Shedding light on darkness visible

Several years ago, Lewis Wolpert, the distinguished embryologist and fellow of the Royal Society, suffered a severe clinical depression. To this confident and successful individual it was a shattering ordeal. "It was the worst experience of my life. More terrible even than watching my wife die of cancer. I am ashamed to admit that my depression felt worse than her death but it is true."

Like William Styron in Darkness Visible , Wolpert wrestles with the difficulty of describing something unimaginable to those who have not suffered it. Malignant Sadness , however, is a pretty good attempt. "I was totally self-involved, negative and thought about suicide most of the time. I could not think properly, let alone work, and wanted to remain curled up in bed all day. I had panic attacks if left alone. Sleep was impossible without sleeping pills: these only worked for a few hours and when I woke up I felt worse. The future was hopeless. I was convinced that I would never work again or recover."

Fortunately, like most sufferers who receive love and support from their families and help from skilled professionals, Wolpert did make a complete recovery. He was disconcerted to discover the lack of solid scientific understanding of what to him is self-evidently a severe illness. The result is this book, which aims to describe what is known about the nature, causes and treatment of the disabling condition.

Wolpert's book is objective, wide-ranging and infused with scientific insight. He notes that depression is common; at least one in ten of us will experience a clinical illness, and although recovery is the rule, recurrence is common. Depression can be lethal; of the 5,000 suicides annually in the United Kingdom, more than half are due to clinical depression, often unrecognised and untreated.

Why do we experience depression? Some regard the illness as having a useful evolutionary function, for example by enabling individuals to adjust to loss in social rank without conflict. Wolpert finds this unconvincing, favouring Freud's proposal that clinical depression is most akin emotionally to the grief that follows bereavement. In developing this theme Wolpert suggests that depression is "malignant sadness", a pathological expression of a normal emotion. The analogy is with cancer, in which normal cell growth and differentiation take on pathological and destructive forms. Sadness is of great evolutionary importance because it is activated by separation and loss and is therefore an incentive to successful attachment, the basis of relationships. Wolpert believes clinical depression arises when the cognitive and biological mechanisms involved in sadness take on pathological form.

This is an intriguing idea, although a good understanding of the cognitive neurobiology of emotion is probably some way off. Fortunately, in medicine, discovery of effective treatment does not always have to wait for elucidation of illness pathophysiology. This is the case with depression, where both antidepressant medication and specific psychotherapies are of indisputable, although not universal, benefit. In Wolpert's case he was too ill at first to make use of cognitive therapy, which uses rational argument to change negative thinking patterns. "I could just recognise how negative I was but it seemed perfectly rational in the condition I was in," he says. Eventually the antidepressant paroxetine produced useful improvement after which cognitive therapy enabled Wolpert to come to terms with his experience and gave him the confidence to pick up his life again.

This is a remarkable book by a remarkable man. It provides a clear and unbiased account of what is known of the disorder and what works in treatment. Inevitably, the most compelling aspect is the way in which Wolpert uses his own experiences and those of others to give a voice to what Styron called depression's "inexplicable agony".

Philip Cowen is professor of psycho-pharmacology, University of Oxford.