Brain-derived Neurotrophic Factor In Children Research Articles

Association between sedentary behavior and Brain-Derived Neurotrophic Factor (BDNF) in children and adolescents: A protocol for systematic review and meta-analysis.

There is evidence in the literature suggesting that high time spent in sedentary behavior (SB) can reduce the Brain-Derived Neurotrophic Factor (BDNF) levels, an important neurotrophin that plays a role in modulating cognition, learning and memory. Children and adolescents usually spend many hours a day on SB, either sitting for a long time and/or using screen equipment. The aim of this study is to describe a systematic review and meta-analysis protocol on the associations between SB and BDNF levels in children and adolescents. This protocol is guided by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols and was published in the International Prospective Register of Systematic Reviews database (PROSPERO: CRD42023392246). The databases that will be searched are EMBASE, Scopus, ScienceDirect, Web of Science, SPORTDiscus, CINAHL, and PubMed. Cross-sectional and cohort studies conducted with children and adolescents (5 to 19 yr) that analyzed the association between SB and BDNF will be included in the systematic review. The characteristics of the studies, methodological aspects, and main results will be described. Then, the risk of bias (assessed by STROBE and Newcastle-Ottawa scales) and the level of evidence (assessed by the GRADE tool) from included studies will be evaluated. Sub-group analysis will also be performed. Two experienced reviewers will perform the studies selection, data extraction, and methodological quality assessment. This systematic review and meta-analysis will analyze the association between SB and BDNF in children and adolescents. The results will provide subsidies to better understand this relationship and will strengthen evidence-based practice for both health professionals and future researches.

Serum concentrations of BDNF in adolescents with metabolic syndrome: a case-control study between normal - BMI adolescents and adolescents with obesity

Brain-Derived Neurotrophic Factor (BDNF) has been linked to various conditions of the cardiovascular and nervous systems. Scarce data exist about the concentrations of BDNF in children and adolescents in relation with obesity and metabolic syndrome (MetS). The aim of this study was to examine the serum BDNF concentrations in adolescents with metabolic syndrome and according to their body mass index (BMI) status. This was a case-control study, assessing BDNF concentrations between adolescents with MetS (with obesity vs. normal-BMI), in relation to sex, anthropometric, metabolic and endocrine parameters. Participants included male and female adolescents, whose anthropometric and metabolic panel, as well as serum BDNF concentrations were measured. A total of 59 adolescents (obesity: 29; normal-BMI: 30) were included in the study. Increased serum BDNF concentrations were observed in MetS adolescents with obesity when compared with normal-BMI adolescents (p < 0.001). Males exhibited higher concentrations of BDNF than females (p = 0.045). The sample was further divided into four categories by sex and BMI status, with normal-BMI females exhibiting significantly lower BDNF concentrations than females and males with obesity(p = 0.005). In the entire study sample, serum BDNF concentrations correlated positively with BMI z-scores, however, this statistical significance was preserved only in the females of the sample. No statistical difference was observed between males of different BMI z-scores categories. Conclusion: Obesity appeared as a major factor for increased serum BDNF concentrations in adolescents with MetS (vs. normal-BMI), with a higher impact on BDNF concentrations in females than males.What is Known:• The brain-derived neurotrophic factor (BDNF) is involved in metabolic syndrome in adults but data in adolescents are scarce.What is New:• Obesity (vs. normal BMI) was a major factor for increased serum BDNF in adolescents with metabolic syndrome.• Obesity had a higher impact on BDNF concentrations in females than males with metabolic syndrome.

Sedentary time play a moderator role in the relationship between physical fitness and brain-derived neurotrophic factor in children: A pilot study

Background/ObjectiveDespite some advances, there are many controversies concerning brain-derived neurotrophic factor (BDNF) and its relationships with variables related to physical fitness and sedentary time, especially in children. The aim of the study was to explore the moderating role of sedentary time on the association between physical fitness and BDNF. Therefore, this study will add to the perspective of understanding how much time children may spend being sedentary with no deleterious influence on the positive association between physical fitness and BDNF. MethodsThis cross-sectional study included 44 children aged between 6 and 11 years (9.02 ± 1.43) from a public school in Porto Alegre, Brazil. Cardiorespiratory fitness (CRF) was determined by the 6-min walk/run test, and muscular strength was determined through the lower limb strength test (LLS). Sedentary time was assessed through accelerometers, and blood samples were collected to determine serum BDNF levels (z score). Moderation analysis was performed using the PROCESS macro adjusted for sex, age, somatic maturation, waist circumference, and socioeconomic level. ResultsSedentary time moderates the relationship between CRF and BDNF, such that children should spend less than 511 minutes per day sedentary to achieve the benefits of CRF in BDNF concentrations. ConclusionSedentary time plays a significant moderating role in the relationship between CRF and BDNF. Therefore, to promote brain health in children, both increasing physical fitness and reducing sedentary time might be encouraged.

