Running head: NEUROANATOMICAL DIFFERENCES IN ADHD 1 Neuroanatomical Differences in Attention-Deficit/Hyperactivity Disorder: Influence of Stimulant Medication Administration

Attention-deficit/hyperactivity disorder (ADHD) is a common psychological disorder for which the preferred treatment is with stimulants (methylphenidate). With medication administration to young children becoming exceedingly common, it is important to investigate the neurodevelopment consequences of doing so. Much of the imaging literature that suggests neuroanatomical differences in ADHD patients has not considered the effects of lifetime medication administration in their samples. Animal studies have demonstrated that acute methylphenidate administration to juveniles causes significant brain structure changes. A multi-dimensional examination of the current literature assessing the structural differences in ADHD with respect to medication administration is the focus for this review. It is concluded that the current administration of methylphenidate to young ADHD patients should be reevaluated to incorporate the possibility for medication-induced neurodevelopment.