Brain-Derived Neurotrophic Factor in children with Autism Spectrum Disorder

Background: 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. Purpose: 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. Methods: 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. Results: 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. Conclusion: 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.