Investigation of serum bdnf levels in children diagnosed with attention deficit hyperactivity disorder

The underlying pathogenesis of this disorder remains largely unknown, nevertheless evidence from various sources suggests primary involvement of the dopaminergic system. However, since Attention Deficit Hyperactivity Disorder (ADHD) is now viewed as a pathophysiologically and clinically heterogenous entity, hypotheses on the etiology of ADHD have evolved from simple one-cause theories to multi-factorial processes that reflect the confluence of many types of risk factors, including genetic, neurochemical, environmental and psychosocial factors.Brain-Derived Neurotrophic Factor (BDNF) enhances the growth and maintenance of several neuronal systems, serves as a neurotransmitter modulator, and participates in mechanismsof neuronal plasticity, suchas long-term potentiation and learning. Preclinical studies demonstrated that BDNF plays a key role in the survival and differentiation of midbrain dopaminergic neurons which is crucial in ADHD pathogenesis.Thirty-one ADHD patients and thirty controls whose ages are between 6-12 were enrolled in this study. ADHD subjects were recruited from the child psychiatry outpatient clinics of the Dokuz Eylul University Hospital. They were medication-naive. Individuals with IQ lower than 70, neurological disorders, pervasive developmental disorders, mood disorders or psychotic disorders were excluded.The mean age for ADHD case group included in this study is 8.45±1.57 and the mean age for the healthy control group is 8.87±1.92. 26 (%83.9) of the ADHD case group were boys, and 19 (%63.3) were girls. As for the healthy control group, 11 (%36.7) were boys, and 19(%63.3) were girls.We investigated the levels of serum BDNF levels in patients with ADHD and found that serum BDNF levels were not different between ADHD and controls. This result do not support the hypothesis that BDNF plays a role in the etiology of ADHD. Therefore, to accurately interpret the meaning of the blood BDNF levels it is necessary to understand the various factors that may affect blood BDNF levels, as well as to understand the origins of the blood BDNF.