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Changes in thinking and memory

Cancer-related cognitive impairment

Every day, your brain controls your thoughts, emotions and behaviour. The natural ageing process affects how the brain works (known as cognition or cognitive function). However, people with cancer often report a noticeable or sudden decline in cognitive function. 

You may notice changes in the way you think and remember information. This is called cancer-related cognitive impairment, but people may also refer to it as 'cancer fog', 'chemo brain' or 'brain fog'.  

Impacts on thinking and memory

Cognitive problems can occur before, during or after cancer treatment. Some people notice small or subtle changes, but for others, the effects are more obvious. These may include:

  • a feeling of mental 'fogginess' or sluggishness
  • difficulty concentrating or focusing
  • memory changes (forgetting names, dates, words and things you would usually recall)
  • difficulty finding words during conversations
  • finding it hard to do more than one thing at a time (multi-tasking)
  • difficulty processing information, including following directions, problem-solving or learning new skills
  • being unusually disorganised
  • feeling unable to keep up with conversations
  • tiredness or fatigue.

Thinking and memory problems are usually temporary and get better with time. Most people say they notice improvements within the first year after finishing treatment. Other people experience longer term effects. 


The exact causes of thinking and memory changes are unknown. So far, studies show the causes may include:

  • cancer treatments
  • treatment side effects, such as trouble sleeping, fatigue, pain, low blood counts and hormone changes
  • medicines given for surgery or to manage side effects of treatment, including anaesthetic, steroids, painkillers and anti-nausea drugs
  • your emotions, such as feelings of depression or anxiety
  • inflammation caused by the cancer, and the way it impacts brain processes
  • in some cases, the physical presence of a tumour in the brain, which can affect mental function.

Although thinking and memory changes do not affect everyone with cancer, research shows it is relatively common. According to one study, it can affect up to three in four people during treatment, about one in three people before treatment and one in three after treatment. 

Managing changes

There are things you can do to cope with cognitive problems, improve your wellbeing and ability to manage daily life.

Keep a diary of the differences you notice, including the time of day and what you were doing. This can make it easier to plan your day, and the record may also be useful when you talk with your healthcare team. The following suggestions have also been found to be effective.

Adjust your daily routine

  • Write things down – keep a to-do list or take notes
  • Use a diary or smartphone/mobile features such as reminders or alarms, and to store lists
  • Set times each day to check your to-do lists and reminders
  • Focus on one thing at a time (try not to multi-task)
  • Avoid distractions – for example, let your phone go to voicemail and listen when you’re ready
  • Pick a specific place to put objects such as your keys, rings or phone, so they are easier to find
  • Pace yourself and include rest breaks to recharge after mentally demanding tasks
  • Do focused tasks when you feel fresher.
  • Ask your pharmacist about a medicine organiser or blister pack (e.g. Webster-pak). 

Involve other people

  • If you feel comfortable, tell family, friends and colleagues what is going on – this can prevent misunderstandings
  • Speak to your employer about reassigning your tasks or deadlines
  • Take a support person to appointments or treatment
  • Talk to your health care team about how you are feeling – they can assess if you have other concerns such as depression
  • Several types of allied health professionals may be helpful in understanding and managing your symptoms or daily challenges. Talk to your treatment team or your GP about referral to a neuropsychologist, clinical psychologist or occupational therapist. You may be able to access support through the hospital system or get a Medicare rebate.

Maintain a healthy lifestyle

  • Eat healthy, nutritious foods, including lots of fruits and vegetables
  • Aim to get at least 7–8 hours' sleep each night and rest when tired
  • Do some physical exercise or stretching to improve your mood and energy levels. A mix of aerobic and resistance training may help you to think more clearly and be more mentally sharp
  • Consider working with an exercise physiologist to incorporate exercise into your lifestyle
  • Minimise stressful activities as much as possible
  • Try meditation or relaxation to reduce stress
  • Listen to the podcast, The Thing About Cancer, for tips on how to cope with cancer.
  • Try meditation or relaxation to reduce stress and worries. Cancer Council's Finding Calm During Cancer podcast offers a series of meditation and relaxation exercises. 

Improve your thinking and memory

  • During conversation, focus carefully and repeat what has been said to you
  • Add meaning to information you need to remember, e.g. picture someone called Robyn with a robin bird above their head
  • Break down new information into smaller chunks, e.g. remember 2507000 by thinking of 2507 as Christmas in July, then 000 as the emergency phone number
  • Take a class to learn a new skill, such as a new language or musical instrument
  • Try doing something creative, like art or crafts
  • Try cognitive rehabilitation.


Your emotional wellbeing

Dealing with cancer-related cognitive impairment can be challenging. You may not feel like yourself, which can affect your relationships with family, friends and colleagues.

Changes in your thinking or memory can have a big impact on your ability to manage at home, while working or studying, or during social activities. This may make you feel upset, scared or frustrated. You might feel you have to put in extra mental effort and energy to do tasks.

Try to be gentle with yourself and allow time to recover. You may find it helpful to speak about how you are feeling with a family member, friend or professional counsellor. You can also call our compassionate cancer nurses on 13 11 20.

Cognitive rehabilitation

Some people who experience changes in thinking and memory find cognitive training or rehabilitation useful, especially if there is a significant and/or lasting impact on their wellbeing and ability to manage.

In this therapy, a trained health professional will assess you and help you work on developing strategies to overcome specific challenges. You may be offered cognitive training (sometimes known as 'brain training') or rehabilitation to improve your symptoms by working on your attention, memory and navigation skills.

Speak to your health care team about accessing cognitive rehabilitation services, which may be available through some hospitals, psychologists or other health services. Medicare rebates are available if treatment is provided under a Mental Health Care Plan. Some private health funds may provide rebates, check with your insurer.

Online options

Online brain training programs may also be helpful. These include brain exercises that you practise regularly for a short time. Most programs offer a free trial, but to continue to using the programs you usually need to pay. Search online or ask your health care team to recommend a program. 

Question checklist

This checklist may be helpful when thinking about questions to ask your doctor.
  • I have been having trouble with my thinking and memory. How can I tell if it’s related to the cancer or cancer treatment?
  • How long are the changes in thinking and memory likely to last?
  • What are some simple ways to improve my thinking and memory?
  • I’m finding the changes in my thinking and memory hard to cope with. Who can I talk to about how I am feeling?
  • Can you refer me to a neuropsychologist, clinical psychologist or occupational therapist who understands cancer-related cognitive impairment? Would I be able to get a Medicare rebate to help cover the cost?
  • Would cognitive testing and cognitive rehabilitation be an option for me?
  • Are there any online braining training programs I could try?
  • Are there any complementary therapies that might help me?


Understanding Changes in Thinking and Memory

Download our Understanding Changes in Thinking and Memory fact sheet to learn more

Download now  


Expert content reviewers:

Dr Haryana Dhillon, Senior Research Fellow, CeMPED, University of Sydney, NSW; Dr Heather Green, Health Psychologist, Griffith University, Gold Coast, QLD; Dr Amanda Hutchinson, Clinical Psychologist, University of South Australia, SA; Celia Marston, Chief Occupational Therapist, Peter MacCallum Cancer Centre, VIC; Prof Janette Vardy, Medical Oncologist, Sydney Survivorship Centre, Concord Repatriation General Hospital, University of Sydney, NSW; Naveena Nekkalapudi, consumer; Monica Conway, 13 11 20 consultant, Cancer Council Victoria, VIC.  

Page last updated:

The information on this webpage was adapted from Understanding Changes in Thinking and Memory - Information for people affected by cancer (2018 edition). This webpage was last updated in September 2021.

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