‘Smart’ drugs can decrease productivity in people without ADHD, new study shows

Image of man taking tablets at work

Workers and students taking so-called cognitive enhancers, or ‘smart’ drugs, commonly prescribed for Attention Deficit Hyperactivity Disorder (ADHD), might actually be inhibiting their performance and productivity, new research shows.

Published in Science Advances, the research from the University of Melbourne and University of Cambridge, casts new light on the belief that these drugs enhance focus and cognitive performance for people without ADHD.

In a double-blinded, placebo-controlled trial in Melbourne, 40 healthy participants took one of three popular ‘smart’ drugs (Methylphenidate (sold under the brand name Ritalin), Modafinil or Dextroamphetamine), or a placebo, and were tested on how they performed.

The test – called the Knapsack Optimization Problem and used as a representation of difficulty in tasks encountered in daily life – was repeated four times, at least one week apart, to measure how they each performed with the drugs and without (placebo condition).

Researchers found that in general, participants taking the drugs saw small decreases in accuracy and efficiency, along with large increases in time and effort relative to their placebo condition.

In addition, participants who performed at a higher level in a placebo condition tended to exhibit a stronger decrease in performance and productivity after receiving a drug. By contrast, participants who had a lower performance in a placebo condition only very occasionally exhibited a slight improvement after taking a drug.

Lead author of the study and researcher at the Centre for Brain, Mind and Markets at the University of Melbourne, Dr Elizabeth Bowman, said the results show the effectiveness of pharmaceutical enhancers when used by healthy people in everyday complex tasks has yet to be established.

“Our research shows drugs that are expected to improve cognitive performance may actually be leading to healthy users working harder while producing a lower quality of work in a longer amount of time.

“We found taking the drugs did not increase a participant’s ability to solve the test correctly, and it decreased the score they obtained compared to when they completed the task without drugs. We also found that participants took longer to complete the task, rather than being more efficient.”

Leverhulme International Professor of Neuroeonomics at the University of Cambridge, Professor Peter Bossaerts, said more research needs to be conducted to find out what effects the drugs are having on users without ADHD.

“It was expected, because of the increased dopamine the drugs induce, we would see increased motivation, and a concurrent increase in the chemical norephinephrine, would cause an increase in effort, which in turn would lead to higher performance,” Professor Bossaerts said.

“Performance did not generally increase, so questions remain about how the drugs are affecting people’s minds and decision-making.”