Relationship between exclusive breastfeeding and brain-derived neurotrophic factor in children.

A positive relationship between breastfeeding and brain-derived neurotrophic factor (BDNF) in infants has been suggested due to the presence of BDNF in human milk. This study aimed to determine the relationship between exclusive breastfeeding and BDNF serum levels in Spanish schoolchildren. A cross-sectional analysis including 202 schoolchildren, aged eight to 11 years, from Cuenca, Spain, was conducted. Information on sociodemographic and anthropometric variables, sexual maturation, birth weight and exclusive breastfeeding ('no exclusive breastfeeding', and exclusive breastfeeding for ≤6 and >6 months), and BDNF serum levels using an ELISA method were obtained. Covariance analyses (ANCOVA) were conducted to examine the relationship between serological BDNF and exclusive breastfeeding after controlling for potential confounders. ANCOVA models showed no significant differences in BDNF levels between children who were exclusively breastfed for more than six months versus those who were not (p > 0.05). No significant differences were observed by age group (eight to nine years versus 10 to 11 years; p > 0.05). Additionally, no clear negative trend in BDNF serum levels according to sexual maturation categories was found (p > 0.05). These findings suggest that exclusive breastfeeding does not have a significant positive association on BDNF from eight to 11 years, since children who were exclusively breastfed did not have significantly higher BDNF levels than those who were not exclusively breastfed. Likewise, BDNF levels were not found to be negatively affected by hormonal development. Future research should examine the influence of exclusive breastfeeding on BDNF over the different developmental stages.

Effects of low-level mercury exposure on brain-derived neurotrophic factor in preschool children

ObjectivesMercury (Hg), a ubiquitous heavy metal, could affect the neurodevelopment of the children, however, these associations are still equivocal. Brain derived neurotrophic factor (BDNF) plays an essential role in the central nervous system development in children. This study aimed to investigate the effects of low-level mercury exposure on serum BDNF levels and the influence of sex and dietary intake on these relationships in children. MethodsIn this cross-sectional study, a total of 541 pre-school children were recruited, the blood mercury concentrations and serum BDNF levels were measured. The background information on demographic characteristics and dietary habits of the children was collected through questionnaires. Multivariable linear models after adjustment for potential confounders were used to evaluate the associations between mercury exposure and levels of BDNF in children. ResultsThe GMs of blood mercury concentrations and serum BDNF levels were 1.06 μg/L, 20.4 ng/mL, respectively. A significant positive association between blood mercury concentrations and serum BDNF levels was found. After stratification by sex, the blood mercury concentrations in children were positive associated with serum BDNF levels in girls but not in boys. However, these associations were attenuated when we further adjusted the children’s dietary intake variables. ConclusionsOur findings suggest that low-levels of mercury exposure may have sex-specific effects on BDNF levels in young children and that dietary intake may be potential confounders in these relationships. However, further studies are warranted to investigate the role of BDNF in the effects of mercury on neurodevelopment.

Increased serum BDNF and ProBDNF levels in children with irritable bowel syndrome

Objective: Irritable bowel syndrome (IBS) is one of the most common functional gastrointestinal disorders among the pediatric population. Recently, neurotrophins have been suggested to be etiological factors or causes of symptoms of IBS. In the present study, the aim was to research the serum brain-derived neurotrophic factor (BDNF) and proBDNF levels in children with IBS.Methods: The study group was selected from pediatric gastroenterology outpatient clinic and control group was recruited from healthy children outpatient clinic. Based on the inclusion and exclusion criteria, 29 children with IBS and 55 healthy children were included in the study. The data were obtained from all participants, and if needed, from their parents. All participants were assessed in terms of anthropometric measurements. The serum (BDNF) and proBDNF levels were compared between the groups.Results: The proBDNF levels in IBS patients were higher compared with the control group in covariance analysis (IBS patients group mean 492.4, SD 534.1; control group mean 332.8, SD 406.7) (p = 0.02; Cohen's d = 0.45). The serum BDNF levels of IBS patients were also higher compared with the control group (IBS patients group mean 3.1, SD 4.3; control group mean 1.7, SD 2.7) (p = 0.02; Cohen's d = 0.51).Conclusions: The present study is the first to demonstrate that there is a higher level of serum BDNF in children with IBS. Moreover, it is the first to demonstrate an increased level of proBDNF in IBS. Additional research is needed to confirm the preliminary results.

