Serum levels of brain-derived neurotrophic factor in major depressive disorder: state-trait issues, clinical features and pharmacological treatment

Omega-3 and omega-6 fatty acid levels in depressive and anxiety disorders

BACKGROUND

Blood levels of polyunsaturated fatty acids (PUFAs) have been associated to current depression. However, it is unclear whether this association extends to remitted depression and to anxiety disorders. This study examined the relationship of PUFAs with the presence and clinical characteristics of depressive and anxiety disorders.

METHODS

Cross-sectional data was used from the Netherlands Study of Depression and Anxiety, including persons with current pure depressive disorder (n=304), current pure anxiety disorder (n=548), current comorbid depressive and anxiety disorder (n=529), remitted depressive/anxiety disorder(s) (n=897), and healthy controls (n=634). Clinical characteristics included severity, subtypes, age of onset, duration of depression and anxiety and antidepressant use. Absolute values of omega-3 (N-3) and omega-6 (N-6) PUFAs and relative measures (as ratio of total Fatty Acids: the N-3:FA and N-6:FA ratio) in plasma were assessed using a nuclear magnetic resonance platform.

RESULTS

Compared to controls, current comorbid depressive and anxiety disorder patients had lower N-3 PUFA levels (Cohen's d=0.09, p=0.012), and lower N-3:FA ratios (p=0.002, Cohen's d=0.11) as did current pure depressive disorder patients (Cohen's d=0.13, p=0.021), whereas N-6 PUFA levels were not different. No differences in PUFA levels were found between remitted patients and controls. Within patients, lower N-3 PUFA levels were only associated with higher depression severity (Beta=-0.42, p=0.023), whereas for N-6 PUFA levels and other clinical characteristics no clear association was observed. PUFA alterations were not associated with pure anxiety.

CONCLUSION

It can be concluded that patients with a current depressive episode (especially the more severe cases with comorbid anxiety) have circulating N-3 PUFA levels lower than those in remission and healthy controls. No relationship was detected for N-6 PUFA levels.

Antidepressant-Like Effects of Acupuncture-Insights From DNA Methylation and Histone Modifications of Brain-Derived Neurotrophic Factor

Sensitive and stable biomarkers that facilitate depression detection and monitor the antidepressant efficiency are currently unavailable. Thus, the objective is to investigate the potential of DNA methylation and histone modifications of brain-derived neurotrophic factor (BDNF) in monitoring severity and antidepressive effects of acupuncture. The depression rat model was imitated by social isolation and chronic unpredicted mild stress (CUMS). The expression of serum BDNF was detected by enzyme-linked immunosorbent assay (ELISA), the hippocampal BDNF, acetylation levels in histone H3 lysine 9 (acH3K9), and HDAC2 by Western blot, the hippocampal mRNA of BDNF by RT-polymerase chain reaction (PCR). The DNA methylation patterns of the promoter I of BDNF was detected by MS-PCR. We investigated that the expression of BDNF in serum and hippocampus were significantly downregulated compared with controls. The same trend was found in mRNA of BDNF. Notably, acupuncture reversed the downregulation of BDNF in serum and hippocampus and mRNA of BDNF compared with model group. Acupuncture reversed the CUMS-induced downregulation of hippocampal acH3K9. On the contrary, the CUMS-induced upregulation of hippocampal HDAC2 in model group was significantly reversed by acupuncture. Collectively, the antidepressant effect of acupuncture might be mediated by regulating the DNA methylation and histone modifications of BDNF, which may represent novel biomaker for detection of depression and monitoring severity and antidepressive effects.

Relation of high neuroticism with increased methylation of the BDNF gene

BACKGROUND

Brain-derived neurotrophic factor (BDNF) is a neurotrophin that has an important function in neuroplasticity and neuronal development. It is suggested that increased methylation of the BDNF gene resulting in decreased BDNF activity is associated with depression. Meanwhile, neuroticism is a well-known risk factor for developing depression. In the present study, the relationship between methylation of the BDNF gene and personality traits including neuroticism was examined.

SUBJECTS AND METHODS

The subjects were 98 healthy Japanese. Methylation levels of the BDNF gene were determined by the bisulfite-pyrosequencing method. Personality traits including neuroticism were assessed by the NEO Personality Inventory-Revised.

RESULTS

There was a positive correlation between neuroticism scores and methylation levels of the BDNF gene. The subjects with higher neuroticism scores had higher levels of BDNF gene methylation compared with those with lower neuroticism scores. Meanwhile, other personality traits were not associated with BDNF gene methylation.

CONCLUSION

The present study suggests that high neuroticism is related to increased methylation of the BDNF gene.

Botanicals as Modulators of Neuroplasticity: Focus on BDNF

The involvement of brain-derived neurotrophic factor (BDNF) in different central nervous system (CNS) diseases suggests that this neurotrophin may represent an interesting and reliable therapeutic target. Accordingly, the search for new compounds, also from natural sources, able to modulate BDNF has been increasingly explored. The present review considers the literature on the effects of botanicals on BDNF. Botanicals considered were Bacopa monnieri (L.) Pennell, Coffea arabica L., Crocus sativus L., Eleutherococcus senticosus Maxim., Camellia sinensis (L.) Kuntze (green tea), Ginkgo biloba L., Hypericum perforatum L., Olea europaea L. (olive oil), Panax ginseng C.A. Meyer, Rhodiola rosea L., Salvia miltiorrhiza Bunge, Vitis vinifera L., Withania somnifera (L.) Dunal, and Perilla frutescens (L.) Britton. The effect of the active principles responsible for the efficacy of the extracts is reviewed and discussed as well. The high number of articles published (more than one hundred manuscripts for 14 botanicals) supports the growing interest in the use of natural products as BDNF modulators. The studies reported strengthen the hypothesis that botanicals may be considered useful modulators of BDNF in CNS diseases, without high side effects. Further clinical studies are mandatory to confirm botanicals as preventive agents or as useful adjuvant to the pharmacological treatment.

Seasonality and BDNF polymorphism influences depression outcome in patients with atopic dermatitis and psoriasis

OBJECTIVES

To examine the effect of seasonality and rs6265 genotype on depression outcome and brain-derived neurotrophic factor (BDNF) level with dermatitis patients from onset through remission.

METHODS

Atopic dermatitis (AD, 56) and psoriasis (PS, 33) patients and healthy controls (HC, 49) were recruited over the 2014 calendar year. Patients were subdivided by immunoglobulin E (IgE) sensitivity (AD only), season and rs6265 genotype. Assessments were performed at onset and week 10 (Hamilton Depression Rating Scale [HAM-D], SCORAD/PASI, IgE, BDNF). Patients received standard corticosteroid and antihistamine interventions.

RESULTS

All patients responded to corticosteroid treatment. Seasonally differential outcomes were observed in all groups. HAM-D was elevated at onset and improved over 10 weeks: AD cohort 1 (autumn/winter, AD-1) patients improved and AD cohort 2 (spring/summer, AD-2) patients remained elevated. BDNF levels were elevated in AD and seasonal differential: AD-2 declined at 10 weeks, whereas AD-1 remained high (intrinsic AD) or elevated further (extrinsic AD). PS cohort 2 declined to below control at 10 weeks. AD Val/Val had persistently elevated HAM-D and AD Val/Met were either normal (AD-1) or persistently elevated (AD-2).

CONCLUSIONS

Findings presented here suggest a strong influence of seasonality on depression outcome and BDNF expression in AD and PS and likely reflect separate patient populations which differentially respond to environment-based stressors.

