Objective: Attention deficit hyperactivity disorder (ADHD), characterized by core symptoms like hyperactivity, attention deficit and impulsivity far beyond the developmental levels is an important psychiatric illness with a prevalence of 5% worldwide and the effects on the patients’ and their families’ quality of life. Even though the pathogenesis of ADHD is still greatly unknown, evidences from different researches point out primarily the dopaminergic system. As a member of the neurotrophin family, brain-derived neurotrophic factor (BDNF) is a widely expressed neurotrophin in the brain. BDNF has an important role in the survival, differentiation and synaptic plasticity of a series of neuronal systems including dopaminergic neurons. For this reason, it is proposed that BDNF might play a role in the ADHD pathophysiology. In this study, a comparison was aimed to be made between serum BDNF levels in children with diagnosed ADHD for pretreatment and posttreatment with methylphenidate.
Method: Fifty children with diagnosis of ADHD within an age range of 6-12 years were recruited in the study. The psychiatric diagnoses were determined by applying a semi-structured interview with Kiddies Schedule for Affective Disorders and Schizophrenia for School Aged Children- Present and Lifetime Version (K-SADS-PL). The symptom severity of ADHD was measured by Clinical Global Impression (CGI) ADHD severity scale. Clinicians filled up Du Paul ADHD scale. The levels of serum BDNF were assessed before and after eight weeks treatment with effective dosages of methylphenidate.
Results: In present study mean plasma BDNF levels in the baseline were 2626.3 pg/ml and 3255.8 pg/ml in the end point, thus showing significantly higher mean serum BDNF levels at post-treatment than pretreatment (t=-2.147, df=49, p=0.037). There was statistical significant difference between three subtypes of ADHD (p=0.004). After Bonferroni correlation it was found that there were significant differences between both mixed subtype and predominantly attention deficit subtype (p=0.03) and between predominantly attention deficit subtype and predominantly hyperactivity-impulsivity subtype (p=0.14). Significant difference was not found in BDNF levels with or without comorbidity (p=0.671) and there was no correlation between BDNF and Du Paul or CGI scores.
Conclusion: The results showed a significant increase in serum BDNF in children with ADHD after 8 weeks treatment with methylphenidate. Also we observed an improvement in attention deficit symptoms with increasing baseline serum BDNF levels. Serum BDNF can be an indicator for prediction of treatment response, prognosis.