Brain-derived Neurotrophic Factor Polymorphism Research Articles

Influence of Functional Variations in Genes of Neurotrophins and Neurotransmitter Systems on the Development of Retinopathy of Prematurity

Retinal neurodevelopment, vascularization, homeostasis, and stress response are influenced by factors such as nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), tyrosine hydroxylase (TH), and erythropoietin (EPO). As retinopathy of prematurity (ROP) is a neurovascular retinal disease, this study analyzed the contributions of NGF (rs6330), BDNF (rs7934165), TH (rs10770141), and EPO (rs507392) genetic functional polymorphisms to the modulation of hematological and biochemical parameters of the first week of life and their association with ROP development. A multicenter cohort of 396 preterm infants (gestational age < 32 weeks or birth weight < 1500 g) was genotyped using MicroChip DNA and iPlex MassARRAY® platform. Multivariate regression followed univariate assessment of ROP risk factors. NGF (GG) genotype was associated with a higher ROP risk (OR = 1.79), which increased further (OR = 2.38) when epistatic interactions with TH (allele C) and BDNF (allele G) were present. Significant circulating biomarker differences, including bilirubin, erythrocytes, monocytes, neutrophils, lymphocytes, and platelet markers, were found between ROP and non-ROP groups, with variations depending on the polymorphism. These findings suggest that NGF (rs6330) and its interactions with related genes contribute to ROP risk, providing valuable insights into the genetic and biological mechanisms underlying the disease and identifying potential predictive biomarkers.

Genetic determinants of serum brain-derived neurotrophic factor (BDNF) after alcohol withdrawal

Peripheral brain-derived neurotrophic factor (BDNF) levels increase during alcohol abstinence in dependent subjects. Meanwhile, the genetic determinants of circulating BDNF this context are poorly understood. Studies of associations between circulating BDNF and single nucleotide polymorphisms (SNPs) of the corresponding gene are mainly restricted by the most studied BDNF SNP rs6265. A recent genome-wide association study demonstrated that the BDNF-related SNP rs75945125 is associated with serum BDNF. However, it is unknown whether this SNP is associated with changes in peripheral BDNF levels in the context of alcohol abstinence. We aimed to assess the association of the BDNF-related SNPs rs75945125 and rs6265 with changes in serum BDNF levels after alcohol withdrawal and the corresponding clinical manifestations. A total of 132 inpatients diagnosed with alcohol withdrawal syndrome were enrolled in the study. Serum BDNF levels were assessed on 2nd, 7th, and 21st days after alcohol withdrawal. Alcohol withdrawal syndrome severity, craving severity, affective symptoms, and cognitive impairment were assessed on 7th and 21st days. BDNF SNPs rs75945125 and rs6265 were genotyped using real-time PCR. BDNF concentrations in the carriers of the rs75945125 C allele on 21st day were higher as compared with TT genotype carriers. BDNF SNP rs75945125 C allele carriers had a longer duration of problem drinking, consumed a lesser volume of alcohol in the last 3 months, and had lower severity of withdrawal syndrome on 7th day compared with TT genotype carriers. BDNF levels were moderated by rs75945125 and rs6265, as well as by the interaction of rs75945125 × rs6265, whereas only the interaction of rs75945125 × rs6265 had an effect on depression scores during abstinence. Thus, the trajectory of serum BDNF changes during alcohol abstinence is determined by both rs75945125 and rs6265. Moreover, BDNF gene-related SNPs are associated with the clinical parameters of alcohol dependence and withdrawal. The longitudinal design without a control group and the relatively small sample size are the limitations of this study. Future studies on the revealed interactions are warranted.

Correlation investigation between BDNF (Val66Met/rs6265) polymorphism and attention deficit hyperactivity disorder susceptibility in Chinese mainland population: a meta-analysis

