Association between brain-derived neurotrophic factor Val66Met and obesity in children and adolescents

The BDNF Val66Met polymorphism and health-related quality of life in youth with obesity

The brain derived-neurotrophic factor (BDNF) Val66Met polymorphism causes functional changes in BDNF, and is associated with obesity and some psychiatric disorders, but its relationship to health-related quality of life (HRQoL) remains unknown. This study examined, in youth with obesity, whether carriers of the BDNF Val66met polymorphism Met-alleles (A/A or G/A) differed from noncarriers (G/G) on HRQoL. The participants were 187 adolescents with obesity. Ninety-nine youth were carriers of the homozygous Val/Val (G/G) alleles, and 88 were carriers of the Val/Met (G/A) or Met/Met (A/A) alleles. Blood samples were drawn in the morning after an overnight fast for genotyping. HRQoL was measured using the Pediatric-Quality of Life core version. Compared to carriers of the Val66Met Val (G/G) alleles, carriers of the Met-Alleles reported significantly higher physical -HRQoL (p = 0.02), school-related HRQoL, (p = 0.05), social-related HRQoL (p = 0.05), and total HRQoL (p = 0.03), and a trend for Psychosocial-HRQoL. Research is needed to confirm our findings and determine whether carriers of the BDNF Val66Met homozygous Val (G/G) alleles may be at risk of diminished HRQoL, information that can influence interventions in a high-risk population of inactive youth with obesity.

Neuroprotection in metabolic syndrome by environmental enrichment. A lifespan perspective

Metabolic syndrome (MetS) is defined by the concurrence of different metabolic conditions: obesity, hypertension, dyslipidemia, and hyperglycemia. Its incidence has been increasingly rising over the past decades and has become a global health problem. MetS has deleterious consequences on the central nervous system (CNS) and neurological development. MetS can last several years or be lifelong, affecting the CNS in different ways and treatments can help manage condition, though there is no known cure. The early childhood years are extremely important in neurodevelopment, which extends beyond, encompassing a lifetime. Neuroplastic changes take place all life through - childhood, adolescence, adulthood, and old age - are highly sensitive to environmental input. Environmental factors have an important role in the etiopathogenesis and treatment of MetS, so environmental enrichment (EE) stands as a promising non-invasive therapeutic approach. While the EE paradigm has been designed for animal housing, its principles can be and actually are applied in cognitive, sensory, social, and physical stimulation programs for humans. Here, we briefly review the central milestones in neurodevelopment at each life stage, along with the research studies carried out on how MetS affects neurodevelopment at each life stage and the contributions that EE models can provide to improve health over the lifespan.

Associations of Plasma BDNF and BDNF Gene Polymorphism with Cardiometabolic Parameters in Thai Children: A Pilot Study

Background

Childhood obesity is an important public health crisis worldwide. The brain-derived neurotrophic factor (BDNF) has been demonstrated to play a role in controlling energy homeostasis and cardiovascular regulation.

Objectives

To examine brain-derived neurotrophic factor (BDNF) levels and anthropometric-cardiometabolic and hematological parameters in obese and nonobese children and to determine whether two BDNF gene polymorphisms (G196A and C270T) are linked to BDNF levels, obesity, and anthropometric-cardiometabolic and hematological parameters among Thai children.

Methods

This case-control study included an analysis of 469 Thai children: 279 healthy nonobese and 190 obese children. Anthropometric-cardiometabolic and hematological variables and BDNF levels were measured. Genotyping of BDNF G196A and C270T was performed using the polymerase chain reaction-restriction fragment length polymorphism technique.

Results

Children in the obese group had significantly higher white blood cell counts and some cardiometabolic parameters. Although the difference in BDNF level between the nonobese and obese groups was not significant, BDNF level was significantly positively correlated with hematological and cardiometabolic parameters, including blood pressure, triglycerides, and triglycerides and the glucose index. The BDNF G196A polymorphism in children was only associated with decreased systolic blood pressure (p < 0.05), while the BDNF C270T polymorphism was found not to be related to BDNF levels, obesity, or other parameters after adjusting for potential covariates.

Conclusions

These findings in Thai children suggest that obesity is associated with increased cardiometabolic risk factors, but not with BDNF levels or the two BDNF polymorphisms studied, while the BDNF G196A polymorphism is a beneficial marker for controlling blood pressure among Thai children.

Methylation Status of Exon IV of the Brain-Derived Neurotrophic Factor (BDNF)-Encoding Gene in Patients with Non-Diabetic Hyperglycaemia (NDH) before and after a Lifestyle Intervention

BDNF signalling in hypothalamic neuronal circuits is thought to regulate mammalian food intake. In light of this, we investigated how a lifestyle intervention influenced serum levels and DNA methylation of BDNF gene in fat tissue and buffy coat of NDH individuals. In total, 20 participants underwent anthropometric measurements/fasting blood tests and adipose tissue biopsy pre-/post-lifestyle (6 months) intervention. DNA was extracted from adipose tissue and buffy coat, bisulphite converted, and pyrosequencing was used to determine methylation levels in exon IV of the BDNF gene. RNA was extracted from buffy coat for gene expression analysis and serum BDNF levels were measured by ELISA. No differences were found in BDNF serum levels, but buffy coat mean BDNF gene methylation decreased post-intervention. There were correlations between BDNF serum levels and/or methylation and cardiometabolic markers. (i) Pre-intervention: for BDNF methylation, we found positive correlations between mean methylation in fat tissue and waist-hip ratio, and negative correlations between mean methylation in buffy coat and weight. (ii) Post-intervention: we found correlations between BDNF mean methylation in buffy coat and HbA1c, BDNF methylation in buffy coat and circulating IGFBP-2, and BDNF serum and insulin. Higher BDNF % methylation levels are known to reduce BNDF expression. The fall in buffy coat mean BDNF methylation plus the association between lower BDNF methylation (so potentially higher BDNF) and higher HbA1c and serum IGFBP-2 (as a marker of insulin sensitivity) and between lower serum BDNF and higher circulating insulin are evidence for the degree of BDNF gene methylation being implicated in insulinisation and glucose homeostasis, particularly after lifestyle change in NDH individuals.

New Insights Into the Pivotal Role of CREB-Regulated Transcription Coactivator 1 in Depression and Comorbid Obesity

Depression and obesity are major public health concerns, and there is mounting evidence that they share etiopathophysiological mechanisms. The neurobiological pathways involved in both mood and energy balance regulation are complex, multifactorial and still incompletely understood. As a coactivator of the pleiotropic transcription factor cAMP response element-binding protein (CREB), CREB-regulated transcription coactivator 1 (CRTC1) has recently emerged as a novel regulator of neuronal plasticity and brain functions, while CRTC1 dysfunction has been associated with neurodegenerative and psychiatric diseases. This review focuses on recent evidence emphasizing the critical role of CRTC1 in the neurobiology of depression and comorbid obesity. We discuss the role of CRTC1 downregulation in mediating chronic stress-induced depressive-like behaviors, and antidepressant response in the light of the previously characterized Crtc1 knockout mouse model of depression. The putative role of CRTC1 in the alteration of brain energy homeostasis observed in depression is also discussed. Finally, we highlight rodent and human studies supporting the critical involvement of CRTC1 in depression-associated obesity.

