Plasma BDNF levels in children with ADHD before and after methylphenidate treatment.

Background: Brain-Derived Neurotrophic Factor (BDNF) is the most abundant neurotrophin in the central nervous system with essential roles in neurodevelopment and maintenance of healthy brain function. Accordingly, BDNF has been suggested to play a role in the pathophysiology of Attention Deficit Hyperactivity Disorder (ADHD). Objectives: To investigate whether medication-naïve children with ADHD exhibit altered plasma BDNF levels compared with healthy controls, and to examine whether methylphenidate treatment is associated with changes in plasma BDNF and clinical outcomes. Methods: In this study we measured plasma BDNF levels before and after 12 weeks of standard treatment with methylpheni-date (MPH) in 21 medication-naïve children (aged 7-12 years) with ADHD and 25 matched control children. Blood samples were drawn after an overnight fast and analyses were controlled for body mass index, pubertal status, and physical activity. Associations between plasma BDNF levels and clinical symptoms were also evaluated. Results: Baseline plasma BDNF levels were significantly higher in the patient group than in the control group and remained significantly higher in the patient group after 12 weeks of MPH treatment. Moreover, higher baseline BDNF levels predicted greater positive effects of MPH treatment as measured by parent-rated inattentive and hyperactivity symptom scores. The findings are discussed in relation to the compensation theory of BDNF for neuropathology.