup of psychotic patients, the high comorbidity with autoimmune and chronic inflammatory conditions suggests a common underlying immune abnormality leading to both conditions. The reviewed data of affective and nonaffective psychosis show that if immune biomarkers exist for such immune abnormality, they may be found in raised macrophage/monocyte inflammatory activation patterns (monocytosis, high-inflammatory gene expression, raised glucocorticoid receptor β/glucocorticoid receptor α ratio, and high levels of proinflammatory and anti-inflammatory monocyte/macrophage derived cytokines in serum/plasma), reduced T cell numbers/proliferation, and TH1 skewing. This activation of the inflammatory response system may be suggestive for microglia activation, as these cells are the macrophages of the brain. Indeed, there is some evidence of activation of the microglia as detected in positron emission tomography scans and in histopathology, and it is assumed that this activation disturbs the development and function of neuronal circuits in the brain. Further, animal models of psychotic conditions (maternal stress and inflammation paradigms) suggest that such monocyte/microglia activation could be seen as the result of a combination of genetic predisposition and an immune-mediated two-hit model. Infection but also environmental stressors during gestation/early life activate microglia, perturbing neuronal development, thereby setting the stage for vulnerability for later psychotic disorders. A second hit, such as endocrine changes, stress, or infection, could further activate microglia, leading to functional abnormalities of the neuronal circuitry in the brain and psychosis.

Female vulnerability for thyroid function abnormality in bipolar disorder: role of lithium treatment

BACKGROUND

Previous studies have provided evidence of subtle thyroid hormone metabolism abnormalities in patients with mood disorders. Although these studies are informative, the precise role of the hypothalamic-pituitary-thyroid axis in bipolar disorder, especially in women, remains unclear. We sought to further corroborate thyroid function in patients with bipolar disorder in comparison to patients with other psychiatric, as well as non-psychiatric, diagnoses.

METHODS

In this retrospective, cross-sectional, naturalistic study, serum thyroid-stimulating hormone (TSH) levels in a total sample of 3,204 patients were compared. The study sample included patients with bipolar disorder (n = 469), unipolar depression (n = 615), and other psychiatric diagnoses (n = 999), patients from endocrinology clinics (n = 645), and patients from dermatology clinics (n = 476). Analyses were completed using two different normal ranges for TDH: a high normal range (0.4-5.0 μIU/mL) and a low normal range (0.3-3.0 μIU/mL).

RESULTS

Patients with bipolar disorder showed significantly higher serum TSH levels compared to all other groups. In women, the rate of above normal range TSH was highest in patients with bipolar disorder for both high (5.0 μIU/mL; 12.1%) and low (3.0 μIU/mL; 30.4%) upper normal limits. In patients with bipolar disorder, serum TSH levels did not differ significantly between different mood states. In the lithium-treated patients (n = 240), a significantly lower percentage of women (55.9%) compared to men (71.2%) fell within the 0.3-3.0 μIU/mL normal TSH window (p = 0.016). For the high normal range (0.4-5.0 μIU/mL), serum lithium levels above 0.8 mmol/L were associated with a significantly lower proportion of female patients (59.2%) falling within the normal range than male patients (88.9%). Non-lithium treatment was not associated with a gender difference.

CONCLUSIONS

Our findings show a higher rate of TSH abnormality in patients with bipolar disorder, particularly those taking lithium, compared to those with other psychiatric and medical conditions. Lithium-associated thyroid dysregulation occurs more frequently in female patients. Using the low normal range TSH values at follow-up can increase sensitivity in recognizing hyperthyroidism in lithium-treated female patients, and help in preventing the development of subclinical hypothyroidism and an adverse course of illness.

Role of immunological factors in the pathophysiology and diagnosis of bipolar disorder: comparison with schizophrenia

Several lines of evidence point to the key role of neurobiological mechanisms and shared genetic background in schizophrenia and bipolar disorder. For both disorders, neurodevelopmental and neurodegenerative processes have been postulated to be relevant for the pathogenesis as well as dysregulation of immuno-inflammatory pathways. Inflammation is a complex biological response to harmful stimuli and it is mediated by cytokines cascades, cellular immune responses, oxidative factors and hormone regulation. Cytokines, in particular, are supposed to play a critical role in infectious and inflammatory processes, mediating the cross-talk between the brain and the immune system; they also possibly contribute to the development of the central nervous system. From this perspective, even though mixed results have been reported, it seems that both schizophrenia and bipolar disorder are associated with an imbalance in inflammatory cytokines; in fact, some of these could represent biological markers of illness and could be possible targets for pharmacological treatments. In light of these considerations, the purpose of the present paper was to provide a comprehensive and critical review of the existing literature about immunological abnormalities in bipolar disorder with particular attention to the similarities and differences with schizophrenia.

Immune dysregulation and autoimmunity in bipolar disorder: Synthesis of the evidence and its clinical application

OBJECTIVE

Increasing evidence suggests that inflammation and immune dysregulation play an important role in the pathogenesis of bipolar disorder. Because the brain can be affected by various autoimmune processes, it is possible that some psychiatric disorders may have an autoimmune basis.