Increased blood BDNF in healthy individuals with a family history of depression

The brain-derive neurotrophic factor (BDNF) may play an important role in the course of depression. We aimed to study the associations between peripheral whole blood BDNF levels in healthy individuals with and without a family history of depression. BDNF levels were significantly increased in healthy individuals with (n = 76), compared with healthy individuals without (n = 39) a family history of depression and persisted after adjustment for age and gender differences. Higher BDNF levels were associated with increasing age and seasonality. A family history of depression may contribute to an elevation of peripheral BDNF levels in healthy individuals.

Psychological sequelae of myocardial infarction

Patient with myocardial infarction (MI) are often affected by psychological disorders such as depression, anxiety, and post-traumatic stress disorder. Psychological disorders are disabling and have a negative influence on recovery, reduce the quality of life and causes high mortality rate in MI patients. Despite tremendous advancement in technologies, screening scales, and treatment strategies, psychological sequelae of MI are currently understudied, underestimated, underdiagnosed, and undertreated. Depression is highly prevalent in MI patients followed by anxiety and post-traumatic stress disorder. Pathophysiological factors involved in psychopathologies observed in patients with MI are sympathetic over-activity, hypothalamic-pituitary-adrenal axis dysfunction, and inflammation. Numerous preclinical and clinical studies evidenced a positive association between MI and psychopathologies with a common molecular pathophysiology. This review provides an update on diagnostic feature, prevalence, pathophysiology, clinical outcomes, and management strategies of psychopathologies associated with MI. Moreover, preclinical research findings on molecular mechanisms involved in post-MI psychopathologies and future therapeutic strategies have been outlined in the review.

The Comparison of Effectiveness of Various Potential Predictors of Response to Treatment With SSRIs in Patients With Depressive Disorder

The substantial non-response rate in depressive patients indicates a continuing need to identify predictors of treatment outcome. The aim of this 6-week, open-label study was (1) to compare the efficacy of a priori defined predictors: ≥20% reduction in MADRS score at week 1, ≥20% reduction in MADRS score at week 2 (RM ≥ 20% W2), decrease of cordance (RC), and increase of serum and plasma level of brain-derived neurotrophic factor at week 1; and (2) to assess whether their combination yields higher efficacy in the prediction of response to selective serotonin re-uptake inhibitors (SSRIs) than when used singly. Twenty-one patients (55%) achieved a response to SSRIs. The RM ≥20% W2 (areas under curve-AUC = 0.83) showed better predictive efficacy compared to all other predictors with the exception of RC. The identified combined model (RM ≥ 20% W2 + RC), which predicted response with an 84% accuracy (AUC = 0.92), may be a useful tool in the prediction of response to SSRIs.

Serum brain-derived neurotrophic factor (BDNF) in sleep-disordered patients: relation to sleep stage N3 and rapid eye movement (REM) sleep across diagnostic entities

Experimental and clinical evidence suggests an association between neuroplasticity, brain-derived neurotrophic factor and sleep. We aimed at testing the hypotheses that brain-derived neurotrophic factor is associated with specific aspects of sleep architecture or sleep stages in patients with sleep disorders. We included 35 patients with primary insomnia, 31 patients with restless legs syndrome, 17 patients with idiopathic hypersomnia, 10 patients with narcolepsy and 37 healthy controls. Morning serum brain-derived neurotrophic factor concentrations were measured in patients and controls. In patients, blood sampling was followed by polysomnographic sleep investigation. Low brain-derived neurotrophic factor levels were associated with a low percentage of sleep stage N3 and rapid eye movement sleep across diagnostic entities. However, there was no difference in brain-derived neurotrophic factor levels between diagnostic groups. Our data indicate that serum levels of brain-derived neurotrophic factor, independent of a specific sleep disorder, are related to the proportion of sleep stage N3 and REM sleep. This preliminary observation is in accordance with the assumption that sleep stage N3 is involved in the regulation of neuroplasticity.

Brain-derived neurotrophic factor Val66Met genotype modulates amygdala habituation

A deficit in amygdala habituation to repeated emotional stimuli may be an endophenotype of disorders characterized by emotion dysregulation, such as borderline personality disorder (BPD). Amygdala reactivity to emotional stimuli is genetically modulated by brain-derived neurotrophic factor (BDNF) variants. Whether amygdala habituation itself is also modulated by BDNF genotypes remains unknown. We used imaging-genetics to examine the effect of BDNF Val66Met genotypes on amygdala habituation to repeated emotional stimuli. We used functional magnetic resonance imaging (fMRI) in 57 subjects (19 BPD patients, 18 patients with schizotypal personality disorder [SPD] and 20 healthy controls [HC]) during a task involving viewing of unpleasant, neutral, and pleasant pictures, each presented twice to measure habituation. Amygdala responses across genotypes (Val66Met SNP Met allele-carriers vs. Non-Met carriers) and diagnoses (HC, BPD, SPD) were examined with ANOVA. The BDNF 66Met allele was significantly associated with a deficit in amygdala habituation, particularly for emotional pictures. The association of the 66Met allele with a deficit in habituation to unpleasant emotional pictures remained significant in the subsample of BPD patients. Using imaging-genetics, we found preliminary evidence that deficient amygdala habituation may be modulated by BDNF genotype.

Association of Val66Met polymorphism at brain derived neurotrophic factor gene with depression among Chinese adolescents after Wenchuan earthquake: An 18months longitudinal study

To longitudinally investigate the association of Val66Met polymorphism at brain derived neurotrophic factor (BDNF) gene (BDNF) with depression in Chinese Han adolescents after the 2008 Wenchuan earthquake, BDNF Val66Met was identified by polymerase chain reaction-restriction fragment length polymorphism analyses and verified by DNA sequencing. Depression was assessed by Beck Depression Inventory (BDI) among high school students at 6, 12 and 18months after the earthquake. The results showed that the females constantly had higher depression prevalence than the males during the follow-up in the Met allele carriers, but not in the Val/Val homozygotes. When compared to that at 6months, the prevalence was lowered at 12months in the male Met allele carriers, and at 18months in all the females and the male Met allele carriers. Moreover, the Met allele carriers had higher BDI scores than the Val/Val homozygotes only in the females at 18months. The females had higher BDI scores than the males constantly during the follow-up in the Met allele carriers and at 12months only in the Val/Val homozygotes. When compared to those at 12months, the scores decreased at 18months in all the females and the male Met allele carriers. In addition, the potential factors of prevalence or predictors of severity of depression were different between the Val/Val homozygotes and the Met allele carriers at different times after the earthquake. The results suggest that interactions may occur after stresses among BDNF Val66Met, gender and time course to influence depression. This may be one of the explanations for the inconsistent relationships reported before between depression and BDNF Val66Met and need to take into account for precision medical and more effective interference of depression in adolescents after disasters.

Illness severity and biomarkers in depression: Using a unidimensional rating scale to examine BDNF

BACKGROUND

Numerous studies have reported reduced peripheral brain-derived neurotrophic factor (BDNF) in major depression (MD). However, most of these studies used multidimensional depression rating scales, and failed to identify a relationship between BDNF levels and depression severity. Unidimensional scales are a more valid measure of syndrome severity. In these scales, items are ordered in increasing severity, so that as scores increase, syndrome severity increases; thus, each item adds unique information, and items can be totaled to a meaningful sum. The current study used the HAM-D6, a unidimensional measure of depression, to examine if it could identify a correlation between serum BDNF and depression severity.

METHODS

Serum BDNF levels and symptom severity were assessed in 163 depressed patients, including those with both unipolar (84.0%) and bipolar (16.0%) depression. The evaluation of depression severity included the total HAM-D17 and 3 subscales, including the HAM-D6.

