Writing in The Oldie, Dalrymple considers whether crosswords, artistic pursuits, and other forms of mental activity can stave off dementia. He examines a French study of over three thousand elderly people suggesting that those who engaged in moderate or high levels of intellectual activity had half the rate of dementia, but cautions against confusing correlation with causation.
I should not like anyone to take from what I have written the idea that mental activity is pointless or worthless. Far from it: but it should be undertaken for its own sake, for the satisfaction and pleasure that it brings, and not as a kind of preventive medicine.