By Erica Wagner

A new book that attempts to bring depression out of the shadows is a compelling and welcome read, says Times literary editor Erica Wagner, a former victim of the disease

It was known simply as "the glass delusion". Sufferers - and there were many in the late 16th century - believed themselves to be made of glass and highly breakable. One insisted he could travel only when packed into a box of straw; several others, Dutchmen, were convinced that their buttocks were glass and therefore could not sit down. Cervantes wrote a novella, The Glass Licentiate, on the subject. Two centuries earlier Charles VI of France was an early victim; he had iron ribs sewn into his clothing to protect himself in case of a fall.

It's funny, isn't it? Yet these "Melancholy provations", as Robert Burton called them - in the Anatomy of Melancholy, first published in 1621 - caused further torment in the sufferer, so that "like a lame dogge or broken-winged goose hee droopes and pines away, and is brought at last to that malady of melancholy it selfe".

And so did Andrew Solomon droop and pine so that, at the height of what Burton called melancholy but which we now know as depression, he was afraid of taking a shower, of leaving his bed. As he writes in his fascinating and warm-hearted book, The Noonday Demon: An Anatomy of Depression: "I remember bursting into tears because I had used up the cake of soap that was in the shower...The reality that I had to put on not just one but two socks and then two shoes so overwhelmed me that I wanted to go back to bed. Paranoia began to set in as well: I started to fear, every time my dog left the room, that it was because he wasn't interested in me."

Yet even at the worst of his distress Solomon knew that there was something that seemed not quite serious about his disease, that allied him with the glassbottomed Dutchmen. I'm sorry, he'd tell his friends when they asked him to dinner, I can't come; I'm afraid of lamb chops again. Yet depression is a disease in the word's most literal sense: disease. In a recent World Health Organisation report, Global Burden of Disease, depression was ranked the fourth most important health problem for the developing world in 1990; it is predicted to be the number one health problem in the developing world in 2020.

In the US, suicide is the third leading cause of death in young people and the second for college students: a survey conducted in 1995 by the Centres for Disease Control and Prevention found that one in ten college students had seriously considered suicide in the year prior to the survey. This is a shocking statistic: imagine reading that one in ten college students was suffering from cancer. But depression can kill you as surely as cancer can. Each year in the UK more than 5,000 people take their lives: the Samaritans estimate that in Britain there is a suicide every 82 minutes. The charity Depression Alliance believes that each year there are about 19,000 suicide attempts by adolescents in Britain alone.

Solomon's book is the latest example of a welcome trend: the attempt to bring depression, and its sufferers, out of the shadows. It follows on the heels of such excellent books as Lewis Wolpert's Malignant Sadness and Kay Redfield Jamison's Night Falls Fast: Understanding Suicide. Like Wolpert and Jamison, Solomon chose to write about depression after his own experience with the illness; unlike them, he is a novelist, not a scientist, and in part it is his novelist's passion and imagination that makes this book so fascinating.

There are two problems in discussing depression. The first is the subjectivity of the experience; X-rays will reveal a lung shadowed by tuberculosis, and an MRI scan will show a brain tumour; but as yet brain imaging has offered little insight into the workings of depression. The second problem is that once this condition is diagnosed, there is an infinite number of treatments - and no one knows how, or why, any of them work.

Electro-convulsive therapy (ECT) can be extremely effective for those at a very low ebb: exactly why is a mystery. Selective serotonin reuptake inhibitors (SSRIs), such as Prozac, do what they say - stop the reuptake of the neurotransmitter serotonin in the brain - but precisely how serotonin affects mood, and how it interacts with other neurotransmitters such as dopamine and norepinephrine, is still not known. As Solomon points out, one of the most important factors in the effectiveness of a treatment is the patient's belief in the treatment. If you think cognitive therapy will work for you, you could be right. If you think jumping up and down naked in rainstorms will help, it well might.

Solomon's depression appears to have been both exogenous - precipitated by the suicide of his mother when she was suffering from terminal cancer - and endogenous, recurring at intervals, for no apparent reason, after he believed he had learnt to live with his grief.