ABSTRACT This meta-analysis evaluated the association between the Val66Met polymorphism of brain-derived neurotrophic factor (BDNF) and the susceptibility to attention deficit hyperactivity disorder (ADHD) in the Chinese mainland population. Eligible documents were selected from online databases including PubMed, Embase, Cochrane Library, CNKI, Wanfang and CBM (updated to 15 October 2023). The evaluation of study quality was conducted according to guidelines of Newcastle-Ottawa Scale. Basic features of patients, OR and 95% CI were retrieved to assess the correlation between ADHD susceptibility and Val66Met polymorphism in four genetic models: allele genetic model (mutation (A) vs. wild-type (G)), additive genetic model (AA vs. GG and AG vs. GG), recessive genetic model (AA vs. AG+GG) and dominant genetic model (AA+AG vs. GG). This study included totally four studies for subsequent meta-analysis. The results indicated that the correlation between ADHD susceptibility and Val66Met polymorphism in A vs. G (OR = 0.8840, 95%CI: [0.6696–1.1672], p = 0.3846), AA vs. GG (OR = 0.8436, 95%CI: [0.5432–1.3102], p = 0.4490), AA+AG vs. GG (OR = 0.8602, 95%CI: [0.6497–1.1391], p = 0.2933), AG vs. GG (OR = 0.9132, 95%CI: [0.7810–1.0679], p = 0.2556) and AA vs. GG+AG (OR = 1.0315, 95%CI: [0.8789–1.2105], p = 0.7044) was not significant. Egger’s test and sensitivity analysis demonstrating the reliability and stability our conclusions, respectively. BDNF Val66Met polymorphism did not contribute to the susceptibility of ADHD in Chinese mainland population.

Genetic variants in BDNF (rs6265 and rs11030119) and stroke susceptibility: a case-control analysis in South India

Background Stroke occurs when the blood supply to part of the cerebral cortex is blocked, depriving it of oxygen and glucose, leading to cell death. It is a multifactorial disorder influenced by genetic, vascular, and environmental factors. Aim This study investigated the association between two polymorphisms of the brain-derived neurotrophic factor (BDNF) gene, rs6265 and rs11030119, and stroke risk in a South Indian population. Subjects and Methods The study included 163 stroke cases and 160 healthy controls. Genomic DNA was extracted, and genotyping of rs6265 and rs11030119 polymorphisms was done using ARMS-PCR. Allelic and genotype frequencies were calculated, and odds ratios (OR) with 95% confidence intervals (CI) were determined using SPSS version 21.0. Results The rs6265 polymorphism was significantly associated with stroke risk, with the GG genotype more frequent in controls (OR 1.79, 95% CI 1.05–1.76, p = 0.01). The rs11030119 polymorphism showed a positive association, with the AA genotype more prevalent in cases (OR 2.70, 95% CI 1.34–5.44, p = 0.003). Conclusion This study suggests an association between BDNF polymorphisms (rs6265, rs11030119) and stroke risk in a South Indian population. Further research in larger populations is necessary to confirm these findings and explore the mechanisms involved.

Association between the Val66Met (rs6265) polymorphism of the brain-derived neurotrophic factor (BDNF) gene, BDNF protein level in the blood and the risk of developing early‑onset Parkinson's disease.

Brain-derived neurotrophic factor (BDNF) is involved in the maintenance of dopamine level and the survival of dopaminergic neurons, which may affect the functionality of brain structures responsible for motor and cognitive function. The aim of the study was to assess the association of individual and combined single nucleotide polymorphism (SNP) in the rs6265 BDNF (Val66Met), rs397595 DAT (SLC6A3), and rs4680 COMT (Val158Met) genes with early‑onset of Parkinson's disease (PD) patients. Moreover, we assessed the association between the BDNF Val66Met polymorphism and the level of BDNF protein in the serum of patients with PD and controls. The study involved 163 patients with idiopathic PD divided into early onset (<55 years) and late‑onset (>55 years) groups and 91 healthy age‑matched people (Control). The SNP were determined using the TaqMan Real‑Time PCR method. Serum BDNF levels were determined by ELISA assay. The risk of developing early PD in people with the BDNF genotype AG increases threefold in comparison with the carriers of the BDNF genotype GG. In PD patients and healthy people with the BDNF genotypes AG and AA, a lower serum BDNF level was found compared to those with the BDNF genotype GG in both groups. The results of our study indicate that the presence of the Val66Met BDNF gene polymorphism is associated with reduced blood BDNF levels and an elevated risk of developing early‑onset PD. This effect appears to be more pronounced in men.

The Role of Central and Peripheral Brain-Derived Neurotrophic Factor (BDNF) as a Biomarker of Anorexia Nervosa Reconceptualized as a Metabo-Psychiatric Disorder.

