Decreased plasma brain derived neurotrophic factor levels in unmedicated bipolar patients during manic episode

The Association Among Bipolar Disorder, Mitochondrial Dysfunction, and Reactive Oxygen Species

Mitochondria, often known as the cell's powerhouses, are primarily responsible for generating energy through aerobic oxidative phosphorylation. However, their functions extend far beyond just energy production. Mitochondria play crucial roles in maintaining calcium balance, regulating apoptosis (programmed cell death), supporting cellular signaling, influencing cell metabolism, and synthesizing reactive oxygen species (ROS). Recent research has highlighted a strong link between bipolar disorder (BD) and mitochondrial dysfunction. Mitochondrial dysfunction contributes to oxidative stress, particularly through the generation of ROS, which are implicated in the pathophysiology of BD. Oxidative stress arises when there is an imbalance between the production of ROS and the cell's ability to neutralize them. In neurons, excessive ROS can damage various cellular components, including proteins in neuronal membranes and intracellular enzymes. Such damage may interfere with neurotransmitter reuptake and the function of critical enzymes, potentially affecting brain regions involved in mood regulation and emotional control, which are key aspects of BD. In this review, we will explore how various types of mitochondrial dysfunction contribute to the production of ROS. These include disruptions in energy metabolism, impaired ROS management, and defects in mitochondrial quality control mechanisms such as mitophagy (the process by which damaged mitochondria are selectively degraded). We will also examine how abnormalities in calcium signaling, which is crucial for synaptic plasticity, can lead to mitochondrial dysfunction. Additionally, we will discuss the specific mitochondrial dysfunctions observed in BD, highlighting how these defects may contribute to the disorder's pathophysiology. Finally, we will identify potential therapeutic targets to improve mitochondrial function, which could pave the way for new treatments to manage or mitigate symptoms of BD.

Utilizing systematic Mendelian randomization to identify potential therapeutic targets for mania

Background

Mania has caused incalculable economic losses for patients, their families, and even society, but there is currently no effective treatment plan for this disease without side effects.

Methods

Using bioinformatics and Mendelian randomization methods, potential drug target genes and key substances associated with mania were explored at the mRNA level. We used the chip expression profile from the GEO database to screen differential genes and used the eQTL and mania GWAS data from the IEU database for two-sample Mendelian randomization (MR) to determine core genes by colocalization. Next, we utilized bioinformatics analysis to identify key substances involved in the mechanism of action and determined related gene targets as drug targets.

Results

After differential expression analysis and MR, a causal relationship between the expression of 46 genes and mania was found. Colocalization analysis yielded six core genes. Five key substances were identified via enrichment analysis, immune-related analysis, and single-gene GSVA analysis of the core genes. MR revealed phenylalanine to be the only key substance that has a unidirectional causal relationship with mania. In the end, SBNO2, PBX2, RAMP3, and QPCT, which are significantly associated with the phenylalanine metabolism pathway, were identified as drug target genes.

Conclusion

SBNO2, PBX2, RAMP3, and QPCT could serve as potential target genes for mania treatment and deserve further basic and clinical research. Medicinal target genes regulate the phenylalanine metabolism pathway to achieve the treatment of mania. Phenylalanine is an important intermediate substance in the treatment of mania that is regulated by drug target genes.

International Trends in Lithium Use for Pharmacotherapy and Clinical Correlates in Bipolar Disorder: A Scoping Review

Lithium remains an effective option in the treatment of bipolar disorder (BD). Thus, we aim to characterize the pharmaco-epidemiological patterns of lithium use internationally over time and elucidate clinical correlates associated with BD using a scoping review, which was conducted using the methodological framework by Arksey and O'Malley (2005). We searched several databases for studies that examined the prescriptions for lithium and clinical associations in BD from inception until December 2023. This review included 55 articles from 1967 to 2023, which collected data from North America (n = 24, 43.6%), Europe (n = 20, 36.4%), and Asia (n = 11, 20.0%). The overall prescription rates ranged from 3.3% to 84% (33.4% before and 30.6% after the median year cutoffs). Over time, there was a decline in lithium use in North America (27.7% before 2010 to 17.1% after 2010) and Europe (36.7% before 2003 to 35.7% after 2003), and a mild increase in Asia (25.0% before 2003 to 26.2% after 2003). Lithium use was associated with specific demographic (e.g., age, male gender) and clinical factors (e.g., lower suicide risk). Overall, we found a trend of declining lithium use internationally, particularly in the West. Specific clinical correlates can support clinical decision-making for continued lithium use.

The effect of subthreshold depressive symptoms on cognitive functions and peripheral biomarkers in bipolar disorder

OBJECTIVE

A global approach to factors responsible for functional impairment in patients with BD is necessary.

METHOD

Ninety-three euthymic patients with BD [49 patients with SD (subthreshold depression) and 44 patients without SD] and 48 healthy controls were invited for evaluation of demographic, clinical, and cognitive characteristics. To define SD, the lower limit was HDRS ≥4 points and the upper limit was HDRS <9 points. Stroop test, California verbal learning test, digit-span test, controlled word association test, and clock drawing test were performed. Serum BDNF levels were measured. Additionally in the BD group; blood drug (lithium, valproic acid), leukocyte, C-reactive protein (CRP), TSH, and vitamin B12 levels were measured.

RESULTS

We found no difference between serum BDNF levels of BD (n = 93) and controls. The cognitive performances of the BD group were worse than the control group (p < 0.001). Attention, working memory, and stroop performance of patients with SD were worse than patients without SD (p < 0.05). Verbal fluency, stroop test, and planning performance decreased as serum CRP level increased in patients with BD (p < 0.05).

CONCLUSIONS

Although the patient group with SD was in euthymia, their cognitive performance was worse than the group without SD. Poor cognitive performance in BD was associated with serum CRP levels.

Can Brain-Derived Neurotrophic Factor Be Considered a Biomarker for Bipolar Disorder? An Analysis of the Current Evidence

Brain-derived neurotrophic factor (BDNF) plays a key role in brain development, contributing to neuronal survival and neuroplasticity. Previous works have found that BDNF is involved in several neurological or psychiatric diseases. In this review, we aimed to collect all available data on BDNF and bipolar disorder (BD) and assess if BDNF could be considered a biomarker for BD. We searched the most relevant medical databases and included studies reporting original data on BDNF circulating levels or Val66Met polymorphism. Only articles including a direct comparison with healthy controls (HC) and patients diagnosed with BD according to international classification systems were included. Of the 2430 identified articles, 29 were included in the present review. Results of the present review show a reduction in BDNF circulating levels during acute phases of BD compared to HC, which increase after effective therapy of the disorders. The Val66Met polymorphism was related to features usually associated with worse outcomes. High heterogeneity has been observed regarding sample size, clinical differences of included patients, and data analysis approaches, reducing comparisons among studies. Although more studies are needed, BDNF seems to be a promising biomarker for BD.

Second messengers and their importance for novel drug treatments of patients with bipolar disorder

Second messenger systems, like the cyclic nucleotide, glycogen synthase kinase-3β, phosphoinositide, and arachidonic acid cascades, are involved in bipolar disorder (BD). We investigated their role on the development of novel therapeutic drugs using second messenger mechanisms. PubMed search and narrative review. We used all relevant keywords for each second messenger cascade combining it with BD and related terms and combined all with novel/innovative treatments/drugs. Our search produced 31 papers most were reviews, and focussed on the PI3K/AKT-GSK-3β/Nrf2-NF-ĸB pathways. Only two human randomized clinical trials were identified, of ebselen, an antioxidant, and celecoxib, a cyclooxygenase-2 inhibitor, both with poor unsatisfactory results. Despite the fact that all second messenger systems are involved in the pathophysiology of BD, there are few experiments with novel drugs using these mechanisms. These mechanisms are a neglected and potentially major opportunity to transform the treatment of bipolar illness.