RESULTS

On average, patients presented moderate to severe depression (HAM-D17=21.2±5.5). Overall BDNF levels were 60.4±22.6ng/mL. The correlation between serum BDNF and depression severity was modest and not different when assessed by the HAM-D6 subscale or the HAM-D17 as a whole (z=0.951; p=0.341), despite being statistically significant for the HAM-D6 (r=-0.185; p=0.019; 95% CI: -0.335 to -0.033), but not for the entire HAM-D17 (r=-0.127; p=0.108; 95% CI: -0.272 to 0.027).

CONCLUSION

We could not identify a strong relationship between serum BDNF levels and depression severity using the HAM-D6. This is in concordance with results of previous studies that reported no correlation between these variables, and indicates that the properties of the clinical measures used cannot explain the results these studies.

Association of lower serum Brain-derived neurotrophic factor levels with larger infarct volumes in acute ischemic stroke

OBJECTIVE

Brain-derived neurotrophic factor (BDNF) plays a potential role in stroke recovery, as it promotes plasticity. The aim of this study is to investigate the association between infarct volume using DWI and BDNF at admission in patients with acute ischemic stroke (AIS).

METHODS

The study population comprised consecutive patients with an AIS diagnosis who had been referred to our hospital between January 2015 and June 2016. The severity of stroke was evaluated by the National Institutes of Health Stroke Scale (NIHSS) at admission. Infarct volumes indicated by DWI were measured with MIPAV software. The relationship between median DWI infarct volume and serum BDNF level quartiles was evaluated using a semiparametric approach with univariate and multivariate quartile regression analysis.

RESULTS

In this study, 270 patients were included and met the study criteria. The median DWI infarct volumes for the serum BDNF level quartiles (lowest to highest) were 10.56, 5.13, 3.75 and 2.43ml. Nonparametric Spearman rank correlation revealed a statistically significant negative correlation between serum BDNF level and DWI infarct volume (r=-0.363; P<0.001). The median DWI infarct volume in the lowest BDNF quartile was significantly larger than those in the upper 3 quartiles (P<0.001). Further, median adjusted DWI infarct volumes (IQR) for each of the BDNF level quartiles were 7.77, 4.56, 3.75, and 2.43ml from lowest to highest quartiles.

CONCLUSIONS

Larger stroke infarct volumes using DWI are associated with lower levels of BDNF at admission. Further investigations are suggested to elucidate the role of BDNF as part of a potential neuroprotective strategy.

Serum levels of brain-derived neurotrophic factor are associated with depressive symptoms in patients with systemic lupus erythematosus

OBJECTIVE

The aim of this study was to explore potential relationships between serum BDNF levels and depression in systemic lupus erythematosus (SLE) patients.

METHODS

We included 208 consecutive SLE patients and 100 age-and sex-matched healthy controls. The presence of depressive symptoms was determined through the Beck Depression Inventory-II (BDI-II) score.

RESULTS

The serum BDNF levels were significantly (P<0.0001) higher in SLE patients as compared to normal controls. There was a negative correlation between levels of BDNF and the SLE disease activity index 2000 (SLEDAI-2K) (r=-0.349, P<0.0001). Depression (defined as BDI-II score≥18) was identified in 54 SLE patients (26.0%, 95%CI: 20%-31.9%). The serum BDNF levels were significantly lower in depression patients at the time of admission as compared with patients without depression [27.6(IQR, 23.2-30.4)ng/ml vs. 36.2(IQR, 31.7-42.3)ng/ml; P<0.0001]. Compared with the first quartile of serum BDNF levels, the second quartile OR for depression was 0.72 (95% CI, 0.61-0.80, P=0.033). For the third and fourth quartiles, it was 0.42 (95% CI, 0.33-0.52, P=0.002) and 0.16 (95% CI, 0.09-0.24; P<0.001).

CONCLUSION

Serum BDNF levels are decreased in SLE patients with depressive symptoms. In SLE, serum BNDF levels are independently associated with depressive disorders, suggesting the role of neurotrophic factors in depression.

Buyang Huanwu Decoction Ameliorates Poststroke Depression via Promoting Neurotrophic Pathway Mediated Neuroprotection and Neurogenesis

Objective. The aim of the present research is to investigate the therapeutic effect of Buyang Huanwu Decoction (BHD) in poststroke depression (PSD) animal model and illustrate its underlying mechanism via promoting neurotrophic pathway mediated neuroprotection and neurogenesis. Methods. To induce PSD rat model, isolation housed rats that received middle cerebral artery occlusion (MCAO) surgery successively suffered from chronic mild stress (CMS) treatment for consecutive twenty-one days. Meanwhile, rats were correspondingly given vehicle, BHD, and fluoxetine. Then, neurologic function was scored and depressive-like behaviors were assessed by sucrose preference test, locomotor activity, novelty-suppressed feeding test, and forced swim test. Thereafter, the neuroprotection and neurogenesis related molecular markers and signaling were detected. Results. We firstly observed a significant neurological function recovery and antidepressants effect of BHD after MCAO together with CMS treatment. Our study also found that treatment with BHD and fluoxetine can significantly rescue neurons from apoptosis and promote neurogenesis in the CA3 and DG regions in the hippocampus. Notably, BHD and fluoxetine treatment can activate BDNF/ERK/CREB signaling. Conclusion. The results suggest that BHD is a promising candidate for treating PSD. Its curative effects can be attributed to neurotrophic pathway mediated neuroprotection and neurogenesis.

Serum brain-derived neurotrophic factor and stability of depressive symptoms in coronary heart disease patients: A prospective study

OBJECTIVE

Brain-derived neurotrophic factor (BDNF) supports neurogenesis, angiogenesis, and promotes the survival of various cell types in the brain and the coronary system. Moreover, BDNF is associated with both coronary heart disease (CHD) and depression. The current study aims to investigate whether serum BDNF levels are associated with the course of depressive symptoms in CHD patients.

METHODS

At baseline, N=225 CHD patients were enrolled while hospitalized. Of these, N=190 (84%) could be followed up 6 months later. Depressive symptoms were assessed both at baseline and at the 6-months follow-up using the Patient Health Questionnaire (PHQ-9). Serum BDNF concentrations were measured using fluorometric Enzyme-linked immunosorbent assays (ELISA).

RESULTS

Logistic regression models showed that lower BDNF levels were associated with persistent depressive symptoms, even after adjustment for age, sex, smoking and potential medical confounders. The incidence of depressive symptoms was not related to lower BDNF levels. However, somatic comorbidity (as measured by the Charlson Comorbidity Index) was significantly associated with the incidence of depressive symptoms.

CONCLUSIONS

Our findings suggest a role of BDNF in the link between CHD and depressive symptoms. Particularly, low serum BDNF levels could be considered as a valuable biomarker for the persistence of depressive symptoms among depressed CHD patients.

Meta-analyses of comparative efficacy of antidepressant medications on peripheral BDNF concentration in patients with depression

Background

Brain derived neurotrophic factor (BDNF) is one of the most important regulatory proteins in the pathophysiology of major depressive disorder (MDD). Increasing numbers of studies have reported the relationship between serum/plasma BDNF and antidepressants (ADs). However, the potential effects of several classes of antidepressants on BDNF concentrations are not well known. Hence, our meta-analyses aims to review the effects of differential antidepressant drugs on peripheral BDNF levels in MDD and make some recommendations for future research.