Neurotrophic factors play pivotal roles in shaping brain development and function, with brain-derived neurotrophic factor (BDNF) emerging as a key regulator in various physiological processes. This review explores the intricate relationship between BDNF and anorexia nervosa (AN), a complex psychiatric disorder characterized by disordered eating behaviors and severe medical consequences. Beginning with an overview of BDNF's fundamental functions in neurodevelopment and synaptic plasticity, the review delves into recent clinical and preclinical evidence implicating BDNF in the pathophysiology of AN. Specifically, it examines the impact of BDNF polymorphisms, such as the Val66Met variant, on AN susceptibility, prognosis, and treatment response. Furthermore, the review discusses the interplay between BDNF and stress-related mood disorders, shedding light on the mechanisms underlying AN vulnerability to stress events. Additionally, it explores the involvement of BDNF in metabolic regulation, highlighting its potential implications for understanding the metabolic disturbances observed in AN. Through a comprehensive analysis of clinical data and animal studies, the review elucidates the nuanced role of BDNF in AN etiology and prognosis, emphasizing its potential as a diagnostic and prognostic biomarker. Finally, the review discusses limitations and future directions in BDNF research, underscoring the need for further investigations to elucidate the complex interplay between BDNF signaling and AN pathology.

Cancer-Related Cognitive Impairment Associated with APOE rs7412 and BDNF rs6265 in Breast Cancer Survivors

ObjectivesCancer-related cognitive impairment (CRCI) is a highly prevalent and debilitating symptom reported by breast cancer survivors (BCS). The etiology of CRCI remains unclear, leading to poor symptom management. Building from prior studies, BCS with the C/C genotype of apolipoprotein E (APOE) rs7412 and the T/T genotype of brain-derived neurotrophic factor (BDNF) rs6265 were hypothesized to experience more severe CRCI. Therefore, we investigated the relationships between the severity of CRCI and polymorphisms of APOE and BDNF among BCS. MethodsThis was a subanalysis of data from a larger descriptive, correlational, and cross-sectional study. Subjective and objective CRCI were measured using the Patient-Reported Outcomes Measurement Information System and CANTAB Cambridge Cognitive assessment, respectively. Buccal swab samples were collected to evaluate the single nucleotide polymorphisms. Multivariable generalized linear regression models were used to analyze data. ResultsAPOE rs7412 and BDNF rs6265 were significantly associated with lower self-reported cognitive abilities in a total of 353 BCS. Age was positively associated with self-reported cognitive scores, indicating that younger BCS perceived lower cognitive abilities. Individuals carrying genotype of C/T for APOE with the C/C or C/T for BDNF showed positive associations with cognitive abilities. ConclusionsYounger BCS with the C/C genotype for APOE rs7412 and the T/T genotype for BDNF rs6265 may be at risk for CRCI. Knowledge regarding predictive markers for CRCI symptoms is essential for precision symptom management. Further investigation with a longitudinal and translational design is necessary to explore the etiologies for CRCI. Implications for Nursing PracticeIntegrating genetic phenotyping into routine clinical practice will provide nurses with unique opportunities to understand individual susceptibilities, and how symptoms may trigger other symptoms. Further, findings from these innovative investigations will provide symptom interventionists and implementation scientists with critical data to optimize individualized strategies for symptom prevention, detection, and management.

A pilot study of the role of the BDNF Val66Met polymorphism in response to exercise-augmented exposure therapy for posttraumatic stress disorder

Brain-Derived Neurotrophic Factor (BDNF) is implicated in extinction learning, which is a primary mechanism of exposure therapy for posttraumatic stress disorder (PTSD). Brief aerobic exercise has been shown to promote BDNF release and augment extinction learning. On the premise that the Val allele of the BDNF Val66Met polymorphism facilitates greater release of BDNF, this study examined the extent to which the Val allele of the BDNF polymorphism predicted treatment response in PTSD patients who underwent exposure therapy combined with aerobic exercise or passive stretching. PTSD patients (N = 85) provided saliva samples in order to extract genomic DNA to identify Val/Val and Met carriers of the BDNF Val66Met genotype, and were assessed for PTSD severity prior to and following a 9-week course of exposure therapy combined with aerobic exercise or stretching. The sample comprised 52 Val/Val carriers and 33 Met carriers. Patients with the BDNF high-expression Val allele display greater reduction of PTSD symptoms at posttreatment than Met carriers. Hierarchical regression analysis indicated that greater PTSD reduction was specifically observed in Val/Val carriers who received exposure therapy in combination with the aerobic exercise. This finding accords with animal and human evidence that the BDNF Val allele promotes greater extinction learning, and that these individuals may benefit more from exercise-augmented extinction. Although preliminary, this result represents a possible avenue for augmented exposure therapy in patients with the BDNF Val allele.

