Individuals with FASD may respond differently to stimulant medication than other children with ADHD. Specifically, children with FASD appear to have a differential response to methylphenidate and dexamphetamine. In a case series of 30 children with FASD and ADHD, 22% (of 23 children) responded to methylphenidate, while 79% (of 19 children) responded to dexamphetamine. Of the children given both medications, eight did not respond to methylphenidate but later responded to dexamphetamine, one child did not respond to dexamphetamine but later responded to methylphenidate, and three children did not respond to either medication.29 The apparently increased response rate to dexamphetamine may be explained by animal work showing that rats who were prenatally exposed to alcohol and had physical hyperactivity showed “hyperresponsiveness” to methylphenidate and that alcohol exposure acts on the D1 dopamine receptors of the mesolimbic system, which is the site of action of dexamphetamine.6,30,31 Decreased effectiveness of methylphenidate in animal and human studies suggests that the front nigrostriatal pathway may not be the mechanism in patients with FASD and comorbid ADHD.6