P.277 Physical activity and step-related behaviors, but not sedentary time, are associated with brain-derived neurotrophic factor in children with overweight/obesity

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Effect of treatment by atomoxetine on the serum level of brain-derived neurotrophic factor in children with Attention Deficit Hyperactivity Disorder

Effect of treatment by atomoxetine on the serum level of brain-derived neurotrophic factor in children with Attention Deficit Hyperactivity Disorder

Association of Peripheral Blood Levels of Brain-Derived Neurotrophic Factor With Autism Spectrum Disorder in Children

Accumulating evidence suggests that brain-derived neurotrophic factor (BDNF) may be implicated in the developmental outcomes of children with autism spectrum disorder (ASD). To use meta-analysis to determine whether children with ASD have altered peripheral blood levels of BDNF. A systematic search of PubMed, PsycINFO, and Web of Science was performed for English-language literature through February 7, 2016. The search terms included brain-derived neurotrophic factor or BDNF in combination with autism, without year restriction. Two additional records were retrieved after a review of the reference lists of selected articles. Studies were included if they provided data on peripheral blood levels of BDNF in children with ASD and healthy control children. Studies that included adults or with overlapping samples were excluded. Data were extracted by 2 independent observers from 19 included studies. Data were pooled using a random-effects model with Comprehensive Meta-analysis software. Blood levels of BDNF in children with ASD compared with healthy controls. Altered levels of BDNF were hypothesized to be related to ASD. This meta-analysis included 19 studies with 2896 unique participants. Random-effects meta-analysis of all 19 studies showed that children with ASD had significantly increased peripheral blood levels of BDNF compared with healthy controls (Hedges g, 0.490; 95% CI, 0.185-0.794; P = .002). Subgroup analyses in 4 studies revealed that neonates diagnosed with ASD later in life had no association with blood levels of BDNF (Hedges g, 0.384; 95% CI, -0.244 to 1.011; P = .23), whereas children in the nonneonate ASD group (15 studies) demonstrated significantly increased BDNF levels compared with healthy controls (Hedges g, 0.524; 95% CI, 0.206 to 0.842; P = .001). Further analysis showed that children in the nonneonate ASD group had increased BDNF levels in serum (10 studies) (Hedges g, 0.564; 95% CI, 0.168 to 0.960; P = .005) but not in plasma (5 studies) (Hedges g, 0.436; 95% CI, -0.176 to 1.048; P = .16). Meta-regression analyses revealed that sample size had a moderating effect on the outcome of the meta-analysis in the nonneonate group. In addition, no publication bias was found in the meta-analysis. Children with ASD have increased peripheral blood levels of BDNF, strengthening the clinical evidence of an abnormal neurotrophic factor profile in this population.

Brain-Derived Neurotrophic Factor in Children and Adolescents with Cirrhosis Due to Biliary Atresia

Background: The nutritional status in patients with cirrhosis is not so easy to assess properly. Considering the relationship between brain-derived neurotrophic factor (BDNF) and energy homeostasis, the main aim of this study was to evaluate the concentration of BDNF in children and adolescents with cirrhosis due to biliary atresia (BA) and correlate it with their nutritional status. Methods: Fifty-three children and adolescents with cirrhosis due to BA and 33 healthy controls were enrolled in this study. Nutritional status was evaluated using anthropometric parameters, and serum BDNF was measured by ELISA. Spearman coefficient was used to evaluate the correlation between variables. Results: In the cirrhosis group, 28.8% were undernourished and in the control group, 100% were well-nourished. BDNF median values for the control and cirrhosis group were 28.5 and 9.0 pg/ml respectively. BDNF and platelets were positively associated with both Standard Deviation Score (SDS) for height-for-age ratio and SDS for triceps skinfold thickness-for-age ratio. Conclusions: Considering these associations, BDNF may be an indirect biomarker of nutritional status in children and adolescents with chronic liver disease. Further studies must be conducted to clarify the role of BDNF in this population.