Association of BDNF polymorphism with gestational diabetes mellitus risk: a novel insight into genetic predisposition.

Gestational diabetes mellitus (GDM) is a prevalent metabolic disorder during pregnancy with potential long-term health implications for the mother and child. The interplay between genetics and GDM susceptibility remains an area of active research. Recently, brain-derived neurotrophic factor (BDNF) was investigated in relation to obesity and impaired glucose metabolism and pathogenesis. We aimed to investigate the association of common BDNF polymorphisms, with GDM risk in Israeli females. A cohort of 4,025 Israeli women data for BDNF common SNPs was analyzed for potential association with GDM using binary logistic regressions analysis (SPSS 29.0 and R) adjusted for confounding variables (age, T1DM, T2DM, PCOS) under different genetic models. The GDM and Non-GDM genetic frequencies for the BDNF rs925946 Tag-SNP were significantly different. The genetic frequencies were 54.16 %, and 66.91 % for the wild type (GG), 38.88 and 29.64 % for the heterozygotes (TC), and 6.94 and 3.48 % for the risk allele homozygotes (TT) for the GDM non-GDM populations, respectively. Carriers of BDNF rs925946 were significantly associated with higher risk for GDM, following the dominant genetic model (OR=1.7, 95 % CI 1.21-2.39, p=0.002), the recessive genetic model (OR=2.05, 95 % CI 1.04-4.03, p=0.03), and the additive genetic model (OR=1.62, 95 % CI 1.13-2.3, p=0.008). This association persisted after adjusting for age, T1DM, T2DM, and polycystic ovary syndrome (PCOS). Carrying BDNF rs925946 polymorphism predisposes to a higher risk of GDM pathogenesis. Its role and implications warrant further investigation, especially when considering preventive measures for GDM development.

The relationship between the rs6265 polymorphism of the BDNF gene and the level of serum neurotrophic factor in patients with Parkinson's disease

To evaluate the clinical features and the level of serum brain-derived neurotrophic factor (BDNF) in groups of patients with Parkinson's disease (PD) differentiated by the genotypes of BDNF polymorphism (rs6265). The level of serum BDNF in the biomarkers' multiplex panel of neurodegenerative diseases (HNDG3MAG-36K) was assessed in 134 PD patients. Allele discrimination was carried out by real-time PCR using TaqMan probes for the analysis of BDNF rs6265 polymorphism in groups of patients and controls (n=192) matched for sex, age and ethnicity. Comparing the distribution of rs6265 genotypes and alleles between groups of patients and controls no significant differences were found (p>0.05). Serum BDNF levels varied significantly by genotype (rs6265) among PD patients. Minimum mean serum BDNF level (320.1±164.6 pg/ml) was noted for individuals with the AA genotype, which significantly differs from the corresponding indicator among individuals with GA (2944.2±1590.6 pg/ml; p=0.0001) and GG genotypes (2949.4±1620.6 pg/ml; p=3.9×10-5). The concentration of BDNF significantly differed between patients with different forms of PD (p=0.0007) and increased as the stage of the disease progressed according to Hoehn and Yahr staging scale (p=1.0×10-6). The BDNF rs6265 polymorphism was not associated with the development of PD in the studied population. The variability of the mean serum BDNF level was established depending on the genotype of the BDNF polymorphism in PD patients and a number of clinical features.

Brain-Derived Neurotrophic Factor Val66Met is Associated with Variation in Cortical Structure in Healthy Aging Subjects.

