Modafinil was developed to treat narcolepsy (excessive sleeping), but it is widely used off-licence as a 'smart drug' to promote cognitive enhancement, where qualities such as alertness and concentration are desired to assist someone with, for example, exam preparation.
Past studies on sleep-deprived individuals have shown a strong positive effect of modafinil on these functions, but there has been less attention and scientific consensus on the drug's overall effectiveness as a cognitive enhancer in people that are not sleep-deprived - presumably the majority of people taking it.
Dr Ruairidh Battleday and Dr Anna-Katharine Brem from the University of Oxford and Harvard Medical School evaluated all research papers on cognitive enhancement with modafinil from January 1990 to December 2014.
They found 24 studies dealing with different benefits associated with taking modafinil, including planning and decision making, flexibility, learning and memory, and creativity.
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Unsurprisingly, they found that the performance-enhancing capacity of modafinil varied according to the task. What emerged was that the longer and more complex the task tested, the more consistently modafinil conferred cognitive benefits.
The 70 per cent of studies that looked at the effects of modafinil on mood and side effects showed very little overall effect.
"In the past, people were using very basic tests of cognition, developed for neurologically-impaired individuals. In contrast, more recent studies have, in general, used more complex tests: when these are used, it appears that modafinil more reliably enhances cognition: in particular 'higher' brain functions that rely on contribution from multiple simple cognitive processes," said Battleday.
"In the face of vanishingly few side effects in these controlled environments, modafinil can be considered a cognitive enhancer; and, second that we need to figure out better ways of testing normal or even supra-normal cognition in a reliable manner," said Brem.
"The authors say "modafinil may well deserve the title of the first well-validated pharmaceutical nootropic agent". In other words, it's the first real example of a 'smart drug', which can genuinely help," said Goodwin.