The Role of Brain-Derived Neurotrophic Factor in Obstructive Sleep Apnea and Endothelial Function in a Pediatric Population With Obesity

BACKGROUND

Childhood obesity has increased worldwide, becoming a significant public health concern. Brain-derived neurotrophic factor (BDNF) plays an important role in the central regulation of food intake and body weight, but little is known regarding its role in childhood obesity. Next to obesity, BDNF has been linked to obstructive sleep apnea (OSA) and endothelial dysfunction, two obesity-related comorbidities. The aim of this study is to investigate how BDNF, OSA and endothelial dysfunction interact in children with obesity and to determine the effect of weight loss on serum BDNF levels.

METHODS

Children and adolescents with obesity aged 8-18 years who were enrolled in a multidisciplinary obesity treatment (MOT) in a tertiary hospital, were prospectively included. Several examinations were conducted during this MOT; at baseline, after 6 months and after 12 months, including the assessment of endothelial function, body composition measurements and a polysomnography. BDNF levels were measured on a serum sample by means of ELISA.

RESULTS

A total of 103 patients with obesity was included, of which 20 had OSA (19.4%). BDNF levels were comparable in children with obesity and OSA and children with obesity but without OSA (26.75 vs. 27.87 ng/ml, p = 0.6). No correlations were found between BDNF and sleep-related variables or between BDNF and endothelial function parameters nor between BDNF and adiposity measures. To investigate if the interaction between OSA and endothelial dysfunction had an influence on BDNF levels, a general linear model was used. This model revealed that a diagnosis of OSA, as well as the interaction between OSA and maximal endothelial dilatation, contributed significantly (p = 0.03, p = 0.04, respectively) to BDNF levels. After 1 year of weight loss therapy, BDNF levels did not change (26.18 vs. 25.46 ng/ml, p = 0.7) in our population.

CONCLUSION

BDNF concentrations were comparable in children with obesity, both with and without OSA, indicating that BDNF levels are not affected by OSA. However, we did find an interaction effect of OSA and endothelial function on BDNF levels.

Associations of the BDNF Val66Met Polymorphism With Body Composition, Cardiometabolic Risk Factors, and Energy Intake in Youth With Obesity: Findings From the HEARTY Study

The brain-derived neurotrophic factor (BDNF) Val66Met polymorphism is functionally related to BDNF, and is associated with obesity and metabolic complications in adults, but limited research exists among adolescents. This study comparatively examined carriers and non-carriers of the BDNF Val66Met polymorphism on body composition, energy intake, and cardiometabolic profile among adolescents with obesity. The sample consisted of 187 adolescents with obesity; 99 were carriers of the homozygous Val (G/G) alleles and 88 were carriers of the Val/Met (G/A) or Met (A/A) alleles. Cardiometabolic profile and DNA were quantified from fasted blood samples. Body composition was assessed by magnetic resonance imaging (MRI). Compared to carriers of the homozygous Val (G/G) allele, carriers of the Val/Met (G/A) or Met/Met (A/A) variants exhibited significantly higher protein (p = 0.01) and fat (p = 0.05) intake, C-Reactive protein (p = 0.05), and a trend toward higher overall energy intake (p = 0.07), fat-free mass (p = 0.07), and lower HDL-C (p = 0.07) Results showed for the first time that among youth with obesity, carriers of the Val66Met BDNF Met-alleles exhibited significantly higher C-reactive protein and energy intake in the form of fat and protein compared to Val-allele carriers, thereby providing support for the possible role of BDNF in appetite, weight, and metabolic regulation during adolescence. Clinical Trial Registration: http://clinicaltrials.gov/, identifier NCT00195858.

Interaction between dietary total antioxidant capacity and BDNF Val66Met polymorphism on lipid profiles and atherogenic indices among diabetic patients

Brain-derived neurotrophic factor (BDNF) belongs to the "neurotrophin" family of growth factors, and it has recently been associated to cardiovascular disease (CVD). We anticipated that BDNF Val66Met polymorphisms may alter CVD risk markers such as serum lipid profile differences, and interaction with total antioxidant capacity of diet (DTAC) could alter these clinical parameters. This cross-sectional study consisted of 667 diabetic patients (39.7% male and 60.3% female). DTAC was calculated by international databases. Biochemical markers including total cholesterol (TC), low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglyceride (TG), superoxide dismutase (SOD), C-reactive protein (CRP), total antioxidant capacity (TAC), pentraxin-3 (PTX3), isoprostaneF2α (PGF2α). interleukin 18 (IL18), leptin and ghrelin were measured by standard protocol. Atherogenic indices (AIP, AC, CR-I, CR-II) were calculated. Genotyping of the BDNF Val66Met polymorphisms was conducted by the real-time PCR-RFLP method. The gene-diet interactions were evaluated using a generalized linear mode (GLMs). Carriers of the Val/Met genotype who were in the higher median intake of FRAP had lower HDL (P:0.04) and higher TG (P:0.005), AIP (P:0.02) and AC (P:0.02) index compared to Val/Val genotypes with lower median intake. Moreover, diabetic patients with Val/Met genotype who consumed higher ORAC intake had increased odds for anthropometric indices (BMI (P:0.01) and WC (P:0.03)), lipid profiles (TG) (P:0.01), and atherogenic index (AIP) (P:0.02), also decreased odds for HDL (P:0.03) concentration compared to reference group whit lower ORAC intake. Individuals with Val/Met genotype who consumed higher TRAP intake had increased odds for WC (P:0.04), TC (P:0.001), TG (P < 0.001), AIP (P < 0.001) and AC (P < 0.001). Finally, Val/Met patients with a higher median intake of TEAC had higher TG (P:0.02), AIP (P:0.009) and AC (P:0.03) compared to the reference group whit lower TEAC intake. Our study showed that Val/Met genotype had also the highest lipid profile and atherogenic indices even in the highest adherence to DTAC. While it seems that the presence of the Val/Val wild-type and BDNF Met/Met homozygotes in diabetic patients with a high DTAC is a protective factor.

The impact of CPT1B rs470117, LEPR rs1137101 and BDNF rs6265 polymorphisms on the risk of developing obesity in an Italian population

OBJECTIVE

This study aimed to analyze 11 single nucleotide polymorphisms (SNPs) belonging to 9 genes involved in metabolic pathways (BDNF rs6265; PNPLA3 rs2294918 and rs2076212; CIDEA rs11545881; NTRK2 rs2289658; ALOX12 rs1126667; ALOX12B rs2304908; LEPR rs1137101; CPT1B rs470117 and rs8142477; rs2305507 CPT1A) in obese patients and controls.

METHODS

Polymorphisms were analyzed in 300 severe obese patients undergoing bariatric surgery (body mass index >30 kg/m²) and 404 control subjects in order to evaluate their association with obesity and clinical variables.

