Biomarkers and staging of bipolar disorder: a systematic review

Shortening of telomere length may be associated with inflammatory cytokine levels in patients with bipolar disorder

BACKGROUND

Bipolar disorder (BD) is hypothesized to be associated with accelerated biological aging. Telomere length (TL) is a biomarker of aging, and although TL decreases with each cell division, the rate of telomere shortening may be affected by inflammation. We aimed to investigate whether TL is decreased in BD patients and to determine the association between TL and inflammatory markers in such patients.

METHODS

137 BD patients and 118 healthy controls (HCs) were recruited. Leukocyte TL and plasma levels of cytokines [tumor necrosis factor (TNF)-α, interleukin (IL)-8, IL-6, IL-10, transforming growth factor (TGF)-β1], C-reactive protein (CRP), and brain-derived neurotrophic factor (BDNF) were assessed.

RESULTS

TL did not differ significantly between the BD patients and HCs after adjustment for potential confounding factors (P = 0.79). TL was significantly negatively associated with age (β = -0.007, P < 0.001). In addition, log TNF-α levels were significantly negatively associated with TL (P = 0.009), in both the BD patients (P = 0.02) and HCs (P = 0.05).

CONCLUSION

We found a significant association between TNF-α levels and TL shortening in both BD patients and HCs. However, BD patients did not display increased TL shortening relative to HCs. Studies that involve larger sample sizes and control for the heterogeneity of BD participants will be needed.

Neutrophil/high-density lipoprotein cholesterol (HDL), monocyte/HDL and platelet/HDL ratios are increased in acute mania as markers of inflammation, even after controlling for confounding factors

OBJECTIVE

Recent studies show that inflammation is related to the pathogenesis of acute mania of bipolar disorder. Neutrophil/high-density lipoprotein (HDL) ratio (NHR), lymphocyte/HDL ratio (LHR), monocyte/HDL ratio (MHR) and platelet/HDL ratio (PHR) have recently been investigated as novel markers of inflammation. In addition, the atherogenic index of plasma (AIP) and atherogenic coefficient (AC) are the leading atherogenic indices. The study aimed to investigate these inflammation and atherogenic index markers in acute mania of bipolar disorder. Another aim was to determine whether there is a relationship between these markers and disease severity and psychotic symptoms.

METHODS

A total of 109 BD-M and 101 (HC) were enrolled in the study. The differences in NHR, LHR, MHR, PHR, AIP and AC and their association with illness severity and psychotic symptoms were analyzed after adjusting for age, sex, total cholesterol level, body-mass index and smoking status. Then, a receiver operating characteristic (ROC) curve and linear discriminant analysis (LDA) were used to analyze these parameters' diagnostic potential. Moreover, the Young Mania Rating Scale (YMRS) and Clinical Global Impression Scale for use in bipolar illness-Severity subscale (CGI-BP-S) were used to assess the severity of clinical symptoms.

RESULTS

We found higher levels of NHR, MHR, PHR and AIP, but not LHR and AC, after adjusting confounding factors in patients with BD-M compared to HCs. In logistic regression analysis, higher levels of MHR and NHR were associated with BD-M. MHR, NHR and PHR were predictors for differentiating the BD-M group from the HC group. However, the severity of the illness or the psychotic feature of the manic episode did not significantly affect the parameters. In the ROC curve analysis of BD-M, the indicators with an area under the curve (AUC) higher than 0.6 were the MHR, NHR, PHR and LHR.

CONCLUSIONS

These results provide information about the role of inflammation in the pathophysiology of BD-M. Even after controlling for confounding factors, MHR, NHR, PHR and AIP are potential biomarkers for BD-M. Moreover, the increase in AIP may explain the co-morbidity between BD and cardiovascular diseases. However, the severity of the illness or the psychotic feature of the manic episode did not significantly affect the levels of inflammation ratios used in our study. Due to the low cost and widespread use of lipid metabolism and related inflammation rates, it may be beneficial to know the MHR, NHR, PHR and AIP levels in BD-M patients.

Biomarkers in psychiatric disorders

Psychiatric disorders represent a significant socioeconomic and healthcare burden worldwide. Of these, schizophrenia, bipolar disorder, major depressive disorder and anxiety are among the most prevalent. Unfortunately, diagnosis remains problematic and largely complicated by the lack of disease specific biomarkers. Accordingly, much research has focused on elucidating these conditions to more fully understand underlying pathophysiology and potentially identify biomarkers, especially those of early stage disease. In this chapter, we review current status of this endeavor as well as the potential development of novel biomarkers for clinical applications and future research study.

Progressive grey matter alterations in bipolar disorder across the life span - A systematic review

OBJECTIVES

To elucidate the relationship between the course of bipolar disorder (BD) and structural brain changes across the life span, we conducted a systematic review of longitudinal imaging studies in adolescent and adult BD patients.

