First came Sudoku, the fiendishly addictive puzzle that time-wasters could reassure themselves was good for their brains. Now Britain is about to be hit by another Japanese craze: the 10-minute mental work-out.
A portable computer game, Professor Kawashima's Brain Training: How Old is Your Brain?, aims to be a personal fitness trainer for the mind. Ryuta Kawashima, a neuroscientist at Tohoku University in Japan, claims that, by following a short programme of maths and language tests every day, users can keep their brains young and improve their long-term memory. The game is aimed primarily at people aged between 30 and 65 and will be advertised in Saga magazine and on Classic FM radio.
Kawashima's animated head appears on the game's screen, warning: 'If you don't use your brain, it will age quickly. You'll have a brain with less power than the ideal brain age of 20. You'll get out of shape and weak! But don't fret! There is nothing to fear. You can train your brain just like your body.'
During 20 years' research into brain scans, Kawashima found that solving simple calculations and reading aloud stimulated five key areas of the brain, including one that recognises the shape of numbers, and 'Wernicke's area', which recognises the meaning of words. His exercises are intended to increase the delivery of oxygen, blood and amino acids to the prefrontal cortex, boosting the brain's health.
'Brain training' involves nine tests to be completed against the clock. They include Sudoku, simple maths, memory and syllable tests and reading aloud, which Kawashima says does more to energise the brain than reading silently.
The machine, which has touchscreen and voice recognition technology, calculates the user's 'brain age' on the basis of their real age and their accuracy and speed in the tests. The better they perform, the closer their brain age will be to 20, when the brain is at its most dynamic.
Sudoku, which has taken Britain by storm, has demonstrated the public's appetite for exercising their grey matter. Kawashima's original book has been programmed on to the Nintendo DS, a hand-held games console. Two versions have sold more than 2.4 million copies.
The British version is expected in May. Nintendo, keen to reach the 'grey gaming' market, plans a £2m marketing campaign, including adverts in programmes such as Channel 4's Countdown.
David Yarnton, general manager of Nintendo UK, said: 'This is an opportunity, in a fun way, to challenge yourself to improve and stimulate the mind to be clearer and sharper.'
Mind training put to the test
Alan Atkinson, Caterer Truro, Cornwall
Real age: 46
Brain age: 72
Says: 'I'm disgusted with that score. I do crosswords during my breaks.'
Edwina Quansah, Photojournalist student, Brockley, south London
Real age: 22
Brain Age: 80
Says: 'It's not very good. I don't do as much mental exercise as I should.'
Arthur Blaney, retired barrister's clerk, Orpington, Kent
Real age: 65
Brain age: 45
Says: 'It makes me feel young - I've just lost a few years.'