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Some people diagnosed with cancer notice changes in the way they think and in the way they remember information. This is known as cancer-related cognitive impairment, but people may also call it “cancer fog”, “chemo brain” or “brain fog”. This page can help you understand more about the changes in thinking and memory that some people experience and how can it be managed. 

What is cancer-related cognitive impairment?  

Your brain controls your thought, behaviour and emotions. While the natural ageing process affects how the brain works (cognitive function or cognition), people with cancer often report a sudden or noticeable decline in cognition.  

Cognitive problems and changes can occur before, during or after cancer treatment. Some changes are small but for some people, changes may be more obvious. These changes can include:  

  • difficulty concentrating 
  • memory changes such as forgetting names, dates and words 
  • a feeling of mental “fogginess” 
  • difficulty processing information such as following directions or learning new skills 
  • finding it hard to do more than one thing at a time 
  • difficulty finding words during a conversation or keeping up with conversations 
  • being unusually disorganized 
  • tiredness. 

What causes cancer-related cognitive impairment?  

While the exact causes of changes in thinking and memory are not known, studies have shown the causes may include: 

  • cancer treatments  
  • side effects from treatment such as difficulty sleeping, fatigue, pain and hormone changes 
  • inflammation caused by the cancer and the way it can impact brain processes 
  • medicines used for surgery or to manage side effects 
  • feelings of depression and anxiety 
  • in some cases, the physical presence of a tumour in the brain. 

 Who is affected by changes in thinking and memory? 

Thinking and memory changes do not affect everyone diagnosed with cancer, but it is relatively common. One study found that it can affect one in three people before treatment, up to three in four people during treatment and one in three after treatment.  

Changes in thinking and memory are usually temporary and improve with time.  

How can I manage cancer-related cognitive impairment? 

Cancer-related cognitive impairment may leave you not feeling like yourself which can affect your relationships with friends, family and colleagues. It can also impact your ability to manage at home.  

There are things you can do to cope with cancer-related cognitive impairment and improve your ability to manage daily life. Some suggestions are:  

  • keep a diary of any differences you note including the time of day and what you were doing as this can make it easier to plan your day 
  • adjust your daily routine – keep a to-do list, use your smartphone/mobile features such as reminders or alarms, try not to multi-task, avoid distractions, put objects like keys in a specific place, pace yourself 
  • maintain a healthy lifestyle – eat healthy foods including lots of fruit and vegetables, try to get 7-8 hours of sleep each night, do some physical exercise, minimize stressful activities, try meditation or relaxation 
  • involve other people – if you feel comfortable talk to friends and family about what is going on, talk to your health care team about how you are feeling, take a support person to appointments or treatment 
  • improve your thinking and memory – in conversation focus carefully and repeat what has been said, break down new information into smaller chunks, take a class to learn a new skill, try doing something creative 
  • try cognitive rehabilitation – a trained health professional will assess you and help you work on developing strategies to overcome specific challenges.  


Where can I get reliable information?  

Cancer Council’s podcast series “The Thing About Cancer” includes an episode on changes to thinking and memory.  Talk to your health care team who can put you in touch with local services. 

You can also call Cancer Council 13 11 20 for more help and information.  

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