RESULTS

Our findings showed significant differences for the allelic distributions of CPT1B rs470117 and LEPR rs11371010 in obese subjects compared to controls. The BDNF rs6265 correlates with obesity only when associated with the other two SNPs. In particular, for CPT1B rs470117 and LEPR rs1137101, the rare allele was associated with a reduced risk of developing the obese phenotype, whereas the simultaneous presence of the common C allele for rs470117 and A allele for rs1137101 was more frequent in obese patients (p = 0.002, OR = 1.417). A significant association between CPT1B rs470117 and steatosis was found. Moreover, we observed that by associating the rare allele T of the BDNF rs6265 with the most common alleles of the SNPs CPT1B rs470117 and LEPR rs1137101, the combination of T-C-A alleles was associated with a higher risk of developing an obese phenotype (p = 0.001, OR = 1.6679).

CONCLUSIONS

Our results suggest that SNPs CPT1B rs470117 and LEPR rs1137101 taken individually and in association with BDNF rs6265 may be involved in an increased risk of developing obese phenotype in an Italian cohort.

Association of PPARG rs3856806 C>T polymorphism with body mass index, glycaemia and lipid parameters in Serbian adolescents

Background/Aim: Peroxisome proliferator-activated receptor gamma (PPARg) belongs to a family of nuclear hormone receptors and ligand-activated transcription factors. PPARG gene is expressed in many tissues including adipose tissue where it plays a crucial role in differentiation of adipocyte, insulin resistance, blood glucose levels and lipid metabolism. The aim of the study was to examine the association of rs3856806 polymorphism with the body mass index (BMI), fasting glucose levels and lipid parameters in Serbian adolescents. Methods: This research included 287 adolescents of both genders (143 boys and 144 girls), 14-15 years of age. Genotype detection was done by polymerase chain reaction-restriction fragment length polymorphism (RFLP) assay. Results: Results showed statistically significant difference in terms of fasting glucose levels among girls (p = 0.013) depending on their genotype. Female carriers of CC genotype had significantly higher level of fasting glucose levels. Also, results showed that in the group of overweight and obese girls, carriers of CT or TT genotype had statistically significant lower values of HDL cholesterol compared to girls - carriers of CC genotype (p = 0.000). However, this result was not confirmed by multiple regression analysis. Statistically significant association of rs3856806 polymorphism was not observed with BMI nor with other lipid parameters. Conclusion: This polymorphism is associated with fasting glucose level and HDL cholesterol among girls. To draw definite conclusions, further research should be conducted including non-genetic factors and other polymorphisms among this gene.

Association of the Brain-derived Neurotrophic Factor Val66Met Polymorphism with Body Mass Index, Fasting Glucose Levels and Lipid Status in Adolescents

Brain-derived neurotrophic factor (BDNF) has an important role in energy balance. It suppresses food intake, reduces hepatic glucose production and converts white fat into brown fat in adipose tissue, leading to energy dissipation, lowered blood glucose and a lean phenotype. Studies have shown that the single nucleotide polymorphism (SNP) Val66Met within BDNF may be associated with obesity, insulin sensitivity, type 2 diabetes mellitus (T2DM) and dyslipidemia. The objective of the study was to investigate the association of the Val66Met polymorphism with body mass index (BMI), fasting glucose levels and lipid profile in Serbian adolescents. The study included 308 randomly selected healthy adolescents, 153 (49.68%) boys and 155 girls (50.32%), 15 years of age. Data including age, gender, height, weight, lipid profile and fasting glucose were recorded. Genotyping was performed by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. No association of this polymorphism was found with BMI and lipid profile. However, significant association was observed between this polymorphism and fasting blood glucose (FBG). Carriers of a Val/Val genotype had significantly higher mean values of fasting glucose level compared to carriers of Val/ Met and Met/Met genotypes (p = 0.01). To confirm these results multiple linear regression analysis was performed. Body mass index and gender were taken as covariates. Carriers of the Val/Val genotype had significantly higher levels of FBG (β = -0.152, p = 0.02). A statistically significant association between BMI and glucose level was also observed (β = 0.124,p = 0.033). This polymorphism could be associated with fasting glucose level in Serbian adolescents, thus further research would be of great interest to validate these results.

Progress in Genetic Polymorphisms Related to Lipid Disturbances Induced by Atypical Antipsychotic Drugs

Metabolic side effects such as weight gain and disturbed lipid metabolism are often observed in the treatment of atypical antipsychotic drugs (AAPDs), which contribute to an excessive prevalence of metabolic syndrome among schizophrenic patients. Great individual differences are observed but the underlying mechanisms are still uncertain. Research on pharmacogenomics indicates that gene polymorphisms involved in the pathways controlling food intake and lipid metabolism may play a significant role. In this review, relevant genes (HTR2C, DRD2, LEP, NPY, MC4R, BDNF, MC4R, CNR1, INSIG2, ADRA2A) and genetic polymorphisms related to metabolic side effects of AAPDs especially dyslipidemia were summarized. Apart from clinical studies, in vitro and in vivo evidence is also analyzed to support related theories. The association of central and peripheral mechanisms is emphasized, enabling the possibility of using peripheral gene expression to predict the central status. Novel methodological development of pharmacogenomics is in urgent need, so as to provide references for individualized medication and further to shed some light on the mechanisms underlying AAPD-induced lipid disturbances.

Evaluating the effect of BDNF Val66Met polymorphism on complex formation with HAP1 and Sortilin1 via structural modeling

Brain derived neurotrophic factor (BDNF) has a critical role in the neurogenesis, differentiation, survival of the neurons, regulation of the appetite, and energy homeostasis. Two key proteins, Huntingtin associated protein-1 (HAP1) and sortilin1, regulate the intracellular trafficking and stabilization of the precursor proBDNF through interaction with its prodomain region and mark it for secretion. Evidence suggests that the most frequent single nucleotide polymorphism (SNP) of BDNF gene (rs6265) has been associated with different psychiatric, neurodegenerative and eating disorders. In this study, structural bioinformatics and molecular dynamics (MD) simulations were applied, in order to get precise insights into the impact of Val66Met polymorphism on the proBDNF structure and its interaction with HAP1 and Sortilin1. Homology modeling, structure validation, refinement and also protein-protein docking were performed using appropriate servers. The stability, the fluctuations and the compactness of protein complexes were measured by MD simulation parameters including root mean square deviation (RMSD), root mean square fluctuation (RMSF) and Radius of gyration (Rg), respectively. The mutant proBDNF complexes with HAP1 and Sortilin1 revealed higher RMSD and RMSF values and also variable R_g over time compared with wild-type proBDNF. These computational results indicated that, wild-type proBDNF possessed more stable structure in binding with HAP1 and Sortilin1 compared with its mutant form. Therefore, Val66Met SNP could be deleterious due to making structural changes. It may cause a decrease in proBDNF secretion, which could possibly lead to different psychiatric, neurodegenerative and eating disorders. Further experimental lab studies are required for a more accurate conclusion.