METHODS

Eleven studies with 329 BD patients and 277 controls met our PICOS criteria (participants, intervention, comparison, outcome and study design): BD diagnosis based on DSM criteria, natural course of disease, comparison of grey matter changes in BD individuals over ≥1-year interval between scans.

RESULTS

The selected studies yielded heterogeneous findings, partly due to varying patient characteristics, data acquisition and statistical models. Mood episodes were associated with greater grey matter loss in frontal brain regions over time. Brain volume decreased or remained stable in adolescent patients, whereas it increased in healthy adolescents. Adult BD patients showed increased cortical thinning and brain structural decline. In particular, disease onset in adolescence was associated with amygdala volume reduction, which was not reported in adult BD.

CONCLUSIONS

The evidence collected suggests that the progression of BD impairs adolescent brain development and accelerates structural brain decline across the lifespan. Age-specific changes in amygdala volume in adolescent BD suggest that reduced amygdala volume is a correlate of early onset BD. Clarifying the role of BD in brain development across the lifespan promises a deeper understanding of the progression of BD patients through different developmental episodes.

Elevation of C-reactive protein in adolescent bipolar disorder vs. anxiety disorders

Bipolar disorder (BD) largely begins in adolescence, but diagnosis lags for years, causing significant morbidity and mortality, and demonstrating the need for better diagnostic tools. Suggesting an association between BD and immune activity, elevated levels of peripheral inflammatory markers, including C-reactive protein (CRP), have been found in adults with BD. As similar data are extremely limited in adolescents, this study examined CRP levels in adolescents with BD (n = 37) compared to those with anxiety disorders (ADs, n = 157) and healthy controls with no psychiatric diagnoses (HCs, n = 2760). CRP blood levels for patients aged 12-17 years were retrieved from a nationwide repository of deidentified clinical data. After excluding patients with inflammatory conditions, differences in CRP were examined using multivariate and weighted regressions (covariates: demographics and BMI). Mean CRP levels were significantly elevated in adolescents with BD relative to those with ADs and HCs. Mean CRP levels were lower in the ADs cohort versus HCs. Although CRP levels were significantly higher in males and younger patients, the significant between-cohort differences in CRP remained after controlling for multiple confounders. To our knowledge, our study is the first to compare CRP levels between adolescent BD, ADs, and HCs, comprising a novel and essential contribution. Our results suggest the presence of a unique immune process in adolescents with BD and indicate that CRP may represent a biomarker with a crucial role in the diagnostic assessment of adolescent BD.

Elevated C-reactive protein among symptomatic youth with bipolar disorder

RATIONALE AND OBJECTIVES

Increased levels of high-sensitivity C-reactive protein (CRP) are associated with mood symptoms in adults with bipolar disorder (BD). The few studies on this topic in youth with BD have not included controls. We, therefore, examined CRP levels in relation to symptomatic status in youth with and without BD.

METHODS

Participants included 154 youth (mean age 17 years; 48 asymptomatic BD, 39 symptomatic BD, 67 healthy controls (HC)). Rank analysis of covariance test examined group differences in CRP, controlling for age and sex. Correlation between CRP and mood symptom severity was examined using Spearman's correlation within the BD group.

RESULTS

There were significant group differences in CRP levels (F_(2,151) = 5.06, p = 0.007, ηp2=0.06); post hoc analyses showed higher CRP levels in the symptomatic BD group compared with HC (p = 0.01). In sensitivity analyses, this finding was no longer significant after controlling for body mass index (BMI). CRP was not significantly associated with symptomatic severity.

CONCLUSIONS

CRP levels are elevated among symptomatic youth with BD, partly related to BMI. As elevated BMI is associated with mood symptom burden, prospective studies are warranted to parse the associations among mood symptoms, BMI, and inflammation. Given the proportion of time that youth with BD are symptomatic, present findings raise concern about the long-term impact of elevated CRP on blood vessels, brain, and related clinical outcomes.

Therapeutic Interventions to Mitigate Mitochondrial Dysfunction and Oxidative Stress–Induced Damage in Patients with Bipolar Disorder

