But there's no point in parents blaming themselves: mental illness is caused by a combination of factors and it can strike anywhere.
When people feel buffeted by forces over which they have no control, he argues, we conclude it is they who need correcting, rather than the forces: "In the long history of scientifically analysing the relationship between subjective feelings and external circumstances, there is always a tendency to see the former as more changeable than the latter." Research by the mental-health charity Young Minds has found that exams are a significant trigger for mental illness in young people.
Under pressure to get the best possible results, schools are inclined to give teenagers the impression that they have only one shot at tests that will determine the rest of their lives (even though this is not true).
Yale professor Bill Deresiewicz has characterised the current generation of high-achieving students as "excellent sheep", haunted by a fear of failure yet clueless about where they're going.
They're probably worried that it's nowhere: the OECD's projections for the world economy between now and 2060 are for slowing world growth and near-stagnation in advanced economies.
The Oxford Martin School has predicted that 47 per cent of US jobs are susceptible to automation.
Sarah Brennan, chief executive of Young Minds, says her organisation is seeing children as young as 11 worrying about unemployment.Last month he personally announced new money and the introduction of waiting times for teenagers with eating disorders.The Duchess of Cambridge has also made young people's mental health one of her major interests.But even if you accept that there's more reporting than there was a decade or two ago, pretty much everyone agrees that something very disturbing is happening.Those who are worried include David Cameron, the first Prime Minister ever to have talked about teenage mental health.With celebrities (Stephen Fry, Ruby Wax, Alastair Campbell) increasingly talking openly about their own mental illnesses, there is much greater awareness than there used to be and correspondingly less stigma, making it easier for teenagers to acknowledge their problems.