Why your brain wants to be challenged

All this week, two eminent neurologists specialising in Alzheimer's are sharing cutting-edge research with Mail readers and revealing how lifestyle tweaks can help fend off the disease. Today, they show how challenging your mind and increasing your social life can help protect your brain against decay . . . You might be fan of a fiendishly complex crossword puzzle or a demon at sudoku, but even if you regularly rattle off the answers when watching University Challenge on TV or flick through the financial pages of the weekend papers, are you properly exercising your brain? Our work as specialists in Alzheimer's has taught us that simple puzzles are not enough. One fundamental factor in the fight to protect yourself against dementia -- and to slow its march if it has already started -- is the quest to build what neuroscientists call'cognitive reserve'. A healthy brain thrives on challenge, especially challenges that are personally relevant and involve many different parts of the brain at the same time. That's because our brains are designed for complexity and they are sustained by it in old age.