P50 Sensory Gating in Children and Adolescents with ADHD and Effects of Methylphenidate Administration on P50 Sensory Gating

Objective: The P50 is thought to reflect a sensory gating mechanism and prevent information overload in humans. Failure to inhibit the P50 auditory event evoked response can occur in attention deficit hyperactivity disorder (ADHD) patients. The aims of the present study were to examine the inhibition of the P50 auditory event evoked potential and the effects of methyphenidate administration on P50 parameters in children and adolescents diagnosed with ADHD. Methods: Twenty-two drug-free subjects, aged 9-14, who were diagnosed with ADHD (the combined type) according to the DSM-IV criteria, and 18 mentally and physically healthy subjects, aged 9-12, were included in the study. First, P50 parameters were measured in drug-free ADHD subjects and healthy controls. Following this measurement, 10 mg of methylphenidate was administered to the ADHD group. The P50 measurement was repeated 1 hour following methylphenidate administration in the ADHD subjects. The healthy control group was not re-examined. Results: A significant difference was found in P50 test latency, test amplitude, and P50 ratio values between the ADHD group and healthy controls. Significant differences were also found in conditioning latency, test latency, test amplitude, and P50 ratio values between before and after methyphenidate administration in the ADHD group. Conclusions: The results of the present study point out an association between P50 and ADHD and they also show that methyphenidate administration increases the P50 suppression level. Since, this is the first study evaluating sensory gating in children and adolescents with ADHD, it should be considered as a preliminary study. Further studies with large study samples are warranted.