Eccentric Training Improves Body Composition by Inducing Mechanical and Metabolic Adaptations: A Promising Approach for Overweight and Obese Individuals

Skeletal muscle generates force by either shortening (concentrically) or lengthening (eccentrically). Eccentric (ECC) exercise is characterized by a lower metabolic demand and requires less muscle activity than concentric (CON) exercise at the same level of exerted force. However, the specific effect of ECC training vs. CON training on lean and fat mass remains underexplored. The first aim of this paper was to review the available evidence regarding the effects of ECC training on whole body and segmental lean and fat mass and, when possible, compare these with the effects of CON training. The second aim was to provide some insights into the main mechanical, physiological, and metabolic adaptations of ECC training that contribute to its effects on body composition. The third aim was to determine the beneficial effects of ECC exercise on health-related parameters in overweight and obese patients. ECC training is an effective modality to improve lean mass, but when matched for load or work, the difference between ECC and CON trainings seems unclear. A few studies reported that ECC training is also efficient at reducing fat mass. By increasing post-exercise resting energy expenditure, modifying metabolic substrate, and improving both blood lipid profile and insulin resistance, ECC training is a potential exercise modality for individuals with chronic conditions such as those who are overweight and obese. Further investigations using standardized experimental conditions, examining not only segmental but also whole body composition, are required to compare ECC and CON trainings.

Inhibition of the CD36 receptor reduces visceral fat accumulation and improves insulin resistance in obese mice carrying the BDNF-Val66Met variant

Obesity-induced metabolic dysfunctions increase the risk for vascular diseases, including type II diabetes and stroke. Managing obesity is of interest to address the worldwide health problem; however, the role of genetic variability in human obesity development and specific targets for obesity-related metabolic disease have not been thoroughly studied. A SNP in the brain-derived neurotropic factor (BDNF) gene that results in the substitution of a valine with a methionine at codon 66 (Val66Met) occurs with a high frequency in humans. This study addressed the effect of genetic variability in developing obesity and the efficacy of the inhibition of cluster of differentiation 36 (CD36), a multifunctional receptor implicated in obesity and insulin resistance, in WT mice and mice with the BDNF Val66Met variant. CD36 inhibition by salvionolic acid B (SAB) in diet-induced obese WT mice reduced visceral fat accumulation and improved insulin resistance. The benefit of SAB was abrogated in CD36 knockout mice, showing the specificity of SAB. In addition, mice with the Val66Met variant in both alleles (BDNF^M/M) fed a high-fat diet exhibited extreme obesity with increased CD36 gene and protein levels in macrophages. Chronic SAB treatment in BDNF^M/M mice significantly decreased visceral fat accumulation and improved insulin resistance. Notably, the effect of SAB was greater in the extremely obese BDNF^M/M mice compared with the WT mice. The study demonstrated a link between BDNF Val66Met and elevated CD36 expression and suggested that CD36 inhibition may be a potential strategy to improve metabolic dysfunctions and to normalize risk factors for vascular diseases in the obese population.

Association Between the Brain-derived Neurotrophic Factor Val66Met Polymorphism and Overweight/Obesity in Pediatric Population

BACKGROUND

The brain-derived neurotrophic factor (BDNF) rs6265 (G196A; Val66Met) single nucleotide polymorphism has been associated with BMI and obesity in distinct populations, both adult and pediatric, with contradictory results involving either Val or Met as the risk variant.

AIM OF THE STUDY

To determine the association between the BDNF Val66Met polymorphism and BMI in Mexican children and adolescents.

METHODS

BDNF Val66Met genotyping by restriction fragment length polymorphism and nutritional status characterized by their BMI-for-age z-scores (BAZ) from pediatric volunteers (n = 498) were analyzed by Fisher's exact test association analysis. Standardized residuals (R) were used to determine which genotype/allele had the major influence on the significant Fisher's exact test statistic. Odds ratios were analyzed to measure the association between genotype and normal weight (≥-2 SD < + 1 SD) and overweight (≥ + 1 SD, including obesity, Ow + Ob) status with 95% confidence intervals to estimate the precision of the effect as well as 95% credible intervals to obtain the most probable estimate.

RESULTS

Comparisons between GG (Val/Val), GA (Val/Met) and AA (Met/Met) genotypes or Met homozygotes vs. Val carriers (combination of GG and GA genotypes) showed significant differences (p = 0.034 and p = 0.037, respectively) between normal weight and the combined overweight and obese pediatric subjects. Our data showed that children/adolescents homozygous for the A allele have increased risk of overweight compared to the Val carriers (Bayes OR = 4.2, 95% CI**[1.09-33.1]).

CONCLUSION

This is the first study showing the significant association between the BDNF rs6265 AA (Met/Met) genotype and overweight/obesity in Mexican pediatric population.

The BDNF Val66Met polymorphism is associated with lower BMI, lower postprandial glucose levels and elevated carbohydrate intake in children and adolescents

BACKGROUND

The amino acid-changing exonic variant rs6265 (Val66Met polymorphism) in the brain-derived neurotrophic factor (BDNF) has been linked to obesity in several genotype-phenotype association studies.

OBJECTIVE

To identify metabolic factors by which this effect might be conveyed, we aimed to investigate its correlation with (i) obesity, (ii) metabolic parameters, (iii) serum levels of BDNF and (iv) measures of energy intake in children and adolescents.

METHODS

We genotyped the variant in 2131 subjects (age 6-18 years) and checked for an association with obesity. Secondly, we correlated the genotype with parameters of glucose and lipid metabolism (fasting/postprandial glucose and insulin levels, HbA1c, homeostasis model assessment, Matsuda, high-density lipoprotein, low-density lipoprotein, total cholesterol and triglycerides) in a smaller subset of 845 subjects. We determined BDNF serum levels in 177 individuals by enzyme-linked immunosorbent assay and assessed the association with genotype and metabolic parameters. Finally, we investigated the association between genotype and macronutrient intake from self-reported food diaries (n = 146).

RESULTS

The minor Met allele was associated with lower BMI standard deviation score (p = 0.002). Post-pubertal Met allele carriers showed lower postprandial glucose levels and a lower HbA1c (β = 0.15, p = 0.046 and β = 0.27, p = 0.012, respectively). Neither the genotype nor any of the metabolic parameters correlated with BDNF serum levels. We observed an increased total calorie intake (β = -0.21, p = 0.007) with increased carbohydrate and protein intake (β = -0.22, p = 0.005 and β = -0.14, p = 0.028, respectively) in Met allele carriers.

CONCLUSIONS

We confirmed the association of the minor Met allele with lower BMI in children and provide new data that it is associated with lower postprandial glucose in post-pubertal subjects. Moreover, Met allele carriers reported to consume more carbohydrates and proteins.

