What is the link between serotonin and depression?
Depression is a serious mental illness that causes people to experience intense feelings of sadness and despair. While it’s normal for us all to feel upset or ‘down’ from time-to-time, people who struggle with depression and their mental health usually experience such crushing low moods that the way they think, feel and act on a daily basis is impaired.
It’s unclear exactly what causes someone to become depressed. Research suggests that both genetic and environmental factors may play a part.
The following factors have been linked to depression:
- Being the victim of abuse and/or neglect, especially during childhood
- Experiencing difficult life events such as a job loss, divorce, or bereavement
- Having a family history of depression or other mental illnesses
- Having a personal history of other mental illnesses
- Suffering from serious physical conditions such as cancer
- Having certain personality traits such as low self-esteem or being overly self-critical
These cause an imbalance of a specific chemical in the brain, known as serotonin.
What is serotonin?
Serotonin is a neurotransmitter - a type of chemical that helps to send messages from one area of the brain to another. It’s believed that serotonin is linked to brain cells involved in a range of psychological processes, as well as brain cells that influence some body functions and systems. Serotonin is thought to impact on:
- Mood and behaviour
- Memory and learning
- Sexual desire and functioning
- Appetite, digestion and bowel movements
- Blood clotting
- Bone health
- Body temperature
The link between serotonin and depression
Serotonin is widely known as being one of the brain’s ‘happy chemicals’, because it appears to be able to influence mood. Research shows that high levels of serotonin in the brain are linked to elevated mood and feeling happy, whereas low levels of serotonin are linked to the symptoms of depression, including feeling sad, upset, and generally low in mood. An imbalance of serotonin levels in the brain has also been linked to other conditions such as obsessive compulsive disorder (OCD), anxiety, panic attacks and anger management issues.
The idea that serotonin levels are related to depression is further supported by the fact that people who are experiencing a ‘comedown’ after drinking alcohol or taking drugs, report feeling sad and depressed. This is because alcohol and drugs such as ecstasy/MDMA are known to cause levels of serotonin to peak and then reduce very quickly. This sudden reduction in serotonin levels therefore has a negative impact on a person’s mood during the drug comedown stage.
However, while there is certainly a connection between serotonin and depression, the direction of this relationship is unclear in terms of whether low serotonin causes depression, or whether depression causes low serotonin.
What are selective serotonin reuptake inhibitors (SSRIs)?
Usually, once neurotransmitters such as serotonin have helped to send a message from one part of the brain to another, they are reabsorbed back into the body. Selective serotonin reuptake inhibitors (SSRIs), are the most common type of antidepressant medication, and they work by preventing serotonin from being reabsorbed by the body. This means that serotonin levels stay high in the brain, which is believed to improve mood and treat depression.
The following are all common types of SSRIs that are prescribed to treat depression:
- Fluoxetine (Prozac)
- Citalopram (Celexa)
- Sertraline (Zoloft)
SSRIs are usually used alongside therapy methods such as cognitive behavioural therapy (CBT) in the treatment of depression. SSRIs are not addictive and they do not cause sedation.
Other ways to boost your serotonin levels
As well as taking prescribed SSRIs, there are a number of natural ways in which you can try and boost the levels of serotonin in your brain, in order to improve your mood. These include:
- Meditate - meditation is known to relieve stress, help you relax, and promote a positive outlook, all of which can increase serotonin levels in the brain
- Get some fresh air and sunlight - the positive effects of light on your mood and wellbeing can’t be underestimated. Simply going outside into the fresh air and sunlight (even when it’s cold), can greatly improve your mood and serotonin levels
- Exercise - exercise is widely thought of as being one of the best natural antidepressants. Even a small amount of exercise each day can help boost your mood and increase serotonin functioning in the brain. If you are able to exercise outside in the sunlight e.g. by going for a walk, this will be even more beneficial
- Diet - research shows that eating foods that contain the amino acid, ‘tryptophan’, may help your body produce more serotonin and enhance mood. Such foods might include eggs, spinach and salmon
While more research is needed in this area, the key message is that serotonin and depression are very much interlinked, with low levels of serotonin being associated with low mood and other symptoms of depression.