Lithium as a Neuroprotective Agent for Bipolar Disorder: An Overview

Lithium (Li+) is a first option treatment for adult acute episodes of Bipolar Disorder (BD) and for the prophylaxis of new depressed or manic episodes. It is also the preferred choice as maintenance treatment. Numerous studies have shown morphological abnormalities in the brains of BD patients, suggesting that this highly heritable disorder may exhibit progressive and deleterious changes in brain structure. Since treatment with Li+ ameliorates these abnormalities, it has been postulated that Li+ is a neuroprotective agent in the same way atypical antipsychotics are neuroprotective in patients diagnosed with schizophrenia spectrum disorders. Li+'s neuroprotective properties are related to its modulation of nerve growth factors, inflammation, mitochondrial function, oxidative stress, and programmed cell death mechanisms such as autophagy and apoptosis. Notwithstanding, it is not known whether Li+-induced neuroprotection is related to the inhibition of its putative molecular targets in a BD episode: the enzymes inositol-monophosphatase, (IMPase), glycogen-synthase-kinase 3β (GSK3), and Protein kinase C (PKC). Furthermore, it is uncertain whether these neuroprotective mechanisms are correlated with Li+'s clinical efficacy in maintaining mood stability. It is expected that in a nearby future, precision medicine approaches will improve diagnosis and expand treatment options. This will certainly contribute to ameliorating the medical and economic burden created by this devastating mood disorder.

The Mechanisms Behind Rapid Antidepressant Effects of Ketamine: A Systematic Review With a Focus on Molecular Neuroplasticity

The mechanism of action underlying ketamine's rapid antidepressant effects in patients with depression, both suffering from major depressive disorder (MDD) and bipolar disorder (BD), including treatment resistant depression (TRD), remains unclear. Of the many speculated routes that ketamine may act through, restoring deficits in neuroplasticity may be the most parsimonious mechanism in both human patients and preclinical models of depression. Here, we conducted a literature search using PubMed for any reports of ketamine inducing neuroplasticity relevant to depression, to identify cellular and molecular events, relevant to neuroplasticity, immediately observed with rapid mood improvements in humans or antidepressant-like effects in animals. After screening reports using our inclusion/exclusion criteria, 139 publications with data from cell cultures, animal models, and patients with BD or MDD were included (registered on PROSPERO, ID: CRD42019123346). We found accumulating evidence to support that ketamine induces an increase in molecules involved in modulating neuroplasticity, and that these changes are paired with rapid antidepressant effects. Molecules or complexes of high interest include glutamate, AMPA receptors (AMPAR), mTOR, BDNF/TrkB, VGF, eEF2K, p70S6K, GSK-3, IGF2, Erk, and microRNAs. In summary, these studies suggest a robust relationship between improvements in mood, and ketamine-induced increases in molecular neuroplasticity, particularly regarding intracellular signaling molecules.

Dietary tryptophan depletion alters the faecal bacterial community structure of compulsive drinker rats in schedule-induced polydipsia

RATIONALE

Compulsive behaviour, present in different psychiatric disorders such as obsessive-compulsive disorder, schizophrenia and drug abuse, is associated with altered levels of serotonin (5-hydroxytryptamine, 5-HT). The gut microbiota regulates tryptophan (TRP) metabolism and may affect global 5-H synthesis in the enteric and central nervous systems, suggesting a possible involvement of gut microbiota in compulsive spectrum disorders.

OBJECTIVES

The present study investigated whether chronic TRP depletion by diet alters the faecal bacterial community profiles of compulsive versus non-compulsive rats in schedule-induced polydipsia (SIP). Peripheral plasma 5-HT and brain-derived neurotrophic factor (BDNF) levels were evaluated.

METHODS

Wistar rats were selected as High Drinkers (HD) or Low Drinkers (LD) according to their SIP behaviour and were fed for 14 days with either a TRP-free diet (T-) or a TRP-supplemented diet (T+). The faecal bacterial community structure was investigated with 16S rRNA gene-targeted denaturing gradient gel electrophoresis (DGGE) fingerprinting analysis.

RESULTS

Compulsive HD rats showed a lower bacterial diversity than LD rats, irrespectively of the diet. The TRP-depleted HD rats, the only group increasing compulsive licking in SIP, showed a reduction of bacterial evenness and a highly functionally organized community compared with the other groups, indicating that this bacterial community is more fragile to external changes due to the dominance of a low number of species. The chronic TRP depletion by diet effectively reduced peripheral plasma 5-HT levels in both HD and LD rats, while plasma BDNF levels were not altered.

CONCLUSIONS

These results highlight the possible implication of reduced microbial diversity in compulsive behaviour and the involvement of the serotonergic system in modulating the gut brain-axis in compulsive spectrum disorders.

Intravenous Ketamine Infusions in Treatment-Resistant Bipolar Depression: An Open-Label Naturalistic Observational Study

PURPOSE

Bipolar disorder is a chronic and recurrent condition often associated with treatment resistance and suicidality. There is an unmet need for effective treatment in this group of patients. Ketamine has been demonstrated to have antidepressant and antisuicidal properties in unipolar depression. Most of the available studies concern unipolar depression. Here, we present the efficacy and safety of IV ketamine as an add-on treatment in patients with bipolar I and bipolar II depression.

PATIENTS AND METHODS

Thirteen patients with treatment-resistant bipolar depression (TRBD) received eight IV infusions of 0.5 mg/kg ketamine twice a week over four weeks. This is an open-label naturalistic observational study. Ketamine is an add-on treatment. Depressive symptoms were measured with the Montgomery-Asberg Depression Rating Scale (MADRS), and manic symptoms were measured with the Young Mania Rating Scale (YMRS). Psychomimetic symptoms were assessed with the Clinician-Administered Dissociative States Scale (CADSS) and the Brief Psychiatric Rating Scale (BPRS).

RESULTS

The rates of response and remission after the seventh infusion of ketamine were 61.5% and 46.2%, respectively. A significant antisuicidal effect was observed in responders at the 7th infusion. Suicidality was measured with item 10 on the MADRS scale. The average time to respond was between 21.1 and 23.2 days to remission. There was an increase in the CADSS scores during the treatment compared to baseline and follow-up, but no differences between responders and non-responders were observed. No affective switch was observed according to the YMRS scale scores. Ketamine treatment was associated with a transient increase in arterial blood pressure. No serious adverse events, however, were observed.

CONCLUSION

This report presents the preliminary results of IV ketamine effectiveness and safety in treatment-resistant bipolar depression. The findings suggest that it is a feasible, safe and well-tolerated treatment option in this group of patients. There is a definite need for more studies in this field.

The Neurobiology of Bipolar Disorder

Bipolar disorders are severe and have a high prevalence; despite this, the neurobiological mechanisms are far from being elucidated, and this limits the development of new treatments. Although the aetiology of bipolar disorders is not yet fully understood, it is accepted that the disorder(s) may result from the interaction between genetic factors that cause susceptibility and predisposing, precipitating and perpetuating environmental factors, such as stress and traumatic events. A pathophysiological formulation of the disease suggests that dysfunctions in intracellular biochemical cascades, oxidative stress and mitochondrial dysfunction impair the processes linked to neuronal plasticity, leading to cell damage and the consequent loss of brain tissue that has been identified in post-mortem and neuroimaging studies. The data we have reviewed suggests that peripheral biomarkers related to hormones, inflammation, oxidative stress and neurotrophins are altered in bipolar disorders, especially during acute mood episodes. Together, these changes have been associated with a systemic toxicity of the disease and the damage resulting from multiple episodes. Systemic toxicity related to recurrent episodes in bipolar disorder may influence brain anatomical changes associated with the progression of stress and neuroplasticity in bipolar disorder and the response to treatment.

