Students who take Adderall to improve their test scores may get a slight benefit, but it’s mainly a placebo effect...Rachel Fargason, a psychiatrist at the University of Alabama, Birmingham, says the idea of stimulants as cognitive enhancers didn’t tally with her experience of patients who were diagnosed incorrectly...To investigate further, Fargason’s team set up a trial in 32 people between the ages of 19 and 30, none of whom had ADHD.