Blood levels of brain derived neurotrophic factor in women with bipolar disorder and healthy control women

Associations of BDNF/BDNF-AS SNPs with Depression, Schizophrenia, and Bipolar Disorder

Brain-Derived Neurotrophic Factor (BDNF) is crucial for various aspects of neuronal development and function, including synaptic plasticity, neurotransmitter release, and supporting neuronal differentiation, growth, and survival. It is involved in the formation and preservation of dopaminergic, serotonergic, GABAergic, and cholinergic neurons, facilitating efficient stimulus transmission within the synaptic system and contributing to learning, memory, and overall cognition. Furthermore, BDNF demonstrates involvement in neuroinflammation and showcases neuroprotective effects. In contrast, BDNF antisense RNA (BDNF-AS) is linked to the regulation and control of BDNF, facilitating its suppression and contributing to neurotoxicity, apoptosis, and decreased cell viability. This review article aims to comprehensively overview the significance of single nucleotide polymorphisms (SNPs) in BDNF/BDNF-AS genes within psychiatric conditions, with a specific focus on their associations with depression, schizophrenia, and bipolar disorder. The independent influence of each BDNF/BDNF-AS gene variation, as well as the interplay between SNPs and their linkage disequilibrium, environmental factors, including early-life experiences, and interactions with other genes, lead to alterations in brain architecture and function, shaping vulnerability to mental health disorders. The potential translational applications of BDNF/BDNF-AS polymorphism knowledge can revolutionize personalized medicine, predict disease susceptibility, treatment outcomes, and guide the selection of interventions tailored to individual patients.

MTORC1 signaling as a biomarker in major depressive disorder and its pharmacological modulation by novel rapid-acting antidepressants

Major depressive disorder (MDD) is a multifactorial psychiatric disorder with obscure pathophysiology. A biomarker-based approach in combination with standardized interview-based instruments is needed to identify MDD subtypes and novel therapeutic targets. Recent findings support the impairment of the mammalian target of rapamycin complex 1 (mTORC1) in MDD. No well-established biomarkers of mTORC1 disease- and treatment-modulated activity are currently available for use in early phase antidepressant drug (AD) development. This review aims to summarize biomarkers of mTORC1 activity in MDD and to suggest how these could be implemented in future early clinical trials on mTORC1 modulating ADs. Therefore, a PubMed-based narrative literature review of the mTORC1 involvement in MDD was performed. We have summarized recent pre-clinical and clinical findings linking the MDD to the impaired activity of several key biomarkers related to mTORC1. Also, cases of restoration of these impairments by classical ADs and novel fast-acting investigational ADs are summarized. The presented biomarkers may be used to monitor pharmacological effects by novel rapid-acting mTORC1-targeting ADs. Based on findings in the peripheral blood mononuclear cells, we argue that those may serve as an ex vivo model for evaluation of mTORC1 activity and propose the use of the summarized biomarkers for this purpose. This could both facilitate the selection of a pharmacodynamically active dose and guide future early clinical efficacy studies in MDD. In conclusion, this review provides a blueprint for the rational development of rapid-acting mTORC1-targeting ADs.

Regular Leisure-Time Physical Activity is Effective in Boosting Neurotrophic Factors and Alleviating Menopause Symptoms

BACKGROUND

The study investigated the effects of regular leisure-time physical activity on the parameters of cognitive function (plasma brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), and cathepsin B) and menopausal symptoms (the climacterium, depression, and cognitive impairment) in obese middle-aged women.

METHODS

All subjects were middle-aged and obese women (n = 52, % body fat > 30%). The participants were divided into premenopausal (PRM) (n = 18, age = 47.56 ± 6.11 years) and postmenopausal (POM) (n = 34, age = 57.79 ± 5.68 years) groups. The participants completed a survey questionnaire related to depression and the climacterium, as well as cognitive tests. Physical activity was performed for 12 weeks. Blood samples from the forearm vein were analyzed after 12 h of fasting. Blood levels of BDNF, NGF, and cathepsin B were analyzed using an R&D kit.

