Genetic determinants of response to acute, sub-chronic, and chronic administration of stimulant drugs have been examined using association studies in several different populations. We have conducted a series of association studies of the acute responses to amphetamine (e.g., Lott et al. 2005; Dlugos et al. 2010). In this double-blind, placebo-controlled study, healthy young adults (ranging from n = 99 to n = 152, depending on the analysis) received oral doses of d-amphetamine (10 and 20 mg) and placebo over the course of three different sessions. Measures of subjective, cardiovascular and behavioral responses were obtained at regular intervals. The subjective measures included the Profile of Mood States (POMS; McNair et al. 1971), Drug Effects Questionnaire (DEQ; Johanson and Uhlenhuth 1980) and Addiction Resource Center Inventory (ARCI; Martin et al. 1971). In children diagnosed with ADHD, methylphenidate is typically administered daily or several times a day in a therapeutic context, and the outcome measure is usually therapeutic response as measured by the Clinical Global Impression-Severity scale (CGI-S; Guy 1976) and the ADHD Rating Scale-IV (ARS; DuPaul et al. 1998). In both studies