Genetic Variants of the Brain-Derived Neurotrophic Factor and Metabolic Indices in Veterans With Posttraumatic Stress Disorder

Posttraumatic stress disorder (PTSD) is a trauma and stressor related disorder that may develop after exposure to an event that involved the actual or possible threat of death, violence or serious injury. Its molecular underpinning is still not clear. Brain-derived neurotrophic factor (BDNF) modulates neuronal processes such as the response to stress, but also weight control, energy and glucose homeostasis. Plasma BDNF levels and a functional BDNF Val66Met (rs6265) polymorphism were reported to be associated with PTSD, as well as with increased body mass index (BMI) and dyslipidaemia in healthy subjects and patients with cardio-metabolic diseases, but these results are controversial. The other frequently studied BDNF polymorphism, C270T (rs56164415), has been associated with the development of different neuropsychiatric symptoms/disorders. As far as we are aware, there are no data on the association of BDNF Val66Met and C270T polymorphisms with metabolic indices in PTSD. Due to high rates of obesity and dyslipidaemia in PTSD, the aim of this study was to elucidate the association of BDNF Val66Met and C270T polymorphisms with BMI and lipid levels in veterans with PTSD. We hypothesized that BDNF variants contribute to susceptibility to metabolic disturbances in PTSD. The study included 333 Caucasian males with combat related PTSD, diagnosed according to DSM-5 criteria. Genotyping of the BDNF Val66Met and C270T polymorphisms was performed using the real-time PCR method. Results were analyzed using hierarchical multiple linear regression and the Mann-Whitney test, with p-value corrected to 0.005. The results showed that BDNF Val66Met and BDNF C270T polymorphisms were not significantly associated with BMI, total cholesterol, LDL-cholesterol, HDL-cholesterol or triglycerides. Although the BDNF C270T polymorphism was nominally associated only with HDL-cholesterol in veterans with PTSD, this significance disappeared after controlling for the effect of age. Namely, slightly higher plasma HDL values in T allele carriers, compared to CC homozygotes, were associated with differences in age. Our results, controlled for the critical covariates, revealed that BDNF Val66Met and C270T were not significantly associated with metabolic indices in veterans with PTSD and that these genetic variants do not contribute to susceptibility to metabolic disturbances in PTSD.

The Brain-Derived Neurotrophic Factor Val66Met Polymorphism, Delivery Method, Birth Weight, and Night Sleep Duration as Determinants of Obesity in Vietnamese Children of Primary School Age

BACKGROUND

Obesity is a complex disease that involves both environmental and genetic factors in its pathogenesis. Several studies have identified multiple obesity-associated loci in many populations. However, their contribution to obesity in the Vietnamese population is not fully described, especially in children. The study aimed to investigate the association of obesity with Val66Met polymorphism in brain-derived neurotrophic factor (BDNF) gene, delivery method, birth weight, and lifestyle factors in Vietnamese primary school children.

METHODS

A case-control study was conducted on 559 children aged 6-11 years (278 obese cases and 281 normal controls). The obesity of the children was classified using both criteria of International Obesity Task Force (IOTF, 2000) and World Health Organization (WHO, 2007). Lifestyle factors, birth delivery, and birth weight of the children were self-reported by parents. The BDNF genotype was analyzed using the polymerase chain reaction-restriction fragment length polymorphism method. Association was evaluated by multivariate logistic regression and cross-validated by the Bayesian model averaging method.

RESULTS

The most significantly independent factors for obesity were delivery method (cesarean section vs. vaginal delivery, β = 0.56, p = 0.007), birth weight (>3500 to <4000 g vs. 2500-3500 g, β = 0.52, p = 0.035; ≥4000 g vs. 2500-3500 g, β = 1.06, p = 0.015), night sleep duration (<8 h/day vs. ≥8 h/day, β = 0.99, p < 0.0001), and BDNF Val66Met polymorphism (AA and GG vs. AG, β = 0.38, p = 0.039).

CONCLUSIONS

The study suggested the significant association of delivery method, birth weight, night sleep duration, and BDNF Val66Met polymorphism, with obesity in Vietnamese primary school children.

Longitudinal Associations Between Childhood Obesity and Academic Achievement: Systematic Review with Focus Group Data

PURPOSE

The purposes of this study were to review the evidence on longitudinal associations between child and adolescent obesity and academic achievement and to provide perceptions of adolescents with obesity and their parents on this topic.

RECENT FINDINGS

Synthesis of 31 studies (from 17 cohorts) suggested that relationships between obesity and academic achievement are not well established, except for adolescent girls' maths attainment, potentially mediated by both weight-related bullying and executive cognitive functions. Focus groups with adolescent girls with obesity confirmed experiences of psychosocial distress at school particularly during Physical Education. Adolescents perceived that obesity was not related to academic achievement directly, but by their attitude to school. Interventions are warranted to promote psychosocial wellbeing and cognitive abilities linked to academic achievement in adolescent girls with obesity. Physical Education should be a positive experience for children and adolescents with obesity.

Potential unfavorable impacts of BDNF Val66Met polymorphisms on metabolic risks in average population in a longevous area

Background

Brain-derived neurotrophic factor (BDNF) has been implicated in cognitive performance and the modulation of several metabolic parameters in some disease models, but its potential roles in successful aging remain unclear. We herein sought to define the putative correlation between BDNF Val66Met and several metabolic risk factors including BMI, blood pressure, fasting plasma glucose (FPG) and lipid levels in a long-lived population inhabiting Hongshui River Basin in Guangxi.

Methods

BDNF Val66Met was typed by ARMS-PCR for 487 Zhuang long-lived individuals (age ≥ 90, long-lived group, LG), 593 of their offspring (age 60–77, offspring group, OG) and 582 ethnic-matched healthy controls (aged 60–75, control group, CG) from Hongshui River Basin. The correlations of genotypes with metabolic risks were then determined.

Results

As a result, no statistical difference was observed on the distribution of allelic and genotypic frequencies of BDNF Val66Met among the three groups (all P > 0.05) except that AA genotype was dramatically higher in females than in males of CG. The HDL-C level of A allele (GA/AA genotype) carriers was profoundly lower than was non-A (GG genotype) carriers in the total population and the CG (P = 0.009 and 0.006, respectively), which maintained in females, hyperglycemic and normolipidemic subgroup of CG after stratification by gender, BMI, glucose and lipid status. Furthermore, allele A carriers, with a higher systolic blood pressure, exhibited 1.63 folds higher risk than non-A carriers to be overweight in CG (OR = 1.63, 95% CI: 1.05 - 2.55, P = 0.012). Multiple regression analysis displayed that the TC level of LG reversely associated with BDNF Val66Met genotype.

Conclusions

These data suggested that BDNF 66Met may play unfavorable roles in blood pressure and lipid profiles in the general population in Hongshui River area which might in part underscore their poorer survivorship versus the successful aging individuals and their offspring.

Electronic supplementary material

The online version of this article (doi:10.1186/s12877-016-0393-0) contains supplementary material, which is available to authorized users.

