Ink and watercolour illustration of the brain of someone experiencing depression

Understanding depression

Depression is a common mental health condition affecting more than 1 in 10 people in the UK, yet it is still often misunderstood. Charlotte Ham compiles this Q&A to help us understand more about it

How many people in the world suffer from depression?

Depression is one of the most common mental illnesses and a leading cause of disability worldwide. It is estimated that more than 350 million people suffer from it – about 5 per cent of the overall global population.

In the UK around 12 per cent of people are affected by some form of depression. Of these, just over three-quarters suffer from mixed depression and anxiety, which is the most common mental disorder in Britain according to the Mental Health Foundation.

What is it? What do we know about it?

Depression is a long-lasting mood disorder, usually brought on by stressful or traumatic life events, or by changes in body chemistry and physical conditions. It often affects your ability to do everyday things and decreases pleasure or interest in activities.

Although it’s common to feel miserable or say you are ‘depressed’ from time to time, with depression these feelings do not go away. The symptoms – which can be mental or physical – vary from person to person. Along with a persistent overall low mood, other symptoms can include tiredness, low self-esteem, difficulty concentrating, self-harm and, in more severe cases, suicidal thoughts.

How is depression treated?

Depression is treatable, but it is not an easy process, and there are many different ways of treating it. Treatment can last for varying lengths of time: for some it can take months or years to recover, but for others recovery means learning how to manage depression in the long term.

There are three main treatments: self-help, medication and talking therapies. Antidepressant medications work to increase the levels of certain chemicals (neurotransmitters) in the brain that, when imbalanced, can lower our mood. However, usually a combination of treatments is needed to address both the symptoms and the causes of depression.

Although individuals with depression need to take an active part in their own treatment, the feelings of worthlessness common in this condition can make this difficult. Therefore, support and encouragement from friends and family is very important – both during and after recovery.

What do scientists think is happening in the brain?

There is not one cause of depression, but there are some theories that can explain the condition in some individuals.

There are many different neurotransmitters in the brain, and several of them are involved in some way with depression, such as dopamine and GABA. (See our drugs and the brain article for more information.)

Stressful life events can trigger depression through an overly severe stress response. Usually this defence is relaxed once a threat has passed. Sometimes, however, levels of the hormone cortisol (released as a result of the stress response) continue to rise or remain too high, which can lead to depression. Of those who are clinically depressed, about 50 per cent secrete excess cortisol.

The regions of the brain affected by depression include the thalamus, the hippocampus and the amygdala.

  • The thalamus is the area of the brain that receives sensory information and passes it on to other parts of the brain.
  • The amygdala is associated with emotions such as fear, and also plays a role in anxiety disorders. There is some evidence that activity in this area is higher when someone is depressed.
  • The hippocampus – a major centre for memory in the brain – stores memories of past emotions. Research shows that the hippocampus of depressed people is smaller on average, and suggests that too much cortisol could prevent the growth of nerve cells.

How likely am I to get it?

Anyone can become depressed, but there are some factors that can cause a person to be more at risk of developing a form of depression.

Some people are more at risk because of their genes. Depression can run in families, as variations in genes can affect mood and result in severe depression – particularly if someone is vulnerable to stress.

Major life changes or stress can also trigger depression, particularly if no support is provided to help someone get through these phases.

Your age and gender can also determine how likely you are to develop depression. One in five older people are affected by depression, with decreasing health and other environmental factors playing a role.

Women appear to be more likely to experience depression than men. This could be due to hormonal changes throughout life, though it could also be that woman are more likely to report symptoms to their doctor.

Can it be prevented?

Depression can affect anyone, even those who may seem less at risk, but there are ways in which we can try and prevent it. A healthy lifestyle can help, which may include a good diet to avoid sugar highs or lows, exercise that releases endorphins and promotes good sleep, and enjoyable activities that keep us motivated. Avoiding too much caffeine and alcohol can also prevent low moods.

What organisations can help?

Mind, the mental health charity

Rethink Mental Illness


Lead image:

This ink and watercolour illustration depicts the brain of someone suffering from depression.

Stephen Magrath/Wellcome Images CC BY NC ND


About this resource

This resource was first published in ‘Thinking’ in August 2014.

Neuroscience, Psychology
Education levels:
16–19, Continuing professional development