Methods

Electronic databases including PubMed, EMBASE, the Cochrane Library, Web of Science, and PsycINFO were searched from 1980 to June 2016. The change in BDNF levels were compared between baseline and post-antidepressants treatment by use of the standardized mean difference (SMD) with 95% confidence intervals (CIs). All statistical tests were two-sided.

Results

We identified 20 eligible trials of antidepressants treatments for BDNF in MDD. The overall effect size for all drug classes showed that BDNF levels were elevated following a course of antidepressants use. For between-study heterogeneity by stratification analyses, we detect that length of treatment and blood samples are significant effect modifiers for BDNF levels during antidepressants treatment. While both SSRIs and SNRIs could increase the BDNF levels after a period of antidepressant medication treatment, sertraline was superior to other three drugs (venlafaxine, paroxetine or escitalopram) in the early increase of BDNF concentrations with SMD 0.53(95% CI = 0.13–0.93; P = 0.009).

Conclusions

There is some evidence that treatment of antidepressants appears to be effective in the increase of peripheral BDNF levels. More robust evidence indicates that different types of antidepressants appear to induce differential effects on the BDNF levels. Since sertraline makes a particular effect on BDNF concentration within a short amount of time, there is potential value in exploring its relationship with BDNF and its pharmacological mechanism concerning peripheral blood BDNF. Further confirmatory trials are required for both observations.

The Role of Nutrients in Protecting Mitochondrial Function and Neurotransmitter Signaling: Implications for the Treatment of Depression, PTSD, and Suicidal Behaviors

Numerous studies have linked severe stress to the development of major depressive disorder (MDD) and suicidal behaviors. Furthermore, recent preclinical studies from our laboratory and others have demonstrated that in rodents, chronic stress and the stress hormone cortisol cause oxidative damage to mitochondrial function and membrane lipids in the brain. Mitochondria play a key role in synaptic neurotransmitter signaling by providing adenosine triphosphate (ATP), mediating lipid and protein synthesis, buffering intracellular calcium, and regulating apoptotic and resilience pathways. Membrane lipids are similarly essential to central nervous system (CNS) function because cholesterol, polyunsaturated fatty acids, and sphingolipids form a lipid raft region, a special lipid region on the membrane that mediates neurotransmitter signaling through G-protein-coupled receptors and ion channels. Low serum cholesterol levels, low antioxidant capacity, and abnormal early morning cortisol levels are biomarkers consistently associated with both depression and suicidal behaviors. In this review, we summarize the manner in which nutrients can protect against oxidative damage to mitochondria and lipids in the neuronal circuits associated with cognitive and affective behaviors. These nutrients include ω3 fatty acids, antioxidants (vitamin C and zinc), members of the vitamin B family (Vitamin B12 and folic acid), and magnesium. Accumulating data have shown that these nutrients can enhance neurocognitive function, and may have therapeutic benefits for depression and suicidal behaviors. A growing body of studies suggests the intriguing possibility that regular consumption of these nutrients may help prevent the onset of mood disorders and suicidal behaviors in vulnerable individuals, or significantly augment the therapeutic effect of available antidepressants. These findings have important implications for the health of both military and civilian populations.

Role of brain-derived neurotrophic factor in the molecular neurobiology of major depressive disorder

Major depressive disorder (MDD) is one of the most common neuropsychiatric disorders, which affects up to 20% of people in their lifetime in the United States. The exact neurobiological mechanisms of MDD remain elusive, and the diagnostics are still uncertain. Basic and clinical research from recent years demonstrated that the etiology of MDD might be associated with genetic changes of neurotrophins, particularly brain-derived neurotrophic factor (BDNF). BDNF plays a key role in neuronal development and neurogenesis. However, the detailed mechanisms related to depression and antidepressant responses are not fully understood. This review summarizes the current knowledge of the causal relationship between BDNF and MDD, and describes the important role of BDNF in the progress of depression in animal models and patients with depressive disorders.

Peripheral Brain-Derived Neurotrophic Factor Levels in Alzheimer's Disease and Mild Cognitive Impairment: a Comprehensive Systematic Review and Meta-analysis

Alzheimer's disease (AD) is becoming a growing global problem, and there is an urgent need to identify reliable blood biomarkers of the risk and progression of this condition. A potential candidate is the brain-derived neurotrophic factor (BDNF), which modulates major trophic effects in the brain. However, findings are apparently inconsistent regarding peripheral blood BDNF levels in AD patients vs. healthy people. We thus performed a systematic review and meta-analysis of the studies that have examined peripheral BDNF levels in patients with AD or mild cognitive impairment (MCI) and healthy controls. We searched articles through PubMed, EMBASE, and hand searching. Over a total pool of 2061 potential articles, 26 met all inclusion criteria (including a total of 1584 AD patients, 556 MCI patients, and 1294 controls). A meta-analysis of BDNF levels between early AD and controls showed statistically significantly higher levels (SMD [95 % CI]: 0.72 [0.31, 1.13]) with no heterogeneity. AD patients with a low (<20) mini-mental state examination (MMSE) score had lower peripheral BDNF levels compared with controls (SMD [95 % CI]: -0.33 [-0.60, -0.05]). However, we found no statistically significant difference in blood (serum/plasma) BDNF levels between all AD patients and controls (standard mean difference, SMD [95 % CI]: -0.16 [-0.4, 0.07]), and there was heterogeneity among studies (P < 0.0001, I ² = 85.8 %). There were no differences in blood BDNF levels among AD or MCI patients vs. controls by subgroup analyses according to age, sex, and drug use. In conclusion, this meta-analysis shows that peripheral blood BDNF levels seem to be increased in early AD and decreased in AD patients with low MMSE scores respectively compared with their age- and sex-matched healthy referents. At present, however, this could not be concluded from individual studies.

The human BDNF gene: peripheral gene expression and protein levels as biomarkers for psychiatric disorders

Brain-derived neurotrophic factor (BDNF) regulates the survival and growth of neurons, and influences synaptic efficiency and plasticity. The human BDNF gene consists of 11 exons, and distinct BDNF transcripts are produced through the use of alternative promoters and splicing events. The majority of the BDNF transcripts can be detected not only in the brain but also in the blood cells, although no study has yet investigated the differential expression of BDNF transcripts at the peripheral level. This review provides a description of the human BDNF gene structure as well as a summary of clinical and preclinical evidence supporting the role of BDNF in the pathogenesis of psychiatric disorders. We will discuss several mechanisms as possibly underlying BDNF modulation, including epigenetic mechanisms. We will also discuss the potential use of peripheral BDNF as a biomarker for psychiatric disorders, focusing on the factors that can influence BDNF gene expression and protein levels. Within this context, we have also characterized, for we believe the first time, the expression of BDNF transcripts in the blood, with the aim to provide novel insights into the molecular mechanisms and signaling that may regulate peripheral BDNF gene expression levels.

7,8-Dihydroxyflavone, a Tropomyosin-Kinase Related Receptor B Agonist, Produces Fast-Onset Antidepressant-Like Effects in Rats Exposed to Chronic Mild Stress

OBJECTIVE

Brain-derived neurotrophic factor (BDNF) and its specific receptor, tropomyosin-related kinase (TrkB), play important roles in treating depression. In this experiment, we examined whether 7,8-dihydroxyflavone, a novel potent TrkB agonist, could reverse the behavioral and biochemical abnormalities induced by the chronic mild stress (CMS) paradigm in rats.

METHODS

SD rats were exposed to a battery of stressors for 56 days. 7,8-dihydroxyflavone (5 and 20 mg/kg) were administered intraperitoneally during the last 28 days of the CMS paradigm. Rats were tested in sucrose consumption test (SCT), forced-swimming test (FST) and elevated T-maze (ETM). Serum corticosterone levels and hippocampal BDNF levels of the rats were measured.