Early predictors of behavioural problems in pre-schoolers - a longitudinal study of constitutional and environmental main and interaction effects.

BackgroundThe early environment is important for child development and wellbeing. Gene-by-environment studies investigating the impact of the serotonin transporter gene-linked polymorphic region (5-HTTLPR) and the Brain Derived Neurotrophic Factor (BDNF) Val66Met polymorphisms by life events on mental health and behaviour problems have been inconclusive. Methodological differences regarding sample sizes, study population, definitions of adversities and measures of mental health problems obstacle their comparability. Furthermore, very few studies included children. The aim of this study was to examine the associations between a broad range of risk factors covering pregnancy and birth, genetic polymorphism, experience of multiple life events and psychosocial environment, and child behaviour at age 3, using a comparably large, representative, population-based sample.MethodsA total of 1,106 children, and their mothers, were followed from pregnancy to age 3. Information on pregnancy and birth-related factors was retrieved from the Medical Birth Register. Questionnaires on depressive symptoms, child behaviour and child experiences of life events were filled in by the mothers. Child saliva samples were used for genotyping the 5-HTTLPR and BDNF Val66Met polymorphisms. Multiple logistic regression was used to investigate the association between psychological scales and genetic polymorphisms.ResultsSymptoms of postpartum depression increased the risk of both internalizing and externalizing problems. Experience of multiple life events was also a predictor of behavioural problems across the scales. No gene-by-environment or gene-by-gene-by-environment interactions were found. Children of immigrants had an increased risk of internalizing problems and parental unemployment was significantly associated with both internalizing and externalizing type of problems.ConclusionThis study shows the importance of the psychosocial environment for psychosocial health in preschool children, and adds to the literature of null-findings of gene-by-environment effects of 5-HTTLPR and BDNF in children.Electronic supplementary materialThe online version of this article (doi:10.1186/s12887-016-0614-x) contains supplementary material, which is available to authorized users.

Brain-Derived Neurotrophic Factor Levels in Children with Asthma and Isolated Chronic Cough

Studies show that neurogenic inflammation is implicated in the pathogenesis of chronic cough. Neurotrophins (NTs) regulate the synthesis of neuropeptides, which cause neurogenic inflammation. There is growing evidence suggesting their involvement in airway inflammation. The role of the brain-derived neurotrophic factor (BDNF), a member of the NT family, is not clear in chronic cough. The aim of this study was to evaluate the role of BDNF in children with nonspecific isolated chronic cough and to compare the differences between patients with asthma and healthy controls. In this case–control study, we included 30 patients with chronic cough (5–15 years) as the patient group. As the control group, 28 asthma patients under control, 30 children with asthma attacks, and 30 healthy children were included. Serum BDNF levels were measured by ELISA in all groups. The median of BDNF levels was 708.12 pg/mL (155–974) in the patient group, 952.94 pg/mL (220–1,018) in the controlled asthma group, 852.09 pg/mL (355–1,036) in the uncontrolled asthma patients, and 572.65 pg/mL (213–818) in the healthy children group. There were differences in the patient group and control groups regarding the BDNF levels (for the patient group and the controlled asthma group, P = 0.0014; for the patient group and the uncontrolled asthma patients, P = 0.0009; for the patient group and healthy children group, P = 0.05). The BDNF levels of asthma patients were statistically different from healthy children (P = 0.0001). Neurogenic inflammation was implicated in the pathogenesis of chronic cough. In patients with chronic cough, high BDNF levels may support the presence of asthma.

Letters to Editor Methodological approach to brain derived neurotrophic factor in children with autism spectrum disorder

