The effect of depression, BDNF gene val66met polymorphism and gender on serum BDNF levels

Associations of brain-derived neurotrophic factor rs6265 polymorphism and cognitive function in breast cancer survivors from a cross-sectional study

BACKGROUND

Breast cancer survivors (BCS) often complain of cancer-related cognitive impairment (CRCI) during and even months after completing primary cancer treatments, particularly chemotherapy. The etiology of CRCI is unknown, but associations of CRCI with germline genetic polymorphisms have been reported, including Brain-Derived Neurotrophic Factor (BDNF) rs6265 polymorphism. The current study investigated the associations of specific BDNF rs6265 with CRCI.

METHODS

Cancer-related cognitive impairment was assessed using subjective reports of cognitive symptoms (the version 1.0, 8-item short-forms of the Patient-Reported Outcomes Measurement Information System®) and computerized objective cognitive function scores (CANTAB®). BDNF rs6265 genotypes were determined from buccal swabs. The associations of specific BDNF rs6265 with CRCI were examined by either one-way analysis of variance or the Kruskal-Wallis test followed by post hoc tests and rank-based regression analysis.

RESULTS

We examined 356 female BCS. The mean (SD) age was 55.6 (9.8) years old, the median (IQR) years since cancer diagnosis were 4.0 (6.0), and 331 (92.7%) were self-described as White. BCS carrying the Met/Met genotype showed poorer results on 'visual episodic memory and new learning' and 'spatial working memory and executive function.' This relationship was observed regardless of prior chemotherapy.

CONCLUSION

Our findings suggest that carrying the BDNF rs6265 Met/Met genotype increases the risk for CRCI in BCS. These results are foundational in nature and provide important information to identify mechanisms underpinning CRCI.

Analysis of EEG features and study of automatic classification in first-episode and drug-naïve patients with major depressive disorder

BACKGROUND

Major depressive disorder (MDD) has a high incidence and an unknown mechanism. There are no objective and sensitive indicators for clinical diagnosis.

OBJECTIVE

This study explored specific electrophysiological indicators and their role in the clinical diagnosis of MDD using machine learning.

METHODS

Forty first-episode and drug-naïve patients with MDD and forty healthy controls (HCs) were recruited. EEG data were collected from all subjects in the resting state with eyes closed for 10 min. The severity of MDD was assessed by the Hamilton Depression Rating Scale (HAMD-17). Machine learning analysis was used to identify the patients with MDD.

RESULTS

Compared to the HC group, the relative power of the low delta and theta bands was significantly higher in the right occipital region, and the relative power of the alpha band in the entire posterior occipital region was significantly lower in the MDD group. In the MDD group, the alpha band scalp functional connectivity was overall lower, while the scalp functional connectivity in the gamma band was significantly higher than that in the HC group. In the feature set of the relative power of the ROI in each band, the highest accuracy of 88.2% was achieved using the KNN classifier while using PCA feature selection. In the explanatory model using SHAP values, the top-ranking influence feature is the relative power of the alpha band in the left parietal region.

CONCLUSIONS

Our findings reveal that the abnormal EEG neural oscillations may reflect an imbalance of excitation, inhibition and hyperactivity in the cerebral cortex in first-episode and drug-naïve patients with MDD. The relative power of the alpha band in the left parietal region is expected to be an objective electrophysiological indicator of MDD.

Association between the BDNF Val66Met polymorphism and major depressive disorder: a systematic review and meta-analysis

Study objectives

This meta-analysis analytically reviewed recent studies concerning the potential associations between the brain-derived neurotrophic factor (BDNF) Val66Met polymorphism and susceptibility to major depressive disorder (MDD), with subgroup analyses for race and age.

Methods

Relevant case-control studies were systematically searched for in PubMed, Embase, the Web of Science, China National Knowledge Infrastructure (CNKI), Wanfang, and Sinomed databases. A total of 24 studies were finally identified to have reported outcomes including alleles, dominant genes, recessive genes, homozygosity, and heterozygosity. Subgroup meta-analyses were performed based on participant age and ethnicity. Publication bias was represented by funnel plots. All meta-analyses of the randomized controlled trials included for evaluation were performed using RevMan5.3 software.

Results

The findings revealed no significant association between BDNF Val66Met polymorphism and MDD. However, the Met allele was found to be associated with genetic susceptibility to MDD among white populations on subgroup analysis (OR = 1.25, 95% CI: 1.05-1.48, P = 0.01). In the genetic model, dominant (OR = 1.40, 95% CI: 1.18-1.66, P = 0.0001), recessive (OR = 1.70, 95% CI: 1.05-2.78, P = 0.03), and homozygous (OR = 1.77, 95% CI: 1.08-2.88, P = 0.02) genes were all associated with MDD.

Conclusions

Despite the outcome limitations, this meta-analysis confirmed that the BDNF Val66Met polymorphism is a susceptibility factor for MDD in white populations.

The Impact of BDNF, NTRK2, NGFR, CREB1, GSK3B, AKT, MAPK1, MTOR, PTEN, ARC, and SYN1 Genetic Polymorphisms in Antidepressant Treatment Response Phenotypes

This study aimed to investigate the influence of genetic variants in neuroplasticity-related genes on antidepressant treatment phenotypes. The BDNF-TrkB signaling pathway, as well as the downstream kinases Akt and ERK and the mTOR pathway, have been implicated in depression and neuroplasticity. However, clinicians still struggle with the unpredictability of antidepressant responses in depressed patients. We genotyped 26 polymorphisms in BDNF, NTRK2, NGFR, CREB1, GSK3B, AKT, MAPK1, MTOR, PTEN, ARC, and SYN1 in 80 patients with major depressive disorder treated according to the Texas Medical Algorithm for 27 months at Hospital Magalhães Lemos, Porto, Portugal. Our results showed that BDNF rs6265, PTEN rs12569998, and SYN1 rs1142636 SNP were associated with treatment-resistant depression (TRD). Additionally, MAPK1 rs6928 and GSK3B rs6438552 gene polymorphisms were associated with relapse. Moreover, we found a link between the rs6928 MAPK1 polymorphism and time to relapse. These findings suggest that the BDNF, PTEN, and SYN1 genes may play a role in the development of TRD, while MAPK1 and GSK3B may be associated with relapse. GO analysis revealed enrichment in synaptic and trans-synaptic transmission pathways and glutamate receptor activity with TRD-associated genes. Genetic variants in these genes could potentially be incorporated into predictive models of antidepressant response.

Brain-derived neurotrophic factor rs6265 (Val66Met) single nucleotide polymorphism as a master modifier of human pathophysiology

Brain-derived neurotrophic factor is the most prevalent member of the nerve growth factor family. Since its discovery in 1978, this enigmatic molecule has spawned more than 27,000 publications, most of which are focused on neurological disorders. Brain-derived neurotrophic factor is indispensable during embryogenesis and postnatally for the normal development and function of both the central and peripheral nervous systems. It is becoming increasingly clear, however, that brain-derived neurotrophic factor likewise plays crucial roles in a variety of other biological functions independently of sympathetic or parasympathetic involvement. Brain-derived neurotrophic factor is also increasingly recognized as a sophisticated environmental sensor and master coordinator of whole organismal physiology. To that point, we recently found that a common nonsynonymous (Val66→Met) single nucleotide polymorphism in the brain-derived neurotrophic factor gene (rs6265) not only substantially alters basal cardiac transcriptomics in mice but subtly influences heart gene expression and function differentially in males and females. In addition to a short description of recent results from associative neuropsychiatric studies, this review provides an eclectic assortment of research reports that support a modulatory role for rs6265 including and beyond the central nervous system.

BDNF Val66Met Moderates the Effects of Hypertension on Executive Functioning in Older Adults Diagnosed With aMCI

OBJECTIVE

To investigate whether the BDNF Val66Met polymorphism influences the associations of hypertension, executive functioning and processing speed in older adults diagnosed with amnestic Mild Cognitive Impairment (aMCI).

DESIGN

Secondary data analysis using moderation modeling.

SETTING

Veterans Affairs Hospital, Palo Alto, CA.

PARTICIPANTS

Sample included 108 community-dwelling volunteers (mean age 71.3 ± 9.2 years) diagnosed with aMCI.

MEASUREMENTS

Cognitive performance was evaluated from multiple baseline assessments (Trail Making Test; Stroop Color-Word Test; Symbol Digit Modality Test) and grouped into standardized composite scores representing executive function and processing speed domains. BDNF genotypes were determined from whole blood samples. Hypertension was assessed from resting blood pressures or by self-report.

RESULTS

Controlling for age, BDNF Val66Met moderated the effects of hypertension on executive functioning, but added no significant variance to processing speed scores. Specifically, hypertensive carriers of the BDNF Met allele performed significantly below the sample mean on tasks of executive functioning, and evidenced significantly lower scores when compared to Val-Val homozygotes and normotensive participants.