RESULTS

Regular leisure-time physical activity had a positive effect on reducing the percentage of body fat in premenopausal and postmenopausal obese women. In addition, the results of the questionnaire showed that regular exercise had a positive effect on body composition caused by lifestyle change and enhanced psychological stability. The BDNF concentration was significantly lower in postmenopausal than in premenopausal obese women. In addition, regular physical activity significantly increased the cathepsin B and NGF levels in postmenopausal obese women.

CONCLUSIONS

Continuous leisure-time physical activity improved body composition and neurotrophic factors and alleviated menopausal symptoms in obese Korean women.

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.

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.

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.

Plasma brain-derived neurotrophic factor levels in patients suffering from post-traumatic stress disorder

A number of studies have been done to investigate the role of brain-derived neurotrophic factor (BDNF) in patients with post-traumatic stress disorder (PTSD). In this study we aimed to test the relationship between plasma BDNF levels and PTSD. We solicited 65 subjects having recently experienced road traffic accidents (RTA) conforming to screening criteria. They were given follow-up examinations after one month, three months, and six months. PTSD was diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-R-TR, American Psychiatric Association, 2000) using the Mini International Neuropsychiatric Interview (MINI). All participants were divided into two groups: a group with PTSD and a group without PTSD. There were no significant differences in plasma BDNF levels between the two groups at either the 48h or six-month examination. Within the PTSD group, no significant differences were found in plasma BDNF levels between the two examinations. BDNF levels in those without PTSD showed a higher trend over time after trauma. Higher BDNF levels may be an important protective factor for the prevention of traumatized subjects from developing PTSD.

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.

Plasma concentrations of BDNF and IGF-1 in abstinent cocaine users with high prevalence of substance use disorders: relationship to psychiatric comorbidity

Recent studies have identified biomarkers related to the severity and pathogenesis of cocaine addiction and common comorbid psychiatric disorders. Monitoring these plasma mediators may improve the stratification of cocaine users seeking treatment. Because the neurotrophic factors are involved in neural plasticity, neurogenesis and neuronal survival, we have determined plasma concentrations of brain-derived neurotrophic factor (BDNF), insulin-like growth factor 1 (IGF-1) and IGF-1 binding protein 3 (IGFBP-3) in a cross-sectional study with abstinent cocaine users who sought outpatient treatment for cocaine (n = 100) and age/body mass matched controls (n = 85). Participants were assessed with the diagnostic interview 'Psychiatric Research Interview for Substance and Mental Disorders'. Plasma concentrations of these peptides were not different in cocaine users and controls. They were not associated with length of abstinence, duration of cocaine use or cocaine symptom severity. The pathological use of cocaine did not influence the association of IGF-1 with age observed in healthy subjects, but the correlation between IGF-1 and IGFBP-3 was not significantly detected. Correlation analyses were performed between these peptides and other molecules sensitive to addiction: BDNF concentrations were not associated with inflammatory mediators, lipid derivatives or IGF-1 in cocaine users, but correlated with chemokines (fractalkine/CX3CL1 and SDF-1/CXCL12) and N-acyl-ethanolamines (N-palmitoyl-, N-oleoyl-, N-arachidonoyl-, N-linoleoyl- and N-dihomo-γ-linolenoyl-ethanolamine) in controls; IGF-1 concentrations only showed association with IGFBP-3 concentrations in controls; and IGFBP-3 was only correlated with N-stearoyl-ethanolamine concentrations in cocaine users. Multiple substance use disorders and life-time comorbid psychopathologies were common in abstinent cocaine users. Interestingly, plasma BDNF concentrations were exclusively found to be decreased in users diagnosed with both primary and cocaine-induced disorders for mood and anxiety disorders. In summary, BDNF, IGF-1 and IGFBP-3 were not affected by a history of pathological use of cocaine supported by the absence of associations with other molecules sensitive to cocaine addiction. However, BDNF was affected by comorbid mood disorders. Further research is necessary to elucidate the role of BDNF and IGF-1 in the transition to cocaine addiction and associated psychiatric comorbidity.

