Brain Derived Neurotrophic Factor (BDNF) in Serum of Children with PDDs and Their Parents

Background: Brain Derived Neurotrophic Factor (BDNF) is a protein widely expressed in the developing brain which is known to regulate neuronal cell survival, differentiation, and plasticity. BDNF has been implicated in the study of Autism among other various disorders, such as Depression and Schizophrenia. Albeit some contradictory findings in various age groups, a BDNF excess theory has been put forward. Objectives: In the present on going study we intend to compare its concentration in the serum both of 50 children with PDDs aged 30-42 months, and their parents with that in normal controls. We are also following up these children to explore the correlation of BDNF concentration fluctuation with their adaptive functioning. Methods: Individuals are assigned case status if they have a clinical diagnosis of autism, atypical autism, Asperger syndrome, or PDD-NOS, meet ADI-R criteria for autism or fall one point below threshold on one of its behavioral domain and meet ADOS-G criteria at least for PDD. Subjects are selected if they are of normal intelligence by the use of Leiter-R and they had no history or signs of any birth complications, seizures or a known cause of Autism such as Fragile-X or Tuberous Sclerosis. Since BDNF concentrations are altered in the presence of atopy, an allergy history is completed, total IgE is measured and skin prick tests are carried out for 10 common allergens. Their adaptive functioning is measured by the Vineland Adaptive Behavior Scales. Parents are assessed for depression symptoms using the Beck Depression Inventory and for feautures of the Broader Autism Phenotype using the Broader Phenotype Autism Symptom Scale (BPASS). The presence of any chronic disorder, apart from Depression or the current use of medications represents an exclusion criterion. Controls are matched for age and sex children in preparation for an orthopedic surgery and age and sex matched adult blood taken from a blood bank, with a total IgE less than 120 kU/ml. Children are to be reassessed at 48, 60 and 72 months of age. Blood is taken from the cubital vein of the participating subjects between 9 and 10.30 a.m. to minimize effects of a possible circadian rhythm of BDNF concentrations. BDNF levels are measured using commercial enzyme-linked immunosorbent assays (ELISA). Results: Results from the first wave of 17 children (mean age 35,8±4,1 months and Non-verbal IQ 106±24) and their families (but no controls) showed that: a) BDNF serum levels in probands was negatively correlated to the severity of Autism symptomatology, as this is expressed with ADOS Total Score (r = -0,733, p=0,025), b) BDNF serum level in parents had no statistical significant correlation neither with age nor with the presence of symptoms of the broader autism phenotype, as indicated by BPASS scores, and c) Parents that did had allergies had a statistical significant higher serum level of BDNF (1928,3±409 vs. 1463,1±666, p=0,028). Conclusions: The findings of 40 families and controls, along with the first 15 follow-up of probands (age 48months) will be presented at IMFAR 2009 conference.