BDNF Val66Met polymorphism, energy intake and BMI: a follow-up study in schoolchildren at risk of eating disorders

Influence of BDNF Val66Met genetic polymorphism in Major Depressive Disorder and Body Mass Index: Evidence from a meta-analysis of 6481 individuals

BACKGROUND

Major depressive disorder (MDD) and obesity are global health problems that frequently co-occur. Among shared etiological factors, genetic variation at the brain-derived neurotrophic factor (BDNF) gene is interesting since its implication in energy balance regulation, food intake and synaptic function. Thus, the aim of this study was to investigate the influence of the BDNF Val66Met polymorphism in relation to MDD and body mass index (BMI) in two large independent cohorts.

METHODS

The sample consisted of 2646 individuals with MDD and 3835 controls from the PISMA-ep and Radiant studies. Linear regressions were performed to test the association between the polymorphism and BMI and the interaction between the polymorphism and MDD on BMI. A meta-analysis across cohorts was conducted.

RESULTS

No association was found between the polymorphism and BMI. However, we found an association with MDD, showing these individuals higher BMI than controls in both cohorts. No differences were found in BMI depending on Val66Met genotype and no interaction between this polymorphism and MDD in relation to BMI was found. Although a tendency towards an interaction was found in the Radiant sample, the results of the meta-analysis did not support this finding.

LIMITATIONS

The use of self-reported height and weight measures to calculate BMI values.

CONCLUSIONS

We provide evidence for an association between BMI and MDD confirming previous results. Our meta-analysis including two large cohorts showed no interaction between BDNF, BMI and MDD. Future studies will be needed to confirm the role of this polymorphism in the relationship between BMI and MDD.

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.

BDNF Gene as a Precision Skill of Obesity Management

The scarcity of the results obtained for the treatment of obesity leads us to consider new strategies, contemplating all the factors involved in the development of the disease. One of the key molecules for controlling body weight and energy homeostasis is the brain-derived neurotrophic factor (BDNF). This work summarizes the mechanisms in which BDNF gene regulates this multifactorial disease. In addition, we discuss the role of other BDNF polymorphisms as genetic determinants of obesity. In this context, a total of 14 SNPs near or inside BDNF/BDNF-AS related to BMI were identified in various GWASs. Finally, we assess gene-diet interaction as a novel tool to prevent obesity and formulate solid and personalized nutritional management. Our research group has performed the first study on the association of BDNF-AS rs925946 polymorphism and calcium intake as potential modulators of the nutritional status. Although these results should be confirmed in future studies, they open the path for new prevention opportunities.

Children's Eating Attitudes Test (ChEAT): a validation study in Finnish children

PURPOSE

To validate the Children's Eating Attitudes Test (ChEAT) in the Finnish population.

MATERIALS AND METHODS

In total 339 children (age 10-15 years) from primary schools in Southern Finland were evaluated at two time points. They answered the ChEAT and SCOFF test questions, and had their weight, height and waist circumference measured. Retesting was performed 4-6 weeks later. Test-retest reliability was evaluated using intra-class correlation (ICC), and internal consistency was examined using Cronbach's alpha coefficient (C-alpha). ChEAT was cross-calibrated against SCOFF and background variables. Factor analysis was performed to examine the factor structure of ChEAT.

RESULTS

The 26-item ChEAT showed high internal consistency (C-alpha 0.79), however, a 24-item ChEAT showed even better internal consistency (C-alpha 0.84) and test-retest reliability (ICC 0.794). ChEAT scores demonstrated agreement with SCOFF scores (p < 0.01). The mean ChEAT score was higher in overweight children than normal weight (p < 0.001). Exploratory factor analysis yielded four factors (concerns about weight, limiting food intake, pressure to eat, and concerns about food), explaining 57.8% of the variance.

CONCLUSIONS

ChEAT is a valid and reliable tool for measuring eating attitudes in Finnish children. The 24-item ChEAT showed higher reliability than the 26-item ChEAT.

LEVEL OF EVIDENCE

Level 5, cross-sectional, descriptive study.