CONCLUSIONS

Results posit that the executive functioning of non-demented older adults may be susceptible to interactions between BDNF genotype and hypertension, and Val-Val homozygotes and normotensive older adults may be more resilient to these effects of cognitive change. Further research is needed to understand the underlying processes and to implement strategies that target modifiable risk factors and promote cognitive resilience.

Acute effects of two different work-to-rest ratio of high-intensity interval training on brain-derived neurotrophic factor in untrained young men

Background: Aerobic exercise could produce a positive effect on the brain by releasing brain-derived neurotrophic factor (BDNF). In untrained healthy humans there seems to be a linear correlation between exercise duration and the positive effect of acute aerobic exercise on brain-derived neurotrophic factor levels. Therefore, we performed two different duration of high-intensity interval training protocols (HIIT), both known to improve cardiovascular fitness, to determine whether then have a similar efficacy in affecting brain-derived neurotrophic factor levels.

Methods: 12 untrained young males (aged 23.7 ± 1.8 years), participated in a randomized controlled cross-over trial. They underwent two different work-to-rest ratio high-intensity interval training protocols: high-intensity interval training 1 (30 min, 15 intervals of 1 min efforts at 85%–90% VO2max with 1 min of active recovery at 50%–60% VO2max) and HIIT2 (30 min, 10 intervals of 2 min efforts at 85%–90% VO2max with 1 min of active recovery at 50%–60% VO2max). Serum cortisol, brain-derived neurotrophic factor were collected at baseline, immediately following intervention, and 30 min into recovery for measurements using a Sandwich ELISA method, blood lactate was measured by using a portable lactate analyzer.

Results: Our results showed that the similar serum brain-derived neurotrophic factor change in both high-intensity interval training protocols, with maximal serum brain-derived neurotrophic factor levels being reached toward the end of intervention. There was no significant change in serum brain-derived neurotrophic factor from baseline after 30 min recovery. We then showed that both high-intensity interval training protocols significantly increase blood lactate and serum cortisol compared with baseline value (high-intensity interval training p < 0.01; high-intensity interval training 2 p < 0.01), with high-intensity interval training 2 reaching higher blood lactate levels than high-intensity interval training 1 (p = 0.027), but no difference was observed in serum cortisol between both protocols. Moreover, changes in serum brain-derived neurotrophic factor did corelate with change in blood lactate (high-intensity interval training 1 r = 0.577, p < 0.05; high-intensity interval training 2 r = 0.635, p < 0.05), but did not correlate with the change in serum cortisol.

Conclusions: brain-derived neurotrophic factor levels in untrained young men are significantly increased in response to different work-to-rest ratio of high-intensity interval training protocols, and the magnitude of increase is exercise duration independent. Moreover, the higher blood lactate did not raise circulating brain-derived neurotrophic factor. Therefore, given that prolonged exercise causes higher levels of cortisol. We suggest that the 1:1work-to-rest ratio of high-intensity interval training protocol might represent a preferred intervention for promoting brain health.

A Brief Overview on BDNF-Trk Pathway in the Nervous System: A Potential Biomarker or Possible Target in Treatment of Multiple Sclerosis?

The growing incidence of neurodegenerative disorders in our populations is leading the research to identify potential biomarkers and targets for facilitating their early management and treatments. Biomarkers represent the crucial indicators of both physiological and pathological processes. Specific changes in molecular and cellular mechanisms of physiological processes result in biochemical alterations at systemic level, which can give us comprehensive information regarding the nature of any disease. In addition, any disease biomarker should be specific and reliable, able to consent of distinguishing the physiological condition of a tissue, organ, or system from disease, and be diverse among the various diseases, or subgroups or phenotypes of them. Accordingly, biomarkers can predict chances for diseases, facilitate their early diagnosis, and set guidelines for the development of new therapies for treating diseases and disease-making process. Here, we focus our attention on brain neurotrophic factor (BDNF)–tropomyosin receptor kinase (Trk) pathway, describing its multiple roles in the maintenance of central nervous system (CNS) health, as well as its implication in the pathogenesis of multiple sclerosis (MS). In addition, we also evidence the features of such pathway, which make of it a potential MS biomarker and therapeutic target.

Brain-derived neurotrophic factor and inflammation in depression: Pathogenic partners in crime?

Major depressive disorder is a debilitating disorder affecting millions of people each year. Brain-derived neurotrophic factor (BDNF) and inflammation are two prominent biologic risk factors in the pathogenesis of depression that have received considerable attention. Many clinical and animal studies have highlighted associations between low levels of BDNF or high levels of inflammatory markers and the development of behavioral symptoms of depression. However, less is known about potential interaction between BDNF and inflammation, particularly within the central nervous system. Emerging evidence suggests that there is bidirectional regulation between these factors with important implications for the development of depressive symptoms and anti-depressant response. Elevated levels of inflammatory mediators have been shown to reduce expression of BDNF, and BDNF may play an important negative regulatory role on inflammation within the brain. Understanding this interaction more fully within the context of neuropsychiatric disease is important for both developing a fuller understanding of biological pathogenesis of depression and for identifying novel therapeutic opportunities. Here we review these two prominent risk factors for depression with a particular focus on pathogenic implications of their interaction.

Exploring the association between brain-derived neurotrophic factor levels and longitudinal psychopathological and cognitive changes in Sardinian psychotic patients

Background and hypothesis

Schizophrenia spectrum disorders are among the most debilitating mental disorders and has complex pathophysiological underpinnings. There is growing evidence that brain-derived neurotrophic factor (BDNF) can play a role in its pathogenesis. The present study investigated the longitudinal variation of serum BDNF levels in a 24-month observational prospective cohort study of Sardinian psychotic patients and its relationship with psychopathological and cognitive changes. Furthermore, we examined whether genetic variation within the BDNF gene could moderate these relationships.

Study design

Every 6 months, 105 patients were assessed for their BDNF serum levels, as well as for a series of psychopathological, cognitive, and social measures. We performed a targeted analysis of four tag single nucleotide polymorphisms within the BDNF gene that were selected and analyzed using polymerase chain reaction. Longitudinal data were analyzed using mixed-effects linear regression models.

Study results

We observed a declining longitudinal trajectory of BDNF levels in psychotic patients in general, and in relation to the severity of depressive and negative symptoms. BDNF serum levels also declined in patients scoring lower in cognitive measures such as attention and speed of information processing and verbal fluency. The rs7934165 polymorphism moderated the significant association between verbal fluency and BDNF levels.

Conclusions

These findings in patients from real-world settings suggest a plausible role of peripheral BDNF levels as a marker of illness burden in schizophrenia spectrum disorders.

Ventromedial and insular cortical volume moderates the relationship between BDNF Val66Met and threat sensitivity

While the BDNF Val66Met polymorphism has been linked to various trauma and anxiety - related psychiatric disorders, limited focus has been on the neural structures that might modulate its relationship with objective measures of threat sensitivity. Therefore, we assessed whether there was an interaction of Val66Met polymorphism with brain area volumes previously associated with anxiety and PTSD, such as the ventromedial prefrontal cortex (vmPFC), insular cortex (IC), and dorsal and ventral anterior cingulate cortices (dACC and vACC), in predicting fear-potentiated psychophysiological response in a clinical sample of Veterans. 110 participants engaged in a fear-potentiated acoustic startle paradigm and provided genetic and imaging data. Fear conditions included no, ambiguous, and high threat conditions (shock). Psychophysiological response measures included electromyogram (EMG), skin conductance response (SCR), and heart rate (HR). PTSD status, trauma history, and demographics were also assessed. There was an interaction of Met allele carrier status with vmPFC, IC, dACC, and vACC volumes for predicting SCR (p < 0.001 for all regions). However, only vmPFC and IC significantly moderated the relationship between Val66Met and psychophysiological response (SCR). The Val66met polymorphism may increase susceptibility to PTSD and anxiety disorders via an interaction with reduced vmPFC and IC volume. Future research should examine whether these relationships might be associated with a differential course of illness longitudinally or response to treatments.

