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  • A new study finds that for people without ADHD, cognitive enhancers may actually inhibit performance and productivity.
  • Drugs like Ritalin are used by people with ADHD to improve concentration.
  • But people without ADHD ended up doing worse on tests that measured problem-solving skills.

Students and others sometimes take certain drugs commonly prescribed for attention deficit hyperactivity disorder (ADHD) to enhance their focus and cognitive performance, even without a diagnosis of ADHD.

But a new study suggests that in people without ADHD, these cognitive enhancers may actually inhibit performance and productivity.

This contrasts with earlier research, which found that these “smart drugs” improve certain types of memory and attention.

“People in highly competitive cognitive environments are often looking for ways to improve their performance, and there are many substances that people have tried,” study author Elizabeth Bowman, PhD, a researcher at the Centre for Brain, Mind and Markets at the University of Melbourne in Australia, told Healthline.

“Unfortunately there is little to no good-quality scientific data on most of them,” she added.

In the study, published June 14 in the journal Science Advances, researchers tested the effects of three popular smart drugs (methylphenidate, modafinil or dextroamphetamine), comparing them to an inactive placebo.

The study involved 40 healthy participants between 18 and 35 years old, without a diagnosis of ADHD.

Participants were randomly assigned to receive one of the drugs or a placebo before four separate experiments, which were done at least one week apart.

The tests were designed to model the decision-making and problem-solving that people do during their daily lives. These were intended to be more complex — and relevant to real life — than tests used in earlier studies, said the researchers.

In one of these tests — known as the “knapsack task” — participants were given a virtual backpack with a certain capacity, and a selection of items with different weights and values. The goal of the task was to place the items in the backpack in a way that maximized the overall value of its contents.

Researchers found that after taking one of the drugs, people spent more time and effort solving the tasks, while also being less accurate and efficient, compared to when not taking the drugs.

For example, on the knapsack task, taking one of the drugs did not reduce the chance that participants would find a solution to the problem, but there was a drop in the value that people attained on the task.

They also spent more effort — measured as either time spent or the number of moves — getting to that solution.

Dr. David Merrill, a geriatric psychiatrist and director of the Pacific Neuroscience Institute’s Pacific Brain Health Center in Santa Monica, Calif., who was not involved in the study, said the study shows these drugs don’t have cognitive benefits for people without ADHD, “at least in terms of performance on the tasks tested.”

The study results also showed that people who performed better on the knapsack task after taking the placebo — compared to the rest of the group — tended to be below average after taking one of the drugs.

The researchers said this was due to people’s choices becoming more erratic after taking one of the drugs. In order for people to succeed at the knapsack task, they need to be systematic in their thinking, researchers said, which the drugs interfered with.

In essence, people using these drugs “may be more motivated to put in effort, but they’re also less efficient,” Merrill told Healthline. “So you’re actually seeing a decline in their task performance.”

Another problem with taking these drugs in the absence of a clinical diagnosis is that they are meant to normalize levels of dopamine in people who have a deficit in this neurotransmitter, he said.

However, “if a system is already normal or optimal, overloading the system by adding more [dopamine] does not necessarily help, and may actually cause harm,” he added.

Methylphenidate, for example, can cause nervousness, irritability, difficulty falling or staying asleep, and other side effects. These side effects may make it more difficult to carry out cognitive tasks efficiently.

While the new study found that cognitive enhancers may not work for people without ADHD, Bowman said the results don’t raise any concerns about their use in people with that condition.

“These medications have been a safe and effective part of ADHD treatment for many years,” she said.

However, “people using pharmaceuticals in ways outside what they are prescribed for is always a concern,” she added.

Merrill agrees that the results of the new study reinforce that prescription drugs should not be used without a clinical diagnosis showing that a person might benefit from these drugs.

”When combined with the potential for abuse and/or dependence — plus the vascular effects — it becomes clear that the risks [of these drugs] are not worth the wishful thinking of benefits,” he said.

If people are concerned about their ability to think clearly or focus, they should talk to a doctor, who can look for the underlying cause — and then discuss possible treatments with them.

In addition, medications are not the only way to boost your productivity and help you focus. Getting a good night’s sleep, doing relaxation breathing, making sure you’re in the right frame of mind, and optimizing your work setting can all help, said Merrill.

The bottom line is that “these findings highlight that stimulant drugs don’t make us superhuman or super-smart,” he said.