Bipolar disorder (BD) is characterized by mood changes, including recurrent manic, hypomanic, and depressive episodes, which may involve mixed symptoms. Despite the progress in neurobiological research, the pathophysiology of BD has not been extensively described to date. Progress in the understanding of the neurobiology driving BD could help facilitate the discovery of therapeutic targets and biomarkers for its early detection. Oxidative stress (OS), which damages biomolecules and causes mitochondrial and dopamine system dysfunctions, is a persistent finding in patients with BD. Inflammation and immune dysfunction might also play a role in BD pathophysiology. Specific nutrient supplements (nutraceuticals) may target neurobiological pathways suggested to be perturbed in BD, such as inflammation, mitochondrial dysfunction, and OS. Consequently, nutraceuticals may be used in the adjunctive treatment of BD. This paper summarizes the possible roles of OS, mitochondrial dysfunction, and immune system dysregulation in the onset of BD. It then discusses OS-mitigating strategies that may serve as therapeutic interventions for BD. It also analyzes the relationship between diet and BD as well as the use of nutritional interventions in the treatment of BD. In addition, it addresses the use of lithium therapy; novel antipsychotic agents, including clozapine, olanzapine, risperidone, cariprazine, and quetiapine; and anti-inflammatory agents to treat BD. Furthermore, it reviews the efficacy of the most used therapies for BD, such as cognitive–behavioral therapy, bright light therapy, imagery-focused cognitive therapy, and electroconvulsive therapy. A better understanding of the roles of OS, mitochondrial dysfunction, and inflammation in the pathogenesis of bipolar disorder, along with a stronger elucidation of the therapeutic functions of antioxidants, antipsychotics, anti-inflammatory agents, lithium therapy, and light therapies, may lead to improved strategies for the treatment and prevention of bipolar disorder.

Gray matter volume covariance networks are associated with altered emotional processing in bipolar disorder: a source-based morphometry study

Widespread regional gray matter volume (GMV) alterations have been reported in bipolar disorder (BD). Structural networks, which are thought to better reflect the complex multivariate organization of the brain, and their clinical and psychological function have not been investigated yet in BD. 24 patients with BD type-I (BD-I), and 30 with BD type-II (BD-II), and 45 controls underwent MRI scan. Voxel-based morphometry and source-based morphometry (SBM) were performed to extract structural covariation patterns of GMV. SBM components associated with morphometric differences were compared among diagnoses. Executive function and emotional processing correlated with morphometric characteristics. Compared to controls, BD-I showed reduced GMV in the temporo-insular-parieto-occipital cortex and in the culmen. An SBM component spanning the prefrontal-temporal-occipital network exhibited significantly lower GMV in BD-I compared to controls, but not between the other groups. The structural network covariance in BD-I was associated with the number of previous manic episodes and with worse executive performance. Compared to BD-II, BD-I showed a loss of GMV in the temporal-occipital regions, and this was correlated with impaired emotional processing. Altered prefrontal-temporal-occipital network structure could reflect a neural signature associated with visuospatial processing and problem-solving impairments as well as emotional processing and illness severity in BD-I.

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.

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.

Unravelling the genetic basis of schizophrenia and bipolar disorder with GWAS: A systematic review

OBJECTIVES

To systematically review findings of GWAS in schizophrenia (SZ) and in bipolar disorder (BD); and to interpret findings, with a focus on identifying independent replications.

METHOD

PubMed search, selection and review of all independent GWAS in SZ or BD, published since March 2011, i.e. studies using non-overlapping samples within each article, between articles, and with those of the previous review (Li et al., 2012).

RESULTS

From the 22 GWAS included in this review, the genetic associations surviving standard GWAS-significance were for genetic markers in the regions of ACSL3/KCNE4, ADCY2, AMBRA1, ANK3, BRP44, DTL, FBLN1, HHAT, INTS7, LOC392301, LOC645434/NMBR, LOC729457, LRRFIP1, LSM1, MDM1, MHC, MIR2113/POU3F2, NDST3, NKAPL, ODZ4, PGBD1, RENBP, TRANK1, TSPAN18, TWIST2, UGT1A1/HJURP, WHSC1L1/FGFR1 and ZKSCAN4. All genes implicated across both reviews are discussed in terms of their function and implication in neuropsychiatry.

CONCLUSION

Taking all GWAS to date into account, AMBRA1, ANK3, ARNTL, CDH13, EFHD1 (albeit with different alleles), MHC, PLXNA2 and UGT1A1 have been implicated in either disorder in at least two reportedly non-overlapping samples. Additionally, evidence for a SZ/BD common genetic basis is most strongly supported by the implication of ANK3, NDST3, and PLXNA2.

Inflammation associated with volume reduction in the gray matter and hippocampus of older patients with bipolar disorder

BACKGROUND

Bipolar disorder (BD) and aging appear to be associated with inflammatory activation. Inflammatory processes might affect hippocampal function, neurogenesis, and gray matter loss. This study investigated the relationship between BD-specific brain regions and the total gray matter volume, peripheral inflammatory markers, and clinical features in older patients with BD.

METHODS

We recruited euthymic patients with bipolar I disorder aged ≥50 years to undergo whole-brain magnetic resonance imaging. Each brain region was divided by an individual's total intracranial volume to obtain that brain region's volume in percentage relative to the total intracranial volume. We measured the plasma levels of soluble tumor necrosis factor receptor-1 (sTNF-R1), soluble interleukin (IL)-2 receptor (sIL-2R), sIL-6R, IL-1β, and IL-1 receptor antagonist when patients were euthymic. Clinical data were obtained by reviewing available medical records and interviewing patients along with their reliable others.