BDNF Val66Met genetic variation and its plasma level in patients with morbid obesity: A case-control study

Obesity is a major public health concern worldwide. Genetic, behavioral, and environmental factors contribute to the multifactorial etiology of obesity. Evidence suggests an association between human Brain-Derived Neurotrophic Factor (BDNF) Val66Met single nucleotide polymorphism (SNP) and obesity. Reduced plasma BDNF levels have also been reported in patients with eating disorders and obesity. We aimed to evaluate the BDNF Val66Met (rs6265) SNP and also plasma BDNF levels in morbidly obese patients compared with healthy normal controls in southern Iran. One hundred morbidly obese patients and one hundred eight healthy normal controls were enrolled. Blood-derived DNA samples were genotyped using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method and confirmed by DNA sequencing. Plasma BDNF levels were evaluated using a commercially available sandwich enzyme-linked immunosorbent assay (ELISA) kit for human BDNF. Data analysis was performed by SPSS software, version 18.0. Genotype distribution was not significantly different between obese patients and controls. However, plasma BDNF levels were significantly lower in obese patients compared with controls. Interestingly, a significant association was found between BDNF Val66Met SNP and plasma BDNF levels. No relationship was observed between BDNF Val66Met SNP and all assessed demographic and clinical characteristics of obese patients. It seems that plasma BDNF levels were associated with both obesity and BDNF Val66Met SNP. However, this association was not found between BDNF Val66Met SNP and obesity. Further studies with larger sample sizes are needed for more detailed assessment of this genetic variation as a potential biomarker for obesity.

New approach to peripheral nerve injury: nutritional therapy

Purpose of review: There is no review in the literature on the effect of nutrition-related factors on peripheral nerve injuries. Therefore, it is aimed to evaluate the effect of nutritional factors on nerve injuries in this compilation. Recent findings: Although there are several fundamental mechanisms by which nutrients and nutritional factors influence individuals, their exact impacts on neurogenesis have not been clearly identified. Recently, some studies showed that some nutrients have an important role in nerve injuries due to their neuroprotective properties. In addition to surgical treatment, in peripheral nerve injuries, these nutrients also may play a role in preserving nerve function and health, as well as in the recovery of an injured nerve tissue. Omega 3 and omega 6 fatty acids, group B vitamins, antioxidants, several minerals, phenolic compounds, and alpha lipoic acid are thought to have impacts on the nervous system. In addition to all of these, gut microbiota has effects on the nervous system, and some nutrient-related factors can also affect neurogenesis via gut microbiota. Summary: Peripheral nerve injury is a condition in which the nerves in the peripheral nervous system become damaged. After the trauma, the peripheral nerve is hardly repaired due to the following reasons; the disability of the regeneration of motor neurons, the lack of a survival environment for Schwann cells, and the poor ability of the nerves to regenerate. Nutrition-related factors, the effects of which were described in recent years, should be more taken into account more.

Gene-environment interaction between the brain-derived neurotrophic factor Val66Met polymorphism, psychosocial stress and dietary intake in early psychosis

AIM

The brain-derived neurotrophic factor (BDNF) is a major participant in the regulation of food intake and may play a role in the regulation of the stress response. We aimed to investigate whether there is a gene-environment interaction in the relationship between stress and BDNF Val66Met polymorphism in relation to dietary patterns in a sample of subjects with early psychosis.

METHODS

We studied 124 early psychotic disorder (PD) patients, 36 At-Risk Mental States (ARMS) and 62 healthy subjects (HS). Dietary patterns were examined by a dietician. Physical activity, life stress and perceived stress were assessed by validated questionnaires. BDNF Val66Met polymorphism (rs6265) was genotyped. A gene-environment interaction was tested with multiple linear regression analysis while adjusting for covariates.

RESULTS

Perceived stress was not associated with calorie intake in HS. In ARMS subjects, Met-carriers who presented low-perceived stress were associated with increased caloric intake. Conversely, those who presented high-perceived stress were associated with reduced caloric intake. In PD, perceived stress was neither associated with increased calorie intake without an effect by BDNF genotype nor a gene-environment interaction. Perceived stress was associated with food craving in PD patients, independent of genotype, and in ARMS or HS who were Val homozygous.

CONCLUSIONS

This study suggests that the common Val66Met polymorphism of the BDNF gene may modulate the relationship between life stress and calorie intake in subjects at risk for psychosis.

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 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.

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

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

The Effect of Exercise Training on Resting Concentrations of Peripheral Brain-Derived Neurotrophic Factor (BDNF): A Meta-Analysis

BACKGROUND

The mechanisms through which physical activity supports healthy brain function remain to be elucidated. One hypothesis suggests that increased brain-derived neurotrophic factor (BDNF) mediates some cognitive and mood benefits. This meta-analysis sought to determine the effect of exercise training on resting concentrations of BDNF in peripheral blood.