Association Between Components of Cognitive Reserve and Serum BDNF in Healthy Older Adults

Background: The brain-derived neurotrophic factor (BDNF) protein has been shown to have a prominent role in neuron survival, growth, and function in experimental models, and the BDNF Val66Met polymorphism which regulates its expression has been linked to resilience toward the effects of aging on cognition. Cognitively stimulating activity is linked to both increased levels of BDNF in the brain, and protection against age-related cognitive decline. The aim of this study was to investigate the associations between serum BDNF levels, the BDNF Val66Met genotype, and components of cognitive reserve in early and mid-life, measured with the Lifetime of Experiences Questionnaire (LEQ). Methods: Serum BDNF levels were measured cross-sectionally in 156 participants from the Tasmanian Healthy Brain Project (THBP) cohort, a study examining the potential benefits of older adults engaging in a university-level education intervention. Multiple linear regression was used to estimate serum BDNF's association with age, education, gender, BDNF Val66Met genotype, later-life university-level study, and cognitively stimulating activities measured by the LEQ. Results: Serum BDNF in older adults was associated with early life education and training, increasing 0.007 log(pg/ml) [95%CI 0.001, 0.012] per unit on the LEQ subscale. Conversely, education and training in mid-life were associated with a -0.007 log(pg/ml) [-0.012, -0.001] decrease per unit on the LEQ subscale. Serum BDNF decreased with age (-0.008 log(pg/ml) [-0.015, -0.001] per year), and male gender (-0.109 log(pg/ml) [-0.203, -0.015]), but mean differences between the BDNF Val66Met polymorphisms were not significant (p = 0.066). All effect sizes were small, with mid-life education and training having the largest effect size ( η p 2 = 0.044). Conclusion: Education in both early and mid-life explained small but significant amounts of variance in serum BDNF levels, more than age or gender. These effects were opposed and independent, suggesting that education at different stages of life may be associated with different cognitive and neural demands. Education at different stages of life may be important covariates when estimating associations between other exposures and serum BDNF.

Effect of interaction between obesity-promoting genetic variants and behavioral factors on the risk of obese phenotypes

The studies investigating gene-gene and gene-environment (or gene-behavior) interactions provide valuable insight into the pathomechanisms underlying obese phenotypes. The Pakistani population due to its unique characteristics offers numerous advantages for conducting such studies. In this view, the current study was undertaken to examine the effects of gene-gene and gene-environment/behavior interactions on the risk of obesity in a sample of Pakistani population. A total of 578 adult participants including 290 overweight/obese cases and 288 normal-weight controls were involved. The five key obesity-associated genetic variants namely MC4R rs17782313, BDNF rs6265, FTO rs1421085, TMEM18 rs7561317, and NEGR1 rs2815752 were genotyped using the TaqMan allelic discrimination assays. The data related to behavioral factors, such as eating pattern, diet consciousness, the tendency toward fat-dense food (TFDF), sleep duration, sleep-wake cycle (SWC), shift work (SW), and physical activity levels were collected via a questionnaire. Gene-gene and gene-behavior interactions were analyzed by multifactor dimensionality reduction and linear regression, respectively. In our study, only TMEM18 rs7561317 was found to be significantly associated with anthropometric traits with no significant effect of gene-gene interactions were observed on obesity-related phenotypes. However, the genetic variants were found to interact with the behavioral factors to significantly influence various obesity-related anthropometric traits including BMI, waist circumference, hip circumference, waist-to-hip ratio, waist-to-height ratio, and percentage of body fat. In conclusion, the interaction between genetic architecture and behavior/environment determines the outcome of obesity-related anthropometric phenotypes. Thus, gene-environment/behavior interaction studies should be promoted to explore the risk of complex and multifactorial disorders, such as obesity.

Frontotemporal Transcranial Direct Current Stimulation Decreases Serum Mature Brain-Derived Neurotrophic Factor in Schizophrenia

Although transcranial direct current stimulation (tDCS) shows promise as a treatment for auditory verbal hallucinations in patients with schizophrenia, mechanisms through which tDCS may induce beneficial effects remain unclear. Evidence points to the involvement of neuronal plasticity mechanisms that are underpinned, amongst others, by brain-derived neurotrophic factor (BDNF) in its two main forms: pro and mature peptides. Here, we aimed to investigate whether tDCS modulates neural plasticity by measuring the acute effects of tDCS on peripheral mature BDNF levels in patients with schizophrenia. Blood samples were collected in 24 patients with schizophrenia before and after they received a single session of either active (20 min, 2 mA, n = 13) or sham (n = 11) frontotemporal tDCS with the anode over the left prefrontal cortex and the cathode over the left temporoparietal junction. We compared the tDCS-induced changes in serum mature BDNF (mBDNF) levels adjusted for baseline values between the two groups. The results showed that active tDCS was associated with a significantly larger decrease in mBDNF levels (mean −20% ± standard deviation 14) than sham tDCS (−8% ± 21) (F = 5.387; p = 0.030; η² = 0.205). Thus, mature BDNF may be involved in the beneficial effects of frontotemporal tDCS observed in patients with schizophrenia.

BDNF affects the mediating effect of negative symptoms on the relationship between age of onset and cognition in patients with chronic schizophrenia

The age of onset of schizophrenia is related to variability in cognitive function and clinical characters, and negative symptoms and cognitive function share similar features that could be closely connected. Alterations in brain-derived neurotrophic factor (BDNF) expression and the Val66Met (rs6562) polymorphism are involved in the pathogenesis of the disease, but few studies have explored its influence on the associations of age of onset, cognitive function and clinical symptoms in schizophrenia. The clinical symptoms of a total of 573 patients with chronic schizophrenia were assessed by using the Positive and Negative Syndrome Scale (PANSS). Cognitive performance was assessed by the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). The serum BDNF level and Val66Met polymorphism were measured after the assessment. Our results showed the following: (1) patients with an earlier age of onset exhibited more negative symptoms and cognitive deficits, as well as lower levels of serum BDNF; (2) negative symptoms and cognitive function showed negative and positive correlations with age of onset, respectively, and worse cognitive function was associated with a high level of negative symptoms and a low level of serum BDNF; and (3) the moderated mediation analyses indicated that negative symptoms partially mediated the relationship between age of onset and cognitive deficits, which was moderated by serum BDNF. The mediating effect of negative symptoms exhibited a Met allele dose-dependent tendency. These results indicate that age of onset, cognitive function, and clinical symptoms of schizophrenia exhibit different relationships under different serum BDNF levels and BDNF Val66met polymorphisms.

BDNF influences neural cue-reactivity to food stimuli and food craving in obesity

There is increasing evidence that brain-derived neurotrophic factor (BDNF) impacts on the development of obesity. We are the first to test the hypothesis that BDNF levels might be associated with neural reactivity to food cues in patients suffering from obesity and healthy controls. We assessed visual food cue-induced neural response in 19 obese patients and 20 matched controls using functional magnetic resonance imaging and analyzed the associations between BDNF levels, food cue-reactivity and food craving. Whole-brain analysis in both groups revealed that food cues elicited higher neural activation in clusters of mesolimbic brain areas including the insula (food > neutral). Patients suffering from obesity showed a significant positive correlation between plasma BDNF levels and visual food cue-reactivity in the bilateral insulae. In addition, patients suffering from obesity with positive food cue-induced insula activation also reported significantly higher food craving than those with low cue-reactivity-an effect that was absent in normal weight participants. The present findings implicate that BDNF levels in patients suffering from obesity might be involved in food craving and obesity in humans. This highlights the importance to consider BDNF pathways when investigating obesity and obesity treatment.

Are serum brain-derived neurotrophic factor concentrations related to brain structure and psychopathology in late childhood and early adolescence?

OBJECTIVE

Mental disorders can have a major impact on brain development. Peripheral blood concentrations of brain-derived neurotrophic factor (BDNF) are lower in adult psychiatric disorders. Serum BDNF concentrations and BDNF genotype have been associated with cortical maturation in children and adolescents. In 2 large independent samples, this study tests associations between serum BDNF concentrations, brain structure, and psychopathology, and the effects of BDNF genotype on BDNF serum concentrations in late childhood and early adolescence.

METHODS

Children and adolescents (7-14 years old) from 2 cities (n = 267 in Porto Alegre; n = 273 in São Paulo) were evaluated as part of the Brazilian high-risk cohort (HRC) study. Serum BDNF concentrations were quantified by sandwich ELISA. Genotyping was conducted from blood or saliva samples using the SNParray Infinium HumanCore Array BeadChip. Subcortical volumes and cortical thickness were quantified using FreeSurfer. The Development and Well-Being Behavior Assessment was used to identify the presence of a psychiatric disorder.

RESULTS

Serum BDNF concentrations were not associated with subcortical volumes or with cortical thickness. Serum BDNF concentration did not differ between participants with and without mental disorders, or between Val homozygotes and Met carriers.

CONCLUSIONS

No evidence was found to support serum BDNF concentrations as a useful marker of developmental differences in brain and behavior in early life. Negative findings were replicated in 2 of the largest independent samples investigated to date.

BDNF polymorphisms across the spectrum of psychiatric morbidity: A protocol for a systematic review and meta-analysis

BACKGROUND

Nowadays, psychiatric morbidities are more and more common, which imposes huge social and economic burden on all countries across the world. Mental illnesses are found to be related to genetics. Over the past few years, a large number of risk genes and loci related to psychiatric morbidities have been reported. The brain-derived neurotrophic factor (BDNF) is one of the main candidates in neuropsychiatric genetics. However, different studies have shown inconsistencies regarding effect modification of BDNF polymorphisms on psychiatric morbidities. Therefore, in the present study, we aim to qualitatively and quantitatively summarize the relationship between BDNF single nucleotide polymorphisms (SNPs) and various psychiatric morbidities through a meta-analysis.

