One of the oddities of the human race is that people living in wealthier nations are less happy and more depressed than those in poorer ones. In France, the Netherlands and America, more than 30 per cent of people have suffered a major depressive episode, compared with 12 per cent in China, according to research from the World Health Organisation.

Overall, one in seven people (15 per cent) in high-income countries is likely to get depression over their lifetime, compared with one in nine (11 per cent) in middle- and low-income countries.

But there are exceptions to the rule. India recorded the highest rate of major depression in the world, at 36 per cent. It is going through unprecedented social and economic change, which often brings depression in its wake. The global study, based on interviews with 89,000 people, shows that women are twice as likely to suffer depression as men.