METHODS

MEDLINE, Embase, PsycINFO, SPORTDiscus, Rehabilitation & Sports Medicine Source, and CINAHL databases were searched for original, peer-reviewed reports of peripheral blood BDNF concentrations before and after exercise interventions ≥ 2 weeks. Risk of bias was assessed using standardized criteria. Standardized mean differences (SMDs) were generated from random effects models. Risk of publication bias was assessed using funnel plots and Egger's test. Potential sources of heterogeneity were explored in subgroup analyses.

RESULTS

In 29 studies that met inclusion criteria, resting concentrations of peripheral blood BDNF were higher after intervention (SMD = 0.39, 95% CI: 0.17-0.60, p < 0.001). Subgroup analyses suggested a significant effect in aerobic (SMD = 0.66, 95% CI: 0.33-0.99, p < 0.001) but not resistance training (SMD = 0.07, 95% CI: -0.15-0.30, p = 0.52) interventions. No significant difference in effect was observed between males and females, nor in serum vs plasma.

CONCLUSION

Aerobic but not resistance training interventions increased resting BDNF concentrations in peripheral blood.

The BDNF gene Val66Met polymorphism as a modifier of psychiatric disorder susceptibility: progress and controversy

Brain-derived neurotrophic factor (BDNF) has a primary role in neuronal development, differentiation and plasticity in both the developing and adult brain. A single-nucleotide polymorphism in the proregion of BDNF, termed the Val66Met polymorphism, results in deficient subcellular translocation and activity-dependent secretion of BDNF, and has been associated with impaired neurocognitive function in healthy adults and in the incidence and clinical features of several psychiatric disorders. Research investigating the Val66Met polymorphism has increased markedly in the past decade, and a gap in integration exists between and within academic subfields interested in the effects of this variant. Here we comprehensively review the role and relevance of the Val66Met polymorphism in psychiatric disorders, with emphasis on suicidal behavior and anxiety, eating, mood and psychotic disorders. The cognitive and molecular neuroscience of the Val66Met polymorphism is also concisely reviewed to illustrate the effects of this genetic variant in healthy controls, and is complemented by a commentary on the behavioral neuroscience of BDNF and the Val66Met polymorphism where relevant to specific disorders. Lastly, a number of controversies and unresolved issues, including small effect sizes, sampling of allele inheritance but not genotype and putative ethnicity-specific effects of the Val66Met polymorphism, are also discussed to direct future research.

Dietary intake and nutritional risk in Mediterranean adolescents in relation to the severity of the eating disorder

OBJECTIVE

To assess the relationship between the degree of severity of eating disorders (ED) and energy and nutrient intakes and nutritional risk in a mixed-sex adolescent population without clinical symptoms.

DESIGN

Cross-sectional study.

SETTING

Data were collected in schools.

SUBJECTS

Adolescents (n 495) aged 14·2 (sd 1·0) years. The Eating Attitudes Test was used to detect adolescents at risk of ED (rED) and a structured interview based on the criteria of the Diagnostic and Statistical Manual of Mental Disorders, 4th edition, was used to diagnose eating disorder not otherwise specified (EDNOS). Dietary intake was quantified using the 24 h recall method over three days and the probability of inadequate intake was determined.

RESULTS

Females presented lower intakes of energy, macronutrients and micronutrients (Ca, Fe, Mg, K, P, Na, thiamin, vitamins E, C, B6, B12, pantothenic acid, folic acid) because the severity of their ED was greater. These lower dietary intakes led to nutritional risk (for Ca, Fe, Mg, P, vitamins A, D, B6) in more than 80 % and 60 % of females with EDNOS and rED, respectively. The multiple linear regression models showed that the rED and EDNOS groups presented a lower energy intake of 1597·4 kJ/d (381·8 kcal/d) and 3153·0 kJ/d (753·6 kcal/d), respectively. In contrast, little difference was observed in the nutritional intakes of males.

CONCLUSIONS

The female adolescents showed lower energy and nutrient intakes as the ED became more severe, which led to energy, vitamin and mineral deficiencies in a high percentage of females with ED. These nutritional risks could hinder adequate physical and psychological development and lead to chronic ED.

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.

