For millions of people who are approaching old age, developing dementia, particularly if there is a family history of the disease, is a frightening prospect. Many of them are asking their doctors for advice on how to slow memory loss, as well as searching the internet for preventive strategies. As a result, over the past two years, the “grey gamer” has become a powerful market force and computer games like Nintendo’s Brain Age, which claim to improve users’ cognitive performance with repeated use, have sold tens of millions of units.

Celebrity endorsements have been a major part of the marketing campaigns, with stars such as actress Nicole Kidman and quiz show host Chris Tarrant appearing in television adverts to promote Nintendo’s brain training programs. But the Brain Age products, which were developed with the help of neuroscientist Ryuta Kawashima, are beginning to face serious competition.

In the United Kingdom, Susan Greenfield, a professor of pharmacology at the University of Oxford and director of the Royal Institution, has been promoting MindFit, a computer program sold by MindWeavers that says it is “Based on science, proven in practice, fun to play.” And in the United States the Brain Fitness Program, sold by Posit Science, a company cofounded by neuroscientist Michael Merzenich, claims to be “clinically proven to help people think faster, focus better, and remember more.”