Association between brain-derived neurotrophic factor genetic polymorphism Val66Met and susceptibility to bipolar disorder: a meta-analysis

BACKGROUND

In view of previous conflicting findings, this meta-analysis was performed to comprehensively determine the overall strength of associations between brain-derived neurotrophic factor (BDNF) genetic polymorphism Val66Met and susceptibility to bipolar disorders (BPD).

METHODS

Literatures published and cited in Pubmed and Wanfang Data was searched with terms of 'Val66Met', 'G196A', 'rs6265', 'BDNF', 'association', and 'bipolar disorder' up to March 2014. All original case-control association studies were meta-analyzed with a pooled OR to estimate the risk and 95% confidence interval (CI) to reflect the magnitude of variance.

RESULTS

Twenty-one case-control association studies met our criteria for the meta-analysis. Overall, there was no significant difference in allelic distribution of Val66Met polymorphism between patients and controls with a pooled OR = 1.03 (95% CI 0.98, 1.08) although there was a trend towards association between Val66Met polymorphism and BPD in Caucasians with an OR of 1.08 (95% CI 1.00, 1.16). However, subgroup analyses showed that there was a significant association of Val allele with decreased disease susceptibility for bipolar disorder type II with a pooled OR of 0.88 (95% CI 0.78, 0.99).

CONCLUSIONS

There is no compelling evidence to supportVal66Met polymorphism in BDNF gene playing an important role in the susceptibility to BPD across different ethnicities.

Elevated levels of plasma brain derived neurotrophic factor in rapid cycling bipolar disorder patients

Impaired neuroplasticity may be implicated in the pathophysiology of bipolar disorder, involving peripheral alterations of the neurotrophins brain derived neurotrophic factor (BDNF) and neurotrophin 3 (NT-3). Evidence is limited by methodological issues and is based primarily on case-control designs. The aim of this study was to investigate whether BDNF and NT-3 levels differ between patients with rapid cycling bipolar disorder and healthy control subjects and whether BDNF and NT-3 levels alter with affective states in rapid cycling bipolar disorder patients. Plasma levels of BDNF and NT-3 were measured in 37 rapid cycling bipolar disorder patients and in 40 age- and gender matched healthy control subjects using enzyme-linked immunosorbent assay (ELISA). In a longitudinal design, repeated measurements of BDNF and NT-3 were evaluated in various affective states in bipolar disorder patients during a 6-12 months period and compared with repeated measurements in healthy control subjects. Careful attention was given to standardization of all procedures and adjustment for potential confounders of BDNF and NT-3. In linear mixed models, adjusting for demographical and lifestyle factors, levels of BDNF were significantly elevated in bipolar disorder patients in euthymic- (p<0.05), depressed- (p<0.005) and manic/hypomanic (p<0.005) states compared with healthy control subjects. Within bipolar disorder patients, adjusting for medication, there was no significant difference in BDNF levels between affective states, with equally elevated levels present in euthymic-, depressive- and manic/hypomanic patients. Levels of BDNF were higher in patients with longer duration of illness compared with patients with shorter duration of illness. We found no difference in NT-3 levels between bipolar disorder patients in any affective state compared with healthy control subjects and no difference in NT-3 levels between affective states in bipolar disorder patients. The results suggest that BDNF may be a marker related to illness stage in bipolar disorder, not varying with affective states in rapid cycling bipolar disorder patients. Due to the nature of comparison, it cannot be excluded that the finding of elevated BDNF levels in bipolar disorder patients compared with healthy controls could be influenced by medication.