No effect of Adderall on normal subjects
Adderall, the treatment for Attention Deficit Hyperactive Disorder (ADHD), is one of the most effective psychiatric drugs in current use, improving attention and behavior in over 70% of ADHD patients. Compare this to serotonin reuptake inhibitors (SSRIs) like Prozac or Zoloft, each of which are effective in about 30% of people with depression.
In a poster abstract at this year’s SfN, Ilieva from the Farah lab at UPenn report on a placebo-controlled double-blind clinical trial with Adderall using cognitively normal subjects. They found no objective effect on working memory and cognitive control. Subjects, interestingly, subjectively reported improved performance in these tasks. Here is the abstract:
A growing number of cognitively normal adults use stimulant medications in order to enhance their cognitive abilities. We investigated whether such medications enhance executive function, which is closely associated with intelligence and is dependent on the catecholaminergic targets of stimulant drugs. The literature to date yields inconsistent results, with as many null results as findings of enhancement. In a double-blind placebo controlled cross-over study using 20 mg of mixed amphetamine salts administered to 48 healthy adults aged 21-30, we assessed working memory and cognitive control with two tasks each (Digit Span, Object-2-Back, Go/No-go and Flanker). Although the study was adequately powered to detect an effect of moderate or greater size, we failed to find an overall effect of the drug, nor did we find enhancement in any individual task. The lack of effect held for both higher and lower performers. In contrast, participants reported more perceived cognitive benefit with amphetamine. We conclude that the objective effects of amphetamine on executive function are at best subtle, whereas the subjective effects of amphetamine are sufficiently salient to measurably affect self-perceived performance in this study. This is consistent with the existing literature on stimulant effects in specific executive function tasks, especially in view of the higher barrier to publishing null results, and also suggests a reason for the popularity of these drugs as cognitive enhancers. It must be added that cognitive abilities other than those tested by us may well have been substantially enhanced.
Adderall doesn’t improve your study abilities, but by associating studying with positive feelings (a side effect of the amphetamine), it makes studying more fun. Pairing studying with an enjoyable drug allows homework to compete with all of the other fun things you could be doing, like video games, facebook, or beer pong.