RESULTS

There were 32 patients with a mean age of 61.2 ± 8.3 years and a mean age at illness onset of 33.4 ± 13.8 years in this study. Stepwise regression showed that the right hippocampal volume was negatively associated with the levels of sIL-2R and sTNF-R1. The left hippocampal volume were negatively associated with the sIL-2R level and body mass index. The total gray matter volume had an inverse relationship with sTNF-R1 and IL-1β levels. The duration of bipolar illness, lithium treatment, and antipsychotic use were not associated with hippocampal and total gray matter volumes.

CONCLUSIONS

It is suggested that persistent inflammation is associated with reduction of hippocampal and gray matter volumes in older patients with BD. This phenomenon is supported by increases in sTNF-R1, sIL-2R, and IL-1β levels. Neuroinflammation due to aging, obesity, and BD pathophysiology may play a role in BD neuroprogression across the life span.

The identification of biomarkers predicting acute and maintenance lithium treatment response in bipolar disorder: A plea for further research attention

The prediction of acute and maintenance lithium treatment response carries major clinical and neurobiological implications, warranting systematic review. A Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) compliant review searched major electronic databases from inception until December 2017 for studies documenting a clinical diagnosis of bipolar disorder (BD) made according to the mainstream diagnostic manuals and confirmed by a structured interview. Eligible studies allowed a quantitative comparison of endpoint vs baseline mean values of a given biomarker, regardless of the mood phase of patients with BD, and the disorder was assessed for severity using validated rating tool(s). Owing to the purposely applied stringent selection criteria, 16 acute and 12 maintenance studies could be included. The anticipated publication bias limited the chances of reportable generalizable findings, hindering a side-by-side comparison of different records across varying biomarkers and subsequent meta-analyses. The PRISMA approach was nonetheless preferred; it aimed at enhancing the homogeneity of the included results and minimizing the chances of "apples and oranges" with respect to the present research theme. The present critical review confirms the need for future research to specifically assess either pretreatment and/or posttreatment putative biomarkers of patients with BD and treated with lithium.

Clinical staging in severe mental disorders; bipolar disorder, depression and schizophrenia

Clinical staging is a diagnostic tool used in other medical specialties, which has resulted from the combination of a categorical and dimensional approach. In the last 2decades, the usefulness of its application in the field of psychiatry has been suggested, mainly as a tool for diagnostic help, and therapeutic and prognostic orientation. In this paper we review the clinical staging models that have been proposed to date for bipolar disorder, depression and schizophrenia. A literature search was performed in PubMed and Medline databases. A total of 15 studies were selected according to inclusion and exclusion criteria. Models were grouped according to the type of disorder for which staging was proposed (bipolar disorder: 4, depression: 5, schizophrenia: 6), and their characteristics were described. As a conclusion, we identify the need to empirically validate these models to demonstrate that staging is a useful tool for clinical practice.

Altered cerebellar functional connectivity in remitted bipolar disorder: A resting-state functional magnetic resonance imaging study

OBJECTIVES

Several recent studies have reported a strong association between the cerebellar structural and functional abnormalities and psychiatric disorders. However, there are no studies to investigate possible changes in cerebellar functional connectivity in bipolar disorder. This study aimed to examine the whole-brain functional connectivity pattern of patients with remitted bipolar disorder II, in particular in the cerebellum.

METHODS

A total of 25 patients with remitted bipolar disorder II and 25 controls underwent resting-state functional magnetic resonance imaging and neuropsychological tests. Voxel-wise whole-brain connectivity was analyzed using a graph theory approach: functional connectivity strength. A seed-based resting-state functional connectivity analysis was further performed to investigate abnormal functional connectivity pattern of those regions with changed functional connectivity strength.

RESULTS

Remitted bipolar disorder II patients had significantly decreased functional connectivity strength in the bilateral posterior lobes of cerebellum (mainly lobules VIIb/VIIIa). The seed-based functional connectivity analyses revealed decreased functional connectivity between the right posterior cerebellum and the default mode network (i.e. right posterior cingulate cortex/precuneus and right superior temporal gyrus), bilateral hippocampus, right putamen, left paracentral lobule and bilateral posterior cerebellum and decreased functional connectivity between the left posterior cerebellum and the right inferior parietal lobule and bilateral posterior cerebellum in patients with remitted bipolar disorder II.

CONCLUSION

Our results suggest that cerebellar dysconnectivity, in particular distributed cerebellar-cerebral functional connectivity, might be associated with the pathogenesis of bipolar disorder.