METHODS

PubMed, Web of Science and Embase will be searched using a specified search strategy to identify relevant studies up to April 2020. The meta-analysis will be performed on (1) allele model, (2) dominant model, (3) recessive model, (4) homozygote, and (5) heterozygote model. Sensitivity analyses will be conducted to explore the impact of individual studies on the overall result by evaluating the odd ratios (ORs) with their corresponding 95% confidence intervals (CIs) before and after removing each of the studies from our meta-analysis. Chi-square test will be used to determine whether the observed allele or genotype frequencies in the controls are consistent with HWE. The statistical heterogeneity will be verified by I statistics. The fixed effects model is needed to estimate the ORs and 95% CIs when there was no heterogeneity between results of included studies (I < 50%); instead, the random effects model should be used when results of included studies showed significant heterogeneity (I > 50%). Publication bias will be evaluated with the use of Begg test and Egger test (P < .05 is considered statistically significant).

DISCUSSION

With this protocol, a methodology is established that explores the effect modification of BDNF polymorphisms on the association with psychiatric morbidities. Findings from this meta-analysis can provide significant insight into the etiology of psychiatric morbidities.

REGISTRATION

Open Science Framework (OSF) Preregistration. September 15, 2020. OSF.IO/QS7XT.

Working memory moderates the relation between the brain-derived neurotropic factor (BDNF) and psychotherapy outcome for depression

BACKGROUND

Insight into patient characteristics that predict response to treatment for major depressive disorder (MDD) may help to personalize treatment and improve outcomes. One mechanism that has been linked to the success of treatment for MDD is brain-derived neurotropic factor (BDNF). BDNF is implicated in learning and memory and may play a role in the effects of psychotherapy that involves changing cognitions and behaviors. In addition, only in individuals with low BDNF, low working memory capacity has been associated with increased symptoms of depression. However, the role of BDNF and working memory capacity in psychotherapy outcome is unclear. The aim of this study was to investigate the role of BDNF and its interaction with working memory capacity in psychotherapy outcomes for MDD.

METHOD

Adult patients with MDD were randomized to weekly or twice weekly sessions of cognitive behavioral therapy or interpersonal psychotherapy. BDNF Val66Met polymorphism (rs6265) (n = 138) was defined and serum BDNF was quantified before (n = 138) and after psychotherapy (n = 82).

RESULTS

Baseline serum BDNF and the Val66Met polymorphism were not associated with outcome and associations did not differ between treatment conditions. Working memory capacity significantly moderated the relation between baseline serum BDNF and outcome: high serum BDNF at baseline was related to less depressive symptoms following psychotherapy in the presence of high working memory capacity, but not low working memory capacity.

DISCUSSION

These findings, if replicated, might indicate that while BDNF may not be related to psychotherapy outcomes in general, they may play a role in the presence of specific learning processes such as working memory capacity.

New insights on brain-derived neurotrophic factor epigenetics: from depression to memory extinction

Advances in characterizing molecular profiles provide valuable insights and opportunities for deciphering the neuropathology of depression. Although abnormal brain-derived neurotrophic factor (BDNF) expression in depression has gained much support from preclinical and clinical research, how it mediates behavioral alterations in the depressed state remains largely obscure. Environmental factors contribute significantly to the onset of depression and produce robust epigenetic changes. Epigenetic regulation of BDNF, as one of the most characterized gene loci in epigenetics, has recently emerged as a target in research on memory and psychiatric disorders. Specifically, epigenetic alterations of BDNF exons are heavily involved in mediating memory functions and antidepressant effects. In this review, we discuss key research on stress-induced depression from both preclinical and clinical studies, which revealed that differential epigenetic regulation of specific BDNF exons is associated with depression pathophysiology. Considering that BDNF has a central role in depression, we argue that memory extinction, an adaptive response to fear exposure, is dependent on BDNF modulation and holds promise as a prospective target for alleviating or treating depression and anxiety disorders.

Genomics testing and personalized medicine in the preoperative setting: Can it change outcomes in postoperative pain management?

Postoperative pain and opioid use are major challenges in perioperative medicine. Pain perception and its response to opioid use are multi-faceted and include pharmacological, psychological, and genetic components. Precision medicine is a unique approach to individualized health care in which decisions in management are based on genetics, lifestyle, and environment of each person. Genetic variations can have an impact on the perception of pain and response to treatment. This can have an effect on pain management in both acute and chronic settings. Although there is currently not enough evidence for making recommendations about genetic testing to guide pain management in the acute care setting, there are some known polymorphisms that play a role in surgical pain and opioid-related postoperative adverse outcomes. In this review, we describe the potential use of pharmacogenomics (PGx) for improving perioperative pain management. We first review a number of genotypes that have shown correlations with pain and opioid use and then describe the importance of PGx-guided analgesic protocols and implementation of screening in a preoperative evaluation clinical setting.

Negative association between left prefrontal GABA concentration and BDNF serum concentration in young adults

Background

The brain's major inhibitory neurotransmitter gamma-aminobutyric acid (GABA) and the brain-derived neurotrophic factor (BDNF) play important roles in several stress-related disorders. Magnetic resonance spectroscopy (MRS) allows for non-invasive quantification of GABA concentration in the brain. We investigated the relationship between GABA concentration in the left dorsolateral prefrontal cortex (DLPFC) and BDNF concentration in the serum in a community-based sample of young subjects.

Methods

For the GABA measurement a single voxel MR spectrum was assessed in the prefrontal lobe (25 × 40 × 30 mm) using the MEGA-PRESS method in 276 subjects. BDNF serum concentrations were assessed with an ELISA kit. For 147 subjects we had both MRS and BDNF serum data, and for 79 subjects we had genotype data on the BDNF rs6265 polymorphism. Depressive psychopathology was assessed using Beck's Depression Inventory (BDI), Montgomery-Asberg Depression Rating Scale (MADRS) and Structured Clinical Interviews for Diagnostic and Statistical Manual of Mental Disorders (SCID) for DSM-IV.

Results

GABA concentration in the left DLPFC was negatively associated with BDNF serum concentration (r = -.264, p = .001). This correlation remained significant if corrected for sex (r = -.264, p = .001). BDNF serum concentration was also positively associated with volumes and surface areas of the left prefrontal cortex (p = .048, p = .005). There were no significant associations or interaction with depressive psychopathology (BDI, MADRS, SCID) or rs6265.

Conclusion

The results of this study suggest that GABA, BDNF and prefrontal brain volumes are interrelated, but do not show a strong association to depressive psychopathology, possibly due to the mild forms of psychiatric conditions present in our community-based sample.

Interaction between job stress, serum BDNF level and the BDNF rs2049046 polymorphism in job burnout

BACKGROUND

Some studies have shown that long-term exposure to job stress could result in burnout, and BDNF polymorphism may play an important role in its psychopathological mechanism. However, the inter-relationships between the job-related stress, serum BDNF level, BDNF genotype and job burnout have not been examined. This study was to explore the job stress × BDNF rs2049046 interaction and the role of serum BDNF level in job burnout in a Chinese Han population.

METHODS

Using a cross-sectional design, 205 healthy subjects were recruited from a public institution in Beijing and assessed for job stress using the House and Rizzo's Work Stress Scale, and job burnout using the Maslach Burnout Inventory (MBI). The BDNF rs2049046 polymorphism was genotyped and serum BDNF (sBDNF) levels were assayed in all of subjects.

RESULTS

The correlations between the job stress score and two burnout subscale scores (emotional exhaustion and cynicism) were significant (both p < 0.001), but not with professional efficacy. There were no significant main effects of the BDNF rs2049046 genotype on burnout, and no significant correlation was observed between sBDNF levels and job burnout. However, the interaction between the job stress and the BDNF rs2049046 genotype (F = 2.709, df = 2, 183, p = 0.032) or between the job stress and sBDNF levels on burnout was significant (t = -2.132, p = 0.035). To be specific, the individuals with the BDNF rs2049046 AT genotype showed a greater susceptibility to the burnout cynicism compared to AA homozygote only in medium-stress group (F = 4.327, df = 1,117, p = 0.015). The individuals who had lower sBDNF showed higher burnout level than those who had higher sBDNF in low-stress group.

CONCLUSIONS

Our findings suggest that the BDNF system may interact with job stress to affect burnout, showing that interaction between BDNF rs2049046 and job stress or the interaction between BDNF levels with work stress on certain burnout dimensions.

Reduced serum BDNF levels are associated with the increased risk for developing MDD: a case-control study with or without antidepressant therapy

Objective

We do not have any consistent markers for major depressive disorder (MDD) though various biological factors are involved in the pathophysiology. We aimed to evaluate the serum brain-derived neurotrophic factor (BDNF) levels in MDD patients with or without antidepressant therapy compared to healthy controls (HCs).

