Methylphenidate, often sold under the brand name Ritalin, can be prescribed to people with ADHD
Turtle Rock Scientific/Science Source/Science Photo Library
Some people try to get a mental boost by taking medicines that are designed to treat ADHD or to counter sleeping disorders, even though they don’t have these conditions. But that may not be such a smart move, as the drugs worsened the performance of people who didn’t have these conditions in a complex problem-solving task.
The drugs involved include two stimulants: methylphenidate, often sold under the brand name Ritalin, and dextroamphetamine. These are both often prescribed to improve concentration and attention in people with ADHD. They are thought to work by raising levels of the brain chemical dopamine, as dopamine-signalling systems may work less well in people with ADHD.
Another drug, called modafinil, is used to help people with excessive fatigue caused by narcolepsy. Modafinil also raises dopamine signalling.
Use of these drugs by people without these conditions has been growing in colleges and workplaces, when cramming for an exam or close to a deadline. People may buy them as “smart drugs” online or from those who have been prescribed them legitimately. “It is really rampant among students in US colleges,” says Peter Bossaerts at the University of Cambridge.
Previous studies have shown that when people without ADHD take stimulants like these, their performance in straightforward memory and concentration tasks is only as good as those taking placebo pills. This suggests that any benefit felt by the study participants might stem from the placebo effect.
Bossaerts and his colleagues wanted to test the drugs in a way that is closer to real-world problem solving. They used an online test called the knapsack problem, in which people have to choose from multiple items of different weights and values to fill a bag, making the total contents as valuable as possible without breaching a weight limit. They can try out different combinations before submitting their answer.
The researchers asked 40 people to do multiple versions of the task after taking one of the three drugs or a placebo tablet. The participants visited the lab four times, at weekly intervals, to be tested after each drug and the placebo.
When taking any one of the drugs, people put more effort into the task, in terms of the number of different options they tried before submitting their answers and how long they spent on the task. But their performance was worse, as measured by the total value of items in the bag, compared with taking a placebo.
People would probably think the drugs are helping them, but they aren’t, says Bossaerts. “They’re spending more time [on the task], they move the items around a lot more, so they see themselves as being busier,” he says.
Rachel Fargason at the University of Alabama at Birmingham says it makes sense that stimulants could be helpful for people with ADHD, but not for those who don’t have the condition. “You can have too much dopamine – there’s an optimum dose,” she says. “This study really demonstrates that beautifully.”
Stephen Faraone at SUNY Upstate Medical University in New York state says that people taking stimulants may not realise the drugs reduce their performance because it feels like they are working harder. “The medications will keep people awake and increase motivation,” he says. “They might confuse motivation with something that’s working.”
Ritalin’s manufacturer Novartis hadn’t replied to requests for a comment at the time of publication. All three drugs are made by multiple companies.
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