Depression is the most common mental illness, affecting one in four people at some time in their lives.
It makes a person feel desperate and affects everything they do.
Anyone may suffer depression, but it's severest during middle and old age. Women are twice as likely to become depressed, but men are three times more likely to commit suicide.
Most people recover completely. Counselling and anti-depressant drugs can help.
Symptoms of depression are deep despair, sadness, tearfulness, anxiety, lack of energy, poor concentration, loss of appetite and not sleeping well.
Depressed people also lose interest in social interactions and have a lack of motivation, feelings of guilt and suicidal thoughts.
The depth of these feelings makes depression very different from simply feeling low.
Difficult circumstances increase the risk of depression.
Social reasons include unemployment, bereavement, broken relationships, isolation or long illness.
Psychological reasons include being unloved or abused in childhood, setting unreasonable standards for oneself or others, or chronic anxiety.
Depression can be caused by poor nutrition, disease, or can occur after giving birth. Sometimes it runs in families.
Recent research suggests that a low level of a brain chemical called serotonin might be partly responsible.
Anti-depressant drugs are often prescribed for depression. The most commonly used raise the level of a brain chemical called serotonin. These include Prozac™ and Seroxat™. Whilst many people find these extremely effective as a treatment, there is growing concern about the nature of their side effects, and the long-term effects of taking these drugs.
Cognitive–behavioural therapy can be very effective, as can other forms of talking therapy. There are also current trials underway in Bristol to look at the effects of specific exercise programmes as compared to drug treatment.
In 2005, scientists in Canada reported that deep brain stimulation was effective in treating a small number of patients with severe depression. In this trial, four out of the six patients experienced a "striking and sustained" let-up in their depression.
These patients had not responded to other treatments such as anti-depressants, psychotherapy and electroconvulsive therapy.
Deep brain stimulation is also a promising treatment for Parkinson’s disease and involves surgically implanting electrodes into a specific area of the brain linked with depression.
For advice and information, go to the MIND (National Association for Mental Health) website.