Brain derived neurotrophic factor in newly diagnosed diabetes and prediabetes

Brain derived neurotrophic factor (BDNF) is thought to play an important role in glucose metabolism, but the exact mechanism has not been elucidated. The aim was to assess differences in serum BDNF levels across individuals with varying levels of glucose tolerance, and the association of serum BDNF levels with genetic variants and DNA methylation. Participants were selected from an ongoing population-based cohort study in rural China. In a randomly selected subsample of healthy participants (n = 33 males, n = 52 female), we assessed serum BDNF and in n = 50 of these, also DNA methylation. In a second subsample (all women; n = 28 with diabetes, n = 104 with prediabetes, and n = 105 age- and body mass index (BMI)-matched controls), we assessed serum BDNF and genetic variants. In a third subsample (all with diabetes; n = 7 normal BMI + low insulin level, n = 9 normal BMI + high insulin level, n = 9 obese + high insulin level), we assessed DNA methylation. Compared to age- and BMI-matched controls (24.71 (IQR, 20.44, 29.80) ng/ml), serum BDNF was higher in participants with prediabetes (27.38 (IQR, 20.64, 34.29) ng/ml), but lower in those with diabetes (23.40 (IQR, 18.12, 30.34) ng/ml) (P < 0.05). Two genetic variants near BDNF (rs4074134 and rs6265) were confirmed to be associated with BMI. BDNF CpG-6 methylation was positively associated with waist-to-hip ratio (P < 0.05). Furthermore, hyper-methylation in this site was found in participants with diabetes and high fasting insulin levels compared to those with diabetes and low fasting insulin levels, regardless of BMI status (P < 0.001 and P = 0.001, respectively). Observed differences in serum BDNF levels, genetic variants, and DNA methylation patterns across different glucose metabolic state suggest that BDNF may be involved in the pathophysiological process of insulin resistance and type 2 diabetes.

The BDNF Val66Met polymorphism enhances glutamatergic transmission but diminishes activity-dependent synaptic plasticity in the dorsolateral striatum

The Val66Met polymorphism in the brain-derived neurotrophic factor (BDNF) gene disrupts the activity-dependent release of BDNF, which might underlie its involvement in several neuropsychiatric disorders. Consistent with the potential role of regulated release of BDNF in synaptic functions, earlier studies have demonstrated that the BDNF Val66Met polymorphism impairs NMDA receptor-mediated synaptic transmission and plasticity in the hippocampus, the medial prefrontal cortex and the central amygdala. However, it is unknown whether the BDNF Val66Met polymorphism affects synapses in the dorsal striatum, which depends on cortical afferents for BDNF. Electrophysiological experiments revealed an enhanced glutamatergic transmission in the dorsolateral striatum (DLS) of knock-in mice containing the variant polymorphism (BDNF^Met/Met) compared to the wild-type (BDNF^Val/Val) mice. This increase in glutamatergic transmission is mediated by a potentiation in glutamate release and NMDA receptor transmission in the medium spiny neurons without any alterations in non-NMDA receptor-mediated transmission. We also observed an impairment of synaptic plasticity, both long-term potentiation and depression in the DLS neurons, in BDNF^Met/Met mice. Thus, the BDNF Val66Met polymorphism exerts an increase in glutamatergic transmission but impairs synaptic plasticity in the dorsal striatum, which might play a role in its effect on neuropsychiatric symptoms. This article is part of the Special Issue entitled 'Ionotropic glutamate receptors'.

Association between obesity and the brain-derived neurotrophic factor gene polymorphism Val66Met in individuals with bipolar disorder in Mexican population

BACKGROUND

The brain-derived neurotrophic factor (BDNF) has been considered as an important candidate gene in bipolar disorder (BD); this association has been derived from several genetic and genome-wide studies. A polymorphic variant of the BDNF (Val66Met) confers some differences in the clinical presentation of affective disorders. In this study, we evaluated a sample population from Mexico City to determine whether the BDNF (rs6265) Val66Met polymorphism is associated with the body mass index (BMI) of patients with BD.

METHODS

This association study included a sample population of 357 individuals recruited in Mexico City. A total of 139 participants were diagnosed with BD and 137 were classified as psychiatrically healthy controls (all individuals were interviewed and evaluated by the Diagnostic Interview for Genetic Studies). Genomic DNA was extracted from peripheral blood leukocytes. The quantitative polymerase chain reaction (qPCR) assay was performed in 96-well plates using the TaqMan Universal Thermal Cycling Protocol. After the PCR end point was reached, fluorescence intensity was measured in a 7,500 real-time PCR system and evaluated using the SDS v2.1 software, results were analyzed with Finetti and SPSS software. Concerning BMI stratification, random groups were defined as follows: normal <25 kg/m(2), overweight (Ow) =25.1-29.9 kg/m(2), and obesity (Ob) >30 kg/m(2).

RESULTS

In the present work, we report the association of a particular BMI phenotype with the presence of the Val66Met allele in patients with BD (P=0.0033 and odds ratio [95% confidence interval] =0.332 [157-0.703]), and correlated the risk for valine allele carriers with Ow and Ob in patients with BD.

CONCLUSION

We found that the methionine allele confers a lower risk of developing Ow and Ob in patients with BD. We also confirmed that the G polymorphism represents a risk of developing Ow and Ob in patients with BD. In future studies, the haplotype analysis should provide additional evidence that BDNF may be associated with BD and BMI within the Mexican population.

Associations between obesity and cognition in the pre-school years

OBJECTIVE

To test the hypothesis that obesity is associated with impaired cognitive outcomes in the pre-school years.

METHODS

Associations were examined between weight status at age 3-5 years and cognitive performance at age 5 years. Cognitive outcome measures were tests of pattern construction (visuospatial skills), naming vocabulary (expressive language skills), and picture similarity (reasoning skills). The sample was the UK Millennium Cohort Study (n = 12,349 participants).

RESULTS

Boys with obesity at 3 years had significantly lower performance in pattern construction at age 5 years compared to those of a healthy weight, even after controlling for confounders (β = -0.029, P = 0.03). Controlling for confounders, boys who developed obesity between the ages of 3 and 5 years had lower scores in pattern construction (β = -0.03, P = 0.03). "Growing out" of obesity had a positive association with picture similarity performance in girls (β = 0.03, P = 0.04).

CONCLUSIONS

Obesity in the pre-school years was associated with poorer outcomes for some cognitive measures in this study. Stronger relationships between obesity and cognition or educational attainment may emerge later in childhood.

Discussing the putative role of obesity-associated genes in the etiopathogenesis of eating disorders

In addition to the identification of mutations clearly related to Mendelian forms of obesity; genome-wide association studies and follow-up studies have in the last years pinpointed several loci associated with BMI. These genetic alterations are located in or near genes expressed in the hypothalamus that are involved in the regulation of eating behavior. Accordingly, it seems plausible that these SNPs, or others located in related genes, could also help develop aberrant conduct patterns that favor the establishment of eating disorders should other susceptibility factors or personality dimensions be present. However, and somewhat surprisingly, with few exceptions such as BDNF, the great majority of the genes governing these pathways remain untested in patients with anorexia nervosa, bulimia nervosa or binge-eating disorder. In the present work, we review the few existing studies, but also indications and biological concepts that point to these genes in the CNS as good candidates for association studies with eating disorder patients.

Controversies about a common etiology for eating and mood disorders

Obesity and depression represent a growing health concern worldwide. For many years, basic science and medicine have considered obesity as a metabolic illness, while depression was classified a psychiatric disorder. Despite accumulating evidence suggesting that obesity and depression may share commonalities, the causal link between eating and mood disorders remains to be fully understood. This etiology is highly complex, consisting of multiple environmental and genetic risk factors that interact with each other. In this review, we sought to summarize the preclinical and clinical evidence supporting a common etiology for eating and mood disorders, with a particular emphasis on signaling pathways involved in the maintenance of energy balance and mood stability, among which orexigenic and anorexigenic neuropeptides, metabolic factors, stress responsive hormones, cytokines, and neurotrophic factors.