Regional Cerebral Blood Flow in Mania: Assessment Using 320-Slice Computed Tomography

Objectives: While evidence that episodes of mania in bipolar I are associated with changes in bioenergetic and regional cerebral blood flow (rCBF) and cerebral blood flow velocity (rCBFV), both the regions and the extent of these changes have not yet been defined. Therefore, we determined the pattern of regional cerebral perfusion mania patients and using patients with major depressive disorder (MDD) as positive controls and healthy participants as negative controls. Methods: Twenty participants with mania, together with 22 MDD patients and 24 healthy volunteers, were recruited for this study. On all participants, Transcranial Doppler (TCD) was conducted to measure rCBFV parameters, 320-slice CT was conducted to measure rCBF in the different cerebral artery regions, and hematological parameters were assessed. ANOVA and Pearson's tests were used for the statistical analysis. Results: Our data indicated that rCBF in the medial temporal lobe and hippocampus, especially in the left medial temporal lobe and the right hippocampus, was increased in the mania group compared with the control and MDD groups (p < 0.01). In contrast, rCBF in the medial temporal lobe and hippocampus was decreased in the depression group (p < 0.01) compared with healthy controls. In addition, values of rCBFV in the bilateral internal carotid arteries (ICAs) and middle cerebral arteries (MCA) were increased in mania (p < 0.01) in comparison to the MDD group. Whole blood viscosity and hematocrit as well as red blood cell sedimentation rate remained unchanged in all group (p > 0.05). Conclusions: In mania, rCBF is increased in the medial temporal lobe and hippocampus, with a corresponding increase in rCBFV in the same regions.

A 50-bp Ins/Del polymorphism at the promoter region of the superoxide dismutase-1 and bipolar disorder type 1

Bipolar disorder type 1 (BPD) is a chronic psychiatric illness and is associated with oxidative stress. Superoxide dismutase-1 (SOD1; OMIM: 147450) metabolizes highly reactive and more dangerous superoxide radicals into less reactive molecules. A functional 50-bp insertion/deletion (Ins/Del) polymorphism in the promoter region of the gene has been reported. The primary aim of the current case-control study was to explore whether the SOD1 Ins/Del polymorphism associated with the risk of BPD. A secondary aim was to investigate the association between the study polymorphism and age of onset of BPD. The present case-control study was performed in Shiraz (southern Iran) on 228 BPD and 224 healthy blood donor controls. The genotypes of the SOD1 Ins/Del polymorphism were determined by polymerase chain reaction. There was no significant association between the genotypes of Ins/Del polymorphism and the risk of BPD. Using Cox proportional hazards regression model, after adjustment for family history of BPD, revealed a significant association between the SOD1 Ins/Del polymorphism and age of onset. The age of onset was significantly lower for the Del/Del genotype than the 'Ins/Ins + Ins/Del' genotypes (hazard ratio = 2.33, 95%CI: 1.08-5.02, p = .030). Our present findings revealed that although the SOD1 Ins/Del polymorphism was not associated with the risk of BPD, it was significantly associated with age of onset of BPD.

Progranulin gene variation affects serum progranulin levels differently in Danish bipolar individuals compared with healthy controls

OBJECTIVES

The identification of peripheral biomarkers for bipolar disorder is of great importance and has the potential to improve diagnosis, treatment and prognosis. Recent studies have reported lower plasma progranulin levels in bipolar individuals compared with controls and association with single nucleotide polymorphisms (SNPs) within the progranulin gene (GRN). In the present study, we investigated the effect of GRN and sortilin (SORT1) gene variation on serum progranulin levels in bipolar individuals and controls.

MATERIALS AND METHODS

In a Danish cohort of individuals with bipolar disorder and controls, we analysed the serum progranulin level (nbipolar=80, ncontrols=76) and five SNPs located within GRN and two SNPs near the SORT1 gene encoding sortilin, a progranulin scavenger receptor known to affect circulating progranulin levels (nbipolar=166, ncontrols=186).

RESULTS

We observed no significant difference in the serum progranulin level between cases and controls and none of the analysed SNPs located within GRN or close to SORT1 were associated with bipolar disorder. Crude and adjusted (adjusted for case-control status, sex and age) linear regression analyses showed no effect of any SNPs on the serum progranulin level. However, we observed that the mean serum progranulin level in cases and controls is affected differently depending on the genotypes of two SNPs within GRN (rs2879096 and rs4792938).

LIMITATION

The sample size is relatively small and detailed information on medication and polarity of the disorder is not available. No correction for multiple testing was performed.

CONCLUSION

Our study suggests that the potential of progranulin as a biomarker for bipolar disorder is genotype dependent.

Pharmacogenetics of lithium effects on glomerular function in bipolar disorder patients under chronic lithium treatment: a pilot study

Bipolar disorder (BD) is a psychiatric disease characterized by alternating episodes of mania and depression. Lithium (Li) represents the mainstay treatment for BD, although a significant proportion of patients shows insufficient or no response. Li is also associated with potentially severe side effects, including renal effects. Several studies reported that Li may induce reduction of glomerular filtration rate (GFR) in patients under long-term treatment. The biological systems and the genetic factors involved in susceptibility to Li-induced renal-side effects have been scarcely explored. The aim of our study was to test the contribution of putatively risk genetic variants in Li-induced reduction in estimated GFR (eGFR) in BD patients under long-term Li treatment. Tag SNPs, located in genes previously shown to be associated with kidney dysfunction or Li mechanism of action, were selected and genotyped in a sample of 70 BD patients of Sardinian origin. SNP rs378448, located in Acid Sensing Ion Channel Neurona-1 (ACCN1) gene, showed a significant interaction with duration of Li treatment on eGFR (F₂=3.623, p=0.033). Our preliminary findings suggest that rs378448 could predispose BD subjects to a detrimental effect of chronic Li treatment on kidney functioning.