RESULTS

Four-week CMS on the rats induced their depression-like behavior in SCT. The CMS-reduced sucrose consumption was reversed starting from 7 days after the 7,8-dihydroxyflavone (20 mg/kg) treatment and remained across the subsequent treatment regime. 7,8-dihydroxyflavone, when given at 5 mg/kg for 3 weeks, reduced the immobility time in the FST in the CMS-subjected rats. Additionally, the 4-week treatment with 7,8-dihydroxyflavone (20 mg/kg) attenuated the CMS-induced increase in anxiety-like behavior in the ETM. For the CMS-subjected rats, 7,8-dihydroxyflavone treatment dose-dependently reduced their serum corticosterone levels but increased their hippocampal BDNF levels only at 5 mg/kg.

CONCLUSION

7,8-dihydroxyflavone was beneficial for both depression and anxiety-like behaviors, and may exert fast-onset antidepressant effects. This provides a new insight into the pharmacological management of depression.

Serum BDNF concentration after delivery is associated with development of postpartum depression: A 3-month follow up study

BACKGROUND

Our aim was to determine whether there is a relationship between serum brain-derived neurotrophic factor (BDNF) and postpartum depression (PPD) in a cohort Chinese population.

METHODS

From May 1, 2014, to September 30, 2014, all eligible women not on medication for depression giving birth at the Fourth Affiliated Hospital of Harbin Medical University were consecutively recruited and followed up for 3 months. At 3 months postpartum, women were screened for depression using the Edinburgh Postnatal Depression Scale (EPDS). The primary outcome measure was an EPDS score of > or =12. Enzyme-linked immunosorbent assay (ELISA) was used to measure serum levels of BDNF at admission. Multivariate analyses were performed using logistic regression models.

RESULTS

During the study period, 340 women were enrolled and completed follow-up. In those women, 37 women (10.9%) were considered as meeting criteria for PPD. Serum BDNF levels in women without PPD were significantly higher than those in women with PPD (P<0.0001). Based on the ROC curve, the optimal cutoff value of serum BDNF levels as an indicator for screening of PPD was estimated to be 12.0ng/ml, which yielded a sensitivity of 82.8% and a specificity of 72.6%, with the area under the curve at 0.809 (95%CI, 0.731-0.887). In multivariate analysis, there was an increased risk of PPD associated with BDNF levels ≤12.0ng/ml (OR 7.243, 95% CI: 3.883-12.746; P<0.0001) after adjusting for possible confounders.

CONCLUSION

The present study demonstrates a strong relationship between reduced serum BDNF levels at admission and the development of PPD within the 3 months.

Seeking an objective diagnosis of depression

Major depressive disorder (MDD: unipolar depression) is widely distributed in the USA and world-wide populations and it is one of the leading causes of disability in both adolescents and adults. Traditional diagnostic approaches for MDD are based on patient interviews, which provide a subjective assessment of clinical symptoms which are frequently shared with other maladies. Reliance upon clinical assessments and patient interviews for diagnosing MDD is frequently associated with misdiagnosis and suboptimal treatment outcomes. As such, there is increasing interest in the identification of objective methods for the diagnosis of depression. Newer technologies from genomics, transcriptomics, proteomics, metabolomics and imaging are technically sophisticated and objective but their application to diagnostic tests in psychiatry is still emerging. This brief overview evaluates the technical basis for these technologies and discusses how the extension of their clinical performance can lead to an objective diagnosis of MDD.

Epigenetics: An Emerging Framework for Advanced Practice Psychiatric Nursing

PURPOSE

The aims of this paper are to synthesize and report research findings from neuroscience and epigenetics that contribute to an emerging explanatory framework for advanced practice psychiatric nursing.

CONCLUSIONS

Discoveries in neuroscience and epigenetics reveal synergistic mechanisms that support the integration of psychotherapy, psychopharmacology, and psychoeducation in practice.

PRACTICE IMPLICATIONS

Advanced practice psychiatric nurses will benefit from an expanded knowledge base in neuroscience and epigenetics that informs and explains the scientific rationale for our integrated practice.

BDNF DNA methylation changes as a biomarker of psychiatric disorders: literature review and open access database analysis

Brain-derived neurotrophic factor (BDNF) plays an important role in nervous system development and function and it is well established that BDNF is involved in the pathogenesis of a wide range of psychiatric disorders. Recently, numerous studies have associated the DNA methylation level of BDNF promoters with certain psychiatric phenotypes. In this review, we summarize data from current literature as well as from our own analysis with respect to the correlation of BDNF methylation changes with psychiatric disorders and address questions about whether DNA methylation related to the BDNF can be useful as biomarker for specific neuropsychiatric disorders.

Synaptic alterations associated with depression and schizophrenia: potential as a therapeutic target

INTRODUCTION

In recent years, the concept of 'synaptopathy' has been extended from neurodegenerative and neurological disorders to psychiatric diseases. According to this nascent line of research, disruption in synaptic structure and function acts as the main determinant of mental illness. Therefore, molecular systems and processes crucial for synaptic activity may represent promising therapeutic targets.

AREAS COVERED

We review data on synaptic structural alterations in depression and schizophrenia and on specific molecular systems and/or mechanisms important for the maintenance of proper synaptic function. Specifically, we examine the involvement of the neuroligin system, the local protein translation, and the neurotrophin BDNF by reviewing clinical and preclinical studies, with particular attention to results provided by using animal models based on the role of stress in psychiatric diseases. Finally, we also discuss the impact of pharmacological treatment on these molecular systems/mechanisms.

EXPERT OPINION

The relevance of synaptic dysfunctions in psychiatric diseases is undoubted and the potential to normalize, ameliorate, and shape such alterations by acting on molecular systems crucial to ensure synaptic function property is fascinating. However, future studies are required to elucidate several open issues.

MeCP2 and the enigmatic organization of brain chromatin. Implications for depression and cocaine addiction

Methyl CpG binding protein 2 (MeCP2) is a highly abundant chromosomal protein within the brain. It is hence not surprising that perturbations in its genome-wide distribution, and at particular loci within this tissue, can result in widespread neurological disorders that transcend the early implications of this protein in Rett syndrome (RTT). Yet, the details of its role and involvement in chromatin organization are still poorly understood. This paper focuses on what is known to date about all of this with special emphasis on the relation to different epigenetic modifications (DNA methylation, histone acetylation/ubiquitination, MeCP2 phosphorylation and miRNA). We showcase all of the above in two particular important neurological functional alterations in the brain: depression (major depressive disorder [MDD]) and cocaine addiction, both of which affect the MeCP2 homeostasis and result in significant changes in the overall levels of these epigenetic marks.

The brain-derived neurotrophic factor pathway, life stress, and chronic multi-site musculoskeletal pain

Introduction

Brain-derived neurotrophic factor (BDNF) disturbances and life stress, both independently and in interaction, have been hypothesized to induce chronic pain. We examined whether (a) the BDNF pathway (val⁶⁶met genotype, gene expression, and serum levels), (b) early and recent life stress, and (c) their interaction are associated with the presence and severity of chronic multi-site musculoskeletal pain.

Methods

Cross-sectional data are from 1646 subjects of the Netherlands Study of Depression and Anxiety. The presence and severity of chronic multi-site musculoskeletal pain were determined using the Chronic Pain Grade (CPG) questionnaire. The BDNF val⁶⁶met polymorphism, BDNF gene expression, and BDNF serum levels were measured. Early life stress before the age of 16 was assessed by calculating a childhood trauma index using the Childhood Trauma Interview. Recent life stress was assessed as the number of recent adverse life events using the List of Threatening Events Questionnaire.