Aging is associated with progressive brain atrophy and declines in learning and memory, often attributed to hippocampal or cortical deterioration. The role of brain-derived neurotrophic factor (BDNF) in modulating the structural and functional changes in the brain and visual system, particularly in relation to BDNF Val66Met polymorphism, remains underexplored. In this present cross-sectional observational study, we aimed to assess the effects of BDNF polymorphism on brain structural integrity, cognitive function, and visual pathway alterations. A total of 108 older individuals with no evidence of dementia and a mean (SD) age of 67.3 (9.1) years were recruited from the Optic Nerve Decline and Cognitive Change (ONDCC) study cohort. The BDNF Met allele carriage had a significant association with lower entorhinal cortex volume (6.7% lower compared to the Val/Val genotype, P = 0.02) and posterior cingulate volume (3.2% lower than the Val/Val group, P = 0.03), after adjusting for confounding factors including age, sex and estimated total intracranial volumes (eTIV). No significant associations were identified between the BDNF Val66Met genotype and other brain volumetric or diffusion measures, cognitive performances, or vision parameters except for temporal retinal nerve fibre layer thickness. Small but significant correlations were found between visual structural and functional, cognitive, and brain morphological metrics. Our findings suggest that carriage of BDNF Val66Met polymorphism is associated with lower entorhinal cortex and posterior cingulate volumes and may be involved in modulating the cortical morphology along the aging process.

Day‐to‐day Sleep Variability in Val66Met BDNF Carriers: A Potential Biological Pathway Between BDNF Activity and Alzheimer’s Disease Pathology?

AbstractBackgroundWe previously showed that day‐to‐day sleep variability was associated with biomarkers of Alzheimer’s disease (AD) pathology. Given that brain‐derived neurotrophic factor (BDNF) activity has been involved in both AD and cognitive impacts of lifestyle risk factors, we sought to evaluate day‐to‐day sleep variability in those carrying the Met allele of the Val66Met BDNF polymorphism, which affects BDNF release. Additionally, we explored whether BDNF polymorphism modified the association between CSF AD pathology and day‐to‐day sleep variability.MethodThe PREVENT‐AD cohort enrolls dementia‐free persons with a parental history of sporadic AD. We characterized 203 dementia‐free participants from this cohort at the polymorphic BDNF locus, identifying 136 persons with genotype Val/Val (age 68.2±5.3y, 75%women), 67 Met heterozygotes/homozygotes (68.4±5.6y, 73% women, including six Met/Met homozygotes). After a week of actigraphy, we calculated these participants’ standard deviation of day‐to‐day sleep characteristics. We used t‐tests to compare day‐to‐day sleep variability in sleep characteristics between Val homozygotes and Met carriers. In a subsample of 101 participants, we assayed CSF Aβ42, t‐tau and p‐tau181, and used age‐ and sex‐adjusted linear regressions with an interaction term to test for moderation by BDNF genotype (36 Met carriers vs. 65 Val homozygotes) between sleep variability and CSF biomarker results.ResultAs compared to Val homozygotes, sleep was disturbed and unstable in BDNF Met carriers (heterozygotes/homozygotes). They had higher day‐to‐day variability in sleep fragmentation (activity counts, wake after sleep onset, fragmentation index), sleep onset latency, and sleep duration, resulting in weekly sleep patterns that were more fragmented and less efficient. Further, BDNF genotype moderated the association between CSF t‐tau and p‐tau181 with day‐to‐day sleep duration variability, such that only Met carriers showed an association between elevated tau concentration and sleep duration variability.ConclusionBDNF Met carriers had disturbed and unstable daily sleep patterns. Because the Met allele is known to decrease plasticity of neural mechanisms, the ability to achieve healthy and stable sleep may depend on such mechanisms. Thus, poorer sleep in Met carriers might be a biological mechanism by which altered BDNF activity affects tau pathology or, alternatively, accumulated AD pathology in Met carriers may disrupt sleep‐wake patterns.

Brain-Heart Axis: Brain-Derived Neurotrophic Factor and Cardiovascular Disease-A Review of Systematic Reviews.

