What are cancer-related cognitive changes?

During cancer treatment, you may notice changes in your memory, concentration or your ability to think clearly. These are called cancer-related cognitive changes (CRCC).

These changes are sometimes called chemo brain. This is because the symptoms were first linked to chemotherapy. But changes in memory and concentration can affect people with cancer who have not had chemotherapy.

Symptoms of cognitive changes

Any problems with concentration or memory are usually temporary and mild. But they can be frustrating and interfere with your normal activities. They may delay some people from going back to work, school or to social events.

Common symptoms include:

  • extreme tiredness (fatigue)
  • feeling like you can’t think clearly
  • finding it hard to remember things
  • being unusually disorganised
  • finding it difficult to do more than one thing at a time
  • getting distracted more easily
  • feeling low in mood.

If you have these symptoms, you should talk to your doctor. It can be helpful to keep a record of your symptoms to show the doctor.

Who gets cognitive changes?

It is not clear how many people develop problems with their concentration or memory during or after cancer treatment.

Causes and risk factors

The causes are unclear. Research suggests that it may be caused by a combination of factors. Some risk factors may include:

  • certain cancer types such as brain tumours
  • cancer treatments including chemotherapy, hormonal therapy, radiotherapy, immunotherapy and steroids
  • treatment to the brain, such as intrathecal chemotherapy or radiotherapy to the brain
  • high-dose treatment with chemotherapy or radiotherapy
  • side effects of cancer treatment, such as infection, low number of red blood cells (anaemia), extreme tiredness (fatigue), sleep problems, poor nutrition and menopause
  • emotional reactions to cancer and treatment, such as anxiety and depression
  • non-cancer drugs such as painkillers or anti-sickness (anti-emetic) medicines.

The benefits of your cancer treatment will usually outweigh the risk of developing CRCC. Your doctor or nurse will talk with you about your treatment if you are worried.

Can cognitive changes be prevented or treated?

It is difficult to prevent or treat problems with memory or concentration because it is not clear what causes them. Research is going on to find ways to prevent cognitive changes and effective treatments.

Coping with cognitive changes

Problems with concentration or memory are often mild and get better with time. But for some people, symptoms can continue for years after treatment.

There are a number of things you can do to help yourself.

  • Keep a diary

    Keeping a record of your symptoms may help you work out if certain things make your memory worse. For example, you may notice that symptoms seem worse first thing in the morning, or when you are tired or hungry. Keeping a diary can help you to plan your day so that you do more difficult tasks when you feel at your best. A diary can also help you notice if things improve over time.

  • Use memory aides

    Writing down information at the time can help you remember important things later:

    • Make lists, such as shopping lists or to-do lists.
    • Write notes and put them where you can easily see them.
    • Use a diary or calendar. There may be apps on your mobile phone.
    • Carry a notebook and write notes.
  • Mental exercises

    Memory exercises may help to train your brain and improve your memory and concentration. You can help keep your mind active by learning something new or starting a hobby.

  • Keep active

    Being more physically active can help you feel more alert and reduce tiredness (fatigue).

  • Reduce stress

    Stress can affect your memory. Relaxation can help to reduce stress and may help to improve your memory and concentration. Do some activities that help you relax, such as listening to music or going for a walk or doing yoga. You could do some relaxation exercises or try using relaxation CDs or DVDs.

  • Learn new habits
    • Keep things simple – try to do one thing at a time.
    • Have a daily routine and try to keep to it. 
    • Avoid distractions – for example, turn off the TV or radio if you need to concentrate.
    • Eat a healthy, well-balanced diet, with lots of fresh fruit and vegetables.
    • Take regular breaks and get plenty of rest and sleep. 
    • Ask for support from others – perhaps join an online forum such as our Online Community or a local support group.     

Research into cancer-related cognitive changes

Research is being done to find out the following:

  • which chemotherapy drugs or combination of drugs affect cognitive functioning
  • how other cancer treatments affect cognitive functioning
  • what can be done to reduce the risk
  • how cognitive functioning improves after treatment
  • what can improve symptoms.

You may be asked to take part in a research trial, and your doctor or nurse will explain fully what this involves. You do not have to take part in the trial if you do not want to. You do not have to give a reason why.

Getting support

Talk to family and friends

Many people find that talking to family and friends can help. Changes in memory or concentration are often less obvious than other side effects of treatment. You may need to explain how you are feeling and how it is affecting you.

Your family and friends may not be aware these problems can be a side effect of treatment. If they have noticed any symptoms, they may be relieved to know that these usually get better with time.

Talk to your doctor or nurse

It is a good idea to write down how these changes are affecting you before you see your doctor. If your memory is bad, it may help to take someone with you. You could also ask the doctor for permission to record the conversation. Your doctor may:

  • check for symptoms or side effects that could be contributing to your symptoms
  • check if any of your medicines could be making symptoms worse
  • refer you for specialist help, such as a counsellor or support group.

Other support

Our cancer support specialists can offer you support. They can also give you details of support organisations and counselling services in your area.

About our information

  • References

    Below is a sample of the sources used in our chemotherapy information. If you would like more information about the sources we use, please contact us at cancerinformationteam@macmillan.org.uk

    Brighton, D. Wood, M. The Royal Marsden Hospital Handbook of Cancer Chemotherapy. Elsevier Churchill Livingstone. 2005.

    National Institute for Health and Care Excellence (NICE) Neutropenic Sepsis Guideline CG151. 2012.

    Perry, MC. The Chemotherapy Source Book (5th ed.) Philadelphia: Lippincott, Williams & Wilkins. 2012.

    UKONS Acute Oncology Initial Management Guidelines Version 3, March 2018. Available from www.ukons.org (accessed June 2021).

  • Reviewers

    This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer. It has been approved by Chief Medical Editor, Professor Tim Iveson, Consultant Medical Oncologist.

    Our cancer information has been awarded the PIF TICK. Created by the Patient Information Forum, this quality mark shows we meet PIF’s 10 criteria for trustworthy health information.

The language we use

We want everyone affected by cancer to feel our information is written for them.

We want our information to be as clear as possible. To do this, we try to:

  • use plain English
  • explain medical words
  • use short sentences
  • use illustrations to explain text
  • structure the information clearly
  • make sure important points are clear.

We use gender-inclusive language and talk to our readers as ‘you’ so that everyone feels included. Where clinically necessary we use the terms ‘men’ and ‘women’ or ‘male’ and ‘female’. For example, we do so when talking about parts of the body or mentioning statistics or research about who is affected.

You can read more about how we produce our information here.

Date reviewed

Reviewed: 01 March 2022
Next review: 01 March 2025
Trusted Information Creator - Patient Information Forum
Trusted Information Creator - Patient Information Forum

Our cancer information meets the PIF TICK quality mark.

This means it is easy to use, up-to-date and based on the latest evidence. Learn more about how we produce our information.