Is Alzheimer's disease related to metabolic syndrome? A Wnt signaling conundrum

Alzheimer's disease (AD) is the most common cause of dementia, affecting more than 36 million people worldwide. AD is characterized by a progressive loss of cognitive functions. For years, it has been thought that age is the main risk factor for AD. Recent studies suggest that life style factors, including nutritional behaviors, play a critical role in the onset of dementia. Evidence about the relationship between nutritional behavior and AD includes the role of conditions such as obesity, hypertension, dyslipidemia and elevated glucose levels. The coexistence of some of these cardio-metabolic risk factors is generally known as metabolic syndrome (MS). Some clinical studies support the role of MS in the onset of AD. However, the cross-talk between the molecular signaling implicated in these disorders is unknown. In the present review, we focus on the molecular correlates that support the relationship between MS and the onset of AD. We also discuss relevant issues such as the role of leptin, insulin and renin-angiotensin signaling in the brain and the possible role of Wnt signaling in both MS and AD. We discuss the evidence supporting the use of ob/ob mice, high-fructose diets, aortic coarctation-induced hypertension and Octodon degus, which spontaneously develops β-amyloid deposits and metabolic derangements, as suitable animal models to address the relationships between MS and AD. Finally, we examine emergent data supporting the role of Wnt signaling in the modulation of AD and MS, implicating this pathway as a therapeutic target in both conditions.

The interaction effect between BDNF val66met polymorphism and obesity on executive functions and frontal structure

The prevalence of obesity is increasing worldwide. Previous research has shown a relationship between obesity and both executive functioning alterations and frontal cortex volume reductions. The Brain Derived Neurotrophic Factor val66met polymorphism, involved in eating behavior, has also been associated with executive functions and prefrontal cortex volume, but to date it has not been studied in relation to obesity. Our aim is to elucidate whether the interaction between the Brain Derived Neurotrophic Factor val66met polymorphism and obesity status influences executive performance and frontal-subcortical brain structure. Sixty-one volunteers, 34 obese and 27 controls, age range 12-40, participated in the study. Participants were assigned to one of two genotype groups (met allele carriers, n = 16, or non-carriers, n = 45). Neuropsychological assessment comprised the Trail Making Test, the Stroop Test and the Wisconsin Card Sorting Test, all tasks that require response inhibition and cognitive flexibility. Subjects underwent magnetic resonance imaging in a Siemens TIM TRIO 3T scanner and images were analyzed using the FreeSurfer software. Analyses of covariance controlling for age and intelligence showed an effect of the obesity-by-genotype interaction on perseverative responses on the Wisconsin Card Sorting Test as well as on precentral and caudal middle frontal cortical thickness: obese met allele carriers showed more perseverations on the Wisconsin Card Sorting Test and lower frontal thickness than obese non-carriers and controls. In conclusion, the Brain Derived Neurotrophic Factor may play an important role in executive functioning and frontal brain structure in obesity.

Neurotrophins and the regulation of energy balance and body weight

Complex interactions between the brain and peripheral tissues mediate the effective control of energy balance and body weight. Hypothalamic and hindbrain neural circuits integrate peripheral signals informing the nutritional status of the animal and in response regulate nutrient intake and energy utilization. Obesity and its many medical complications emerge from the dysregulation of energy homeostasis. Excessive weight gain might also arise from alterations in reward systems of the brain that drive consumption of calorie dense, palatable foods in the absence of an energy requirement. Several neurotrophins, most notably brain-derived neurotrophic factor, have been implicated in the molecular and cellular processes underlying body weight regulation. Here, we review investigations interrogating their roles in energy balance and reward centers of the brain impacting feeding behavior and energy expenditure.

The skinny on brain-derived neurotrophic factor: evidence from animal models to GWAS

Obesity and its sequelae constitute a major international healthcare problem. The obesity epidemic is due in part to higher calorie diets and reduced exercise over the past 30 years; however, increasing evidence has established genetic regulation of body weight as a major contributor to obesity. Brain-derived neurotrophic factor (BDNF) regulates development and plasticity of the central nervous system, and recent work has established a clear role for signaling through BDNF and its receptor TrkB in the control of body weight. Here we review research findings from animal models and human populations indicating that BDNF is a negative regulator of appetitive behavior and body weight.

Lack of association between brain-derived neurotrophic factor Val66Met polymorphism and body mass index change over time in healthy adults

Obesity is becoming the epidemic health problem worldwide with a very complex etiology. The interaction between diverse genetic and environmental factors contributes to development of obesity. Among myriad of functions in central and peripheral tissues, brain-derived neurotrophic factor (BDNF) also regulates energy homeostasis, food intake and feeding behavior, and has a role in obesity and increased body mass index (BMI). BDNF Val66Met (rs6265) polymorphism is associated with BMI gain, but both positive associations and non-replications are reported. Since BMI changes over time and since genetic influences on BMI vary with age, the aim of the study was to evaluate association between BDNF Val66Met polymorphism and BMI gain in healthy subjects with middle or old age. The study included a cohort of 339 adult healthy Caucasians of Croatian origin, free of eating and metabolic disorders, evaluated in three time periods in the year 1972, 1982 and 2006, when the subjects were around 40, 50 and 70 years old, respectively. The results revealed a significant effect of smoking on BMI, but a lack of significant association between BDNF Val66Met polymorphism and overweight or obesity, and no significant association between BDNF Val66Met and BMI changes over time. These results did not confirm the major role of BDNF Val66Met in the regulation of BMI changes in adult and old healthy subjects.

Brain-derived neurotrophic factor and its relation to leptin in obese children before and after weight loss

OBJECTIVE

Brain-derived neurotrophic factor (BDNF) is a regulator of energy homeostasis and food intake through hypothalamic signaling. Currently, data regarding BDNF in children with obesity are lacking. We evaluated serum BDNF concentrations in obese children, both before and after lifestyle intervention, in reference to those of lean children.

METHODS

A total of 90 (24 normal weight; 66 obese) children were studied utilizing a cross-sectional clinical outpatient study design. In addition, longitudinal data analysis was performed in 30 obese children participating in a lifestyle intervention for one year.

RESULTS

Fasting serum BDNF concentrations were higher in obese vs. normal weight children (BDNF 20.3±1.0 vs. 12.5±1.7 ng/mL, respectively, mean±SEM, p<0.001) and correlated significantly to BMI standard deviation score (r=0.426, p<0.001), and leptin (r=0.414, p<0.01). BDNF concentrations were not regulated in response to food, 60 min after ingestion of a liquid test meal. After one year lifestyle intervention, delta BDNF correlated significantly to delta leptin (r=0.475, p<0.01), but not to changes of insulin resistance index HOMA-IR, systolic and diastolic blood pressure, HDL, LDL, and triglycerides. In a multiple stepwise linear regression adjusted for pubertal stage, age, sex, and BMI, delta BDNF correlated significantly (p<0.05) to delta leptin and delta triceps skinfold and in tendency to delta subscapularis skinfold thickness (p=0.050).