The brain-heart axis is an intra- and bidirectional complex that links central nervous system dysfunction and cardiac dysfunction. In recent decades, brain-derived neurotrophic factor (BDNF) has emerged as a strategic molecule involved in both brain and cardiovascular disease (CVD). This systematic review of systematic reviews aimed to (1) identify and summarize the evidence for the BDNF genotype and BDNF concentration in CVD risk assessment, (2) evaluate the evidence for the use of BDNF as a biomarker of CVD recovery, and (3) evaluate rehabilitation approaches that can restore BDNF concentration. A comprehensive search strategy was developed using PRISMA. The risk of bias was assessed via ROBIS. Seven studies were identified, most of which aimed to evaluate the role of BDNF in stroke patients. Only two systematic reviews examined the association of BDNF concentration and polymorphism in CVDs other than stroke. The overall evidence showed that BDNF plays a fundamental role in assessing the risk of CVD occurrence, because lower BDNF concentrations and rs6265 polymorphism are often associated with CVD. Nevertheless, much work remains to be carried out in current research to investigate how BDNF is modulated in different cardiovascular diseases and in different populations.

Association of BDNF risk variant and dorsolateral cortical thickness with long-term treatment response to valproate in type I bipolar disorder: An exploratory study.

Valproate is among the most prescribed drugs for bipolar disorder; however, 87% of patients do not report full long-term treatment response (LTTR) to this medication. One of valproate's suggested mechanisms of action involves the brain-derived neurotrophic factor (BDNF), expressed in the brain areas regulating emotions, such as the prefrontal cortex. Nonetheless, data about the role of BDNF in LTTR and its implications in the structure of the dorsolateral prefrontal cortex (dlPFC) is scarce. We explore the association of BDNF variants and dorsolateral cortical thickness (CT) with LTTR to valproate in bipolar disorder type I (BDI). Twenty-eight BDI patients were genotyped for BDNF polymorphisms rs1519480, rs6265, and rs7124442, and T1-weighted 3D brain scans were acquired. LTTR to valproate was evaluated with Alda's scale. A logistic regression analysis was conducted to evaluate LTTR according to BDNF genotypes and CT. We evaluated CT differences by genotypes with analysis of covariance. LTTR was associated with BDNF rs1519480 and right dlPFC thickness. Insufficient responders with the CC genotype had thicker right dlPFC than TC and TT genotypes. Full responders reported thicker right dlPFC in TC and TT genotypes. In conclusion, different patterns of CT related to BDNF genotypes were identified, suggesting a potential biomarker of LTTR to valproate in our population.

Brain-Derived Neurotrophic Factor (BDNF) as a Predictor of Treatment Response in Major Depressive Disorder (MDD): A Systematic Review.

Brain-derived neurotrophic factor (BDNF) has been studied as a biomarker of major depressive disorder (MDD). Besides diagnostic biomarkers, clinically useful biomarkers can inform response to treatment. We aimed to review all studies that sought to relate BDNF baseline levels, or BDNF polymorphisms, with response to treatment in MDD. In order to achieve this, we performed a systematic review of studies that explored the relation of BDNF with both pharmacological and non-pharmacological treatment. Finally, we reviewed the evidence that relates peripheral levels of BDNF and BDNF polymorphisms with the development and management of treatment-resistant depression.

Thirty years of BDNF study in central myelination: From biology to therapy.

Being the highest expressed neurotrophin in the mammalian brain, the brain-derived neurotrophic factor (BDNF) is essential to neural development and plasticity in both health and diseases. Following the discovery of BDNF by Yves-Alain Barde in 1982, the main feature of BDNF's activity in myelination was first described by Cellerino et al. in 1997. Since then, genetic manipulation of the BDNF-encoding gene and its receptors in murine models has revealed the contribution of BDNF to the myelinating process in the central nervous system (CNS). The series of BDNF or receptor mouse mutants as well as the BDNF polymorphism in humans have provided new insights into the roles that BDNF signaling plays in myelination in a complex manner. 2024 marks the 30th year of BDNF's research in myelination. Here, we share our perspective on the 30-year history of BDNF in the field of CNS myelination from phenotyping to therapeutic development, focusing on genetic evidence regarding the mechanism by which BDNF regulates myelin formation and repair in the CNS. This review also discusses the current hypotheses of BDNF's action on CNS myelination: axonal- and oligodendroglial-driven mechanisms, which may be ultimately activity-dependent. Last, this review raises the challenges and opportunities of developing BDNF-based therapies for neurodegenerative diseases, opening unanswered questions for future investigation.

