Cognitive training, including puzzles, handicrafts and life skills, are known to reduce the risk and help slow down the progress of dementia among the elderly. But healthy, older adults can benefit from such mental activity too - improved reasoning, memory, language, and hand-eye co-ordination - according to a Shanghai-based study by Chinese researchers published in the journal BMC Medicine in March.
By 2050, it's estimated that the number of people over 65 years old will have increased to 1.1 billion worldwide, and that 37 million of them will suffer from dementia. So it's no wonder that in recent years, brain training has evolved into a multibillion-dollar industry.
But cognitive gymnastics needn't cost much. In fact, if you're looking for a daily challenge for the mind, the South China Morning Post has a new one - Shikaku. If the puzzle sounds uncannily like the ubiquitous logic-based game of numbers Sudoku, that's because it's by the same creator, Maki Kaji.
Launched yesterday in the City section, Shikaku - also known as 'rectangles' - involves dividing a grid-like board into small rectangular or square boxes. Each box must contain a number that indicates the area of the box (detailed instructions at promotions.scmp.com/shikaku). Beginners to this puzzle may start with a guess, but soon realise that the fun lies in searching for rectangles using logic.
Just like its more popular sibling, Shikaku uses only numbers, rather than letters, like a crossword. Anyone can solve and enjoy it. 'These puzzles speak the same language, because numbers are universal and can be understood by everyone no matter where they live,' says 61-year-old Kaji.
'My policy is that puzzles are entertainment. They should be relaxing rather than challenging or educational as such. Laughing and humour are important.'