Preventive effects of blueberry extract on behavioral and biochemical dysfunctions in rats submitted to a model of manic behavior induced by ketamine

The aim of the present study was to evaluate the protective effects of blueberry extract on oxidative stress and inflammatory parameters in a model of mania induced by ketamine administration in rats. Male rats were pretreated with blueberry extract (200mg/kg, once a day for 14days), lithium chloride (45mg/kg, mood stabilizer used as a positive control, twice a day for 14days), or vehicle. Between the 8th and 14th days, rats also received an injection of ketamine (25mg/kg) or vehicle. In the 15th day, thirty minutes after ketamine administration the hyperlocomotion of the animals was assessed in the open - field apparatus. Immediately after the behavioral analysis brain and blood were collected for biochemical determinations. ketamine treatment induced hyperlocomotion and oxidative damage in cerebral cortex, hippocampus and striatum such as an increase in lipid peroxidation and a decrease in the antioxidant enzymes activities (superoxide dismutase, catalase e glutatione peroxidase). Ketamine administration also increased the IL-6 levels in serum in rats. Pretreatment of rats with blueberry extract or lithium prevented the hyperlocomotion, pro - oxidant effects and inflammation induced by ketamine. Our findings suggest that blueberry consumption has a neuroprotective potential against behavioral and biochemical dysfunctions induced in a preclinical model that mimic some aspects of the manic behavior.

Quercetin reduces manic-like behavior and brain oxidative stress induced by paradoxical sleep deprivation in mice

Quercetin is a known antioxidant and protein kinase C (PKC) inhibitor. Previous studies have shown that mania involves oxidative stress and an increase in PKC activity. We hypothesized that quercetin affects manic symptoms. In the present study, manic-like behavior (hyperlocomotion) and oxidative stress were induced by 24h paradoxical sleep deprivation (PSD) in male Swiss mice. Both 10 and 40mg/kg quercetin prevented PSD-induced hyperlocomotion. Quercetin reversed the PSD-induced decrease in glutathione (GSH) levels in the prefrontal cortex (PFC) and striatum. Quercetin also reversed the PSD-induced increase in lipid peroxidation (LPO) in the PFC, hippocampus, and striatum. Pearson's correlation analysis revealed a negative correlation between locomotor activity and GSH in the PFC in sleep-deprived mice and a positive correlation between locomotor activity and LPO in the PFC and striatum in sleep-deprived mice. These results suggest that quercetin exerts an antimanic-like effect at doses that do not impair spontaneous locomotor activity, and the antioxidant action of quercetin might contribute to its antimanic-like effects.

Challenges and developments in research of the early stages of bipolar disorder

Recently, attention in the field of bipolar disorder (BD) has focused on prevention, including early detection and intervention, as these strategies have the potential to delay, lessen the severity, or even prevent full-blown episodes of BD. Although knowledge of the neurobiology of BD has advanced substantially in the last two decades, most research was conducted with chronic patients. The objective of this paper is to comprehensively review the literature regarding the early stages of BD, to explore recent discoveries on the neurobiology of these stages, and to discuss implications for research and clinical care. The following databases were searched: PubMed, PsycINFO, Cochrane Library, and SciELO. Articles published in English from inception to December 2015 were retrieved. Several research approaches were used, including examination of offspring studies, retrospective studies, prospective studies of clinical high-risk populations, and exploration of the progression after the first manic episode. Investigations with neuroimaging, cognition assessments, and biomarkers provide promising (although not definitive) evidence of alterations in the neural substrate during the at-risk stage. Research on BD should be expanded to encompass at-risk states and aligned with recent methodological progress in neuroscience.

The Differential Levels of Inflammatory Cytokines and BDNF among Bipolar Spectrum Disorders

OBJECTIVE

Emerging evidence suggests that inflammation and neurodegeneration underlies bipolar disorder. To investigate biological markers of cytokines and brain-derived neurotrophic factor between bipolar I, bipolar II, and other specified bipolar disorder with short duration hypomania may support the association with inflammatory dysregulation and bipolar disorder and, more specifically, provide evidence for other specified bipolar disorder with short duration hypomania patients were similar to bipolar II disorder patients from a biological marker perspective.