Results

We assessed serum BDNF levels among three groups: drug-naïve MDD patients (n = 41), drug-treated MDD patients (n = 44), and age-and sex-matched HCs (n = 82). Serum BDNF levels were measured by enzyme-linked immunosorbent assay (ELISA) kit. Serum levels of BDNF were detected significantly lower in drug-naïve MDD patients compared to HCs. No significant alterations of serum BDNF levels between drug-treated patients and HCs were identified. Significant negative correlations between serum BDNF levels and Hamilton depression rating (Ham-D) scores were observed in both drug-naïve and drug-treated MDD patients. Receiver operating characteristic (ROC) analysis showed good diagnostic value for serum BDNF levels in drug-naïve MDD patients with the area under the curve at 0.821. The present study suggests that low serum BDNF levels may be involved in the pathophysiology of MDD. The reduced serum BDNF levels might be used as an early risk assessment marker for major depression.

The Combined Effect of APOE and BDNF Val66Met Polymorphisms on Spatial Navigation in Older Adults

BACKGROUND

The apolipoprotein E (APOE) ɛ4 allele is associated with episodic memory and spatial navigation deficits. The brain-derived neurotrophic factor (BDNF) Met allele may further worsen memory impairment in APOEɛ4 carriers but its role in APOEɛ4-related spatial navigation deficits has not been established.

OBJECTIVE

We examined influence of APOE and BDNF Val66Met polymorphism combination on spatial navigation and volumes of selected navigation-related brain regions in cognitively unimpaired (CU) older adults and those with amnestic mild cognitive impairment (aMCI).

METHODS

187 participants (aMCI [n = 116] and CU [n = 71]) from the Czech Brain Aging Study were stratified based on APOE and BDNF Val66Met polymorphisms into four groups: ɛ4-/BDNFVal/Val, ɛ4-/BDNFMet, ɛ4+/BDNFVal/Val, and ɛ4+/BDNFMet. The participants underwent comprehensive neuropsychological examination, brain MRI, and spatial navigation testing of egocentric, allocentric, and allocentric delayed navigation in a real-space human analogue of the Morris water maze.

RESULTS

Among the aMCI participants, the ɛ4+/BDNFMet group had the least accurate egocentric navigation performance (p < 0.05) and lower verbal memory performance than the ɛ4-/BDNFVal/Val group (p = 0.007). The ɛ4+/BDNFMet group had smaller hippocampal and entorhinal cortical volumes than the ɛ4-/BDNFVal/Val (p≤0.019) and ɛ4-/BDNFMet (p≤0.020) groups. Among the CU participants, the ɛ4+/BDNFMet group had less accurate allocentric and allocentric delayed navigation performance than the ɛ4-/BDNFVal/Val group (p < 0.05).

CONCLUSION

The combination of APOEɛ4 and BDNF Met polymorphisms is associated with more pronounced egocentric navigation impairment and atrophy of the medial temporal lobe regions in individuals with aMCI and less accurate allocentric navigation in CU older adults.

Obsessive-compulsive disorder and growth factors: A comparative review

The goal of this article is to clarify the role of various growth factors in the establishment and progression of obsessive-compulsive disorder (OCD). OCD is a chronic mental disorder with recurrent intrusive thoughts and/or repetitive compulsive behaviors that increase during stressful periods. Growth and neurotrophic factors may be contributing factors in the pathophysiology of OCD. Many of them are synthesized and released within the central nervous system and act as trophic agents in neurons; some of them are involved in brain growth, development, neurogenesis, myelination and plasticity, while others take part in the protection of the nervous system following brain injuries. This paper attempts to identify all articles investigating the relationship between OCD and neurotrophic and growth factors, in both animal and human studies, with a focus on adult brain studies. Based on the PubMed and Scopus and Science Direct search tools, the available articles and studies are reviewed. Out of 230 records in total, the ones related to our review topic were taken into account to further understand the pathophysiological mechanism(s) of OCD, providing methods to improve its symptoms via the modification of neurotrophins and growth factor imbalances.

Investigating the Contribution of NPSR1, IL-6 and BDNF Polymorphisms to Depressive and Anxiety Symptoms in Hemodialysis Patients

AIMS

Psychological symptoms are prevalent in hemodialysis (HD) patients. Previous investigations showed that brain-derived neurotrophic factor (BDNF) and interleukin-6 (IL-6) as well as the interaction with neuropeptide S receptor 1 (NPSR1) are linked to the development of psychological distress. This study examined the association of polymorphisms of genes encoding these proteins with depression and anxiety in a representative group of Jordanian HD patients.

METHODS

A total of 302 HD patients were involved in the study and categorized into three groups based on the Hospital Anxiety and Depression Scale, HADS-D or HADS-A scores as follows: normal (<7), mild (8-10) and moderate-severe (11-21). Single nucleotide polymorphism (SNP) of NPSR1 Asn107Ile (rs324981), IL-6 G174C (rs1800795), and BDNF Val66Met (rs6265) was genotyped using blood samples.

RESULTS

The frequency of Ile-allele of NPSR1 Asn107Ile was significantly higher in patients with moderate-severe HADS-A scores versus normal (53% vs. 40.8%, p = .035). Using ordinal regression analysis, Asn-allele of NPSR1 polymorphism was nominally significantly associated with a lower risk of anxiety (OR = 0.57, CI: 0.33-0.97, p = .038) after adjusting for other covariates. A marginally significant difference in genotype distribution of IL-6 G174C was observed among patients according to HADS-D scores (p = .05). Furthermore, carriers of IL-6174 CC genotype showed lower median IL-6 serum concentration versus carriers of GG genotype (5.2 vs. 1.35 pg/mL, p < .05).

CONCLUSIONS

The results support the genetic role of NPSR1 in the pathogenesis of anxiety and suggest that carriers of NPSR1 Ile-allele are at increased risk of anxiety in HD patients. Neither BDNF Val66Met nor IL-6 G174C were linked to psychological symptoms. Future studies among other ethnicities are necessary to verify the observations.

Brain-Derived Neurotrophic Factor: A Key Molecule for Memory in the Healthy and the Pathological Brain

Brain Derived Neurotrophic Factor (BDNF) is a key molecule involved in plastic changes related to learning and memory. The expression of BDNF is highly regulated, and can lead to great variability in BDNF levels in healthy subjects. Changes in BDNF expression are associated with both normal and pathological aging and also psychiatric disease, in particular in structures important for memory processes such as the hippocampus and parahippocampal areas. Some interventions like exercise or antidepressant administration enhance the expression of BDNF in normal and pathological conditions. In this review, we will describe studies from rodents and humans to bring together research on how BDNF expression is regulated, how this expression changes in the pathological brain and also exciting work on how interventions known to enhance this neurotrophin could have clinical relevance. We propose that, although BDNF may not be a valid biomarker for neurodegenerative/neuropsychiatric diseases because of its disregulation common to many pathological conditions, it could be thought of as a marker that specifically relates to the occurrence and/or progression of the mnemonic symptoms that are common to many pathological conditions.

Modulation of Serum Brain-Derived Neurotrophic Factor by a Single Dose of Ayahuasca: Observation From a Randomized Controlled Trial

Serotonergic psychedelics are emerging as potential antidepressant therapeutic tools, as suggested in a recent randomized controlled trial with ayahuasca for treatment-resistant depression. Preclinical and clinical studies have suggested that serum brain-derived neurotrophic factor (BDNF) levels increase after treatment with serotoninergic antidepressants, but the exact role of BDNF as a biomarker for diagnostic and treatment of major depression is still poorly understood. Here we investigated serum BDNF levels in healthy controls (N = 45) and patients with treatment-resistant depression (N = 28) before (baseline) and 48 h after (D2) a single dose of ayahuasca or placebo. In our sample, baseline serum BDNF levels did not predict major depression and the clinical characteristics of the patients did not predict their BDNF levels. However, at baseline, serum cortisol was a predictor of serum BDNF levels, where lower levels of serum BDNF were detected in a subgroup of subjects with hypocortisolemia. Moreover, at baseline we found a negative correlation between BDNF and serum cortisol in volunteers with eucortisolemia. After treatment (D2) we observed higher BDNF levels in both patients and controls that ingested ayahuasca (N = 35) when compared to placebo (N = 34). Furthermore, at D2 just patients treated with ayahuasca (N = 14), and not with placebo (N = 14), presented a significant negative correlation between serum BDNF levels and depressive symptoms. This is the first double-blind randomized placebo-controlled clinical trial that explored the modulation of BDNF in response to a psychedelic in patients with depression. The results suggest a potential link between the observed antidepressant effects of ayahuasca and changes in serum BDNF, which contributes to the emerging view of using psychedelics as an antidepressant. This trial is registered at http://clinicaltrials.gov (NCT02914769).

