After the death of his father, John O'Donoghue stayed off school to look after his mother. He was 14 years old. He was as incapable of looking after his mother as she was of looking after him. She took to wandering the roads and was soon taken into hospital. The social worker asked him if he wanted to be fostered and he said yes. Two years later, he was admitted to a psychiatric hospital.

"That was the beginning of it all: medication, ECT, the locked ward," he said. "I've been sectioned five times, in and out of asylums, homeless hostels, squats and on the streets. I nearly hit the end of the road."

This week, at the Edinburgh International Book Festival, he spoke movingly of his travails. His searing account of his experiences of electroconvulsive therapy - in one instance, lapsing into such a catatonic state before the electrodes were attached that he was given the last rites - was heard in the Bookfest tent in a silence broken only by the flapping of the canvas. It was all the more powerful because of his unflamboyant, matter-of-fact delivery. What was remarkable was his lack of self-pity, and his sense of humour.

O'Donoghue's book, Sectioned: A Life Interrupted, should be required reading for mental health professionals. It isn't an attack on the mental health services, and it's not just another misery memoir. But as an articulate account of one young man's experience of mental illness and the shadow worlds he inhabited, it is as thought-provoking as it is compelling. O'Donoghue's unsentimental honesty about his descent into institutional and personal chaos in London in the 1980s avoids the melodramatic, while holding unflinchingly to what is harrowing. As a young man adrift in a world he could not cope with, he moved through institutions, squats, prison and time with the Hare Krishnas.

This is no rant, and O'Donoghue refuses to play the part of victim. He also praises some of the people who gave him wise help along his tortuous road. Yet he shines a light into some dark places, where far too many young people who have been devastated by fractured family relationships and crippling self-hatred lurk and flit and damage themselves more than others. Far too many mentally unstable young people, addicted to drugs which deaden the pain of their lives, end up in prisons which are ill equipped to mend the brokenness of the shipwrecked young.

We are witnessing an epidemic of depression amongst children, who grow up in a society which is rich in consumer goods but not in caring time, and in an over-sexualised body-beautiful culture which provides an odd, pressurising version of "normal". Where does sickness begin and end? Why are the struggles of the depressed young not at the heart of our national agenda?

There are people doing good work on this; but as a consequence of the inevitable global debt-fuelled downturn, there will be big cuts in public services. While the retired financiers sit in their personal counting houses, resources for the mentally fragile young will be squeezed. Sorry pal, this is the "real" world, one which is largely created by those who have the power to call the shots.

So how did O'Donoghue break free? Two things helped. He acknowledges a happy childhood up till the age of 14, when everything fell apart. These years afforded him some latent emotional resources. The second thing was literature. He had the opportunity to complete a degree in English and American literature, and now lectures in creative writing at the University of Hertfordshire. He is married, with four children.

O'Donoghue is wary of presenting himself as "cured". The bi-polar stranger he talks about is never entirely distant. But he does say resolutely that "diagnosis is not destiny".

His gifts and earliest family experiences have helped him. But what of those who lack similar resources? What of the depressed children and the desperate young people whose toehold on the ledge of sanity is none too robust? Who carries the banner for them? And who is asking radical questions about what it might mean to live a properly human life today?