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This factsheet is available as a pdf.



Depression is a long lasting low mood that interferes with the ability to function, feel pleasure, or take an interest in things, and not something people can “snap out of”. Depression can be mild, moderate or severe. In its severe form, major (clinical) depression is a mental illness which can be life threatening due to the risk of subjects committing suicide or neglecting to eat and drink.

Some cases fit well-recognised patterns, such as post-natal depression and seasonal affective disorder, and depression can occur within distinct mental health conditions like bipolar disorder.

Who does it affect?

Around 1 in 10 people* in the UK experience some form of depression in their life, and more women are diagnosed with depression than men. Many people will experience only one or two depressive episodes, but about 1 in 5 people do not benefit from any antidepressant strategies and so their condition becomes chronic.

Different factors are thought to contribute towards depression, such as genetics, brain chemistry, lifestyle and upbringing. Key triggers include stressful life events, medical illness and alcohol abuse.


Symptoms include persistent sadness, constantly feeling tired, lack of sleep, poor appetite, low sex drive, and aches and pains. People with depression may also lack motivation and have low self-esteem. Those with major depression can have suicidal thoughts, self-harm and be at risk of suicide.

How is it recognised?

There are currently no physical tests for depression but a GP may use urine or blood tests to rule out other conditions with similar symptoms (e.g. having an underactive thyroid). The main way depression is diagnosed is through questions about a person’s general health and how their feelings affect them mentally and physically. Various scientifically validated scales exist for measuring depression.


Treatments for more severe depression include antidepressant medication and talking therapies, such as cognitive behavioural therapy (CBT), while treatment for milder cases include exercise therapy and self-help groups. Electroconvulsive therapy (ECT), though rarely used and often misunderstood, is the most effective treatment for the severest forms of depression and can be life-saving.


Further reading

*2000 figure for UK. New Zealand’s ’Dunedin’ cohort study of 1037 people from 2005- puts this figure at 1 in 6.

This is a fact sheet issued by the Science Media Centre to provide background information on science topics relevant to breaking news stories. This is not intended as the ‘last word’ on a subject, but rather a summary of the basics and a pointer towards sources of more detailed information. These can be read as supplements to our roundups and/or briefings.

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