Results

Compared to val⁶⁶val, BDNF met carriers more often had chronic pain, whereas no differences were found for BDNF gene expression and serum levels. Higher levels of early and recent stress were both associated with the presence and severity of chronic pain (p < 0.001). No interaction effect was found for the BDNF pathway with life stress in the associations with chronic pain presence and severity.

Conclusions

This study suggests that the BDNF gene marks vulnerability for chronic pain. Although life stress did not alter the impact of BDNF on chronic pain, it seems an independent factor in the onset and persistence of chronic pain.

Electroconvulsive therapy (ECT) and aerobic exercise training (AET) increased plasma BDNF and ameliorated depressive symptoms in patients suffering from major depressive disorder

BACKGROUND

To treat patients suffering from major depressive disorder (MDD), research has focused on electroconvulsive therapy (ECT) and aerobic exercise training (AET). Brain derived neurotrophic factor (BDNF) seems to be key in MDD. The aims of the present study were therefore two-fold, to investigate in a three-arm interventional study the differential effects of ECT, ECT plus AET, and AET alone in patients suffering from TR-MDD on 1. depressive symptoms and 2. plasma BDNF (pBDNF).

METHODS

60 patients with MDD (mean age: 31 years; 31.6% female patients) were randomly assigned either to the ECT, ECT + AET, or AET condition. The AET condition consisted of treadmill exercise for 45 min, three times a week. Both depression severity and pBDNF levels were assessed at baseline and 4 weeks later. All patients were further treated with an SSRI standard medication.

RESULTS

pBDNF levels increased over time in all three study conditions, though, highest increase was observed in the ECT + EAT condition, and lowest increase was observed in the AET condition. Depressive symptoms decreased in all three conditions over time, though, strongest decrease was observed in the ECT + AET condition. The combination of ECT + AET led to significantly greater remission rates than in either the ECT or AET alone conditions. BDNF levels were not associated with symptoms of depression.

CONCLUSIONS

The pattern of results suggests that ECT, AET and particularly their combination are promising directions for the treatment of patients suffering from MDD, and that it remains unclear to what extent pBDNF is key and a reliable biomarker for MDD.

Exploring the Association between Serum BDNF and Attempted Suicide

Suicide is a leading cause of death and a significant public health concern. Brain-derived neurotrophic factor (BDNF), a protein important to nervous system function, has been implicated in psychiatric disorders and suicidal behaviour. We investigated the association between serum levels of BDNF and attempted suicide in a sample of 281 participants using a case-control study design. Participants were recruited from clinical and community settings between March 2011 and November 2014. Cases (individuals who had attempted suicide) (n = 84) were matched on sex and age (within five years) to both psychiatric controls (n = 104) and community controls (n = 93) with no history of suicide attempts. We collected fasting blood samples, socio-demographic information, physical measurements, and detailed descriptions of suicide attempts. We used linear regression analysis to determine the association between BDNF level (dependent variable) and attempted suicide (key exposure variable), adjusting for age, sex, body mass index, current smoking status, and antidepressant use. 250 participants were included in this analysis. In the linear regression model, attempted suicide was not significantly associated with BDNF level (β = 0.28, SE = 1.20, P = 0.82). Our findings suggest that no significant association exists between attempted suicide and BDNF level. However, the findings need to be replicated in a larger cohort study.

Increased brain-derived neurotrophic factor (BDNF) protein concentrations in mice lacking brain serotonin

The interplay between BDNF signaling and the serotonergic system remains incompletely understood. Using a highly sensitive enzyme-linked immunosorbent assay, we studied BDNF concentrations in hippocampus and cortex of two mouse models of altered serotonin signaling: tryptophan hydroxylase (Tph)2-deficient (Tph2 (-/-)) mice lacking brain serotonin and serotonin transporter (SERT)-deficient (SERT(-/-)) mice lacking serotonin re-uptake. Surprisingly, hippocampal BDNF was significantly elevated in Tph2 (-/-) mice, whereas no significant changes were observed in SERT(-/-) mice. Furthermore, BDNF levels were increased in the prefrontal cortex of Tph2 (-/-) but not of SERT(-/-) mice. Our results emphasize the interaction between serotonin signaling and BDNF. Complete lack of brain serotonin induces BDNF expression.

No effect of escitalopram versus placebo on brain-derived neurotrophic factor in healthy individuals: a randomised trial

OBJECTIVE

Brain-derived neurotrophic factor (BDNF) seems to play an important role in the course of depression including the response to antidepressants in patients with depression. We aimed to study the effect of an antidepressant intervention on peripheral BDNF in healthy individuals with a family history of depression.

METHODS

We measured changes in BDNF messenger RNA (mRNA) expression and whole-blood BDNF levels in 80 healthy first-degree relatives of patients with depression randomly allocated to receive daily tablets of escitalopram 10 mg versus placebo for 4 weeks.

RESULTS

We found no statistically significant difference between the escitalopram and the placebo group in the change in BDNF mRNA expression and whole-blood BDNF levels. Post hoc analyses showed a statistically significant negative correlation between plasma escitalopram concentration and change in whole-blood BDNF levels in the escitalopram-treated group.

CONCLUSION

The results of this randomised trial suggest that escitalopram 10 mg has no effect on peripheral BDNF levels in healthy individuals.

Serum BDNF levels before and after the development of mood disorders: a case-control study in a population cohort

Serum levels of brain-derived neurotrophic factor (BDNF) are low in major depressive disorder (MDD), and were recently shown to decrease in chronic depression, but whether this is a trait or state marker of MDD remains unclear. We investigated whether serum BDNF levels decrease before or after the developments of MDD and other mood disorders through a case-control study nested in a cohort of 1276 women aged 75-84 years in 2008. Psychiatrists using the Structured Clinical Interview for DSM-IV identified incident cases of mood disorders at follow-up surveys in 2010 and 2012: 28 of MDDs, 39 of minor depressive disorders (minDDs) and 8 of minor depressive episodes with a history of major depressive episodes (minDEs with MDE history). A total of 106 representative non-depressed controls were also identified in the 2012 follow-up. We assayed BDNF levels in preserved sera of cases and controls at baseline and at follow-up. Serum BDNF levels at baseline in cases of MDD, minDD or minDE with MDE history were no lower than those in controls. The decrease in the serum BDNF level from baseline to follow-up was greater in cases of MDD or minDE with MDE history than in controls or cases of minDD. These results show that serum BDNF levels are not a trait marker of MDD in old women but appeared to be a state marker. The different changes in BDNF levels among diagnostic groups suggest that MDD has a pathophysiologic relation to minDE with MDE history, rather than to minDD.

Antidepressant-like effects of sodium butyrate and its possible mechanisms of action in mice exposed to chronic unpredictable mild stress

Sodium butyrate (NaB) has exhibited neuroprotective activity. This study aimed to explore that NaB exerts beneficial effects on chronic unpredictable mild stress (CUMS)-induced depression-like behaviors and its possible mechanisms. The behavioral tests including sucrose preference test (SPT), open field test (OFT), tail suspension test (TST) and forced swimming test (FST) were to evaluate the antidepressant effects of NaB. Then changes of Nissl's body in the hippocampus, brain serotonin (5-HT) concentration, brain-derived neurotrophic factor (BDNF) and tight junctions (TJs) proteins level were assessed to explore the antidepressant mechanisms. Our results showed that CUMS caused significant depression-like behaviors, neuropathological changes, and decreased brain 5-HT concentration, TJs protein levels and BDNF expression in the hippocampus. However, NaB treatment significantly ameliorated behavioral deficits of the CUMS-induced mice, increased 5-HT concentration, increased BDNF expression, and up-regulated Occludin and zonula occludens-1(ZO-1) protein levels in the hippocampus, which demonstrated that NaB could partially restore CUMS-induced blood-brain barrier (BBB) impairments. Besides, the pathologic changes were alleviated. In conclusion, these results demonstrated that NaB significantly improved depression-like behaviors in CUMS-induced mice and its antidepressant actions might be related with, at least in part, the increasing brain 5-HT concentration and BDNF expression and restoring BBB impairments.

