The effect of methylphenidate on brain hemodynamics of attention-deficit/hyperactivity disorder measured by functional near infrared spectroscopy

Abstract

Attention-deficit/hyperactivity disorder (ADHD) is a very common neurodevelopmental disorder. Approximately 30% 60% of individuals diagnosed with ADHD in youth have symptoms that persist into adulthood. This neurobehavioral disorder results in significant functional impairment. It decreases the life quality of the patients. Therefore, the need for recognition and treatment of patients with ADHD is necessary. Methylphenidate (MPH) is known to reduce hyperactivity in individuals with ADHD. Yet little is known about how it alters neural activity and how this relates to its clinical effects. Functional Near-Infrared Spectroscopy (fNIRS) is a portable, non-invasive brain imaging method measuring the changes in oxygenated hemoglobin [HbO2] and deoxyhemoglobin [HbH] levels particularly in prefrontal cortex. In this study, 15 adult, right handed cases with DSM-IV diagnosis of Attention deficit hyperactivity disorder (ADHD) were evaluated with fNIRS during a cognitive task which is Stroop test. The goal of this study is to examine MPH-induced hemodynamic changes during a cognitive activity, and to examine how these changes correlate with measures of behavioral response to the drug during Stroop task. It is found that MPH effectively decreased HbO levels. The reason of the decreased level of HbO after medication is vasoconstriction. MPH normalized the behavior during an executive function test. MPH has a great effect on the response time of the subjects to NS, CS, and IS. MPH always shortens the durations of the reaction times.|Keywords: Functional Near-Infrared Spectroscopy, Attention-Deficit/Hyperactivity Disorder (ADHD), Methylphenidate, Stroop task, adult.