METHODS

We enrolled patients with bipolar I disorder (n=234), bipolar II disorder (n=260), other specified bipolar disorder with short duration hypomania (n=243), and healthy controls (n=140). Their clinical symptoms were rated using the Hamilton Depression Rating Scale and Young Mania Rating Scale. Inflammatory cytokine (tumor necrosis factor-α, C-reactive protein, transforming growth factor-β1, and interleukin-8) and brain-derived neurotrophic factor levels were measured in each group. Multivariate analysis of covariance and linear regression controlled for possible confounders were used to compare cytokine and brain-derived neurotrophic factor levels among the groups.

RESULTS

Multivariate analysis of covariance adjusted for age and sex and a main effect of diagnosis was significant (P<.001). Three of the 5 measured biomarkers (tumor necrosis factor-α, transforming growth factor-β1, and interleukin-8) were significantly (P=.006, .01, and <.001) higher in all bipolar disorder patients than in controls. Moreover, covarying for multiple associated confounders showed that bipolar I disorder patients had significantly higher IL-8 levels than did bipolar II disorder and other specified bipolar disorder with short duration hypomania patients in multivariate analysis of covariance (P=.03) and linear regression (P=.02) analyses. Biomarkers differences between bipolar II disorder and other specified bipolar disorder with short duration hypomania patients were nonsignificant.

CONCLUSION

The immunological disturbance along the bipolar spectrum was most severe in bipolar I disorder patients. Other specified bipolar disorder with short duration hypomania patients and bipolar II disorder patients did not differ in these biological markers.

The role of macrophage polarization on bipolar disorder: Identifying new therapeutic targets

OBJECTIVE

Bipolar disorder is a chronic, severe and disabling disease; however, its pathophysiology remains poorly understood. Recent evidence has suggested that inflammation and immune dysregulation play a significant role in the pathophysiology of bipolar disorder. This review is aimed to highlight the importance of systemic inflammation in modulating the inflammatory response of microglia and hence its potential involvement with bipolar disorder. We also discuss novel therapeutic strategies that emerge from this new research.

METHOD

This article presents a theoretical synthesis of the effects of systemic inflammation on the immune response of the central nervous system in bipolar disorder. The complex relationship between stress, pro-inflammatory cytokines and microglial dysfunction is summarized, emphasizing the role of the kynurenine pathway in this process and, consequently, their effects on neuronal plasticity.

RESULTS

Bipolar patients demonstrate increased serum levels of pro-inflammatory cytokines (interleukin-1β, interleukin-6 and tumor necrosis factor-α) and lower hypothalamic-pituitary-adrenal axis sensitivity. This imbalance in the immune system promotes a change in blood-brain barrier permeability, leading to an inflammatory signal spread in the central nervous system from the periphery, through macrophages activation (M1 polarization). Chronic microglial activation can result in neuronal apoptosis, neurogenesis inhibition, hippocampal volume reduction, lower neurotransmitters synthesis and cytotoxicity, by increasing glutamate production and kynurenine metabolism.

CONCLUSIONS

This review provides an overview of the mechanisms involved in the immune system imbalance and its potential involvement in the pathophysiology of bipolar disorder. Consequently, new strategies that normalize the immune-inflammatory pathways may provide a valuable therapeutic target for the treatment of these disorders.

Comparing clinical responses and the biomarkers of BDNF and cytokines between subthreshold bipolar disorder and bipolar II disorder

Patients with subthreshold hypomania (SBP; subthreshold bipolar disorder) were indistinguishable from those with bipolar disorder (BP)-II on clinical bipolar validators, but their analyses lacked biological and pharmacological treatment data. Because inflammation and neuroprogression underlies BP, we hypothesized that cytokines and brain-derived neurotrophic factor (BDNF) are biomarkers for BP. We enrolled 41 drug-naïve patients with SBP and 48 with BP-II undergoing 12 weeks of pharmacological treatment (valproic acid, fluoxetine, risperidone, lorazepam). The Hamilton Depression Rating Scale (HDRS) and Young Mania Rating Scale (YMRS) were used to evaluate clinical responses at baseline and at weeks 0, 1, 2, 4, 8, and 12. Inflammatory cytokines (tumour necrosis factor [TNF]-α, transforming growth factor [TGF]-β1, interleukin [IL]-6, IL-8 and IL-1β) and BDNF levels were also measured. Mixed models repeated measurement was used to examine the therapeutic effect and changes in BDNF and cytokine levels between the groups. HDRS and YMRS scores significantly (P < 0.001) declined in both groups, the SBP group had significantly lower levels of BDNF (P = 0.005) and TGF-β1 (P = 0.02). Patients with SBP and BP-II respond similarly to treatment, but SBP patients may have different neuroinflammation marker expression.

