Depression
Doctors link depression to a chemical imbalance in the brain. This usually involves a drop in chemical levels in the brain. They are called neurotransmitters.
Neurotransmitters take messages from your brain to your nerve cells. The common ones involved in depression are serotonin, norepinephrine, and dopamine.
A physical or emotional (psychological) event in your life can trigger a chemical imbalance. Sometimes it is hard to know if it was one or the other. Often both types may play a part.
Some illnesses, such as cancer and Parkinson’s disease, are more likely to cause depression than others.
Doctors think this is because of the physical effect rather than the emotional one. Some other diseases, which are as serious, don’t cause the same amount of depression. We don’t fully understand why this is.
Changes in hormone levels may contribute to depression in some people. The lower levels of some hormones during menopause can cause depression.
Many treatments for cancer affect your hormone levels including:
surgery to remove your ovaries and womb
hormone treatments for prostate cancer or breast cancer
We now better understand why some people are more likely to become depressed than others. One reason is a family history.
If you have a close relative who has had depression, you are more likely to get depressed yourself when faced with a period of stress.
Sometimes the chemical changes in the brain that go with depression are long lasting. This means that after recovering from an episode of depression, you may be more prone to depression in the future. We don't know this for certain. Because of that, you should seek support when you notice the first signs of depression.
Read more about treating depression
Maudsley Learning, part of the South London and Maudsley NHS Foundation Trust, has a set of cancer and mental wellbeing videos for people affected by cancer.
The videos have information and advice on what to do if a cancer diagnosis affects your mental health. They cover several topics, including:
breaking bad news
managing anxiety
common reactions to a diagnosis
relationships
Last reviewed: 24 Mar 2026
Next review due: 24 Mar 2029
Symptoms of depression, such as weight loss and tiredness, can be caused by your cancer or by cancer treatment. They are not always reliable signs of depression in people with cancer.
Depression is different from feeling sad, it is an illness and needs treatment.
After a diagnosis of cancer, you might have a range of feelings including fear, sadness, anxiety and depression. These are normal responses to a stressful life experience.
There are a few ways to go about finding a counsellor.
Counselling can help you come to terms with your cancer. Understanding what it is and how it can help, can help you decide if it is right for you.
About Cancer generously supported by Dangoor Education since 2010. Learn more about Dangoor Education
Search our clinical trials database for all cancer trials and studies recruiting in the UK.
Connect with other people affected by cancer and share your experiences.
Questions about cancer? Call freephone 0808 800 40 40 from 9 to 5 - Monday to Friday. Alternatively, you can email us.