Psychological distress and lack of PINK1 promote bioenergetics alterations in peripheral blood mononuclear cells

Psychological distress induces oxidative stress and alters mitochondrial metabolism in the nervous and immune systems. Psychological distress promotes alterations in brain metabolism and neurochemistry in wild-type (WT) rats in a similar manner as in Parkinsonian rats lacking endogenous PTEN-induced kinase 1 (PINK1), a serine/threonine kinase mutated in a recessive forms of Parkinson’s disease. PINK1 has been extensively studied in the brain, but its physiological role in peripheral tissues and the extent to which it intersects with the neuroimmune axis is not clear. We surmised that PINK1 modulates the bioenergetics of peripheral blood mononuclear cells (PBMCs) under basal conditions or in situations that promote oxidative stress as psychological distress. By using an XF metabolic bioanalyzer, PINK1-KO-PBMCs showed significantly increased oxidative phosphorylation and basal glycolysis compared to WT cells and correlated with motor dysfunction. In addition, psychological distress enhanced the glycolytic capacity in PINK1-KO-PBMCs but not in WT-PBMCs. The level of antioxidant markers and brain-derived neurotrophic factor were altered in PINK1-KO-PBMCs and by psychological distress. In summary, our data suggest that PINK1 is critical for modulating the bioenergetics and antioxidant responses in PBMCs whereas lack of PINK1 upregulates compensatory glycolysis in response to oxidative stress induced by psychological distress.

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

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

Ketamine in Bipolar Disorder: A Review

Bipolar disorder (BD) is a psychiatric illness associated with high morbidity, mortality and suicide rate. It has neuroprogressive course and a high rate of treatment resistance. Hence, there is an unquestionable need for new BD treatment strategies. Ketamine appears to have rapid antidepressive and antisuicidal effects. Since most of the available studies concern unipolar depression, here we present a novel insight arguing that ketamine might be a promising treatment for bipolar disorder.

Current understanding of bipolar disorder: Toward integration of biological basis and treatment strategies

Biological studies of bipolar disorder initially focused on the mechanism of action for antidepressants and antipsychotic drugs, and the roles of monoamines (e.g., serotonin, dopamine) have been extensively studied. Thereafter, based on the mechanism of action of lithium, intracellular signal transduction systems, including inositol metabolism and intracellular calcium signaling, have drawn attention. Involvement of intracellular calcium signaling has been supported by genetics and cellular studies. Elucidation of the neural circuits affected by calcium signaling abnormalities is critical, and our previous study suggested a role of the paraventricular thalamic nucleus. The genetic vulnerability of mitochondria causes calcium dysregulation and results in the hyperexcitability of serotonergic neurons, which are suggested to be susceptible to oxidative stress. Efficacy of anticonvulsants, animal studies of candidate genes, and studies using induced pluripotent stem cell-derived neurons have suggested a relation between bipolar disorder and the hyperexcitability of neurons. Recent genetic findings suggest the roles of polyunsaturated acids. At the systems level, social rhythm therapy targets circadian rhythm abnormalities, and cognitive behavioral therapy may target emotion/cognition (E/C) imbalance. In the future, pharmacological and psychosocial treatments may be combined and optimized based on the biological basis of each patient, which will realize individualized treatment.

Brain-derived neurotrophic factor (BDNF) and bipolar disorder

Brain-derived neurotrophic factor (BDNF) is deemed to be associated with the psychopathology of bipolar I disorder (BD). However, studies focusing on accuracy of BDNF levels to differentiate these patients from healthy controls (HCs) are scarce. Over a discrete twelve-year period, we investigated serum BDNF levels in patients with BD and compared them to age-, sex- and body mass index (BMI)-matched HCs. There were lower serum BDNF levels in 83 samples with BD than in 222 HCs samples (5.7 ± 4.2 ng/ml vs. 12.2 ± 7.5 ng/ml, F = 46.784). Pearson's correlation test showed significant positive correlations between Young Mania Rating Scale scores and the BDNF levels among 61 manic patients (γ = 0.339). The receiver operating characteristic curve analysis showed BDNF levels demonstrated a moderate accuracy of being able to differentiate BD patients from HCs (AUC = 0.801). The most adequate cut-off points of the BDNF level were 6.74 ng/ml (sensitivity = 82.0%, specificity = 63.9%). Our results support that BDNF demonstrated moderate accuracy to distinguish BD patients from HCs. In the future, greater samples would be required to prove these results.

Neurotrophins, cytokines, oxidative stress mediators and mood state in bipolar disorder: systematic review and meta-analyses

BACKGROUND

A reliable biomarker signature for bipolar disorder sensitive to illness phase would be of considerable clinical benefit. Among circulating blood-derived markers there has been a significant amount of research into inflammatory markers, neurotrophins and oxidative stress markers.AimsTo synthesise and interpret existing evidence of inflammatory markers, neurotrophins and oxidative stress markers in bipolar disorder focusing on the mood phase of illness.

METHOD

Following PRISMA (Preferred Reporting Items for Systematic reviews and Meta-analyses) guidelines, a systematic review was conducted for studies investigating peripheral biomarkers in bipolar disorder compared with healthy controls. We searched Medline, Embase, PsycINFO, SciELO and Web of Science, and separated studies by bipolar mood phase (mania, depression and euthymia). Extracted data on each biomarker in separate mood phases were synthesised using random-effects model meta-analyses.

RESULTS

In total, 53 studies were included, comprising 2467 cases and 2360 controls. Fourteen biomarkers were identified from meta-analyses of three or more studies. No biomarker differentiated mood phase in bipolar disorder individually. Biomarker meta-analyses suggest a combination of high-sensitivity C-reactive protein/interleukin-6, brain derived neurotrophic factor/tumour necrosis factor (TNF)-α and soluble TNF-α receptor 1 can differentiate specific mood phase in bipolar disorder. Several other biomarkers of interest were identified.

CONCLUSIONS

Combining biomarker results could differentiate individuals with bipolar disorder from healthy controls and indicate a specific mood-phase signature. Future research should seek to test these combinations of biomarkers in longitudinal studies.Declaration of interestNone.

Toward Precision Psychiatry in Bipolar Disorder: Staging 2.0

Personalized treatment is defined as choosing the "right treatment for the right person at the right time." Although psychiatry has not yet reached this level of precision, we are on the way thanks to recent technological developments that may aid to detect plausible molecular and genetic markers. At the moment there are some models that are contributing to precision psychiatry through the concept of staging. While staging was initially presented as a way to categorize patients according to clinical presentation, course, and illness severity, current staging models integrate multiple levels of information that can help to define each patient's characteristics, severity, and prognosis in a more precise and individualized way. Moreover, staging might serve as the foundation to create a clinical decision-making algorithm on the basis of the patient's stage. In this review we will summarize the evolution of the bipolar disorder staging model in relation to the new discoveries on the neurobiology of bipolar disorder. Furthermore, we will discuss how the latest and future progress in psychiatry might transform current staging models into precision staging models.

An Oldie but Goodie: Lithium in the Treatment of Bipolar Disorder through Neuroprotective and Neurotrophic Mechanisms

Lithium has been used for the treatment of bipolar disorder (BD) for the last sixty or more years, and recent studies with more reliable designs and updated guidelines have recommended lithium to be the treatment of choice for acute manic, mixed and depressive episodes of BD, along with long-term prophylaxis. Lithium’s specific mechanism of action in mood regulation is progressively being clarified, such as the direct inhibition on glycogen synthase kinase 3β, and its various effects on neurotrophic factors, neurotransmitters, oxidative metabolism, apoptosis, second messenger systems, and biological systems are also being revealed. Furthermore, lithium has been proposed to exert its treatment effects through mechanisms associated with neuronal plasticity. In this review, we have overviewed the clinical aspects of lithium use for BD, and have focused on the neuroprotective and neurotrophic effects of lithium.