Val66Met polymorphism association with serum BDNF and inflammatory biomarkers in major depression

OBJECTIVES

Current evidence supports participation of neurotrophic and inflammatory factors in the pathogenesis of major depressive disorder (MDD). Some studies reported an association between the Val66Met polymorphism (rs6265) of brain-derived neurotrophic factor (BDNF) gene with MDD and peripheral BDNF levels. However, no previous studies have examined the association of this polymorphism with inflammation. The present study assessed the association of the Val66Met polymorphism with serum levels of BDNF and inflammatory markers among depressed outpatients.

METHODS

All participants (n = 73) met DSM-IV criteria for a unipolar depressive episode. The serum levels of BDNF and inflammatory biomarkers (IL-2, IL-4, IL-6, IL-10, TNF-α and IFN-γ) were compared between individuals presenting with at least one Met allele (Met-carriers) and those homozygous for the Val allele.

RESULTS

In our sample (84.9% female, mean age 52.4 ± 10.3 years), 24.7% (n = 18) were Met-carriers. After Bonferroni correction, the Met allele was significantly associated with higher BDNF and lower TNF-α. These associations persisted after adjusting for potential confounders.

CONCLUSIONS

The pattern of low BDNF and high inflammation in MDD may be influenced by the Val66Met polymorphism. The association of a polymorphism in the BDNF gene with inflammatory markers in addition to BDNF levels suggests an interaction between these systems.

BDNF Polymorphism: A Review of Its Diagnostic and Clinical Relevance in Neurodegenerative Disorders

Brain-derived neurotrophic factor (BDNF) has a unique role in the neuronal development, differentiation, and survival in the developing and adult nervous system. A common single-nucleotide polymorphism in the pro-region of the human BDNF gene, resulting in a valine to methionine substitution (Val66Met), has been associated with the susceptibility, incidence, and clinical features of several neurodegenerative disorders. Much research has been dedicated to evaluating the effects of polymorphism in the past decade, and functional effects of this genetic variation. A better understanding of how this naturally occurring polymorphism associates with or influences physiology, anatomy, and cognition in both healthy and diseased adults in neurodegenerative conditions will help understand neurochemical mechanisms and definable clinical outcomes in humans. Here we review the role and relevance of the BDNF Val66Met polymorphism in neurodegenerative diseases, with particular emphasis on glaucoma, multiple sclerosis (MS), Alzheimer’s disease (AD) and Parkinson’s disease (PD). Several controversies and unresolved issues, including small effect sizes, possible ethnicity, gender, and age effects of the BDNF Val66Met are also discussed with respect to future research.

Association of BDNF Val66Met Polymorphism and Brain BDNF Levels with Major Depression and Suicide

BACKGROUND

Brain-derived neurotrophic factor is implicated in the pathophysiology of major depressive disorder and suicide. Both are partly caused by early life adversity, which reduces brain-derived neurotrophic factor protein levels. This study examines the association of brain-derived neurotrophic factor Val66Met polymorphism and brain brain-derived neurotrophic factor levels with depression and suicide. We hypothesized that both major depressive disorder and early life adversity would be associated with the Met allele and lower brain brain-derived neurotrophic factor levels. Such an association would be consistent with low brain-derived neurotrophic factor mediating the effect of early life adversity on adulthood suicide and major depressive disorder.

METHODS

Brain-derived neurotrophic factor Val66Met polymorphism was genotyped in postmortem brains of 37 suicide decedents and 53 nonsuicides. Additionally, brain-derived neurotrophic factor protein levels were determined by Western blot in dorsolateral prefrontal cortex (Brodmann area 9), anterior cingulate cortex (Brodmann area 24), caudal brainstem, and rostral brainstem. The relationships between these measures and major depressive disorder, death by suicide, and reported early life adversity were examined.

RESULTS

Subjects with the Met allele had an increased risk for depression. Depressed patients also have lower brain-derived neurotrophic factor levels in anterior cingulate cortex and caudal brainstem compared with nondepressed subjects. No effect of history of suicide death or early life adversity was observed with genotype, but lower brain-derived neurotrophic factor levels in the anterior cingulate cortex were found in subjects who had been exposed to early life adversity and/or died by suicide compared with nonsuicide decedents and no reported early life adversity.

CONCLUSIONS

This study provides further evidence implicating low brain brain-derived neurotrophic factor and the brain-derived neurotrophic factor Met allele in major depression risk. Future studies should seek to determine how altered brain-derived neurotrophic factor expression contributes to depression and suicide.

Val66Met functional polymorphism and serum protein level of brain-derived neurotrophic factor (BDNF) in acute episode of schizophrenia and depression

BACKGROUND

Brain-derived neurotrophic factor (BDNF) influences neuron differentiation during development as well as the synaptic plasticity and neuron survival in adulthood. BDNF has been implicated in the pathogenesis of schizophrenia and depression. Val66Met polymorphism and BDNF serum level are potential biomarkers in neuropsychiatric disorders. The aim of this study was to determine the effect of BDNF gene Val66Met functional polymorphism on serum BDNF concentration in patients with schizophrenia, during depression episode and in healthy control group.

METHODS

183 participants were recruited (61 patients with depressive episode, 56 females with schizophrenia, 66 healthy controls) from Polish population. Serum BDNF levels were measured using ELISA method. Val66Met polymorphism was genotyped using PCR- RFLP method.

RESULTS

Serum BDNF levels were not associated with Val66Met polymorphism in either of the groups. A significant increase of BDNF level in schizophrenia (p = 0.0005) and depression (p = 0.026) comparing to the control group has been observed.

CONCLUSIONS

Our results suggest that the functional Val66Met BDNF polymorphism is not associated with BDNF serum levels, which is in line with previous findings. Replication studies on larger groups are needed.

The effect of acute exercise on blood concentrations of brain-derived neurotrophic factor in healthy adults: a meta-analysis

It has been hypothesized that one mechanism through which physical activity provides benefits to cognition and mood is via increasing brain-derived neurotrophic factor (BDNF) concentrations. Some studies have reported immediate benefits to mood and various cognitive domains after a single session of exercise. This meta-analysis sought to determine the effect of a single exercise session on concentrations of BDNF in peripheral blood, in order to evaluate the potential role of BDNF in mediating the beneficial effects of exercise on brain health. MEDLINE, Embase, PsycINFO, SPORTDiscus, Rehabilitation & Sports Medicine Source, and CINAHL databases were searched for original, peer-reviewed reports of peripheral blood BDNF concentrations before and after acute exercise interventions. Risk of bias within studies was assessed using standardized criteria. Standardized mean differences (SMDs) were generated from random effects models. Risk of publication bias was assessed using a funnel plot and Egger's test. Potential sources of heterogeneity were explored in subgroup analyses. In 55 studies that met inclusion criteria, concentrations of peripheral blood BDNF were higher after exercise (SMD = 0.59, 95% CI: 0.46-0.72, P < 0.001). In meta-regression analysis, greater duration of exercise was associated with greater increases in BDNF. Subgroup analyses revealed an effect in males but not in females, and a greater BDNF increase in plasma than serum. Acute exercise increased BDNF concentrations in the peripheral blood of healthy adults. This effect was influenced by exercise duration and may be different across genders.

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.

Determinants of Blood Brain-Derived Neurotrophic Factor Blood Levels in Patients with Alcohol Use Disorder

BACKGROUND

Blood brain-derived neurotrophic factor (BDNF) levels are influenced by both addiction and mood disorders, as well as somatic conditions, gender, and genetic polymorphisms, leading to widely varying results. Depressive symptoms and episodes are frequently observed in patients with alcohol use disorder, and vary widely over time, making it a challenge to determine which aspects are specifically involved in variations of serum BDNF levels in this population.

METHODS

We assessed 227 patients with alcohol dependence involved in a detoxification program, at baseline and after a follow-up of 6 months, for the Alcohol Use Disorders Identification Test score, the length of alcohol dependence, and the number of past detoxification programs. The Beck Depression Inventory and information on current tobacco and alcohol use, suicidal ideation, body mass index, age, gender, and psychotropic treatments were also collected. Serum BDNF (ELISA) and 2 genetic polymorphisms of the BDNF gene (Val33Met and rs962369) were analyzed.

RESULTS

The presence of the Met allele, 2 markers of the history of alcohol dependence (gamma glutamyl transferase and the number of past treatments in detoxification programs), and the presence of a depressive episode (but not depressive score) were significantly associated with the 2 blood levels of BDNF at baseline and after 6 months. After controlling for baseline BDNF levels, the presence of the Met allele and an ongoing depressive episode were the only variables associated with changes in BNDF levels after 6 months.

CONCLUSIONS

Low serum BDNF levels are associated with characteristics related to alcohol consumption and mood disorders, and variants of the BDNF gene in alcohol use disorder patients. The factors that most strongly influenced changes in serum BDNF levels following treatment in an alcohol detoxification program were variants of the BDNF gene and ongoing depression.