Association of the Brain-Derived Neurotrophic Factor Gene (BDNF) Val66Met Polymorphism with Individual Alpha Peak Frequency and Alpha Power in Adults

—A single nucleotide polymorphism in the brain-derived neurotrophic factor (BDNF) gene (Val66Met) functions to regulate activity-dependent secretion of (BDNF), which plays an important role in neuroprotection and synaptic plasticity. In several studies, the Met allele was associated with lower electroencephalogram (EEG) α-power values, calculated in the standard frequency range, in young subjects. In addition to α-power, one of the inherited EEG correlates of brain functioning is individual alpha peak frequency (IAPF). Although IAPF has a separate functional role, its association with BDNF Val66Met polymorphism has not been studied. IAPF is also used to determine the boundaries of individual frequency ranges, which, unlike the standard ones, are more consistent with functional rhythm characteristics. Using a sample of 192 subjects aged 18–78 years, the association between parietal-occipital IAPF and BDNF polymorphism, as well as the genotype differences in α-power calculated in standard (8–12 Hz) and individual frequency ranges (from (IAPF –2) to (IAPF +2) Hz) were examined. A decrease of IAPF in Val/Met compared to Val/Val was observed. For power calculated in the individual frequency range, genetic differences in both eyes-closed (Val/Met > homozygous genotypes) and eyes-open (Val-carriers > Met/Met) conditions were revealed. Analysis within the standard frequency range showed differences only in the eyes-open condition, which could be due to a shift of power indicators calculated in the α-rhythm functional range to the low frequency region among Val/Met carriers, which showed a decrease in IAPF. The results suggest that the inclusion of Val/Met in the pooled group of Met carriers in the analysis of genetic differences in brain activity may level out the differences between the Val/Val and Val/Met genotypes and show the advantage of using individual frequency bands in the analysis of BDNF Val66Met-associated EEG features.

Val66Met Polymorphism of Brain-Derived Neurotrophic Factor (BDNF) is Associated with Individual Alpha Peak Frequency and Alpha Power in Adults

Single-nucleotide polymorphism within the BDNF gene (Val66Met) influences activity-dependent secretion of the brain-derived neurotrophic factor (BDNF), which affects neuroprotection and synaptic plasticity. Several studies found associations between Met allele and lower power of the EEG α-rhythm determined in the standard frequency range in young adults. Along with the power, one of the highly heritable EEG correlates of brain functions is the individual α-peak frequency (IAPF). Although IAPF has independent functional significance, its association with the Val66Met BDNF polymorphism has not been studied. IAPF is also used to determine the boundaries of individual frequency ranges; in contrast to the standard ones, they reflect functional characteristics of rhythms to a greater extent. We explored in 192 subjects aged 18–78 years whether parieto-occipital IAPF is associated with BDNF polymorphism and tested genotypic differences in α-power calculated in standard (8−12 Hz) and individual (from (IAPF –2) to (IAPF +2) Hz) frequency ranges. IAPF was decreased in Val/Met in comparison to Val/Val. For individual frequency range, genetic differences were found in both eyes closed (Val/Met homozygous genotypes) and eyes open (Val-carriers Met/Met) condition. For standard frequency range – only in eyes open condition, which may be due to a shift of the α-functional range towards a region of low frequencies among Val/Met-carriers that showed a decrease in IAPF. The results indicate that the inclusion of Val/Met in the combined group of Met-carriers in the analysis of genetic differences in brain activity can eliminate the differences between Val/Val and Val/Met genotypes, as well as the advantage of using individual frequency bands in the analysis of BDNF-associated features of EEG.

Brain‐derived neurotrophic factor genes are associated with neuropsychiatric symptom progression in dementia. The Cache county dementia progression study