Neurotrophic and inflammatory markers in bipolar disorder: A prospective study

Altered neurotrophic signaling is thought to impair neuroplasticity in bipolar disorder (BD). Brain-derived neurotrophic factor (BDNF) is proposed as a neurotrophic marker in BD. However, the current evidence for its use in monitoring disease activity and illness progression is conflicting and an exploration of additional neurotrophic markers is needed. This prospective case-control study investigated mood-specific changes in potential neurotrophic markers and their association to inflammatory activity. Patients with BD were included during an acute mood episode, either depressive (n=35) or (hypo)manic (n=32). Fifty-nine patients (88%) and 29 healthy controls (97%) completed the study. Peripheral blood levels of BDNF, vascular endothelial growth factor A (VEGF), soluble fms-like tyrosine kinase-1 (sFlt-1) and tumor necrosis factor alpha (TNF-α) were measured at baseline and after 2 months. Biomarker levels in patients were compared to controls and correlated to HDRS-17 and YMRS total scores and the PANSS positive subscale scores. Linear mixed model analysis revealed no significant differences in neurotrophic markers between patients and controls. We found significantly increased TNF-α levels in patients and a subsequent normalization during euthymia. None of the biomarkers strongly correlated to mood symptom severity. Despite standardized methodological practices, BDNF and VEGF levels had a wide distribution range. We need a better understanding of methodological aspects influencing the analysis of neurotrophic factors to improve future research on markers for mood state monitoring and illness progression in BD.

Symptomatic menopausal transition and subsequent bipolar disorder among midlife women with major depression: a nationwide longitudinal study

Previous studies suggested that menopausal transition played an important role in the clinical course of major depression and bipolar disorder. However, the role of symptomatic menopausal transition in diagnostic conversion from major depression to bipolar disorder was still unknown. Using the Taiwan National Health Insurance Research Database, 50,273 midlife women aged between 40 and 60 years in 2002∼2008 with major depression were enrolled in our study and divided into two subgroups based on the presence (n = 21,120) or absence (n = 29,153) of symptomatic menopausal transition. Subjects who had subsequent bipolar disorder during the follow-up were identified. Midlife women with major depression and symptomatic menopausal transition had a higher incidence of the diagnostic conversion to bipolar disorder (7.3 vs. 6.6%, p = 0.003) than those with major depression alone. Cox regression analysis after adjusting for demographic data and psychiatric comorbidities further showed that symptomatic menopausal transition was associated with an increased risk of developing bipolar disorder (HR 1.14, 95% CI 1.07∼1.23) among midlife women with major depression. Sensitivity test after excluding the 1-year and 3-year observation exhibited the consistent findings (HR 1.18, 95% CI 1.09∼1.28; HR 1.20, 95% CI 1.08∼1.34). Midlife women with the dual diagnoses of major depression and symptomatic menopausal transition had an increased risk of the diagnostic conversion to bipolar disorder compared to those with major depression alone. Further studies may be required to investigate the underlying mechanisms among menopausal transition and the diagnostic conversion from major depression to bipolar disorder.

Effect of Oxcarbazepine on Serum Brain Derived Neurotrophic Factor in Bipolar Mania: An Exploratory Study

Objective

In bipolar disorder, serum brain-derived neurotrophic factor (BDNF) level decreases leading to dysfunctions of critical neurotrophic, cellular plasticity and neuroprotective processes. The present study was conducted to evaluate the change in serum BDNF level with oxcarbazepine monotherapy in bipolar mania.

Methods

The present study is a prospective, interventional, open label clinical study conducted on 25 patients of bipolar mania and 25 healthy controls. Detailed history, clinical evaluation including Young Mania Rating Scale (YMRS) scoring and serum BDNF were assessed at baseline for all 50 subjects. The bipolar patients were prescribed tablet oxcarbazepine and followed up after 4 weeks for clinical evaluation and re-estimation of serum BDNF and YMRS scoring.

Results

The serum BDNF level in bipolar manic patients were compared with healthy controls at baseline and results revealed that there is a significant reduction (p=0.002) in serum BDNF level in bipolar patients. At follow-up after 4 weeks, the mean change in serum BDNF in bipolar group who were on oxcarbazepine monotherapy was found statistically significant (p=0.02) in comparison to healthy controls. In bipolar group, the YMRS score and serum BDNF at baseline have an inverse relation(r=−0.59) whereas change of the YMRS score had a positive correlation (r=0.67) with the change of serum BDNF over 4 weeks.

Conclusion

In bipolar mania serum BDNF level is low and it is found to be increased with short term monotherapy with oxcarbazepine.

Body mass index associates with white matter microstructure in bipolar depression

OBJECTIVES

Obesity has been reported in over 60% of bipolar disorder (BD) patients. It worsens the severity of illness, and influences cognition and functional outcomes. White matter (WM) abnormalities are one of the most consistently reported findings in neuroimaging studies of BD. We hypothesized that body mass index (BMI) could correlate with WM integrity in bipolar patients.

METHODS

We evaluated BMI in a sample of 164 depressed patients affected by BD. We performed whole-brain tract-based spatial statistics with threshold-free cluster enhancement for the diffusion tensor imaging (DTI) measures of WM integrity: fractional anisotropy; axial, radial, and mean diffusivity.

RESULTS

We observed that BMI was associated with DTI measures of WM integrity in several fiber tracts: anterior corona radiata, anterior thalamic radiation, inferior fronto-occipital fasciculus and corpus callosum.

CONCLUSIONS

The association of BMI in key WM tracts that are crucial to mood regulation and neurocognitive functioning suggests that BMI might contribute to the pathophysiology of BD through a detrimental action on structural connectivity in critical cortico-limbic networks.

Association of Lipid Peroxidation and Brain-Derived Neurotrophic Factor with Executive Function in Adolescent Bipolar Disorder

BACKGROUND

Executive dysfunction is common and impairing in youth bipolar disorder (BD), and oxidative stress (OS) and brain-derived neurotrophic factor (BDNF) have been implicated in executive deficits of adult BD. This study aimed to determine the association between OS and executive dysfunction in BD adolescents and the influence of BDNF on this association.

METHODS

Serum levels of lipid hydroperoxides (LPH) and 4-hydroxy-2-nonenal (4-HNE) and BDNF levels were measured in 29 BD and 25 control adolescents. The intra-extra-dimensional (IED) set-shifting task assessed executive function. Lower IED scores indicated better performance. High and low BDNF subgroups were defined by median split.

RESULTS

IED Z-scores were impaired in the BD group compared to controls, whereas biomarker levels were not significantly different between groups. LPH-BDNF correlations were significantly different between BD and controls (Z = 2.046, p = 0.041). In high BDNF BD subjects, LPH was significantly positively correlated with IED completed stage trials (ρ = 0.755, p = 0.001) and pre-extra-dimensional shift errors (ρ = 0.588, p = 0.017). Correlations were opposite in controls. In a linear model, LPH, BDNF, and the LPH-BDNF interaction each significantly explained variance of IED total trials (adjusted) (model r ² = 0.187, F = 2.811, p = 0.035).

CONCLUSIONS

There is a negative association between LPH and executive function in BD adolescents, which may be modulated by BDNF. LPH and BDNF may be useful biomarkers of executive function in BD. These findings highlight the importance of examining multiple peripheral biomarkers in relation to cognitive functions in BD adolescents. Future studies should explore these factors in longitudinal designs to determine the directionality of observed associations.

Telomere Length, Oxidative Stress, Inflammation and BDNF Levels in Siblings of Patients with Bipolar Disorder: Implications for Accelerated Cellular Aging

BACKGROUND

Growing evidence supports the existence of neurobiological trait abnormalities in individuals at genetic risk for bipolar disorder. The aim of this study was to examine potential differences in brain-derived neurotrophic factor, cytokines, oxidative stress, and telomere length markers between patients with bipolar disorder, their siblings, and healthy controls.