Dear Editor, In a recent issue of Annals of Neurosciences, we read with great interest the article by Kasarpalkar and colleagues entitled “Brain-Derived Neurotrophic Factor in children with Autism Spectrum Disorder” in which the investigators reported that the protective effect of brain derived neurotrophic factor (BDNF) due to relatively higher levels in mild phenotypes of autism compared to severe autism and its possible diagnostic role in autism spectrum disorders.1 However, we think that some points should be discussed. BDNF is signaling protein that involved in the central regulation of energy homeostasis. Maffioletti and colleagues reported that serum preparation procedure is quite important issue to present robust methodology while measuring serum BDNF.2 BDNF level is presumably affected from duration of the clotting procedure due to being stored in thrombocytes. They observed progression on serum BDNF concentrations, which reached 38% of the plateau value after 10 min, 91.8% after 30 min, and 100% after 1 hour. Therefore, they recommended the minimum clotting duration for a correct serum BDNF dosage as 1 hour. However, in this study, the authors stated that serum samples were separated immediately after blood was collected. We think that standardization of clotting process is highly important to prevent misinterpretation of serum BDNF levels. Previous studies suggested that certain diseases such as epilepsy, allergic rhinitis and atopic dermatitis could likely affect BDNF levels.3 In addition, medications such as aspirin and corticosteroids, and dietary supplements such as vitamin E, vitamin A, vitamin B12, folic acid, zinc, omega-3 fatty acids, and ginkgo biloba extracts can influence BDNF levels.4-6 In this regard, without defining these contributing factors, interpreting the results is problematic. The authors did not express any of above contributors. In conclusion, clarifying these concerns will certainly provide a clearer picture when interpreting serum BDNF levels among participants.

Serum concentration of brain-derived neurotrophic factor in epileptic children

There are interesting evidences for the involvement of the neurotrophin brain-derived neurotrophic factor in the mechanism of epileptogenesis. In this study we measured the serum concentrations of brain-derived neurotrophic factor in children with epilepsy and age-matched healthy controls. There was no statistically significant difference between the mean serum concentrations of brain-derived neurotrophic factor in epileptic children (13.8 ± 1.1 ng/mL) and age-matched healthy controls (13.9 ± 0.1 ng/mL). The mean concentration of serum brain-derived neurotrophic factor was not different between generalized epilepsy and partial epilepsy. We also did not find significant difference regarding the associated clinical features of epilepsy (the presence of history of febrile convulsion, cerebral palsy). However, epileptic children with mental retardation showed lower levels of brain-derived neurotrophic factor (P = 0.015). Here we studied serum brain-derived neurotrophic factor concentration in a group of children without an active epileptogenesis based on the clinical and electroencephalographic state. Brain-derived neurotrophic factor concentrations should be investigated in children with active epileptogenesis who had refractory epilepsy and epileptic encephalopathy.

The effect of regular aerobic exercise on urinary brain-derived neurotrophic factor in children

Background Nervous system development in early lifeinfluences the quality of cognitive ability during adulthood.Neuronal development and neurogenesis are highly influencedby neurotrophins. The most active neurotrophin is brain-derivedneurotrophic factor (BDNF). Physical activity has a positiveeffect on cognitive function. However, few experimental studieshave been done on children to assess the effect of aerobic regularexercise on BDNF levels.Objective To assess the effect of regular aerobic exercise onurinary BDNF levels in children.Methods This clinical study was performed in 67 children aged6-8 years in Palembang. The intervention group (n=34) engagedin aerobic gymnastics three times per week for 8 weeks, while thecontrol group (n=33) engaged in gymnastic only once per week.Measurements of urinary BDNF were performed on both groupsbefore and after intervention. Mann-Whitney and Wilcoxon ranktests were used to analyze the differences between groups.Results There was no difference in urinary BDNF levels betweenthe two groups prior to the intervention. After intervention,the mean urinary BDNF levels were significantly higher in theintervention group than in the control group, 230.2 (SD 264.4)pg/mL vs. 88.0 (SD 35.4) pg/mL, respectively (P=0.027). We alsofound that engaging in aerobic gymnastics significantly increasedurinary BDNF levels from baseline in both groups (P=0.001).Conclusion Regular aerobic exercise can increase urinary BDNFlevels and potentially improve cognitive function. Aerobic exerciseshould be a routine activity in school curriculums in combinationwith the learning process to improve children’s cognitive ability.