CONCLUSIONS

Our results in children do not indicate a significant relationship between BDNF and insulin resistance or cardiovascular risk factors. However, the correlation between changes of BDNF and changes of leptin suggests a relationship between BDNF and fat mass.

BDNF and the central control of feeding: accidental bystander or essential player?

A considerable body of evidence links diminished brain-derived neurotrophic factor (BDNF) signaling to energy balance dysregulation and severe obesity in humans and rodents. Because BDNF exhibits broad neurotrophic properties, the underpinnings of these effects and its true role in the central regulation of food intake remain topics of debate in the field. Here, I discuss recent evidence supporting a critical role for this neurotrophin in physiological mechanisms regulating nutrient intake and body weight in the mature brain. They include reports of functional interactions of BDNF with central anorexigenic and orexigenic signaling pathways and evidence of recognized appetite hormones exerting neurotrophic effects similar to those of BDNF.

Brain-derived neurotrophic factor Val66Met polymorphism and alcohol-related phenotypes

Alcoholism is a chronic psychiatric disorder affecting neural pathways that regulate motivation, stress, reward and arousal. Brain-derived neurotrophic factor (BDNF) regulates mood, response to stress and interacts with neurotransmitters and stress systems involved in reward pathways and addiction. Aim of the study was to evaluate the association between a single nucleotide polymorphism (BDNF Val66Met or rs6265) and alcohol related phenotypes in Caucasian patients. In ethnically homogenous Caucasian subjects of the Croatian origin, the BDNF Val66Met genotype distribution was determined in 549 male and 126 female patients with alcohol dependence and in 655 male and 259 female healthy non-alcoholic control subjects. Based on the structured clinical interview, additional detailed clinical interview, the Brown-Goodwin Scale, the Hamilton Rating Scale for Depression and the Clinical Global Impression scores, alcoholic patients were subdivided into those with or without comorbid depression, aggression, delirium tremens, withdrawal syndrome, early/late onset of alcohol abuse, prior suicidal attempt during lifetime, current suicidal behavior, and severity of alcohol dependence. The results showed no significant association between BDNF Val66Met variants and alcohol dependence and/or any of the alcohol related phenotypes in either Caucasian women, or men, with alcohol dependence. There are few limitations of the study. The overall study sample size was large (N=1589) but not well-powered to detect differences in BDNF Val66Met genotype distribution between studied groups. Healthy control women were older than female alcoholic patients. Only one BDNF polymorphism (rs6265) was studied. In conclusion, these data do not support the view that BDNF Val66Met polymorphism correlates with the specific alcohol related phenotypes in ethnically homogenous medication-free Caucasian subjects with alcohol dependence.

The role of brain-derived neurotrophic factor (BDNF) gene variants in antipsychotic response and antipsychotic-induced weight gain

BACKGROUND

Brain-derived neurotrophic factor (BDNF) has extensive effects on the nervous system including cell survival, differentiation, neuronal growth and maintenance, as well as cell death. Moreover, it promotes synaptic plasticity and interacts with dopaminergic and serotonergic neurons, suggesting an important role on the alteration of brain function with antipsychotic medications and induced weight gain in schizophrenia patients. The differential effects of BDNF gene variants could lead to changes in brain circuitry that would in turn cause variable response to antipsychotic medication. Therefore, we hypothesized that genetic variation in this candidate gene helps in explaining the inter-individual variation observed in antipsychotic drug treatment with respect to response and induced weight gain.

METHOD

We examined four single-nucleotide polymorphisms across the BDNF gene, including Val66Met (rs6265). Prospective BPRS change scores and weight change after six weeks were obtained from a total of 257 schizophrenia patients of European ancestry.

RESULTS

The markers rs11030104 and Val66Met were associated with antipsychotic response (P=0.04; 0.007, respectively). On the other hand, marker rs1519480 was associated with weight gain (P=0.04). Moreover, a two-marker haplotype across rs6265 and rs1519480 was associated with weight change (P=0.001). Results with Val66Met in response, and results with rs6265-rs1519480 haplotypes remained significant at the modified Bonferroni corrected alpha of 0.017.

CONCLUSION

BDNF genetic variants might play an important role in predicting antipsychotic response and antipsychotic-induced weight gain. However, replication in larger and independent samples is required.

Plasma BDNF levels vary in relation to body weight in females

Brain derived neurotrophic factor (BDNF) has been implicated in the pathophysiology of depression as well as neuropsychiatric and neurodegenerative disorders. Recent studies show a role of BDNF in energy metabolism and body weight regulation. We examined BDNF levels in plasma and cerebrospinal fluid (CSF) samples from age matched elderly depressed and control subjects. Also, the association of BDNF levels with age, gender, body weight, body mass index (BMI), and cognitive performance was evaluated. We did not find any significant differences in plasma and CSF BDNF levels between depressed and control subjects. Plasma BDNF levels were negatively correlated with age (but not with BMI and body weight), when analyses were performed including both depressed and control subjects. A significant reduction in plasma BDNF levels was observed in females as compared to male subjects, and the change in BDNF levels were significantly and positively related to body weight in females. Furthermore, significant increases in Total Recall and Delayed Recall values were found in females as compared to males. In conclusion, the lower BDNF levels observed in females suggest that changes in peripheral BDNF levels are likely secondary to an altered energy balance. However, further studies using larger sample size are warranted.

Neurogenetics and Epigenetics in Impulsive Behaviour: Impact on Reward Circuitry

Adverse, unfavourable life conditions, particularly during early life stages and infancy, can lead to epigenetic regulation of genes involved in stress-response, behavioral disinhibition, and cognitive-emotional systems. Over time, the ultimate final outcome can be expressed through behaviors bedeviled by problems with impulse control, such as eating disorders, alcoholism, and indiscriminate social behavior. While many reward gene polymorphisms are involved in impulsive behaviors, a polymorphism by itself may not translate to the development of a particular behavioral disorder unless it is impacted by epigenetic effects. Brain-derived neurotrophic factor (BDNF) affects the development and integrity of the noradrenergic, dopaminergic, serotonergic, glutamatergic, and cholinergic neurotransmitter systems, and plasma levels of the neurotrophin are associated with both cognitive and aggressive impulsiveness. Epigenetic mechanisms associated with a multitude of environmental factors, including premature birth, low birth weight, prenatal tobacco exposure, non-intact family, young maternal age at birth of the target child, paternal history of antisocial behavior, and maternal depression, alter the developmental trajectories for several neuropsychiatric disorders. These mechanisms affect brain development and integrity at several levels that determine structure and function in resolving the final behavioral expressions.

Weighing in the role of BDNF in the central control of eating behavior

The prevalence of obesity and its associated medical complications, including type 2 diabetes and cardiovascular disease, continues to rise globally. Lifestyle changes in the last decades have greatly contributed to the current obesity trends. However, inheritable biological factors that disrupt the tightly regulated equilibrium between caloric intake and energy expenditure also appear to play a critical part. Mounting evidence obtained from human and rodent studies suggests that perturbed brain-derived neurotrophic factor (BDNF) signaling in appetite-regulating centers in the brain might be a culprit. Here, we review findings that inform the critical roles of BDNF and its receptor TrkB in energy balance and reward centers of the brain impacting feeding behavior and body weight.