Possible involvement of brain-derived neurotrophic factor in eating disorders

Eating disorders (EDs) manifest as abnormal patterns of eating behavior and weight regulation driven by low self-esteem due to weight preoccupation and perceptions toward body weight and shape. Two major groups of such disorders are anorexia nervosa (AN) and bulimia nervosa (BN). The etiology of EDs is complex and evidence indicates that both biological/genetic and psychosocial factors are involved. Several lines of evidence indicate that brain-derived neurotrophic factor (BDNF) plays a critical role in regulating eating behaviors and cognitive impairments in the EDs. BDNF is involved in neuronal proliferation, differentiation, and survival during development. BDNF and its tyrosine kinase receptor (TrkB) are expressed in hypothalamic nuclei associated with eating behaviors. A series of studies using BDNF knockout mice and the human BDNF gene indicate an association of BDNF and EDs with predisposition and vulnerability. In the previous studies, serum BDNF levels in subjects with EDs are reduced significantly compared with healthy controls, hence, we proposed that levels of serum BDNF would be a useful diagnostic indicator for EDs.

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

Obesity in children and adolescents is a worldwide health problem, characterized by various somatic, psychosocial and psychiatric complications, and is often associated with adult obesity and related complications. Brain-derived neurotrophic factor (BDNF) is a neurotrophin with important roles in feeding behavior, food intake regulation, energy metabolism and weight control. A common polymorphism of the BDNF genotype (Val66Met) has been associated with various forms of eating disorders, alterations in body mass index (BMI) values and obesity in adult populations. The aim of this study was to determine the association between the gene variants of the BDNF Val66Met polymorphism and obesity in 300 healthy Caucasian children and adolescents of the same ethnic background of Croatian origin, subdivided according to the BMI percentile, but without any form of eating disorders. The frequency of the Met/Met, Met/Val and Val/Val genotypes, Met and Val alleles, and Met carriers (the combined Met/Met and Met/Val genotypes versus the homozygous Val/Val genotype) differed significantly between underweight, normal weight, overweight and obese children, and the presence of one or two Met alleles contributed to this significant effect. These results showed for the first time the significant association between the presence of one or two Met alleles and obesity in ethnically homogenous groups of healthy Caucasian children and adolescents. These data confirmed the major role of BDNF in energy metabolism, food regulation and BMI.

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.

Association between BDNF rs6265 and obesity in the Boston Puerto Rican Health Study

Brain-derived neurotrophic factor (BDNF) has been associated with regulation of body weight and appetite. The goal of this study was to examine the interactions of a functional variant (rs6265) in the BDNF gene with dietary intake for obesity traits in the Boston Puerto Rican Health Study. BDNF rs6265 was genotyped in 1147 Puerto Rican adults and examined for association with obesity-related traits. Men (n = 242) with the GG genotype had higher BMI (P = 0.009), waist circumference (P = 0.002), hip (P = 0.002), and weight (P = 0.03) than GA or AA carriers (n = 94). They had twice the risk of being overweight (BMI ≥ 25) relative to GA or AA carriers (OR = 2.08, CI = 1.02-4.23, and P = 0.043). Interactions between rs6265 and polyunsaturated fatty acids (PUFA) intake were associated with BMI, hip, and weight, and n-3 : n-6 PUFA ratio with waist circumference in men. In contrast, women (n = 595) with the GG genotype had significantly lower BMI (P = 0.009), hip (P = 0.029), and weight (P = 0.027) than GA or AA carriers (n = 216). Women with the GG genotype were 50% less likely to be overweight compared to GA or AA carriers (OR = 0.05, CI = 0.27-0.91, and P = 0.024). In summary, BDNF rs6265 is differentially associated with obesity risk by sex and interacts with PUFA intake influencing obesity traits in Boston Puerto Rican men.

The lighter side of BDNF

Brain-derived neurotrophic factor (BDNF) mediates energy metabolism and feeding behavior. As a neurotrophin, BDNF promotes neuronal differentiation, survival during early development, adult neurogenesis, and neural plasticity; thus, there is the potential that BDNF could modify circuits important to eating behavior and energy expenditure. The possibility that "faulty" circuits could be remodeled by BDNF is an exciting concept for new therapies for obesity and eating disorders. In the hypothalamus, BDNF and its receptor, tropomyosin-related kinase B (TrkB), are extensively expressed in areas associated with feeding and metabolism. Hypothalamic BDNF and TrkB appear to inhibit food intake and increase energy expenditure, leading to negative energy balance. In the hippocampus, the involvement of BDNF in neural plasticity and neurogenesis is important to learning and memory, but less is known about how BDNF participates in energy homeostasis. We review current research about BDNF in specific brain locations related to energy balance, environmental, and behavioral influences on BDNF expression and the possibility that BDNF may influence energy homeostasis via its role in neurogenesis and neural plasticity.