Brain-derived neurotrophic factor promoter methylation and cortical thickness in recurrent major depressive disorder

Recent studies have reported that methylation of the brain-derived neurotrophic factor (BDNF) gene promoter is associated with major depressive disorder (MDD). This study aimed to investigate the association between cortical thickness and methylation of BDNF promoters as well as serum BDNF levels in MDD. The participants consisted of 65 patients with recurrent MDD and 65 age- and gender-matched healthy controls. Methylation of BDNF promoters and cortical thickness were compared between the groups. The right medial orbitofrontal, right lingual, right lateral occipital, left lateral orbitofrontal, left pars triangularis, and left lingual cortices were thinner in patients with MDD than in healthy controls. Among the MDD group, right pericalcarine, right medical orbitofrontal, right rostral middle frontal, right postcentral, right inferior temporal, right cuneus, right precuneus, left frontal pole, left superior frontal, left superior temporal, left rostral middle frontal and left lingual cortices had inverse correlations with methylation of BDNF promoters. Higher levels of BDNF promoter methylation may be closely associated with the reduced cortical thickness among patients with MDD. Serum BDNF levels were significantly lower in MDD, and showed an inverse relationship with BDNF methylation only in healthy controls. Particularly the prefrontal and occipital cortices seem to indicate key regions in which BDNF methylation has a significant effect on structure.

BDNF in sleep, insomnia, and sleep deprivation

The protein brain-derived neurotrophic factor (BDNF) is a member of the neurotrophin family of growth factors involved in plasticity of neurons in several brain regions. There are numerous evidence that BDNF expression is decreased by experiencing psychological stress and that, accordingly, a lack of neurotrophic support causes major depression. Furthermore, disruption in sleep homeostatic processes results in higher stress vulnerability and is often associated with stress-related mental disorders. Recently, we reported, for the first time, a relationship between BDNF and insomnia and sleep deprivation (SD). Using a biphasic stress model as explanation approach, we discuss here the hypothesis that chronic stress might induce a deregulation of the hypothalamic-pituitary-adrenal system. In the long-term it leads to sleep disturbance and depression as well as decreased BDNF levels, whereas acute stress like SD can be used as therapeutic intervention in some insomniac or depressed patients as compensatory process to normalize BDNF levels. Indeed, partial SD (PSD) induced a fast increase in BDNF serum levels within hours after PSD which is similar to effects seen after ketamine infusion, another fast-acting antidepressant intervention, while traditional antidepressants are characterized by a major delay until treatment response as well as delayed BDNF level increase. Key messages Brain-derived neurotrophic factor (BDNF) plays a key role in the pathophysiology of stress-related mood disorders. The interplay of stress and sleep impacts on BDNF level. Partial sleep deprivation (PSD) shows a fast action on BDNF level increase.

A novel herbal treatment reduces depressive-like behaviors and increases brain-derived neurotrophic factor levels in the brain of type 2 diabetic rats

BACKGROUND

Radix Puerariae and hawthorn fruit have been demonstrated to treat diabetes. They offer potential benefits for preventing depression in diabetes.

OBJECTIVE

The aim of this study was to investigate whether the combination of Radix Puerariae and hawthorn fruit (CRPHF) could prevent depression in a diabetic rat model generated by feeding the rats with a high-fat diet and a low-dose streptozotocin (STZ).

METHODS

The CRPHF was provided by the Shanghai Chinese Traditional Medical University. Twenty-four rats were randomly divided into four groups: normal control, normal-given-CRPHF (NC), diabetic control, and diabetic-given-CRPHF (DC) groups. The type 2 diabetic model was created by feeding the rats with a high-fat diet for 4 weeks followed by injection of 25 mg/kg STZ. CRPHF was given at 2 g/kg/d to the rats of NC and DC groups by intragastric gavage daily for 4 weeks after the type 2 diabetic model was successfully created. Body weight, random blood glucose (RBG), oral glucose tolerance test, total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) were measured during the study. Depressive-like behavior was evaluated at the end of the treatment by using the open field test (OFT), the elevated plus-maze test (EPMT), locomotor activity test (LAT), and forced swimming test (FST). Levels of extracellular signal-regulated protein kinase (ERK) and brain-derived neurotrophic factor (BDNF) in the prefrontal cortex were evaluated by using Western blot.

RESULTS

1) CRPHF reduced RBG and improved glucose tolerance in diabetic rats; 2) CRPHF reduced TC and TG but did not significantly change HDL-C or LDL-C in diabetic rats; 3) CRPHF reversed the loss in body weights observed in diabetic rats; 4) CRPHF reduced depressive-like behavior as measured by OFT, EPMT, LAT, and FST; 5) BDNF was upregulated, and ERK was activated in the prefrontal cortex of diabetic rats treated with CRPHF.

CONCLUSION

CRPHF has the potential of preventing depression in patients with diabetes.

Is there Progress? An Overview of Selecting Biomarker Candidates for Major Depressive Disorder

Major depressive disorder (MDD) contributes to a significant worldwide disease burden, expected to be second only to heart disease by 2050. However, accurate diagnosis has been a historical weakness in clinical psychiatry. As a result, there is a demand for diagnostic modalities with greater objectivity that could improve on current psychiatric practice that relies mainly on self-reporting of symptoms and clinical interviews. Over the past two decades, literature on a growing number of putative biomarkers for MDD increasingly suggests that MDD patients have significantly different biological profiles compared to healthy controls. However, difficulty in elucidating their exact relationships within depression pathology renders individual markers inconsistent diagnostic tools. Consequently, further biomarker research could potentially improve our understanding of MDD pathophysiology as well as aid in interpreting response to treatment, narrow differential diagnoses, and help refine current MDD criteria. Representative of this, multiplex assays using multiple sources of biomarkers are reported to be more accurate options in comparison to individual markers that exhibit lower specificity and sensitivity, and are more prone to confounding factors. In the future, more sophisticated multiplex assays may hold promise for use in screening and diagnosing depression and determining clinical severity as an advance over relying solely on current subjective diagnostic criteria. A pervasive limitation in existing research is heterogeneity inherent in MDD studies, which impacts the validity of biomarker data. Additionally, small sample sizes of most studies limit statistical power. Yet, as the RDoC project evolves to decrease these limitations, and stronger studies with more generalizable data are developed, significant advances in the next decade are expected to yield important information in the development of MDD biomarkers for use in clinical settings.

BDNF methylation and depressive disorder in acute coronary syndrome: The K-DEPACS and EsDEPACS studies

OBJECTIVE

Epigenetic regulation investigated by methylation tests has been associated with pathogenesis and treatment response in depressive disorders. However, these hypotheses have rarely been tested in patients with acute coronary syndrome (ACS) vulnerable to depression. This study aimed to investigate whether brain derived neurotrophic factor (BDNF) methylation status is associated with occurrence and treatment response of depressive disorder in ACS.

