The wilder shores of brain boosting

The Genius Within: Unlocking Your Brain’s Potential David Adam Pegasus: 2018.

Is there a common element that binds diverse mental abilities, from language to mental arithmetic? Or do these skills compete for our brains’ limited resources? In The Genius Within, David Adam tackles the controversial topic of intelligence, in a follow-up to his exceptional book on obsessive–compulsive disorder (OCD), The Man Who Couldn’t Stop (Picador, 2014).

Adam (Nature’s Editorials editor, with whom I worked on a film about the use of animals in OCD research) deftly surveys attempts to test intelligence starting more than a century ago, by statistician and eugenicist Francis Galton and others. Psychologist Charles Spearman introduced g as a measure of overall performance across, for instance, verbal and spatial capacities. Alfred Binet introduced the first practical test for intelligence quotient (IQ), purporting to determine a child’s ‘mental age’. In the ensuing decades, intelligence testing has come under fire for cultural bias, as well as limited scope; it excludes ‘emotional intelligence’, for example. Adam explores the dissent, from calls for recognition of neurodiversity to the furore over Richard Herrnstein and Charles Murray’s 1994 book The Bell Curve (Free Press).

Adam’s book hinges on one question: can we beef up our intelligence? Ever perspicacious and intrepid, Adam turns guinea pig, exploring means from ‘brain training’ to cognitive-enhancer drugs. He takes modafinil (licensed for treating the sleep disorder narcolepsy) and finds, consistent with lab studies, enhanced mental focus as he works: “I did feel different … like I was concentrating on the words I wrote in a more deliberate way.” He also endures bouts of crude electrical brain stimulation that simulates the effects of transcranial direct current stimulation (tDCS), administered by his spouse. In the lab, tDCS has been claimed to promote learning by exciting or inhibiting neural activity across specific regions of the cortex.

Adam concludes there is evidence that intelligence can be boosted. Improving cognitive performance is important in people affected by Alzheimer’s disease, for instance, or conditions such as attention deficit hyperactivity disorder. But he argues that enhancing ‘normal’ performance could also be a viable goal. The claim that most people perform optimally is palpably false: think of the effects of fatigue on exam performance. Moreover, surveys reveal that students and academics use cognitive-enhancer drugs. Yet successful cognitive enhancement carries myriad ethical implications. Is it fair to take modafinil while studying for exams? Could an employer insist on treatment for employees? How would all this be regulated?

Importantly, does cognitive improvement carry a neurological price? Is it possible to enhance g, or does boosting one aspect of intelligence, such as working memory, degrade another? A study last year found that modafinil can enhance the performance of people playing chess against computers, but they lose more games through time defaults (A. G. Franke et al. Eur. Neuropsychopharmacol. 27, 248–260; 2017).