METHOD

This article reviews the literature on peripheral and central immune dysregulation and autoimmunity in bipolar disorder. The mechanisms of the innate and adaptive immune systems in the pathophysiology of bipolar disorder are explored. The clinical features and pathogenesis of neuropsychiatric systemic lupus erythematosus, anti-NMDA encephalitis, and Hashimoto's encephalopathy are summarized.

RESULTS

Neuroinflammation and peripheral immune dysregulation may play a role in the pathophysiology of bipolar disorder. This involves a complex interaction between immune cells of the central nervous system and periphery resulting in cellular damage through mechanisms involving excitotoxicity, oxidative stress, and mitochondrial dysfunction. Neuropsychiatric systemic lupus erythematosus, anti-NMDA encephalitis, and Hashimoto's encephalopathy are important differentials for a psychiatrist to consider when suspecting autoimmune encephalopathy.

CONCLUSIONS

The link between immune dysregulation, autoimmunity, and bipolar disorder may be closer than previously thought. Psychiatrists should be vigilant for autoimmunity in presentations of bipolar disorder due to its high morbidity and therapeutic implications. Advances in neuroimaging and biomarker identification related to immune dysregulation and neuroinflammation will contribute to our knowledge of the pathophysiology of bipolar disorder.

Differential neuroendocrine and immune responses to acute psychosocial stress in women with type 1 bipolar disorder

Bipolar disorder (BD) has been associated with immune imbalance, including lymphocyte activation and increased pro-inflammatory cytokines. Immune activation is part of stress response, and psychosocial stress has been implicated in the pathogenesis of psychiatric disorders. Here, we investigated the neuroendocrine and immune responses to acute psychosocial stress challenge in BD. Thirteen euthymic participants with type 1 BD and 15 healthy controls underwent the Trier Social Stress Test protocol (TSST). Blood samples were collected before and after TSST. Lymphocytes were isolated and stimulated in vitro to assess lymphocyte activation profile, lymphocyte sensitivity to dexamethasone, mitogen-activated protein kinase (MAPK) and nuclear factor kappa B (NF-κB) signaling by flow cytometry. Heart rate and salivary cortisol levels were monitored across the task. BD participants exhibited blunted stress responses as shown by reduced heart rate and salivary cortisol levels in comparison to healthy controls. BD was also associated with reduction in the percentage of regulatory T cells, but with expansion of activated T cells. When compared to controls, patients showed increased lymphocyte MAPK p-ERK and p-NF-κB signaling after the stress challenge, but exhibited a relative lymphocyte resistance to dexamethasone. In conclusion, stress-related neuroendocrine responses are blunted, associated with increased immune activation and lower sensitivity to glucocorticoids in BD. An inability in reducing NF-κB and MAPK signaling following TSST could be underlying the immune imbalance observed in BD.

Immunity, inflammation, and bipolar disorder: diagnostic and therapeutic implications

Bipolar disorder is now known to be associated not only with highly prevalent co-occurring psychiatric and substance use disorders but also with medical comorbidities, such as cardiovascular diseases, diabetes mellitus, obesity and thyroid dysfunction. Inflammatory disturbances repeatedly observed in bipolar disorder, can explain some of the comorbidity between bipolar disorder and medical disorder. This revised perspective of bipolar disorders should promote the development of therapeutic tools. Immuno-inflammatory dysfunction may well represent a significant component of the underlying pathophysiology of the disorder. We therefore propose to review the immuno-inflammatory hypothesis in bipolar disorder considering the co-occurence with autoimmune diseases, immunological and inflammatory markers, as well as immuno-genetic markers which could lead to personalized treatments.

Inflammation and neurological disease-related genes are differentially expressed in depressed patients with mood disorders and correlate with morphometric and functional imaging abnormalities

Depressed patients show evidence of both proinflammatory changes and neurophysiological abnormalities such as increased amygdala reactivity and volumetric decreases of the hippocampus and ventromedial prefrontal cortex (vmPFC). However, very little is known about the relationship between inflammation and neuroimaging abnormalities in mood disorders. A whole genome expression analysis of peripheral blood mononuclear cells yielded 12 protein-coding genes (ADM, APBB3, CD160, CFD, CITED2, CTSZ, IER5, NFKBIZ, NR4A2, NUCKS1, SERTAD1, TNF) that were differentially expressed between 29 unmedicated depressed patients with a mood disorder (8 bipolar disorder, 21 major depressive disorder) and 24 healthy controls (HCs). Several of these genes have been implicated in neurological disorders and/or apoptosis. Ingenuity Pathway Analysis yielded two genes networks, one centered around TNF with NFKβ, TGFβ, and ERK as connecting hubs, and the second network indicating cell cycle and/or kinase signaling anomalies. fMRI scanning was conducted using a backward-masking task in which subjects were presented with emotionally-valenced faces. Compared with HCs, the depressed subjects displayed a greater hemodynamic response in the right amygdala, left hippocampus, and the ventromedial prefrontal cortex to masked sad versus happy faces. The mRNA levels of several genes were significantly correlated with the hemodynamic response of the amygdala, vmPFC and hippocampus to masked sad versus happy faces. Differentially-expressed transcripts were significantly correlated with thickness of the left subgenual ACC, and volume of the hippocampus and caudate. Our results raise the possibility that molecular-level immune dysfunction can be mapped onto macro-level neuroimaging abnormalities, potentially elucidating a mechanism by which inflammation leads to depression.