The effect of regular aerobic exercise on urinary brain-derived neurotrophic factor in children

The effect of regular aerobic exercise on urinary brain-derived neurotrophic factor in children

Brain-Derived Neurotrophic Factor in children with Autism Spectrum Disorder

Autism Spectrum Disorder (ASD) is a complex neurobehavioral syndrome with no known biomarker so far for early detection. It has been challenging, both to classify typical autism and associate a suitable biomarker with clinical phenotype spectrum. Brain-derived neurotrophic factor (BDNF) has emerged as a key neurotrophin regulating synaptic plasticity, neuronal differentiation and survival. Recently, BDNF depletion is reported in neurodegenerative as well as in psychiatric disorders, associated with severity of neurological dysfunction. Role of BDNF as a biomarker in ASD is gaining significance. Pre-clinical results have linked BDNF depletion in autism and mental retardation, however, with conflicting findings. In view of this, a preliminary study was carried out to measure serum BDNF levels in 48 children with ASD and mental retardation, and 29 age-matched controls. Serum BDNF levels were found significantly higher (p<0.001) in atypical autistic subjects (clinically milder phenotype) as compared to controls, but not in typical ASD cases (clinically severe phenotype). BDNF levels were significantly lower in females with typical/Rett Syndrome (p<0.05), but not in males with typical autism (p>0.1), as compared to controls. Lower BDNF levels indicate impairment in neuroprotective mechanism, while higher levels may imply a manifested protective response. Our study highlights the differential BDNF response based on the severity of neurobehavioral deficit, indicating a possible neuroprotective role of this molecule and supporting its exploration in targeted therapy in ASD.

Effect of methylphenidate treatment on appetite and levels of leptin, ghrelin, adiponectin, and brain-derived neurotrophic factor in children and adolescents with attention deficit and hyperactivity disorder

Objectives. We aimed to explore whether the use of methylphenidate relates leptin, ghrelin, adiponectin, and brain-derived neurotrophic factor (BDNF). In addition, the relationship between methylphenidate-related weight loss in attention deficit hyperactivity disorder (ADHD) patients and these biomolecules were evaluated. Methods. Thirty ADHD patients receiving methylphenidate and 20 healthy controls were included. Leptin, ghrelin, adiponectin, and BDNF levels were measured at baseline and after two-month treatment in both groups. Results. At baseline, leptin, ghrelin, adiponectin, and BDNF levels were similar in the ADHD and control groups. The most common adverse events occurring in the ADHD group after a 2-month treatment period included loss of appetite (70%) and weight loss (66.7%). A significant difference was found in body weight, BMI, and CGI scores of the ADHD patients after the treatment. While post-treatment ghrelin and adiponectin levels were significantly higher in the ADHD group, BDNF level was significantly lower. Post-treatment decrease in leptin levels was not significant. Conclusions. Leptin and BDNF were not associated with poor appetite and/or weight loss due to methylphenidate treatment. However, ghrelin and adiponectin might be biomolecules that play a role in underlying neurobiological mechanisms of methylphenidate-related appetite or weight loss.

Possible role of brain-derived neurotrophic factor (BDNF) in autism spectrum disorder: current status.

Brain-derived neurotrophic factor (BDNF), a member of the neurotrophin family of survival-promoting molecules, plays a vital role in the growth, development, maintenance, and function of several neuronal systems. The purpose of this review is to document the support for the involvement of this molecule in the maintenance of normal cognitive, emotional functioning, and to outline recent developments in the content of Autism spectrum disorder (ASD). Current and future treatment development can be guided by developing understanding of this molecule's actions in the brain and the ways the expression of BDNF can be planned. Over the years, research findings suggested a critical role played by BDNF in the development of autism including increased serum concentrations of BDNF in children with autism and identification of different forms of BDNF in families of autistic individuals.

Changes of Serum Brain-Derived Neurotrophic Factor in Children with Obstructive Sleep Apnoea–Hypopnoea Syndrome following Adenotonsillectomy

Children with obstructive sleep apnoea syndrome (OSAS) have substantial cognitive functional morbidity. Brain-derived neurotrophic factor (BDNF) is a key mediator of memory and cognition, but its regulation in OSAS is unknown. Circulating BDNF, transforming growth factor-β(1) and 5-hydroxytryptamine levels, cognitive ability and overnight polysomnography were evaluated in 44 children with newly-diagnosed OSAS and in 26 healthy children. All parameters were monitored pre-operatively and at 3, 6 and 12 months after adenotonsillectomy. Pre-operative cognitive ability and sleep parameters were significantly poorer in children with OSAS compared with controls, but BDNF levels were similar. At 3 months post-operation, serum BDNF concentrations decreased, but cognitive ability and sleep parameters remained deficient. At 6 months post-operation, serum BDNF levels, sleep parameters and cognitive ability had improved and, by 12 months, there were no differences between the two groups. It is concluded that adenotonsillectomy can rapidly normalize sleep parameters and improve the cognitive ability of children with OSAS, by regulating the circulating level of BDNF.