METHODS

Thirty-six patients with bipolar disorder type I, 39 siblings, and 44 healthy controls were assessed. Serum levels of brain-derived neurotrophic factor, interleukin-6, interleukin-10, tumor necrosis factor-α, C-C motif chemokine 11, C-C motif chemokine 24, and 3-nitrotyrosine were measured, as were the activities of glutathione peroxidase, glutathione reductase, and glutathione S-transferase. Telomere length (T/S ratio) was measured using quantitative polymerase chain reaction.

RESULTS

Telomere length was different between the 3 groups (P = .041) with both patients and siblings showing a shorter T/S ratio compared with healthy controls. Patients showed increased levels of interleukin-6 (P = .005) and interleukin-10 (P = .002) compared with controls as well as increased levels of interleukin-6 (p = 0.014) and CCL24 (P = .016) compared with their siblings. C-C motif chemokine 11 levels were increased in siblings compared with controls (P = .015), and a similar tendency was found in patients compared with controls (P = .045). Glutathione peroxidase activity was decreased in patients compared with controls (P = .006) and siblings (P = .025). No differences were found for the other markers.

CONCLUSIONS

The present results suggest that unaffected siblings may present accelerated aging features. These neurobiological findings may be considered as endophenotypic traits. Further prospective studies are warranted.

Beyond the therapeutic shackles of the monoamines: New mechanisms in bipolar disorder biology

Multiple novel biological mechanisms putatively involved in the etiology of bipolar disorders are being explored. These include oxidative stress, altered glutamatergic neurotransmission, mitochondrial dysfunction, inflammation, cell signaling, apoptosis and impaired neurogenesis. Important clinical translational potential exists for such mechanisms to help underpin development of novel therapeutics - much needed given limitations of current therapies. These new mechanisms also help improve our understanding of how current therapeutics might exert their effects. Lithium, for example, appears to have antioxidant, immunomodulatory, signaling, anti-apoptotic and neuroprotective properties. Similar properties have been attributed to other mood stabilizers such as valproate, lamotrigine, and quetiapine. Perhaps of greatest translational value has been the recognition of such mechanisms leading to the emergence of novel therapeutics for bipolar disorders. These include the antioxidant N-acetylcysteine, the anti-inflammatory celecoxib, and ketamine - with effects on the glutamatergic system and microglial inhibition. We review these novel mechanisms and emerging therapeutics, and comment on next steps in this space.

The correlation between plasma brain-derived neurotrophic factor and cognitive function in bipolar disorder is modulated by the BDNF Val66Met polymorphism

We explored the effect of the Brain-derived neurotrophic factor (BDNF) Val66Met polymorphism (rs6265) on correlation between changes in plasma BDNF levels with cognitive function and quality of life (QoL) after 12 weeks of treatment in bipolar disorder (BD). Symptom severity and plasma BDNF levels were assessed upon recruitment and during weeks 1, 2, 4, 8 and 12. QoL, the Wisconsin Card Sorting Test (WCST), and the Conners’ Continuous Performance Test (CPT) were assessed at baseline and endpoint. The BDNF Val66Met polymorphism was genotyped. Changes in cognitive function and QoL over 12 weeks were reduced using factor analysis for the evaluation of their correlations with changes in plasma BDNF. Five hundred forty-one BD patients were recruited and 65.6% of them completed the 12-week follow-up. Changes in plasma BDNF levels with factor 1 (WCST) were significantly negatively correlated (r = −0.25, p = 0.00037). After stratification of BD subtypes and BDNF genotypes, this correlation was significant only in BP-I and the Val/Met genotype (r = −0.54, p = 0.008). We concluded that changes in plasma BDNF levels significantly correlated with changes in WCST scores in BD and is moderated by the BDNF Val66Met polymorphism and the subtype of BD.

Clinical correlates of plasma brain-derived neurotrophic factor in post-traumatic stress disorder spectrum after a natural disaster

Clinical correlates of plasma Brain-Derived Neurotrophic Factor (BDNF) have been investigated in a clinical population with Post Traumatic Stress Disorder (PTSD) symptoms and healthy control subjects who survived to the L'Aquila 2009 earthquake. Twenty-six outpatients and 14 control subjects were recruited. Assessments included: Structured Clinical Interview for DSM-IV Axis-I disorders Patient Version, Trauma and Loss Spectrum-Self Report (TALS-SR) for post-traumatic spectrum symptoms. Thirteen patients were diagnosed as Full PTSD and 13 as Partial PTSD. The subjects with full-blown PTSD showed lower BDNF level than subjects with partial PTSD and controls. Different relationship patterns of BDNF with post-traumatic stress spectrum symptoms have been reported in the three samples. Our findings add more insight on the mechanisms regulating BDNF levels in response to stress and further proofs of the utility of the distinction of PTSD into full and partial categories.

Cytokines, brain-derived neurotrophic factor and C-reactive protein in bipolar I disorder - Results from a prospective study

BACKGROUND

Peripheral blood brain-derived neurotrophic factor (BDNF) and inflammatory markers may reflect key pathophysiological mechanisms in bipolar disorder in relation to disease activity and neuroprogression.

AIMS

To investigate whether neutrophins and inflammatory marker vary with mood states and are increased in patients with bipolar disorder type I during euthymia as well as in all affective states as a group, compared to levels in healthy control subjects.

METHODS

In a prospective 6-12 months follow-up study, we investigated state specific, intra-individual alterations in levels of BDNF, hsCRP, IL-1β, IL-6, IL-8, IL-18 and TNF-α in 60 patients with bipolar I disorder with an acute severe manic index episode and in subsequent euthymic and depressive and manic states and compared with repeated measurements in healthy control subjects. Data were analysed with linear mixed effects model and with adjustment for gender, age, BMI, alcohol intake and smoking.

RESULTS

From inclusion to end of the 6-12 months follow-up, samples of blood were drawn from the 60 patients during a total of 180 affective states, comprising 57 manic, 11 mixed, 23 depressive and 89 states of euthymia. Further, 69 blood samples were drawn from 35 healthy control subjects with three months apart. In unadjusted mixed-model analysis, levels of IL-6 and IL-8 were increased 64% (b=1.64, 95% CI: 1.31-2.05, p=<0.0001) and 24% (b=1.24, 95% CI: 1.05-1.47, p=0.013), respectively in patients with bipolar disorder overall compared with healthy control subjects. However, in adjusted models, no statistically significant differences were found in any measure between patients and control individuals. Levels of hsCRP in depressive states were decreased with 40% (95% CI: 5-62%, p=0.029) compared with euthymia and with 48% (95% CI: 17-66%, p=0.006) when compared with hypomanic/manic states after adjustment. BDNF and the other inflammatory markers did not vary according to affective state in adjusted mixed models.

LIMITATIONS

Patients were all medicated, specifically with high doses of atypical antipsychotics during the manic index episodes.

CONCLUSIONS

In a sample recruited during hospitalization for acute mania, levels of hsCRP varied according to affective state with higher levels during manic states compared with depressive states.

Animal models of bipolar mania: The past, present and future

Bipolar disorder (BD) is the sixth leading cause of disability in the world according to the World Health Organization and affects nearly six million (∼2.5% of the population) adults in the United State alone each year. BD is primarily characterized by mood cycling of depressive (e.g., helplessness, reduced energy and activity, and anhedonia) and manic (e.g., increased energy and hyperactivity, reduced need for sleep, impulsivity, reduced anxiety and depression), episodes. The following review describes several animal models of bipolar mania with a focus on more recent findings using genetically modified mice, including several with the potential of investigating the mechanisms underlying 'mood' cycling (or behavioral switching in rodents). We discuss whether each of these models satisfy criteria of validity (i.e., face, predictive, and construct), while highlighting their strengths and limitations. Animal models are helping to address critical questions related to pathophysiology of bipolar mania, in an effort to more clearly define necessary targets of first-line medications, lithium and valproic acid, and to discover novel mechanisms with the hope of developing more effective therapeutics. Future studies will leverage new technologies and strategies for integrating animal and human data to reveal important insights into the etiology, pathophysiology, and treatment of BD.

