Posh Spice, who claims she has never read a book, is about to find out (if she can be bothered to read this).

We all learn to read but what happens in adult life when we fail to keep this up? Does the brain shrink like a withered prune? Studies in America found that continued intellectual activity from age 20 to 60 may protect against dementia in later life. One study found that continuing intellectual pursuits reduced the risk of Alzheimer's disease by a third. In another study, relatively inactive patients were 250% more likely to develop Alzheimer's.

Damaged brains can adapt and learn. Researchers who have used brain scanners have found that other parts of the brain can compensate. But exercising the brain, in much the same way one would exercise a damaged muscle, perhaps by repeating a list of items, does not help regrowth.

Are you going to benefit more by reading Shakespeare than Vogue? It probably doesn't matter as long as the brain is exposed to new information that stimulates your cells. Luckily for Posh (author, as is her husband, of an autobiography) physical activity also counts. Whether physical exercise is as beneficial as intellectual activity remains unknown.