Everyone — children, teenagers , adults and older people — is prone to negative thoughts and feelings of sadness. If these last consistently for two weeks or more, it is likely to be depression. Currently, 4.5 per cent of Indians suffer from depression, and 7.5 per cent from a deadly combination of depression and anxiety, which can result in suicide.

Depression may be triggered by an adverse life event. In lower and middle-income families, it may be debt or ill health. Usually, time is a great healer and most people gradually return to regular activities as the event fades from immediate memory. In some people, the negative feelings persist and cause insomnia or excess of sleep, loss of appetite or overeating, lack of energy and inability to cope or concentrate. There may be unexplained physical symptoms such as aches and pains. Sometimes, medication given for other diseases (such as high blood pressure) can trigger depression.

Depressed children may refuse food and become clingy. They may refuse to go to school. Teenagers may avoid social interaction, get hooked on to social media, have few friends and start using recreational drugs or alcohol.

In depressed people, the levels of neurotransmitters responsible for mood elevation are low. Women are more prone to depression than men because of their fluctuating levels of estradiol (female hormones) during reproductive years. Estradiol keeps the level of serotonin (mood-elevating chemical) high. Low levels of other hormones like thyroid and cortisol may also contribute to depression.

Brain scans using contrast material have shown that there some changes in the brains of depressed individuals. Areas like the hippocampus, thalamus, amygdala, frontal and prefrontal cortices either shrink or were smaller to begin with.

Many members of a family may be depressed. This may be genetic with inherited defects in brain anatomy and neurotransmitter levels or it may be environmental. It may also be a combination of both. A child brought up in a depressed house is more likely to be affected.

A complete evaluation, including blood tests for thyroid disorders (which can also run in families), vitamin deficiencies, chronic diseases and a psychiatric evaluation are needed before a diagnosis of depression can be made.

A variety of drugs are available to treat depression. The dosage and medication need to be individualised. Sometimes, anti-anxiety drugs are added. Medication slowly increases the neurotransmitter levels, so an adequate response may take a few weeks. Medicine works better when it is combined with psychotherapy so that the person can talk through their problems.

Many non-medical adjustments such as avoiding alcohol and recreational drugs, and eating balanced, nutritious meals can help fight depression. Aerobic exercises such as walking, running, swimming or cycling releases mood-elevating chemicals from the calf muscles. Exercise becomes even more effective if it is combined with yoga and meditation. People who have the habit of exercising regularly from childhood are less likely to fall into the throes of depression. They recover from adverse life events faster and have a more positive approach to life.

To prevent incapacitating depression, inculcate the habit of exercise in yourself and in your children from a young age. Once a child is set on the correct path, he is unlikely to deviate from it.

The writer is a paediatrician with a family practice at Vellore and author of Staying Healthy in Modern India.

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