Serum BDNF levels in unaffected first-degree relatives of patients with bipolar disorder

Objective:

Unaffected relatives of bipolar disorder (BD) patients have been investigated for the identification of endophenotypes in an attempt to further elucidate the pathophysiology of the disease. Brain-derived neurotrophic factor (BDNF) is considered to be implicated in the pathophysiology of BD, but its role as an endophenotype has been poorly studied. We investigated abnormal serum BDNF levels in BD patients, in their unaffected relatives, and in healthy controls.

Methods:

BDNF levels were obtained from 25 DSM-IV bipolar I disorder patients, 23 unaffected relatives, and 27 healthy controls. All BD patients were in remission. The unaffected subjects were first-degree relatives of the proband who had no lifetime DSM-IV diagnosis of axis I disorder. BDNF serum levels were determined by sandwich ELISA using monoclonal BDNF-specific antibodies.

Results:

There were no statistical differences in BDNF levels among BD patients, relatives, and healthy controls.

Conclusion:

Serum BDNF levels may not indicate high genetic risk for BD, possibly acting as state markers rather than trait markers of the disease.

Neither cortisol nor brain-derived neurotrophic factor is associated with serotonin transporter in bipolar disorder

Converging evidence indicates the hypothalamus-pituitary-adrenal axis and serotonergic neurons exert reciprocal modulatory actions. Likewise, brain-derived neurotrophic factor (BDNF) has been implicated as a growth and differentiation factor in the development of serotonergic neurons. The aim of this study was to examine the interaction of cortisol and BDNF on serotonin transporter (SERT) in bipolar disorder (BD). Twenty-eight BD and 28 age- and gender-matched healthy controls (HCs) were recruited. (123)I-ADAM with single-photon emission computed tomography (SPECT) was applied for measurement of SERT availability in the brain, which included the midbrain, thalamus, putamen and caudate. Ten milliliters of venous blood was withdrawn, when the subject underwent SPECT, for the measurement of the plasma concentration of cortisol and BDNF. SERT availability was significantly decreased in the midbrain and caudate of BD compared with HCs, whereas plasma concentration of cortisol and BDNF did not show a significant difference. The linear mixed-effect model revealed that there was a significant interaction of group and cortisol on SERT availability of the midbrain, but not BDNF. Linear regression analyses by groups revealed that cortisol was associated with SERT availability in the midbrain in the HCs, but not in BD. Considering previous studies, which showed a significant association of cortisol with SERT availability in the HCs and major depressive disorder (MDD), our result replicated a similar finding in HCs. However, the negative finding of the association of cortisol and SERT availability in BD, which was different from MDD, suggests a different role for cortisol in the pathophysiology of mood disorder.

Peripheral blood brain-derived neurotrophic factor in bipolar disorder: a comprehensive systematic review and meta-analysis

Peripheral blood brain-derived neurotrophic factor (BDNF) has been proposed as a potential biomarker related to disease activity and neuroprogression in bipolar disorder, speculated to mirror alterations in brain expression of BDNF. The research area is rapidly evolving; however, recent investigations have yielded conflicting results with substantial variation in outcomes, highlighting the need to critically assess the state of current evidence. The aims of the study were to investigate differences in peripheral blood BDNF concentrations between bipolar disorder patients and healthy control subjects and between affective states in bipolar disorder patients, including assessment of the effect of treatment of acute episodes on BDNF levels. A systematic review of English language studies without considering publication status was conducted in PubMed (January 1950-November 2014), Embase (1974-November 2014) and PsycINFO (1806-November 2014), and 35 studies comprising a total of 3798 participants were included in the meta-analysis. The results indicated that crude peripheral blood BDNF levels may be lower in bipolar disorder patients overall (Hedges' g=-0.28, 95% CI: -0.51 to -0.04, P=0.02) and in serum of manic (g=-0.77, 95% CI: -1.36 to -0.18, P=0.01) and depressed (g=-0.87, 95% CI: -1.42 to -0.32, P=0.002) bipolar disorder patients compared with healthy control subjects. No differences in peripheral BDNF levels were observed between affective states overall. Longer illness duration was associated with higher BDNF levels in bipolar disorder patients. Relatively low study quality, substantial unexplained between-study heterogeneity, potential bias in individual studies and indications of publication bias, was observed and studies were overall underpowered. It could thus not be excluded that identified differences between groups were due to factors not related to bipolar disorder. In conclusion, limitations in the evidence base prompt tempered conclusions regarding the role of peripheral BDNF as a biomarker in bipolar disorder and substantially improving the quality of further research is warranted.

Bipolar Disorder: Role of Inflammation and the Development of Disease Biomarkers

Bipolar disorder is a severe and enduring psychiatric condition which in many cases starts during early adulthood and follows a relapsing and remitting course throughout life. In many patients the disease follows a progressive path with brief periods of inter-episode recovery, sub-threshold symptoms, treatment resistance and increasing functional impairment in the biopsychosocial domains. Knowledge about the neurobiology of bipolar disorder is increasing steadily and evidence from several lines of research implicates immuno-inflammatory mechanisms in the brain and periphery in the etiopathogenesis of this illness and its comorbidities. The main findings are an increase in the levels of proinflammatory cytokines during acute episodes with a decrease in neurotrophic support. Related to these factors are glial cell dysfunction, neuro-endocrine abnormalities and neurotransmitter aberrations which together cause plastic changes in the mood regulating areas of the brain and neuroprogression of the bipolar diathesis. Research in the above mentioned areas is providing an opportunity to discover novel biomarkers for the disease and the field is reaching a point where major breakthroughs can be expected in the not too distant future. It is hoped that with new discoveries fresh avenues will be found to better treat an otherwise recalcitrant disease.

Noradrenaline plays a critical role in the switch to a manic episode and treatment of a depressive episode

Although antidepressants may increase the risk of switching to mania in bipolar disorder (BD), clinicians have been using antidepressants to treat patients with bipolar depression. Appropriate treatments for bipolar depression remain controversial. In BD, antidepressants comprise a double-edged sword in terms of their efficacy in treating depression and the increased risk of switching. This review presents an important table outlining the benefit in terms of depression improvement and the risk of switching in the clinical setting. It also proposes strategies based on the characteristics of antidepressants such as their pharmacology, specifically the equilibrium dissociation constant (K_D) of the noradrenaline transporter. This table will be useful for clinicians while considering benefit and risk. Antidepressants augmenting noradrenaline may be effective in bipolar depression. However, it is easily presumed that such antidepressants may also have a risk of switching to mania. Therefore, antidepressants augmenting noradrenaline will be the recommended treatment in combination with an antimanic agent, or they may be used for short-term treatment and early discontinuation. The corresponding medical treatment guidelines probably need to be reevaluated and updated based on biological backgrounds. From previous studies, we understand that the stability of noradrenaline levels is important for BD amelioration, based on the pathophysiology of the disorder. It is hoped that researchers will reevaluate BD by conducting studies involving noradrenaline.

A new look at an old drug: neuroprotective effects and therapeutic potentials of lithium salts

Increasing evidence highlights bipolar disorder as being associated with impaired neurogenesis, cellular plasticity, and resiliency, as well as with cell atrophy or loss in specific brain regions. This has led most recent research to focus on the possible neuroprotective effects of medications, and particularly interesting findings have emerged for lithium. A growing body of evidence from preclinical in vitro and in vivo studies has in fact documented its neuroprotective effects from different insults acting on cellular signaling pathways, both preventing apoptosis and increasing neurotrophins and cell-survival molecules. Furthermore, positive effects of lithium on neurogenesis, brain remodeling, angiogenesis, mesenchymal stem cells functioning, and inflammation have been revealed, with a key role played through the inhibition of the glycogen synthase kinase-3, a serine/threonine kinase implicated in the pathogenesis of many neuropsychiatric disorders. These recent evidences suggest the potential utility of lithium in the treatment of neurodegenerative diseases, neurodevelopmental disorders, and hypoxic-ischemic/traumatic brain injury, with positive results at even lower lithium doses than those traditionally considered to be antimanic. The aim of this review is to briefly summarize the potential benefits of lithium salts on neuroprotection and neuroregeneration, emphasizing preclinical and clinical evidence suggesting new therapeutic potentials of this drug beyond its mood stabilizing properties.

