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‘Smart drugs’ not so smart when it comes to complex problems

Recent reports suggest stimulant drugs, usually used to treat ADHD are being taken by students and employees to increase their academic and work productivity. These drugs include methylphenidate, dextroamphetamine and modafinil. While we know they are effective in treating the conditions they are prescribed for, the literature on their effects in people who don’t have ADHD is mixed.

In a new study, 40 people aged between 18 and 35 were randomised to receive a standard adult dose of methylphenidate, dextroamphetamine, modafinil or a placebo. Then they were asked to solve eight different instances of the ‘knapsack test.’ In this test, people have to choose which of a list of items of certain value and weight they’ll include in a knapsack of a specific weight capacity. The goal of the test is to maximise the value of the items you choose, while keeping under the weight capacity of the knapsack. This was intended to simulate a challenging, modern-day workplace where you might be weighing up multiple goals or calculating several things at once. For each test, the capacity of the knapsack changed so participants had to adapt their thinking each time.

The researchers found that while those taking these drugs performed about as well as the placebo group in finding the correct solution to a knapsack problem (getting the most value), the non-placebo participants tended to take more time on the problem and expended more effort and activity during the problem (they moved items in or out of the virtual knapsack more often and tended to make moves with less of an impact than the placebo group).

The authors suggest that using these smart drugs outside their intended treatment purpose may not be so clever – given they made little difference to performance (and in many cases made people worse) and led only to a significantly elevated level of frantic activity.

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