Unlike many who suffer from depression, Solomon had both the support of his family (the book is movingly dedicated to his father, "who gave me life not once, but twice") and the financial resources to afford continuing psychotherapy and psychopharmacological care: he has no doubts that without these support systems he might not have survived. One of the book's great strengths is his recognition of his good luck in these matters, and the way he addresses the situations of those who are not so fortunate.

The book is sensibly divided with simple chapter headings: Treatments, Populations, Addiction, Suicide, and so on. His personal story, told with openness, modesty - and fine restrained emotion where his mother's death is concerned - is woven in throughout.

His factual research has been zealous, as his bibliography attests; but more remarkable are the interviews he conducted with people from all walks of life, all over the world. He went to Greenland and met Inuits, whose life in long months of darkness and in close confinement has meant that depression has been both endemic and, until recently, taboo.

He travelled to Senegal to take part in the ndeup ceremonies for mental illness performed by the Lebou people: he was tied to a live ram, which was later slaughtered as he stood over it; its blood was rubbed into every inch of his body; he was made to address the spirits that had afflicted him. He was, he writes, more impressed by the ndeup ritual than by many forms of group therapy he had seen practised in the US; as he notes, "it was a ritual, and the effect of any ritual - being covered in the mixed blood of a ram and a cockerel or telling a professional what your mother did when you were small - is not to be underestimated".

He spoke, too, to the disadvantaged, whose chances of access to the therapeutic ritual are almost nil; people whose stories were so awful that the editor of a wide-circulation news magazine dismissed them as ludicrous. That Solomon is able to give such people a voice is admirable; that he - from a more than privileged background - was able to forge such evidently lasting connections with many of them is evidence of the power of the illness: a power not simply of despair, but also of connection and hope.

Hope is the title of his final chapter; a bold and generous choice. But he is right. On the night of my 31st birthday, I told the friends I had invited to a party in a local bar that I was ill, that I had the flu and that I was sorry, but I couldn't come. So they had the party, and I was ill, but did not have the flu. I lay on my kitchen floor and cried, and when two friends showed up to see how I was, I was nearly speechless with horror.

At the time I had a job and I was writing a book, and those things I managed to keep doing despite the grey horror that had enveloped my life - a horror that was no stranger to me, though this time it was worse than it had been before. Work and writing gave me some sense of myself, some reason for being: everything else, though, seemed to fall away.

I did not want to take medication. Why? When I was younger I had suffered from mild epilepsy; yet I had never considered the pills I took to control seizures a sign of weakness. Yet my husband had to work hard to persuade me to see a doctor - a medical doctor who could give me pills, rather than just talk to me. But I'd done a lot of talking and was finally persuaded that if I'd spent 15 years thinking about something and still hadn't figured it out, maybe I needed some other kind of help.

SSRIs are not immediately effective. But three weeks after I swallowed the first pill the grey horror blew away like mist. To me, it was nothing short of miraculous: one morning it was gone. By weird coincidence, that night my husband was attacked on a bus coming home from a party and was lucky to escape with a black eye - my distress at this was somehow mitigated by amazement at my own ability to look after him, to abandon my role as the family patient. I came off medication after six months; I continued therapy for a while longer - as Solomon notes, a balance between the two is often the most effective course of treatment. There were underlying causes of my depression that seemed to have less to do with brain chemistry than circumstance; but without altering the chemistry I had been unable to face the circumstance. You can't see out of the window if you can't pull up the blind. I am fine, now. Of course, I wonder what lies in the future, but I feel stronger because of what I have come to understand and by knowing there is help, that the abyss is not all there is.

Solomon's experience was far more crippling than my own, and his spirit was not broken by it. Quite the opposite. Of his blackest emotions he writes: "I hate those feelings, but I know that they have driven me to look deeper at life, to find and cling to reasons for living. I cannot find it in me to regret entirely the course my life has taken. Every day, I choose, sometimes gamely and sometimes against the moment's reason, to be alive. Is that not a rare joy?"

It is indeed. Andrew Solomon's book is compelling, wide-ranging, open-minded, useful. It is also testimony of the mind's power to overcome the most formidable obstacles, whatever they may be: and that offers hope to us all.