Brain-Derived Neurotropic Factor Val66Met Polymorphism and Posttraumatic Stress Disorder among Survivors of the 1998 Dongting Lake Flood in China

OBJECTIVE

This study mainly aimed to explore the association between brain-derived neurotropic factor (BDNF) Val66Met polymorphism and posttraumatic stress disorder (PTSD) among flood survivors in China.

METHODS

Individuals who experienced the 1998 Dongting Lake flood in Southeast Huarong, China, were enrolled in this study. Qualified health personnel carried out face-to-face interviews with participants. PTSD was identified using PTSD Checklist-Civilian version (PCL-C). Blood samples were collected from the participants to extract DNA for genotyping.

RESULTS

A total of 175 participants were enrolled in this study. The prevalence of PTSD among flood survivors at 17-year follow-up was 16.0% (28/175). Individuals with PTSD were more likely to be female, experience at least three flood-related stressors, experience at least three postflood stressors, and carry the Met than those without PTSD. Compared with Val/Val homozygotes, Met carriers had higher scores of PCL-C (mean ± standard error: 23.60 ± 7.23 versus 27.19 ± 9.48, P < 0.05). Multivariable logistic regression analysis indicated that Met carriers (aOR = 4.76, 95% CI = 1.02-22.15, P < 0.05) were more likely to develop PTSD than Val/Val homozygotes.

CONCLUSIONS

Met carriers for BDNF rs6265 are at higher risk of developing PTSD and also exhibit more severe PTSD symptoms than Val/Val homozygotes among flood survivors in China.

Associations Between Neurotransmitter Genes and Fatigue and Energy Levels in Women After Breast Cancer Surgery

CONTEXT

Fatigue is a common problem in oncology patients. Less is known about decrements in energy levels and the mechanisms that underlie both fatigue and energy.

OBJECTIVES

In patients with breast cancer, variations in neurotransmitter genes between lower and higher fatigue latent classes and between the higher and lower energy latent classes were evaluated.

METHODS

Patients completed assessments before and monthly for six months after surgery. Growth mixture modeling was used to identify distinct latent classes for fatigue severity and energy levels. Thirty candidate genes involved in various aspects of neurotransmission were evaluated.

RESULTS

Eleven single-nucleotide polymorphisms or haplotypes (i.e., ADRB2 rs1042718, BDNF rs6265, COMT rs9332377, CYP3A4 rs4646437, GALR1 rs949060, GCH1 rs3783642, NOS1 rs9658498, NOS1 rs2293052, NPY1R Haplotype A04, SLC6A2 rs17841327, and 5HTTLPR + rs25531 in SLC6A4) were associated with latent class membership for fatigue. Seven single-nucleotide polymorphisms or haplotypes (i.e., NOS1 rs471871, SLC6A1 rs2675163, SLC6A1 Haplotype D01, SLC6A2 rs36027, SLC6A3 rs37022, SLC6A4 rs2020942, and TAC1 rs2072100) were associated with latent class membership for energy. Three of 13 genes (i.e., NOS1, SLC6A2, and SLC6A4) were associated with latent class membership for both fatigue and energy.

CONCLUSIONS

Molecular findings support the hypothesis that fatigue and energy are distinct, yet related symptoms. Results suggest that a large number of neurotransmitters play a role in the development and maintenance of fatigue and energy levels in breast cancer patients.

Voluntary running improves depressive behaviours and the structure of the hippocampus in rats: A possible impact of myokines

This study investigated the impact of voluntary exercise on depressive behaviours, serum and hippocampal levels of myokines, and histopathological features of hippocampal formation in rats. Depressed rats were allowed to voluntarily run on a wheel for 3weeks. Locomotor activity was assessed by a forced swimming test and the myokine levels in sera and hippocampal homogenates were measured using Enzyme-linked Immunosorbent Assay. Brain sections were analysed for hippocampal structure and neuronal counts. Voluntary running produced significant increase in the distance moved by rats and significant decrease in immobility duration. After voluntary running, there were significant increases in serum and hippocampal brain-derived neurotrophic factor (BDNF) and macrophage migration inhibitory factor (MIF), significant increase in hippocampal vascular endothelial growth factor (VEGF), and significant decrease in serum interleukin-6 (IL-6). Significant correlation was detected between the serum levels of BDNF and MIF (r=0.276) as well as IL-6 (r=-0.340). In addition, significant correlation was observed between hippocampal BDNF levels and MIF (r=0.500) and VEGF levels (r=0.279). After voluntary running, there was significant decrease in number degenerated neurons in hippocampal areas and significant increase in number of healthy neurons in the upper limb of the dentate gyrus, but not in its lower limb, compared to depression group. This study showed the relation of myokines to the development and/or relief of depression, as well as the correlation between serum and hippocampal myokine levels. Attention should be paid to studying the biological effects of myokines on different hippocampal areas that could respond differently to treatments.

Brain-Derived Neurotrophic Factor Gene Val66Met Polymorphism Is a Risk Factor for Attention-Deficit Hyperactivity Disorder in a Turkish Sample

OBJECTIVE

Attention-deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder that negatively affects different areas of life. We aimed to evaluate the associations between the Val66Met polymorphism of brain-derived neurotrophic factor (BDNF) and ADHD and to assess the effect of the BDNF polymorphism on the neurocognitive profile and clinical symptomatology in ADHD.

METHODS

Two hundred one ADHD cases and 99 typically developing subjects (TD) between the ages of 8 and 15 years were involved in the study. All subjects were evaluated using a complete neuropsychological battery, Child Behavior Checklist, the Teacher's Report Form (TRF) and the DSM-IV Disruptive Behavior Disorders Rating Scale-teacher and parent forms.

RESULTS

The GG genotype was significantly more frequent in the patients with ADHD than in the TD controls, and the GG genotype was also significantly more frequent in the ADHD-combined (ADHD-C) subtype patients than in the TDs. However, there were no significant associations of the BDNF polymorphism with the ADHD subtypes or neurocognitive profiles of the patients. The teacher-assessed hyperactivity and inattention symptom count and the total score were higher, and the appropriately behaving subtest score of the TRF was lower in the GG genotypes than in the GA and AA (i.e., the A-containing) genotypes.

CONCLUSION

We found a positive association between the BDNF gene Val66Met polymorphism and ADHD, and this association was observed specifically in the ADHD-C subtype and not the ADHD-predominantly inattentive subtype. Our findings support that the Val66Met polymorphism of BDNF gene might be involved in the pathogenesis of ADHD. Furthermore Val66Met polymorphism of BDNF gene may be more closely associated with hyperactivity rather than inattention.

Interaction of BDNF rs6265 variants and energy and protein intake in the risk for glucose intolerance and type 2 diabetes in middle-aged adults

OBJECTIVES

Brain-derived neurotrophic factor (BDNF) is associated with the risk for Alzheimer's disease and type 2 diabetes. The aim of this study was to examine the association of BDNF variants with type 2 diabetes and the interactions of different BDNF genotypes with dietary habits and food and nutrient intakes in middle-aged adults.

METHODS

The study population included 8840 adults ages 40 to 65 y from the Ansan and Asung areas in the Korean Genome Epidemiology Study, a cross-sectional study of Korean adults, conducted from 2001 to 2002. Adjusted odd ratios for the prevalence of glucose intolerance and type 2 diabetes according to BDNF genotypes were calculated after adjusting for age, sex, residence area, body mass index, physical activity, and smoking and stress status. Nutrient intake was calculated from usual food intake determined by semiquantitative food frequencies using the nutrient assessment software.

RESULTS

BDNF rs6265 Val/Met and Met/Met variants were negatively associated with the risk for type 2 diabetes after adjusting for covariates. Serum glucose levels after glucose loading and hemoglobin A1c, but not serum insulin levels, also were negatively associated with BDNF Val/Met and Met/Met. In subgroup analysis, sex and stress levels had an interaction with BDNF Val/Met in the risk for type 2 diabetes. Glucose-intolerant and diabetic, but not nondiabetic, patients with BDNF Met/Met had nominally, but significantly higher intakes of energy than those with BDNF Val/Val. BDNF rs6265 had consistent gene-diet interactions with energy and protein intake. With low-energy, low-protein, and high-carbohydrate intake, BDNF Val/Met lowered the risk for type 2 diabetes after adjusting for confounding factors. BDNF Val/Met did not compensate for developing type 2 diabetes with high-energy intake. Additionally, indexes of insulin resistance and insulin secretion showed the same gene-energy interaction as type 2 diabetes.

CONCLUSIONS

BDNF Val/Met and Met/Met variants (rs6265) decreases the risk for glucose intolerance and type 2 diabetes. BDNF variants interacted with nutrient intake, especially energy and protein intake: Middle-aged individuals with BDNF Val/Val are prone to developing type 2 diabetes even with low energy and protein intake.