AbstractBackgroundPolymorphisms in genes coding for the neurotrophin, brain‐derived neurotrophic factor (BDNF) or its receptors, have been associated with Alzheimer’s disease and related disorders (ADRD), with sex‐dependent effects. Associations with neuropsychiatric symptom (NPS) progression after dementia onset has been largely unexplored. In a population‐based cohort, we examined the relationships between BDNF gene single‐nucleotide polymorphisms (SNPs) and NPS progression after dementia onset.Method880 participants [61.3% female; mean (SD) age = 82.0 (71) years] with dementia [68.2% AD; 13.5% Vascular Dementia (VaD); 18.3% other dementia (OD)] were assessed on the Neuropsychiatric Inventory (NPI) every six‐to‐18 months. Mean(SD) baseline dementia duration was 2.9(2.7) years. The following SNPs were examined as predictors of NPI scores over time in linear mixed‐effects models: rs6265 (BDNF G196A/Val66Met), rs56164415 (BDNF C270T), rs2289656 (NTRK2 receptor TrkB), and rs2072446 (NGFR p75NTR). Covariates included age of dementia onset, education, apolipoprotein E genotype, and dementia type and duration at baseline.ResultSex‐dependent effects were found for two SNPs. Compared to those with major alleles, males with the rs56164415 minor allele exhibited a lower initial Apathy score, that increased over time (C/t*sex*time2:b = ‐0.063, SE = 0.029, p = .033); by contrast, females showed no differences by SNP alleles. Females homozygous for the rs2289656 minor allele exhibited a rapid increase in Anxiety that decreased over time (t/t*sex*time2: b = ‐0.145, SE = 0.054, p = .0073). For both sexes, presence of minor alleles for BDNF polymorphisms rs6265 (G/a*time2: b = ‐0.017, SE = 0.004, p &lt; .001; a/a*time2: b = ‐0.035, SE = 0.013, p = .006) and rs56164415 (C/t*time2: b = 0.019, SE = 0.005, p &lt; .001) was associated with increased NPI Agitation/Aggression well after baseline. Rs6265 minor allele homozygotes (a/a*time2: b = ‐0.049, SE = 0.013, p &lt; .001) and rs2072446 minor allele carriers (Ct/tt*time2: b = ‐0.012, SE = 0.005, p = .025) exhibited initial increases in Delusions, which diminished approximately 5 years thereafter.ConclusionSpecific BDNF genotypes were associated with NPS presentation after dementia onset, with some sex‐dependent effects. Future research on enhancing BDNF signaling may present possible targets for intervention.

Association between chronic tinnitus and brain-derived neurotrophic factor antisense RNA polymorphisms linked to the Val66Met polymorphism in BDNF

Tinnitus is the sound heard in the ear or head of a person in the absence of external stimuli. Its etiopathogenesis is still not fully understood and the etiological causes responsible for tinnitus are quite variable. Brain-derived neurotrophic factor (BDNF) is one of the key neurotrophic factors in the growth, differentiation, and survival of neurons and in the developing auditory pathway, including the inner ear sensory epithelium. The regulation of BDNF gene is known to be managed by BDNF antisense (BDNF-AS) gene. BDNF-AS is located downstream of the BDNF gene and transcribes a long non-coding RNA. Inhibition of BDNF-AS upregulates BDNF mRNA, which increases protein levels and stimulates neuronal development and differentiation. Thus, BDNF and BDNF-AS both may play roles in the auditory pathway. Polymorphisms in both genes may have impact on hearing performance. A link was suggested between tinnitus and BDNF Val66Met polymorphism. However, there is no study questioning the relationship of tinnitus with BDNF-AS polymorphisms linked with BDNF Val66Met polymorphism. Therefore, this study aimed to scrutinize the role of BDNF-AS polymorphisms showing linkage with the BDNF Val66Met polymorphism in the course of tinnitus pathophysiology. Six BDNF-AS polymorphisms were analyzed on the tinnitus patients (n = 85) and the control subjects (n = 60) by Fluidigm Real-Time PCR using the Fluidigm Biomark microfluidic platform. When BDNF-AS polymorphisms were compared between the groups in terms of genotype and gender distribution, statistically significant differences were detected in rs925946, rs1519480, and rs10767658, polymorphisms (p less than 0.05). When the polymorphisms were compared by the duration of tinnitus, significant differences were found in rs925946, rs1488830, rs1519480, and rs10767658 polymorphisms (p less than 0.05). According to genetic inheritance model analysis, 2.33 and 1.53-fold risks were found for the rs10767658 polymorphism in the recessive and the additive models, respectively. For the rs1519480 polymorphism, a 2.25 fold risk was observed in the additive model. For the rs925946 polymorphism, 2.44 fold protective effect in dominant model, and 0.62 fold risk was found in the additive model. In conclusion, four of the polymorphisms in BDNF-AS gene (rs955946, rs1488830, rs1519480, and rs10767658) are potential gene loci that may play a role in the auditory pathway and affect auditory performance.