Feelings of sadness, often accompanied by loss of interest in life and reduced energy

  • More common from the late 30s onwards
  • More common in females
  • Sometimes runs in families
  • Social isolation is a risk factor

Sadness is an expected reaction to adversity or personal misfortune and may last for a considerable time. Depression exists when feelings of unhappiness intensify and daily life becomes difficult. Depression is one of the most common mental health disorders in the UK. It affects about 1 in 3 people at some time in life, most commonly from the late 30s onwards. Women are twice as likely to have depression as men. In some cases, the disorder lifts spontaneously after days or weeks, but other people may need professional help and support. In severe cases, hospital admission may be necessary to protect a person from neglect or self-harm.

Depression is often accompanied by symptoms of anxiety (see Anxiety disorders). For example, there may be a persistent sense of foreboding and repetitive, worrying thoughts. People with depression may also misuse alcohol or other drugs.

Reduced brain activity in depression

These images show large areas of low activity in the brain of a depressed person compared with small areas of low activity in the brain of a normal person.

What are the causes?

Depression may develop when a person has to face one or more stressful life events. The trigger is often some form of loss, such as the breakdown of a close relationship or a bereavement.

A traumatic experience in childhood, such as abuse or the death of a parent, may in-crease susceptibility to depression later on. A tendency towards the disorder may also run in families.

Several physical illnesses may cause depression. These include some infections, such as infectious mononucleosis; neurological disorders, such as Parkinson’s disease; and hormonal disorders, such as Cushing’s syndrome. Hormonal changes at the menopause or after childbirth may also trigger the disorder (see Depression after childbirth).

A number of mental health disorders may lead to depression. They include phobias, the eating disorder anorexia nervosa, alcohol dependence, and drug dependence. Some people feel generally low and become depressed only during the winter months, a condition known as seasonal affective disorder. Depression can also be a side effect of certain drugs, such as oral contraceptives and beta-blockers. However, often depression has no identifiable cause.

What are the symptoms?

A typical sign of depression is a feeling of sadness, even misery, that is worse in the morning and lasts for most of the day. Other common symptoms include:

  • Loss of interest in and enjoyment of work and leisure activities.

  • Diminished energy levels.

  • Poor concentration.

  • Reduced self-esteem.

  • Feelings of guilt.

  • Tearfulness.

  • Inability to make decisions.

  • Early waking and inability to resume sleep (see Insomnia) or an excessive need to sleep.

  • Loss of hope for the future.

  • Recurrent thoughts of death.

  • Weight loss or increase in weight.

  • Decreased sex drive.

In an elderly person, other symptoms may occur, including confusion, forgetfulness, and personality changes, that may be mistakenly attributed to dementia. Neglect of personal hygiene and diet in an elderly person may also be an indication of underlying depression. Sometimes, depressive illness manifests itself as a physical symptom, such as tiredness (see Somatization), or may cause associated physical problems, such as constipation or headache.

Severely depressed people may see or hear things that are not there. Irrational delusions may also occur. For instance, a depressed person may become convinced that his or her partner is having a sexual relationship with someone else.

Depression may also alternate with periods of euphoria in a person who has manic depression (see Bipolar affective disorder).

Are there complications?

Rarely, if the condition is not treated, a depressive stupor may develop, in which speech and movement are greatly reduced. Left untreated, depression can delay recovery from a physical illness and intensify pain whatever the cause, which then increases the depression. A person who is severely depressed may contemplate or attempt suicide (see Attempted suicide and suicide).

What might be done?

If your depression is mild, your symptoms may disappear spontaneously if you are given sympathy and support from those close to you.

However, if you do need help for depression, it can almost always be treated effectively, and you should not put off seeing your doctor if you continue to feel low. He or she may examine you and arrange for blood tests to make sure that your low energy levels and mood are not caused by a physical illness. You may be asked to have a psychological assessment in case there are other mental health problems that may be causing or contributing to your depression.

If depression is diagnosed, you may be treated with drugs, a psychological therapy such as cognitive–behavioural therapy, or therapy and drugs. Rarely, severe cases are treated with electroconvulsive therapy.

Drug treatments

The doctor usually prescribes a course of antidepressant drugs. There are several different types, and your doctor will choose the one most suitable for your needs. Although some have undesirable side effects, other side effects may be useful. For example, an antidepressant drug that is mildly sedating may relieve a sleeping problem. Your mood usually improves after you have been taking an antidepressant for 2–4 weeks, although some symptoms may improve more quickly. If your depression shows little improvement after a month or if you have troublesome side effects from your treatment, your doctor may adjust the dosage or prescribe an alternative drug. Once your depression has lifted, you should continue taking antidepressants for as long as your doctor suggests. Treatment usually lasts for at least 6 months, but the length of time depends on the severity of the depressive symptoms and whether you have ever had any previous episodes of depression. Depression may recur if antidepressant drugs are stopped too soon.

Psychological treatments

Support from your doctor or other health professionals is essential while you are depressed. Your doctor may refer you to a therapist for treatments such as cognitive–behavioural therapy to help you to change negative patterns of thinking or psychoanalytic-based psychotherapy to look into the reasons for your depression. Counselling, either on an individual basis or as part of a group, may help you to identify your feelings and make sense of them.

Electroconvulsive therapy

In rare cases, treatment with electroconvulsive therapy (ECT) is given for severe depression. In this procedure, which is carried out under general anaesthesia, an electrical stimulus that causes a brief seizure in the brain is given by placing two electrodes on the head. Between 6 and 12 treatments may be given over a period of about 1 month. ECT is particularly useful for treating depression that is accompanied by delusions. After treatment, antidepressants are given for at least a few months to prevent relapse.

What is the prognosis?

Antidepressants are effective in treating about 3 in 4 people with depression. When drug treatments and psychological therapy are used in combination, the symptoms of depression can often be relieved completely in 2–3 months. Of the small number of people who are treated with ECT, about 9 in 10 make a successful recovery. However, for some people, depression can last for years or recur with no obvious trigger.

Self-help: Recovering from Depression

From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.

The subjects, conditions and treatments covered in this encyclopaedia are for information only and may not be covered by your insurance product should you make a claim.

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