A comprehensive analysis of NDST3 for schizophrenia and bipolar disorder in Han Chinese

A novel susceptibility locus (rs11098403) for schizophrenia and bipolar disorder (BD) was identified in an Ashkenazi Jewish population by a recent large-scale genome-wide association study. The rs11098403 is located in the vicinity of the gene encoding N-deacetylase/N-sulfotransferase (heparan glucosaminyl) 3, (NDST3). This study aimed to replicate the results in a Han Chinese population and then potentially extend these findings. We performed a two-stage study to investigate the association of NDST3 with the schizophrenia and BD risk in the Han Chinese. In stage 1, a total of 632 patients with schizophrenia, 654 patients with BD and 684 healthy controls were recruited from the Shanghai region. In stage 2, 522 schizophrenia patients and 547 normal subjects were enrolled from the Hangzhou region. Then, we conducted a meta-analysis based on the present literature. In stage 1, the single nucleotide polymorphism (SNP) rs11098403 showed a significant association with schizophrenia (corrected P=0.005). The frequency of the rs11098403 G allele was significantly lower among schizophrenia patients than among the controls (odds ratio (OR)=0.68, 95% confidence interval (CI): 0.55-0.84, corrected P=0.002). No significant difference was observed in individual SNP marker genotypes or allele distributions between the BD and control groups. In stage 2, the association of rs11098403 with schizophrenia could be validated (genotypic P=0.001 and allelic P=0.0003). After pooling all data from 1861 patients with schizophrenia and 2081 controls, we observed a significant association of the rs11098403 G allele with schizophrenia (Z=5.56, P<0.001), with an OR=0.70 (95% CI: 0.61-0.79). Then, we performed an expression quantitative trait loci analysis to investigate the functional effect of rs11098403 on NDST3 expression in the brain. We observed a significant association of rs11098403 with NDST3 expression in the hippocampus (P=0.027), although the significance did not survive after multiple testing correction. Our findings provided preliminary evidence that rs11098403 might modify the genetic risk of schizophrenia in the Han Chinese. Further investigations are warranted to identify the precise mechanism regulating brain NDST3 expression in the Han Chinese. These results would help to explain the pathophysiological mechanism of schizophrenia.

Electrical mapping in bipolar disorder patients during the oddball paradigm

Bipolar disorder (BD) is characterized by an alternated occurrence between acute mania episodes and depression or remission moments. The objective of this study is to analyze the information processing changes in BP (Bipolar Patients) (euthymia, depression and mania) during the oddball paradigm, focusing on the P300 component, an electric potential of the cerebral cortex generated in response to external sensorial stimuli, which involves more complex neurophysiological processes related to stimulus interpretation. Twenty-eight bipolar disorder patients (BP) (17 women and 11 men with average age of 32.5, SD: 9.5) and eleven healthy controls (HC) (7 women and 4 men with average age of 29.78, SD: 6.89) were enrolled in this study. The bipolar patients were divided into 3 major groups (i.e., euthymic, depressive and maniac) according to the score on the Clinical Global Impression--Bipolar Version (CGI-BP). The subjects performed the oddball paradigm simultaneously to the EEG record. EEG data were also recorded before and after the execution of the task. A one-way ANOVA was applied to compare the P300 component among the groups. After observing P300 and the subcomponents P3a and P3b, a similarity of amplitude and latency between euthymic and depressive patients was observed, as well as small amplitude in the pre-frontal cortex and reduced P3a response. This can be evidence of impaired information processing, cognitive flexibility, working memory, executive functions and ability to shift the attention and processing to the target and away from distracting stimuli in BD. Such neuropsychological impairments are related to different BD symptoms, which should be known and considered, in order to develop effective clinical treatment strategies.

Glucose metabolism alterations in patients with bipolar disorder

Patients with bipolar disorder (BD) are more frequently affected by metabolic syndrome (MetS) than the general population, but the neurobiological correlates underlying such association are still not clarified and few studies in BD have evaluated the role of regulators of lipid and glucose metabolism. The present study was aimed to investigate putative alterations in markers linked to metabolic dysfunctions as C-peptide, Ghrelin, GIP, GLP-1, Glucagon, Insulin, Leptin, PAI-1 (total), Resistin and Visfatin in a sample of BD patients compared to controls. Furthermore, associations between changes of metabolic markers and relevant clinical features, such as severity of symptomatology, number and type of past mood episodes, drug treatments and presence/absence of metabolic alterations (MetS, diabetes and cardiovascular disease) were analyzed. A total of 57 patients with BD and 49 healthy controls were recruited. The main results showed lower serum levels of Glucagon, GLP-1, Ghrelin, and higher levels of GIP in BD patients as compared to controls (p = 0.018 for Ghrelin; p < 0.0001 for Glucagon; p < 0.0001 for GLP-1; p < 0.0001 for GIP). Further, Glucagon and GLP-1 levels were significantly associated with the number of past mood episodes. These findings support the hypothesis that alterations in Glucagon, GLP-1, GIP and Ghrelin might be involved in BD pathogenesis and might represent useful biomarkers for the development of preventive and personalized therapies in this disorder.