Cutting-edge games keep brain razor-sharp

A man sits on a train solving a crossword puzzle, a woman broods over a Sudoku grid while an ad for an electronic memory game flashes across a television screen. There is no shortage of ways to improve the brain's memory powers - after all, lots of people want to improve their mental abilities.

But are Sudoku, crosswords and other training games any good at improving memory? Are they really effective in training the mind or just a nice way of passing the time?

"If you train your brain, you can improve your performance," says Carsten Brandenburg from Germany's Memory Training Association. But not every exercise can radically change a person's ability to remember things.