Serum Brain-Derived Neurotrophic Factor Mediates the Relationship between Abdominal Adiposity and Executive Function in Middle Age

OBJECTIVES

Excessive adipose tissue, especially in the abdominal area, is associated with increased risk of dementia in older adults. However, the mechanisms underlying this relationship are poorly understood. As increased adiposity is also associated with lower circulating levels of brain-derived neurotrophic factor (BDNF), a key molecule modulating brain plasticity and neuronal regeneration, we hypothesized that the changes in cognition that occur as a result of excessive abdominal adiposity would be driven by lower levels of circulating BDNF.

METHODS

Fasting blood samples were obtained from 60 participants aged 40-60 years (mean±SD=52.3±5.6) and BDNF levels were assessed with an enzyme linked immunosorbent assay. Abdominal adiposity was measured using a ratio of waist circumference to hip circumference (WHR). Participants also completed a neuropsychological assessment battery to assess executive function. Statistical mediation was assessed using traditional causal steps and nonparametric bootstrapping.

RESULTS

Higher WHR was significantly associated with poorer performance on the Controlled Oral Word Association (COWA) letter fluency test (β=-0.489; p=.003) and lower levels of circulating BDNF (β=-0.345; p=.006). Linear regression and bootstrapping methods indicated that BDNF fully mediated the relationship between WHR and performance on the COWA (β=0.60; 95% confidence interval [-3.79, -0.26]).

CONCLUSIONS

The relationship between higher WHR and verbal fluency was fully statistically mediated by circulating BDNF levels. The BDNF pathway is thus a useful probable mechanism through which executive function decline occurs in individuals with high abdominal adiposity. BDNF enhancing interventions (physical exercise and dietary restriction) could thus be used to improve executive function in these individuals.

Reduced severity of posttraumatic stress disorder associated with Val allele of Val66Met polymorphism at brain-derived neurotrophic factor gene among Chinese adolescents after Wenchuan earthquake

The aim of the present study was to longitudinally investigate the association of BDNF Val66Met with PTSD symptoms in Chinese Han adolescents who experienced the 2008 Wenchuan earthquake. Variants of BDNF Val66Met were identified by polymerase chain reaction-restriction fragment length polymorphism analyses and verified by DNA sequencing. PTSD symptoms were assessed by the PTSD Checklist-Civilian Version (PCL-C) among high school students at 6, 12, and 18 months after the earthquake. No differences of PTSD prevalence and PCL-C scores were found between the Val/Val homozygotes and the Met allele carriers at 6, 12, and 18 months after the earthquake regardless of gender. Decreased PTSD prevalence was observed at 12 and 18 months when compared with that at 6 months after the earthquake regardless of gender and the genotype. Meanwhile, PCL-C scores were decreased consecutively in the female subjects regardless of the genotypes. However, the scores at 18 months were lower when compared with those at 12 months in the male Val/Val homozygotes, but not in the male Met allele carriers. In addition, differences were found for the predictors of PCL-C scores and PTSD prevalence between the Val/Val homozygotes and the Met allele carriers during follow-up. These findings suggest that the association of BDNF Val66Met with PTSD is longitudinally different in Chinese Han adolescents after the 2008 Wenchuan earthquake. The Val allele may be associated with reduced PTSD severity in male adolescents in the later stage of PTSD rehabilitation during follow-up.

BDNF Val66Met polymorphism and stressful life events in melancholic childhood-onset depression

INTRODUCTION

Brain-derived neurotrophic factor (BDNF) polymorphisms have been examined for their contribution toward depression with equivocal results. More homogeneous phenotypes might be used to improve our understanding of genetic liability to depression. The aim of our study was to (a) test for an association between the BDNF Val66Met polymorphism and childhood-onset melancholic depression and (b) to examine the interactive effects of stressful life events (SLE) and the Val66Met polymorphism on the risk of childhood-onset melancholic depression.

MATERIALS AND METHODS

A total of 583 depressed probands were involved in this study (162 of the melancholic subtype). Diagnoses were derived through the Interview Schedule for Children and Adolescents - Diagnostic Version and life event data were collected using an Intake General Information Sheet.

RESULTS

Overall, 27.8% of the participants fulfilled the criteria for melancholy. In the melancholic group, the proportion of females was higher (53.1%), although there were more males in the overall depressed sample. We detected no significant differences in genotype or allele frequency between the melancholic and the nonmelancholic depressed group. The BDNF Val66Met polymorphism and SLE interaction was not significantly associated with the melancholy outcome.

CONCLUSION

In our study, females were more prone to developing the early-onset melancholic phenotype. To our knowledge, this is the first study to investigate the differentiating effect of the genotype and the G×E interaction on the melancholic phenotype in a large sample of depressed young patients. We did not find an association between the melancholic subtype of major depression and the BDNF genotype and SLE interaction in this sample, which is representative of the Hungarian clinic-referred population of depressed youths.

High-intensity interval training evokes larger serum BDNF levels compared with intense continuous exercise

Exercise can have a positive effect on the brain by activating brain-derived neurotrophic factor (BDNF)-related processes. In healthy humans there appears to be a linear relationship between exercise intensity and the positive short-term effect of acute exercise on BDNF levels (i.e., the highest BDNF levels are reported after high-intensity exercise protocols). Here we performed two experiments to test the effectiveness of two high-intensity exercise protocols, both known to improve cardiovascular health, to determine whether they have a similar efficacy in affecting BDNF levels. Participants performed a continuous exercise (CON) protocol at 70% of maximal work rate and a high-intensity interval-training (HIT) protocol at 90% of maximal work rate for periods of 1 min alternating with 1 min of rest (both protocols lasted 20 min). We observed similar BDNF kinetics in both protocols, with maximal BDNF concentrations being reached toward the end of training (experiment 1). We then showed that both exercise protocols significantly increase BDNF levels compared with a rest condition (CON P = 0.04; HIT P < 0.001), with HIT reaching higher BDNF levels than CON (P = 0.035) (experiment 2). These results suggest that shorter bouts of high intensity exercise are slightly more effective than continuous high-intensity exercise for elevating serum BDNF. Additionally, 73% of the participants preferred the HIT protocol (P = 0.02). Therefore, we suggest that the HIT protocol might represent an effective and preferred intervention for elevating BDNF levels and potentially promoting brain health.

BDNF Val66Met Polymorphism on Functional MRI During n-Back Working Memory Tasks

Val66Met polymorphism on the brain-derived neurotrophic factor (BDNF) gene is associated with hippocampal pathology and impaired episodic memory. However, the influence of this polymorphism on working memory (WM) performance and patterns of brain activation is controversial. This study investigated the effects of BDNF Val66Met polymorphism on functional magnetic resonance imaging (fMRI) during n-back WM tasks in healthy middle-aged adults.A total of 110 participants without subjective or objective cognitive impairment underwent BDNF genotyping. Eleven Met allele carriers and 9 noncarriers underwent fMRI during WM tasks.The WM performance was similar between the 2 groups. Increased brain activation in response to increases in WM loads was observed in both groups. The Met allele carrier group showed consistently lower brain activation in the right superior frontal gyrus (SFG) and the middle occipital gyrus than that of the noncarrier group (P < 0.001). No brain region showed increased activation during WM tasks in the Met allele group.BDNF Val66Met polymorphism may affect the WM network. Met allele carriers have lower brain activation in the right SFG and middle occipital gyrus than do noncarriers during WM tasks. Defective development of the WM network during brain maturation or differentiation is a possible mechanism. Additional studies with a larger sample and longer follow-up period are warranted.

Serotonin transporter gene: a new polymorphism may affect response to antidepressant treatments in major depressive disorder

BACKGROUND AND OBJECTIVES

Several gene variants have been related to major depressive disorder (MDD) treatment outcomes; however, few studies have investigated a possible different effect on pharmacotherapy and brief psychotherapy response.

METHODS

A total of 137 MDD patients were randomized to either interpersonal counseling (IPC; n = 40) or antidepressant pharmacological treatment (n = 97). Outcomes were remission, response, and symptom improvement at week 8. Five genetic variants were investigated (5HTR2A rs6314, BDNF rs6265, SLC6A4 rs8076005, CREB1 rs2253206, and TPH2 rs11179023) as possible modulators of outcomes.

RESULTS

The LC6A4 rs8076005 AA genotype and A allele were associated with response rate in the antidepressant group (p = 0.015 and 0.005, respectively) and in the whole sample (p = 0.03 and 0.02, respectively). In the IPC group a non-significant trend in the same direction was observed. The TPH2 rs11179023 A allele showed a marginal association with symptom improvement in the IPC group only. Other gene variants did not impact on outcomes in any treatment group.

CONCLUSION

Our study suggests that rs8076005 in the SLC6A4 gene may be a modulator of antidepressant response, especially when pharmacological treatment is used.