While everyone now accepts that children do get depressed, genuinely clinically depressed and not simply sad, the condition is still hard to recognise and to treat. Children do not show their depression as openly as do adults, so by the time it is noticeable it is also severe. It may well be the nice child, who sits in the back row giving no trouble, who is depressed.

Cytryn and McKnew have a long track record in treating childhood depression and indeed the first version of the book appeared, under a different title, in 1983. They write in the brisk and efficient tone characteristic of doctors, but they could not deal with such a topic without having compassion, though they do not parade it.

They consider that there are three main types of depression in children: acute, chronic and masked. The first two have similar features, including impairment of social and academic functioning, disturbances of sleep and appetite, despair, slowing of movement, and occasionally suicidal thoughts.The differences lie in the precipitating causes, with the chronic type having a less definite onset and a longer history, often coupled with depression in other members of the family.

The masked type is more controversial: with it, severe depression may be obscured by aggressive behaviour or physical symptoms. I used to see this when I worked in a psychiatric hospital. The first stage of the therapeutic effort used to be summed up as “trying to turn bad boys into sad boys” as they came to terms with what caused their behaviour.

A particular difference between child and adult depression is that there is often a disparity between the child’s account and that of others, and that the child is the most reliable informant. Psychological testing is not of much assistance. However, children will often open up to sensitive questioning, and there are tests, such as the Rorschach inkblot tests, which tap into a child’s unconscious and allow the expression of buried worries.

There is a useful section on danger signs. The most important are dysphoria or low mood, in which the child is sad, worried or irritable, and anhedonia or inability to take pleasure. Others include loss of energy or appetite, sleep problems, self reproach, poor concentration and thoughts of death or suicide. It may be worth just waiting at first. Much depression will clear up of itself, with smaller matters resolving within a week or two, and severe ones, such as losses of loved ones, showing some remission after six months. If it persists, some gentle questioning may be indicated, together with some specialist help.

The authors are particularly concerned about severe and lasting depressions, where more active treatment is required. Such treatment may be both psychotherapeutic and also psychopharmacological (using both talking and drug therapies), and the authors argue that they are most effective when used together. Yet the most effective treatment may be the sustained attention and personal concern of a parent.

Those most at risk are those who have a parent with a similar problem. It may be passed on by a combination of genetic and environmental factors; however, some children show a surprising resistance to them, and many affected parents have long stable periods so that, with treatment, they can care satisfactorily for their children. Hyperactive, delinquent and abused children are also at risk, and in general, depression is far more common among the poor than the rich.

For some children, particularly those where there is a family history of depression and sometimes an inability of a parent to show love, their situation is genuinely hopeless as it stands. The authors found that such children improved dramatically when brought into hospital, in a way contrary to that of most children. For this group they argue for intervention, using the courts and foster parents to provide a better environment for the child.

In conclusion, the authors argue for early intervention. It certainly is not helpful to leave that sad child at the back of the class in the hope that things will clear up.

Stephen Barber is a social worker.