METHODS

Of 969 patients with recently developed ACS were recruited at baseline, 711 were followed 1 year thereafter. Depressive disorder was diagnosed according to DSM-IV criteria, and classified as baseline prevalent, and follow-up incident or persistent depressive disorder according to status at the two examinations. In addition, of 378 baseline participants with depressive disorder, 255 were randomized to a 24-week double blind trial of escitalopram (N=127) or placebo (N=128), while the remaining 123 received conventional medical treatment for ACS. BDNF methylation percentages were estimated using leukocyte DNA, and a range of demographic and clinical characteristics were evaluated as covariates.

RESULTS

In logistic regression models, higher BDNF methylation status was independently associated with prevalent depressive disorder at baseline and with its persistence at follow-up. Escitalopram was more effective than placebo for treating depressive disorder in those with a higher methylation, and this effects lead to prevent persistent depressive disorder.

CONCLUSIONS

ACS patients with higher BDNF methylation were susceptible to early depressive disorder, and to its persistence one year later. Adequate antidepressants treatment may effective particularly in those with higher BDNF methylation and then can overcome epigenetic vulnerability for depression persistence in ACS patients. ClinicalTrial.gov identifier for the 24 week drug trial, NCT00419471.

Neurodevelopment and ages of onset in depressive disorders

How and why do clinical depressive disorders emerge in adolescence? In this Personal View, we present a neurodevelopmental theory to address causes for adolescent onsets of clinical depressive disorders. We argue that theories should account for three perplexing aspects of depressive disorders in adolescence: the episodic nature of depression; differences between sexes in rates of depression across development; and age-differentiated onsets. We consider how theories such as psychosocial acceleration, heterochronic brain development, dual-process models, glucocorticoid vulnerability hypothesis linked to early life stress, and epigenetic and genetic susceptibility might explain some aspects of adolescent depressive disorders. We argue that some synthesis between existing theories might be needed to establish a sufficient neurodevelopmental theoretical framework to explain onsets of depressive disorders in adolescence.

Serum BDNF as a peripheral biomarker of treatment-resistant depression and the rapid antidepressant response: A comparison of ketamine and ECT

BACKGROUND

Ketamine is associated with rapid antidepressant efficacy but the biological mechanisms underpinning this effect are unclear. Serum brain-derived neurotrophic factor (sBDNF) is a potential circulating biomarker of treatment-resistant depression (TRD) and ketamine response but it is unclear if this is a common target of both ketamine and electroconvulsive therapy (ECT), the current gold standard for TRD. Moreover, the impact of multiple ketamine infusions on sBDNF has not yet been established.

METHODS

Thirty five TRD patients with a current DSM-IV diagnosis of recurrent depressive disorder received up to 12 ECT sessions (N=17) or up to three intravenous infusions of low-dose (0.5mg/kg) ketamine (N=18). Blood samples were taken over the course of the study for assessment of sBDNF. Symptom severity and response were monitored using the 17-item Hamilton Depression Rating Scale (HDRS). sBDNF was assessed in 20 healthy controls to allow comparison with TRD patients.

RESULTS

As expected, sBDNF was lower in TRD patients at baseline compared to healthy controls. Ketamine and ECT treatment were both associated with significant reductions in depressive symptoms. However, sBDNF was significantly elevated only at one week following the first ketamine infusion in those classified as responders one week later. sBDNF was not elevated following subsequent infusions. ECT reduced depressive symptoms, as expected, but was not associated with an enhancement in BDNF.

LIMITATIONS

Patients continued with their psychotropic medications throughout this trial.

CONCLUSIONS

SBDNF normalisation does not appear to be a prerequisite for symptomatic improvement in TRD following ketamine or ECT treatment.

Brain-derived neurotrophic factor serum levels in genetically isolated populations: gender-specific association with anxiety disorder subtypes but not with anxiety levels or Val66Met polymorphism

Anxiety disorders (ADs) are disabling chronic disorders with exaggerated behavioral response to threats. This study was aimed at testing the hypothesis that ADs may be associated with reduced neurotrophic activity, particularly of Brain-derived neurotrophic factor (BDNF), and determining possible effects of genetics on serum BDNF concentrations. In 672 adult subjects from six isolated villages in North-Eastern Italy with high inbreeding, we determined serum BDNF levels and identified subjects with different ADs subtypes such as Social and Specific Phobias (PHSOC, PHSP), Generalized Anxiety Disorder (GAD), and Panic Disorder (PAD). Analysis of the population as a whole or individual village showed no significant correlation between serum BDNF levels and Val66Met polymorphism and no association with anxiety levels. Stratification of subjects highlighted a significant decrease in serum BDNF in females with GAD and males with PHSP. This study indicates low heritability and absence of any impact of the Val66Met polymorphism on circulating concentrations of BDNF. Our results show that BDNF is not a general biomarker of anxiety but serum BDNF levels correlate in a gender-specific manner with ADs subtypes.

First evidence for glial pathology in late life minor depression: S100B is increased in males with minor depression

Minor depression is diagnosed when a patient suffers from 2 to 4 depressive symptoms for at least 2 weeks. Though minor depression is a widespread phenomenon, its pathophysiology has hardly been studied. To get a first insight into the pathophysiological mechanisms underlying this disorder we assessed serum levels of biomarkers for plasticity, glial and neuronal function: brain-derived neurotrophic factor (BDNF), S100B and neuron specific enolase (NSE). 27 subjects with minor depressive episode and 82 healthy subjects over 60 years of age were selected from the database of the Leipzig population-based study of civilization diseases (LIFE). Serum levels of BDNF, S100B and NSE were compared between groups, and correlated with age, body-mass index (BMI), and degree of white matter hyperintensities (score on Fazekas scale). S100B was significantly increased in males with minor depression in comparison to healthy males, whereas other biomarkers did not differ between groups (p = 0.10–0.66). NSE correlated with Fazekas score in patients with minor depression (r_s = 0.436, p = 0.048) and in the whole sample (r_s = 0.252, p = 0.019). S100B correlated with BMI (r_s = 0.246, p = 0.031) and with age in healthy subjects (r_s = 0.345, p = 0.002). Increased S100B in males with minor depression, without alterations in BDNF and NSE, supports the glial hypothesis of depression. Correlation between white matter hyperintensities and NSE underscores the vascular hypothesis of late life depression.

Serum brain-derived neurotrophic factor levels and psychotic symptoms in heroin dependence

OBJECTIVES

Psychotic symptoms are commonly observed among heroin users. Low serum brain-derived neurotrophic factor (BDNF) levels have been reported in schizophrenia and psychosis; however, studies assessing the relationship between serum BDNF levels and psychotic symptoms in heroin dependence are lacking.

METHOD

A total of 31 heroin-dependent patients who had never experienced psychotic symptoms during heroin consumption and 21 patients with a history of psychotic symptoms were consecutively recruited. We measured by enzyme-linked immunosorbent assay (ELISA) serum BDNF levels during early abstinence. A gender- and age-matched sample of healthy controls was also recruited and underwent measurement of BDNF.

RESULTS

BDNF levels were significantly lower in patients with psychotic symptoms than in those without psychotic symptoms (P<0.001). BDNF levels were not found to be correlated with sex, age, age of onset, duration of heroin use, average daily dose of heroin use, frequency of heroin use, SDS scores, BAI scores and BDI scores in the psychotic subsamples (all P>0.05).

CONCLUSIONS

Our findings suggest that heroin-dependent patients with psychotic symptoms share some of the neurotrophic insult that characterizes schizophrenia and psychosis.