Depression explained

Everyone feels sad, moody or low from time to time. For some people, though, these feelings are intense, last for weeks, months or even years, and sometimes occur for no apparent reason. Depression is more than a low mood. It is a serious condition that affects both physical and mental health.

Depression is common. Over a lifetime, around one in six women and one in eight men will experience it. The good news is that depression is treatable and effective treatments are available. The sooner a person seeks support, the sooner they can recover.

How depression affects people#

Depression affects how people think, feel and act. It makes day-to-day life harder and can interfere with study, work and relationships.

A person may be depressed if, for more than two weeks, they have felt sad, down or miserable most of the time, or lost interest or pleasure in most of their usual activities, and have also noticed several other changes in how they feel, think and behave.

It is important to remember that everyone has some of these experiences from time to time, and they do not necessarily mean a person is depressed. Equally, not everyone with depression will have all of them.

Feelings#

A person with depression may feel:

• sad, miserable or unhappy
• irritable or overwhelmed
• guilty or disappointed
• lacking in confidence
• indecisive, or unable to concentrate

Thoughts#

A person with depression may have thoughts such as:

• “I’m a failure.”
• “It’s my fault.”
• “Nothing good ever happens to me.”
• “I’m worthless.”
• “There is nothing good in my life.”
• “Things will never change.”
• “Life’s not worth living.”
• “People would be better off without me.”

Behaviour#

A person with depression may:

• withdraw from close family and friends
• stop going out
• give up their usual enjoyable activities
• struggle to get things done at work or school
• rely on alcohol or sedatives

Physical symptoms#

A person with depression may experience:

• being tired all the time
• feeling sick and run down
• frequent headaches, or stomach or muscle pains
• a churning gut
• sleep problems
• loss or change of appetite
• significant weight loss or gain

What causes depression#

The exact cause of depression is not known, but a number of things can be associated with its development. Depression usually does not result from a single event. Instead, it tends to arise from a combination of biological, psychological, social and lifestyle factors.

Personal factors#

• Family history. Depression can run in families, and some people are at increased genetic risk. This does not mean a person will automatically become depressed if a parent or close relative has had the condition.
• Personality. Some people may be more at risk because of their personality, particularly if they tend to worry a lot, have low self-esteem, are perfectionists, are sensitive to criticism, or are self-critical and negative.
• Serious medical conditions. These can bring on depression directly, or contribute to it through the stress and worry involved, especially with long-term illness or chronic pain.
• Drug and alcohol use. This can both lead to and result from depression. Many people with depression also have drug and alcohol problems.

Life events#

Continuing difficulties, such as long-term unemployment, living in an abusive or uncaring relationship, long-term isolation or loneliness, or prolonged stress at work, can increase the risk of depression. Major adverse life events, such as losing a job, going through a separation or divorce, or being diagnosed with a serious illness, may also trigger depression, particularly in people who are already at risk.

Changes in the brain#

Although there has been a great deal of research in this area, much is still unknown. Depression is not simply the result of a chemical imbalance, such as having too much or too little of a particular brain chemical. However, disturbances in the normal chemical messaging between nerve cells in the brain are believed to contribute to it. Factors that can affect mood regulation in the brain include genetic vulnerability, severe life stressors, some medical conditions, and the use of some medicines, drugs and alcohol.

Most modern antidepressants act on the brain’s chemical transmitters, in particular serotonin and noradrenaline, which carry messages between brain cells. This is thought to be how these medicines help with depression. For severe depression that has not improved with lifestyle changes, social support, psychological therapy and medication, other treatments such as transcranial magnetic stimulation (TMS) and electroconvulsive therapy (ECT) may sometimes be recommended. These also affect the brain’s chemical messaging, although exactly how they work is still being researched.

Why early support matters#

Depression is often not recognised and can continue for months or even years if left untreated. Seeking support early is important, because the sooner a person gets treatment, the sooner they can recover.

Untreated depression can have many harmful effects, including serious relationship and family problems, difficulty finding and holding a job, and drug and alcohol problems. There is no single proven path to recovery, but a range of effective treatments and health professionals can help. There are also many things people with depression can do for themselves to recover and stay well. The key is to find the right treatment and the right health professional for each person’s needs.

