Subjects with a history or presence of clinically important cardiac, renal, hepatic, endocrine (including diabetes mellitus), pulmonary, biliary, gastrointestinal, pancreatic, or neurologic disorders that, in the judgment of the Investigator, would interfere with the subject's ability to provide informed consent, comply with the study protocol (which might confound the interpretation of the study results), or put the subject at undue risk.
The use of prescription stimulants is especially prevalent among students. Surveys suggest that 0.7–4.5% of German students have used cognitive enhancers in their lifetime. Stimulants such as dimethylamylamine and methylphenidate are used on college campuses and by younger groups. Based upon studies of self-reported illicit stimulant use, 5–35% of college students use diverted ADHD stimulants, which are primarily intended for performance enhancement rather than as recreational drugs. Several factors positively and negatively influence an individual's willingness to use a drug for the purpose of enhancing cognitive performance. Among them are personal characteristics, drug characteristics, and characteristics of the social context.