Peripheral brain-derived neurotrophic factor (BDNF) as a biomarker in bipolar disorder: a meta-analysis of 52 studies

BACKGROUND

The neurotrophic hypothesis postulates that mood disorders such as bipolar disorder (BD) are associated with a lower expression of brain-derived neurotrophic factor (BDNF). However, its role in peripheral blood as a biomarker of disease activity and of stage for BD, transcending pathophysiology, is still disputed. In the last few years an increasing number of clinical studies assessing BDNF in serum and plasma have been published. Therefore, it is now possible to analyse the association between BDNF levels and the severity of affective symptoms in BD as well as the effects of acute drug treatment of mood episodes on BDNF levels.

METHODS

We conducted a systematic review and meta-analysis of all studies on serum and plasma BDNF levels in bipolar disorder.

RESULTS

Through a series of meta-analyses including a total of 52 studies with 6,481 participants, we show that, compared to healthy controls, peripheral BDNF levels are reduced to the same extent in manic (Hedges' g = -0.57, P = 0.010) and depressive (Hedges' g = -0.93, P = 0.001) episodes, while BDNF levels are not significantly altered in euthymia. In meta-regression analyses, BDNF levels additionally negatively correlate with the severity of both manic and depressive symptoms. We found no evidence for a significant impact of illness duration on BDNF levels. In addition, in plasma, but not serum, peripheral BDNF levels increase after the successful treatment of an acute mania episode, but not of a depressive one.

CONCLUSIONS

In summary, our data suggest that peripheral BDNF levels, more clearly in plasma than in serum, is a potential biomarker of disease activity in BD, but not a biomarker of stage. We suggest that peripheral BDNF may, in future, be used as a part of a blood protein composite measure to assess disease activity in BD.

Omics-Based Biomarkers: Application of Metabolomics in Neuropsychiatric Disorders

One of the major concerns of modern society is to identify putative biomarkers that serve as a valuable early diagnostic tool to identify a subset of patients with increased risk to develop neuropsychiatric disorders. Biomarker identification in neuropsychiatric disorders is proposed to offer a number of important benefits to patient well-being, including prediction of forthcoming disease, diagnostic precision, and a level of disease description that would guide treatment choice. Nowadays, the metabolomics approach has unlocked new possibilities in diagnostics of devastating disorders like neuropsychiatric disorders. Metabolomics-based technologies have the potential to map early biochemical changes in disease and hence provide an opportunity to develop predictive biomarkers that can be used as indicators of pathological abnormalities prior to development of clinical symptoms of neuropsychiatric disorders. This review highlights different -omics strategies for biomarker discovery in neuropsychiatric disorders. We also highlight initial outcomes from metabolomics studies in psychiatric disorders such as schizophrenia, bipolar disorder, and addictive disorders. This review will also present issues and challenges regarding the implementation of the metabolomics approach as a routine diagnostic tool in the clinical laboratory in context with neuropsychiatric disorders.

Relationship between a BDNF gene polymorphism and the brain volume in treatment-naive patients with major depressive disorder: A VBM analysis of brain MRI

The brain-derived neurotrophic factor (BDNF) relates to basic neuronal functions, such as cell survival, axonal outgrowth, and dendritic growth. The Val66Met polymorphism of the BDNF gene may affect genetic susceptibility to major depressive disorder (MDD). We prospectively investigated the relationship between the Val66Met BDNF genotype and voxel-based morphometry (VBM) findings for first episode and drug-naïve MDD patients and healthy subjects (HS). Participants comprised 38 MDD patients and 42 age- and sex-matched HS were divided into groups based on their BDNF genotype. The effects of diagnosis and genotype, as well as the genotype-diagnosis interaction, in relation to brain morphology were evaluated using a voxel-by-voxel statistical analysis of high-resolution magnetic resonance imaging (MRI) findings. Among the Met-carriers, the volume of the left middle frontal gyrus (composition of the prefrontal cortex [PFC]) was significantly smaller for MDD patients than for the HS, i.e., there was a significant genotype-diagnosis interaction effect on brain morphology noted in the left PFC. The BDNF polymorphism was associated with atrophy of the PFC in MDD patients, which suggests that the BDNF Val66Met polymorphism may play an important role in the pathogenesis of early stages of MDD.

Plasma BDNFs level initially and post treatment in acute mania: comparison between ECT and atypical antipsychotic treatment and healthy controls

BACKGROUND

Inconsistent findings concerning brain-derived neurotrophic factor (BDNF) levels across different episodes in bipolar disorder have been reported, which is also in line with the treatment effects on BDNF levels in acute mania. We aimed to compare plasma BDNF level alterations after pure antipsychotic drug or ECT plus antipsychotic drug treatment in acute mania.

METHODS

Sixty-eight patients with mania were divided into two treatment arms: the antipsychotic treatment arm (AP) and electroconvulsive therapy (ECT)+AP arm. In addition, 30 healthy controls were included in the study.

RESULTS

There was no significant statistical difference according to mean age, education level, marital and working status between patients and healthy controls. The initial serum BDNF level in patients with acute mania was significantly lower than healthy controls. The initial BDNF level between the ECT arm and AP arm was not significant. The BDNF level decreased significantly after reaching remission in patients with acute mania. The change in BDNF level in the AP arm was not significant while in the ECT arm it was significant after treatment.

CONCLUSIONS

In this study, for the first time we revealed a significant decrease in BDNF levels after ECT sessions in acute manic patients. Besides clinical remission after treatment in acute mania, the decrement in BDNF levels does not seem to be related to clinical response. Thus cumulative effects of mood episodes for the ongoing decrease in BDNF levels might be borne in mind despite the achievement of remission and/or more time being required for an increase in BDNF levels after treatment.

The bipolar depression electrical treatment trial (BETTER): design, rationale, and objectives of a randomized, sham-controlled trial and data from the pilot study phase

Background. Bipolar depression (BD) is a prevalent condition, with poor therapeutic options and a high degree of refractoriness. This justifies the development of novel treatment strategies, such as transcranial direct current stimulation (tDCS) that showed promising results in unipolar depression. Methods. We describe a randomized, sham-controlled, double-blinded trial using tDCS for refractory, acutely symptomatic BD (the bipolar depression electrical treatment trial, BETTER). Sixty patients will be enrolled and assessed with clinical and neuropsychological tests. The primary outcome is change (over time and across groups) in the scores of the Hamilton Depression Rating Scale (17 items). Biological markers such as blood neurotrophins and interleukins, genetic polymorphisms, heart rate variability, and motor cortical excitability will be assessed. Twelve anodal-left/cathodal-right 2 mA tDCS sessions over the dorsolateral prefrontal cortex will be performed in 6 weeks. Results. In the pilot phase, five patients received active tDCS and were double-blindly assessed, two presenting clinical response. TDCS was well-tolerated, with no changes in cognitive scores. Conclusion. This upcoming clinical trial will address the efficacy of tDCS for BD on different degrees of refractoriness. The evaluation of biological markers will also help in understanding the pathophysiology of BD and the mechanisms of action of tDCS.

Glial pathology in bipolar disorder: potential therapeutic implications

Bipolar disorder (BD) is a chronic and severe mental disorder with recurrent episodes of mania and depression. In addition to neuronal alterations, accumulating evidences have revealed the importance of glial system in pathophysiology and phenotype of the illness. Postmortem studies have repeatedly demonstrated the alterations in glial cells and its functions in patients with BD. The activated microglia and inflammatory cytokines are proposed to be the potential biomarkers that may help to predict disease exacerbation in BD. On the other hand, anti-BD drugs have been shown to produce profound effects on glial activity, which not only contributes to the therapeutic efficacy, but may also provide a potential target for the drug development of BD. We will focus on the recent development of glial abnormalities and potential therapeutic benefits targeted to glial modulation in BD.