Types of depression#

There are different types of depression, and symptoms can range from relatively minor to severe.

Major depression#

Major depression, or major depressive disorder, is the technical term for the most common type of depression. Other terms sometimes used include unipolar depression or clinical depression. It can be described as mild, moderate or severe.

Melancholia#

Melancholia is an older term still used to describe a more severe form of depression with a strong biological basis, where physical symptoms are especially evident. For example, the person may be observed to move more slowly, or to have significant changes in sleep and appetite. They are also more likely to have a depressed mood marked by a complete loss of pleasure in almost everything.

Dysthymia#

The symptoms of dysthymia (sometimes called persistent depressive disorder) are similar to those of major depression, but are less severe and more persistent. A person must have this milder depression for more than two years to be diagnosed with dysthymia.

Psychotic depression#

Sometimes people with a depressive condition lose touch with reality. This can involve hallucinations (seeing or hearing things that are not there) or delusions (false beliefs not shared by others), such as believing they are bad or evil, that they are being watched or followed, or that everyone is against them. This is known as psychotic depression.

Antenatal and postnatal depression#

Women are at increased risk of depression during pregnancy (the antenatal or prenatal period) and in the year after childbirth (the postnatal period). Together, this is sometimes called the perinatal period. The causes at this time can be complex and often involve a combination of factors.

In the days just after birth, many women experience the “baby blues”, a common condition related to hormonal changes that affects up to 80 per cent of women who have given birth. The baby blues, and the general stress of adjusting to pregnancy or a new baby, are common but different from depression. Depression lasts longer and can affect not only the mother but also her relationship with her baby, the child’s development, and her relationships with her partner and other family members.

Up to one in 10 women will experience depression during pregnancy, and this rises to about 16 per cent in the first three months after having a baby.

Bipolar disorder#

Bipolar disorder used to be known as “manic depression” because the person has periods of depression and periods of mania, with periods of normal mood in between. The symptoms of mania are the opposite of those of depression and can vary in intensity. They include:

• feeling great or “high”
• having plenty of energy
• racing thoughts
• little need for sleep
• talking fast
• feeling frustrated or irritable
• having difficulty focusing on tasks

This is more than a fleeting experience. Sometimes the person loses touch with reality and has hallucinations or delusions, particularly about their own ideas, abilities or importance. A family history of bipolar disorder can increase a person’s risk.

Because bipolar disorder includes periods of depression, it is not unusual for it to be misdiagnosed as major depression until the person has a manic or hypomanic episode. It can also be confused with other conditions such as schizophrenia. Treatment for bipolar disorder is often different from treatment for major depression, so it is important to check for it whenever someone is assessed for depression.

Cyclothymic disorder#

Cyclothymic disorder is an uncommon condition often described as a milder form of bipolar disorder. The person has chronic, fluctuating moods over at least two years, with periods of hypomania (a mild to moderate level of mania) and periods of depressive symptoms, separated by very short periods (no more than two months) of normal mood. The symptoms last a shorter time, are less severe and are less regular, so they do not meet the criteria for bipolar disorder or major depression.

Seasonal affective disorder (SAD)#

SAD is a mood disorder with a seasonal pattern. Its cause is unclear but may be related to the variation in light exposure across the seasons. It is marked by mood disturbances (either depression or mania) that begin and end in a particular season. Depression in winter only is the most common form. SAD is usually diagnosed after a person has had the same symptoms during winter for two or more years. People with SAD are more likely to lack energy, sleep too much, overeat, gain weight and crave carbohydrates. SAD is uncommon near the equator and more likely in regions with short days and long periods of winter darkness.

Key points#

• Depression is treatable, and effective treatments are available.
• Not every person who is experiencing depression will have all of the symptoms.
• The exact cause of depression is not known, but a number of factors can be associated with its development.
• It is important to seek support as early as possible, because the sooner a person gets treatment, the sooner they can recover.
• A range of effective treatments and health professionals can help people on the road to recovery.

Where to get help and trusted information#

For evidence-based global health guidance, see Source: World Health Organization (WHO).