The symptoms of depression, such as occasionally feeling sad and tearful, are common in young people and are temporary. Depressive illness is different in scale, with the mood disturbance occurring most of the time, during most days and over several weeks. It is often accompanied by other symptoms such as:

• losing interest and motivation to do things that used to be enjoyable.
• withdrawing socially and not wanting to see people.
• difficulty concentrating on schoolwork, leading to falling grades.
• tiredness, aches and pains.
• changes in sleeping pattern (difficulty sleeping or sleeping more than usual).
• changes in appetite and weight (feeling more hungry or less hungry).
• feeling useless, worthless and unloved.
• black, pessimistic thoughts about the future.
• thoughts of death and acts of self-harm.

These symptoms can cause distress, or difficulty coping with schoolwork, or affect relationships with friends and family. Other people usually notice the young person is not their usual self, although parents are not always aware of how unwell their child is - often adolescents will open up to friends first.

After the age of about eight years, the symptom patterns of depression are similar to those of adults and include many or most of the symptoms described above. However, children and adolescents may seem irritable rather than sad, which can be confusing, particularly if the young person withdraws and shuts themselves away.

Depressive symptoms can also occur as part of other psychiatric disorders, or in physical illness. Depressed children and adolescents often have other psychiatric problems as well, such as behavior problems or anxiety, which may mask the underlying depression. The young person will need help for these problems in their own right even after the doctor has diagnosed depression. If a parent is also depressed, it is vital that they get the appropriate help and if there are conflicts and rows in the family, then family therapy or counseling may be helpful.

Depressed children and adolescents can be withdrawn, irritable or uncooperative, and often have difficulty identifying and expressing their feelings.

Some youngsters, particularly boys, deny feeling sad; the only observable complaint will be of irritability, moodiness and boredom. As a result, they may get in fights or other trouble at school, interact less socially and lose friends. They may also 'act out' suicidal feelings, eg by cutting themselves, which can be misinterpreted by parents and teachers as manipulative rather than as a communication of distress. All these things can worsen a depressed state.

How common is childhood depression?

• Depressive illness, or what doctors call major depressive disorder, occurs in 2 to 4 per cent of children, although is rare under the age of eight.
• It becomes more common after puberty, rising to 4 to 8 per cent of adolescents.
• In adolescents, depression is more common in girls.
• The number of children and adolescents being diagnosed with a depressive illness is increasing. This may be because of advances in mental health with the symptoms being recognised earlier, or it could be the illness is actually occurring earlier compared to the previous generation.

Who gets depressed and why?

The tendency to develop depressive illness involves a complex mixture of factors, such as inherited (genetic) factors and life experiences.

Children and adolescents who get depressed have often had adverse experiences. There is some evidence that an early negative experience, eg losing a parent or being abused as a child, raises the risk of depression later on. Recent life events often precipitate an episode of depression. Friendship difficulties and disappointments are common triggers for depression in children and adolescents.

Having a family history of depression can also put individuals more at risk, because there is some genetic contribution to depression.

Although there is no evidence that family difficulties actually cause depression, when there is a lot of family conflict, this can interfere with a person's recovery.

From puberty onwards, depression is more common in girls. This sex difference is probably due to a variety of reasons, such as biological (eg hormonal changes), psychological and social factors.

How long will it last?

Most episodes of depression in children and adolescents last less than nine months. After one year, 70 to 80 per cent of children will have recovered, but 1 in 10 remains persistently depressed. Around half of young people will relapse within two months of getting better.

Clinical depression recurs in 70 per cent of children and adolescents after five years. Around a third of children and adolescents who have depressive illnesses will have recurrent episodes, even into adulthood. Recurrence of depression is more likely the earlier in life it starts, the more times it recurs and the more severe it is.

Up to 30 per cent of children and adolescents who have a depressive illness will go on to have bipolar affective disorder link, though it may take 5 to 10 years before this becomes clear.

There may be several different kinds of depression in early life, only some of which are strongly linked to depressive illness in adulthood.

Adolescents with depression are just as likely to develop recurrent depression as an adult who is depressed - but 10 to 20 years earlier in their life. Worse still, depressive episodes may get longer and more severe with recurrences. This can cause huge disruption to young people's social lives and schooling, and there is a risk of suicide. It is vital that adolescents with depression get properly treated and are helped to get well and stay well.

What should you do if a child or adolescent in the family is depressed?

If a parent is concerned that their child or adolescent might have a depressive illness, they should consult their GP and ask to be referred to local child and adolescent mental health services, as these are the main source of treatment.

School counselors can also advise a young person who thinks they might be depressed on how to get help.

The most important thing for a young person to do is to tell someone how low they are feeling, preferably a professional such as a GP or school counselor.

How is it diagnosed?

There is no blood test or other diagnostic test for depression. The diagnosis is established when a trained professional (usually a child psychiatrist or clinical psychologist) interviews the young person and talks to their parents. It is not uncommon for parents to be unaware of how depressed their child has been.

How is depression treated?

Child and adolescent psychiatrists most commonly diagnose and treat depression in young people under the age of 18. Education, individual talking treatments (psychotherapy), family sessions and drug treatments are all used, depending on how severe the symptoms are and the age and development of the child.

Other psychiatric disorders in the child or in the family will need to be managed as well. Because depressed children often have multiple problems, several modes of treatment may be needed .

Psychotherapy

The first choice for mild to moderate depression (where there are only a few symptoms) is talking treatments from a psychiatrist, psychologist or counsellor who sees the young person on their own.

Educating the young person and their family about the illness is also an important part of treatment. The child psychiatrist or therapist can help to educate parents and teachers about depressive illness, so that they will be better equipped to manage and help the young person.

The strongest evidence is for cognitive behavioral therapy, but other types of therapy and counseling may be helpful too. If the depression is really severe (with bad sleep disturbance, weight loss or persistent suicidal ideas), treatment with antidepressants may be helpful.

Cognitive behavioral therapy

Cognitive behavioral therapy (CBT) is the best studied of the psychological treatments for child and adolescent depression. CBT aims to address the negative thinking that may maintain depression.

CBT for children and adolescents is usually given in courses of 8 to 12 individual weekly sessions each lasting 50 minutes, including a final 10 minutes with parents. CBT may also be given in groups.

Antidepressant medication

Treatment with antidepressants is recommended for severe depressive illness or where depression fails to respond to an adequate trial of talking treatment. It should never be the only type of treatment.

Serotonin re-uptake inhibitors (SSRIs) like fluoxetine (Prozac), paroxetine (Seroxat) and sertraline (Lustral) are the first choice to treat childhood and adolescent depression, because they are safer in overdose and have less troublesome side effects.

Antidepressants don't start to work for two weeks, and this is when any side effects are at their greatest, so it is important to persevere. If the first antidepressant that is tried doesn't suit the young person, a different one is worth trying.

All antidepressants should be started gradually, taken for at least a six-month course and withdrawn very slowly over six weeks.

What can be done to prevent depression recurring?

Because of the high risk of relapse within the first few months of recovery from a depressive illness, it is a good idea to keep in contact with treatment services for a few months after feeling better.

Adolescents who have had two or three episodes of depression should stay on some treatment for at least one year after feeling better.

It is important to be aware of the early signs of relapse, so that help can be given early (sleeping problems for a few days can be an early warning sign). If you think depression might be recurring let a doctor or therapist know immediately.