Correlation of plasma brain-derived neurotrophic factor and metabolic profiles in drug-naïve patients with bipolar II disorder after a twelve-week pharmacological intervention

OBJECTIVE

Brain-derived neurotrophic factor (BDNF) is thought to be involved in the pathophysiology of bipolar disorder (BD) and metabolic syndrome. We investigated the correlation between plasma BDNF with mood symptoms and metabolic indices in patients with BD-II over a 12-week pharmacological intervention.

METHOD

Drug-naïve patients with BD-II (n=117) were recruited. Metabolic profiles [cholesterol, triglyceride, HbA1C, fasting serum glucose, body mass index (BMI)] and plasma BDNF wtrun "tblautotrun "tblsctrun "tbl_contere measured at baseline and 2, 8, and 12 weeks after beginning medication. To adjust within-subject dependence over repeated assessments, multiple linear regressions with generalized estimating equation methods were used.

RESULTS

Seventy-six (65.0%) patients completed the intervention. Plasma BDNF levels were significantly associated with BMI (P=9.6E-5), low-density lipoprotein (P=0.034) and total (P=0.001) cholesterol, but not with the Hamilton Depression Rating Scale-17 and Young Mania Rating Scale scores over the 12-week treatment.

CONCLUSION

We found initial evidence of a positive correlation between plasma BDNF levels and BMI, low-density lipoprotein and total cholesterol in drug-naïve patients with BD-II. The specific function of BDNF in regulating and maintaining peripheral metabolic health requires additional investigation.

Riluzole stimulates BDNF release from human platelets

Brain-derived neurotrophic factor (BDNF) has several functions in the central nervous system, where it contributes to brain development and its functionality through affecting neuronal survival and activity and also modulating neurotransmitter levels. This neurotrophin is also found in the serum, but its origin and peripheral function remain unknown. Although the source of circulating BDNF is uncertain, it is stored in platelets and can be released through pharmacological treatment. Decreased levels of BDNF in the serum have been related to the pathophysiology of depression, and this relationship is reinforced by the reversal of this condition by treatment with antidepressants. Recently, riluzole has been proposed for the treatment of depression because it has the ability to lower extracellular glutamate levels and increase BDNF expression; and both mechanisms could be associated with its antidepressant action. Considering that riluzole enhances BDNF levels in the serum of patients, we investigated if treatment with this drug could stimulate the release of this neurotrophin from human platelets obtained from healthy subjects. When platelets were incubated with riluzole for 4 h, the basal value of BDNF (92.9 ± 11.1 pg 10(-6) platelets) was significantly increased (P < 0.05, n = 27). This stimulatory effect was achieved at low concentrations of riluzole (from 10 µM) and was not observed when platelets were incubated with the drug for 24 h. The direct action of riluzole evoking BDNF release from human platelets at therapeutic concentrations is important and may contribute to the understanding of its mechanisms of action in the treatment of depression.

Elevated neurotrophin-3 and neurotrophin 4/5 levels in unmedicated bipolar depression and the effects of lithium

BACKGROUND

Bipolar disorder (BD) has been associated with diverse abnormalities in neural plasticity and cellular resilience. Neurotrophin-3 (NT-3) and neurotrophin-4/5 (NT-4/5) support synaptic neuronal survival and differentiation. NT-3 and NT-4/5 levels were found to be altered in BD, potentially representing a physiological response against cellular stress. However, the use of psychopharmacological agents and heterogeneous mood states may constitute important biases in such studies. Thus, we aimed to assess NT-3 and NT-4/5 levels in medication-free BD type I or II individuals in a current depressive episode, before and after 6 weeks of lithium monotherapy and matched with healthy controls.

METHODS

Twenty-three patients with BD type I or II during a depressive episode and 28 healthy controls were studied. Patients were required to have a 21-item Hamilton Depression Rating Scale score ≥18 and had not undergone any psychopharmacological treatment for at least 6 weeks prior to study entry. Patients were treated with lithium for 6 weeks and plasma NT-3 and NT-4/5 levels were determined at baseline and endpoint using ELISA method.

RESULTS

Baseline plasma levels of both NT-3 and NT-4/5 were significantly increased in acutely depressed BD subjects in comparison to healthy controls (p=0.040 and 0.039, respectively). The NT-3 and NT-4/5 levels did not significantly change after lithium treatment. NT-3 and NT-4/5 levels were positively correlated to illness duration in BD (p=0.032 and 0.034, respectively).

CONCLUSION

Our findings suggest that NT-3 and NT-4/5 levels are increased in the depressive phase of BD, which seems directly associated with illness duration. The increased levels of NT-3 and NT-4/5 may underlie a biological response to cellular stress associated with the course of BD.

A Review of Biomarkers in Mood and Psychotic Disorders: A Dissection of Clinical vs. Preclinical Correlates

Despite significant research efforts aimed at understanding the neurobiological underpinnings of mood (depression, bipolar disorder) and psychotic disorders, the diagnosis and evaluation of treatment of these disorders are still based solely on relatively subjective assessment of symptoms as well as psychometric evaluations. Therefore, biological markers aimed at improving the current classification of psychotic and mood-related disorders, and that will enable patients to be stratified on a biological basis into more homogeneous clinically distinct subgroups, are urgently needed. The attainment of this goal can be facilitated by identifying biomarkers that accurately reflect pathophysiologic processes in these disorders. This review postulates that the field of psychotic and mood disorder research has advanced sufficiently to develop biochemical hypotheses of the etiopathology of the particular illness and to target the same for more effective disease modifying therapy. This implies that a "one-size fits all" paradigm in the treatment of psychotic and mood disorders is not a viable approach, but that a customized regime based on individual biological abnormalities would pave the way forward to more effective treatment. In reviewing the clinical and preclinical literature, this paper discusses the most highly regarded pathophysiologic processes in mood and psychotic disorders, thereby providing a scaffold for the selection of suitable biomarkers for future studies in this field, to develope biomarker panels, as well as to improve diagnosis and to customize treatment regimens for better therapeutic outcomes.

Brain-derived neurotrophic factor as a suicide factor in mental disorders

OBJECTIVE

Brain-derived neurotrophic factor (BDNF) plays a critical role in brain plasticity processes and serum levels have been demonstrated to be altered in patients with different mental disorder including suicidal behaviour. The objective of this study was to examine the association between serum BDNF levels as a possible peripheral indicator of suicide behaviour in subjects suffering from depression, personality disorders (PDs) and adjustment disorders (ADs) with or without suicide attempt.

METHODS

The research included 172 randomly selected individuals suffering from recurrent depressive disorder (RDD; F 33.2), emotionally unstable PD (F 60.3) and AD (F 43.2), with or without attempted suicide according to the criteria of the ICD-10 (International Statistical Classification of Diseases and Related Health Problems 10th Revision) and 60 phenotypically health control subjects. In the group of patients, 73% subjects took some form of psychopharmacotherapy. Serum BDNF levels were measured by enzyme linked immunosorbent assay.

RESULTS

Subjects with PD and AD with suicide attempts had significantly lower serum BDNF levels than those without suicide attempts. In groups of subjects with PD and AD, those taking psychopharmacotherapy had higher serum BDNF levels. In the group of subjects with RDD, there were no differences with respect to suicide attempts or psychopharmacotherapy. Logistical regression analysis was indicated that psychopharmacotherapy and serum BDNF levels statistically correlated with suicide attempts.

CONCLUSION

The lower levels of BDNF in subjects suffering from PD and AD with suicide attempts, suggest that the serum BDNF level is a potential marker of suicidal behaviour, independent of mental disorders.