Stop the presses: David Blunkett has discovered why four times as many people now claim incapacity benefit than 25 years ago. Apparently, they are stressed and depressed. What is more, he has found a cure. At a seminar in Westminster on Monday, Blunkett declared that down-in-the-mouth benefit claimants should get off their sofas, tear themselves away from daytime TV and get back to work. Could there be a more damning indicator of how far attitudes to mental health in this country have not come?

While a broken leg is considered a bona fide reason for time off, a bout of depression is seen as a euphemism for swinging the lead. The "village idiots" of the middle ages have been rebranded for the 21st century as "malingerers" - mental weaklings who would rather vegetate at home than do a day's work.

The half-dozen patients a week who come to my surgery with depression or stress are keenly aware of this stigma. Like the teenager who pops into the chemist for condoms and comes out with a tube of toothpaste, they will beat around the bush and discuss any little physical symptom rather than what is really on their minds. And when they finally pluck up the courage and get to the point of their visit, they will invariably preface the discussion with the words, "I feel such a fool for not pulling myself together, doctor."

Of course, contrary to what Blunkett might think, it is often not that simple. Sure, the sick-day epidemic is a real problem: an editorial in the British Medical Journal in April reported that a million people call in sick each week, costing the government £13bn in benefit payouts annually, with psychological disorders accounting for more of this sum than the classic "bad back". But blaming This Morning and its ilk is a gross oversimplification of the underlying causes of such disorders.

Depression, of course, is nothing new. It crops up in the Bible and in texts from the ancient Greeks, and in 1621 clergyman Robert Burton published his influential book, Anatomy of Melancholy. But doctors have been pretty poor at spotting it, and effective treatments such as antidepressants and cognitive behavioural therapy became available only in the 1960s. As recently as 1992, doctors were deemed so poor at diagnosing depression that the Royal College of Psychiatrists launched its "Defeat Depression" campaign to try to educate GPs to better recognise and manage the condition.

A lot has changed since then, with a doubling in the annual number of antidepressant prescriptions issued between 1991 and 2000 and an increase in our understanding of the causes of the condition (such as divorce, alcoholism, bereavement, loneliness, work stress and our genes.)

So what are the symptoms to look out for? There are numerous telltale signs, but most people experience five or six of the following: loss of interest in life, difficulty making decisions, tiredness, loss of appetite, insomnia, poor sex drive, lack of concentration and, at the severe end of the scale, suicidal ideas or plans.

It is easy to see how someone with a combination of these symptoms would be significantly disabled and find it hard to function at work. Imagine the havoc that could be caused by an air-traffic controller with poor concentration, or a suicidal bus driver. Are they better off at work or at home in front of the telly while their treatments take the average month or so to kick in?

Admittedly, those who are down because of loneliness or bereavement may well get better with something to take their minds off things, and we must be wary of over-medicalising unhappiness. But, as ever in medicine, we are treating individuals and it is impossible to group everyone together in an amorphous blob we call "the depressed". One person's depression will be very different from another's and so will their cure - there is no such thing as an off-the-peg treatment.

So while returning to work may help some patients, others may be crippled by this approach, or even pose a danger to others. And they would certainly be better rather than worse off with a sick note and a copy of the Radio Times.

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