Many children under the age of four are being treated for depression, according to a report. Linda Blair, a clinical psychologist at the University of Bath, writes that even the very young are likely to suffer from the pressures of modern life.

There is no doubt that children today face a whole array of new pressures.

Nowadays younger and younger children are expected to spend less time playing and more time in formal education.

From the earliest age they have targets to reach and are expected to keep up with the academic achievements of their peers.

Because relationships and families break down and people are more mobile, many children have little continuity in their lives.

Many are passed from one childminder to another, all of which can add to their anxieties.

More of children are unfit and overweight, choosing to spend time alone playing computer games, rather than going out into the fresh air with friends.

All these factors can trigger stress, anxiety and obsessive behaviour.

But, I find it astonishing to read that 150 Scottish children under the age of four have been treated for depression.

I am very concerned as to how the condition was diagnosed.

To be classified as depression the person must have been in a constant state of low mood for the previous two weeks.Children's moods fluctuate so frequently they are unlikely to suffer from full blown depression.

A diagnosis is also highly complicated because very young children do not always understand our questions - or understand them in a different way.

Often, a toddler will be more interested in getting the answer right and pleasing the interviewer, than actually saying what he or she thinks. They find it very hard to express how they feel in words.

I have never had to treat a case of full-blown depression in a child under the age of four, but I am prepared to consider that it could happen.

Research into mothers who suffered from depression found that their children can sometimes be slower to respond, which suggests that there are effects on children that young and that a certain environment can make a child depressed.

But actually finding out is very difficult and I would be loath to suggest giving any sort of antidepressant medication to a child with a growing body.

Rather than depression, I see more cases of anxiety in the children I treat.

Anxiety in children can manifest itself in nightmares, nervous ticks, excessive crying, hair pulling, not eating or overeating, bad sleeping patterns and resistance to any sort of change.

I saw one little girl of only nine recently who was pulling the hair out of her head. It was very distressing.

Many children find it hard to cope with the constant changes of modern life.

People are more mobile, so families and friends often move from place to place. Parents are more likely to split up and children are often looked after by a variety of frequently changing carers.

Family breakdown and moving home are major life changes and many find this lack of stability difficult to understand and deal with.

A constant network of friends and confidants is one very effective aid to avoiding depression.

Without a circle of playmates, children will find it hard to learn social interaction, which is another way of storing up problems for the future.

Research shows that people who lack the support of friends and family are more vulnerable to depression and other mental illness.

Unfortunately, many young people spend far too much time on their own - sitting in front of the television or computer screen for hours on end.

Children no longer spend their time in the fresh air, just playing games and riding bicycles.

Not only is this a way of interacting with others, the exercise would also be a way of releasing stress and anxiety.

Obesity is an increasing problem among children. In America a staggering one in four children is obese.

Exercise is one way to improve mood and people who are confident in their bodies are more likely to feel positive in their minds.

Active play can reduce stress by releasing endorphins, the feelgood hormones that improve mood, motivation and even tolerance to pain and other stimuli.

Play is the way in which children learn to explore their own imaginations.

They must be given the chance to express themselves freely or we are in danger of producing a generation of very unimaginative adults.

In Japan, where children begin formal education as young as three, I have read that the suicide rate among adolescents is higher than anywhere else in the world.

We must be wary about diagnosing depression in very young children but there is no doubt that children need more freedom to express themselves in a stable, loving and safe environment.

Linda Blair is a clinical psychologist at the University of Bath.