All Living Well

If you have been diagnosed with cancer, or are undergoing treatment for it, you may be noticing changes in your ability to think clearly or remember things. Also known as ‘cognitive impairment’, ‘cancer fog or ‘brain fog’, these changes may happen for a few different reasons.1

What causes difficulty thinking and remembering?

It’s not always clear what causes difficulty thinking and remembering. But often these side effects are associated with treatment. They are sometimes called ‘chemo brain’ but can be caused by other treatments too.1,2

The cancer itself may also cause these symptoms. If the cancer is pressing on the brain, it may cause problems thinking and remembering. Emotional reactions such as anxiety, stress or depression can also affect the way the brain thinks and remembers information.1,2

What are the symptoms?

Thinking may be affected in one or more of the following ways:1,2,3

  • Trouble finding the right words to say or keeping up with conversations
  • Trouble learning new things
  • Trouble processing new information – such as directions, names or lists
  • Trouble doing more than one thing at a time
  • Having a ‘foggy’ brain or feeling sluggish
  • Having a shorter attention span
  • Taking longer to do routine tasks 

Memory may be affected in one or more of the following ways:1,2,3

  • Finding it hard to remember what you’ve said to people
  • Trouble remembering what you’ve seen
  • Struggling to remember things that have happened lately
  • Trouble recalling new information – such as directions, names or lists 

Who is most at risk of having difficulty thinking and remembering?

Anyone with cancer or having treatment for cancer may experience problems thinking and remembering. Data indicates that one in three people are affected before treatment, up to three in every four people on treatment, and up to one in three after treatment.1,4

Some people are more at risk than others. These people:2,4

  • Have brain cancer or cancer that has spread to the brain
  • Have had higher doses of chemotherapy or radiation
  • Have had radiation to the brain
  • Are older at the time of diagnosis and treatment
  • Have previously experienced anxiety, depression, post-traumatic stress disorder (PTSD), difficulty sleeping (insomnia) or extreme tiredness (fatigue) 

How to cope with thinking and memory changes?

Adjust your daily routine 

Little tweaks to your daily routine may help you more easily take on information and remember things. For example:1,3

  • Write things down whenever possible – you may wish to carry round a small notepad and pen, or you may prefer to type things into a notes app on your phone
  • Write to-do lists and make reminders for the important things you need to do
  • Try to focus on just one thing at a time instead of multitasking
  • Put important objects like your keys and phone in a specific place when they’re not in use – this may make them easier to find
  • Keep a diary to record how you are feeling – you might feel sharper at certain times of the day
  • Pay attention to your body and tackle certain tasks when you feel better prepared for them 

Don’t be afraid to ask for support 

People may not know what you are going through unless you tell them. Open up with your loved ones and support circle when, and how, you feel ready to:1,3

  • If you are feeling open, tell your family, friends, colleagues and support circle exactly how you are feeling – be honest with them about your difficulty thinking and remembering at the moment
  • Speak to your manager at work about your workload – are there some things you’re struggling with more than usual at the moment? There may be support available
  • If you would like to speak to people who understand what you’re experiencing, try reaching out to a support group – see our page on support groups to learn more
  • Make sure you tell your doctor how you are feeling – they will be able to offer recommendations and support specific to you 

Help your brain to help you 

There are small things you can do which may help you take on and remember information. These include:3,5

  • When talking to someone, focus on what they are saying and repeat back any important information they have shared
  • Add meaning to information you’ve been given or make a ‘story’ out of it – you may wish to picture things in your head or make a rhyme or word association to remember
  • Make lists out of the information you have been given, grouping items in a way that makes sense to you 

Maintain healthy choices

Keeping on top of your general health helps to support you body and wellbeing. Here are some ways you can look after your health:1,3

  • Aim to get at least 7 to 8 hours of sleep each night – read more about getting a good night’s sleep here
  • Prioritise rest when you’re feeling tired
  • Eat lots of healthy, nutritious foods – read more about what a healthy diet looks like here)
  • Try to stay active and exercise regularly – read more about ways to move your body when living with cancer here
  • Try relaxation methods such as yoga or meditation 

 

It can be tough living with brain fog and having trouble thinking and remembering. Be kind to yourself during this time, and don’t be afraid to tell others how you are feeling. The good news is that often these symptoms and side effects are temporary, meaning they get better once the cancer is treated and you recover from treatment.1

We hope some of the information here will help you to cope with your brain fog. Remember, always speak to your doctor about any new, unusual or worsening symptoms or side effects that you are experiencing. They will be able to offer information and support specific to you. 


References 

  1. Cancer Council. Changes in thinking and memory. Available from: https://www.cancer.org.au/cancer-information/cancer-side-effects/changes-in-thinking-and-memory [Accessed June 2026].
  2. Macmillan. Cognitive changes (chemo brain). Available from: https://www.macmillan.org.uk/cancer-information-and-support/impacts-of-cancer/chemo-brain [Accessed June 2026].
  3. Cancer Council Victoria. Understanding and managing ‘chemo brain’. Available from: https://www.cancervic.org.au/get-support/stories/understanding-and-managing-chemo-brain.html  [Accessed June 2026].
  4. Cancer Research UK. What are cognitive changes (chemo brain)? Available from: https://www.cancerresearchuk.org/about-cancer/treatment/cancer-drugs/side-effects/chemo-brain/about [Accessed June 2026].
  5. VeryWell Health. 10 mnemonics that can help you remember anything. Available from: https://www.verywellhealth.com/memory-tip-1-keyword-mnemonics-98466 [Accessed June 2026].