This section answers common questions about changes to thinking and memory that can occur during and after cancer treatment.
Learn the answers to these questions:
- How does cancer affect thinking and memory?
- What kinds of changes might you notice?
- Why do these changes happen?
- Who is affected?
- How long does it last?
- Your feelings about change
How does cancer affect thinking and memory?
Many people diagnosed with cancer notice changes in the way they think and remember information. This is called cancer-related cognitive impairment, but people may also call it “cancer fog”, “chemo brain” or “brain fog”. Even people who have never had chemotherapy can experience this.
While changes in how the brain works (cognitive function) can be a normal part of getting older, cancer-related cognitive impairment is different. It can also happen quite suddenly. If you notice any changes, speak to your doctor.
What kinds of changes might you notice?
Often the changes to thinking and memory will be small, but even small changes can be challenging, and affect day-to-day tasks.
You may find it hard to:
- think clearly
- focus or pay attention
- remember names, dates or words
- do more than one thing at a time (multitask)
- process information, including following directions, problem-solving or learning new skills.
You may also:
- have mental “fogginess”
- feel disorganised
- be unable to keep up with conversations
- feel very tired or exhausted
- have trouble starting things or finding the motivation you used to have.
Problems with thinking and memory can happen at any stage. You may notice changes before treatment starts, during treatment or after treatment has finished.
What used to take me 5 minutes, now takes me 20 or 30. I’ve also found it difficult to go back to my old job. It’s frustrating. I’ve had to adopt ways of getting around it.
NAVEENA
Why do these changes happen?
The exact causes of thinking and memory changes after a cancer diagnosis are unknown. The changes might happen because of:
- cancer treatments
- side effects, such as trouble sleeping, fatigue, pain, low blood counts and hormone changes
- medicines for surgery or to manage treatment side effects, including anaesthetics, steroids, pain medicines and anti-nausea drugs
- your emotions, such as feeling overwhelmed, depressed or anxious
- inflammation caused by the cancer
- in some cases, a brain tumour, which can affect how the brain works.
Who is affected?
Thinking and memory changes are common for people who have cancer. According to one study, it can affect up to 3 in 4 people during treatment, about 1 in 3 people before treatment and 1 in 3 after treatment.
How long does it last?
Changes to thinking and memory problems are usually short term (6–12 months). Most people start to notice improvements after cancer treatment ends. For some people, problems may continue for years.
Changes may come and go, and may be worse when you are tired, stressed or unwell. If problems keep affecting your daily life, talk to your doctor.
Your feelings about the changes
| Coping with changes in thinking and memory | It can be challenging to experience changes in thinking or memory, even if the changes are small. You may not feel like yourself, which can affect your relationships with family, friends and colleagues. |
| Impact on daily life | Changes in your thinking or memory can have a big impact on managing at home, 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. |
| Reassurance and support | It may be reassuring to know that many people experience changes, and for most people it gets better with time. Even if the changes are long term, help is available (see Managing changes). |
| Seeking help | 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 call Cancer Council 13 11 20 to talk to an experienced health professional about your concerns. They may also be able to connect you with someone who has had a similar cancer experience. |
→ READ MORE: Managing thinking and memory changes
Be kind to yourself and utilise whatever resources you can. Don’t be ashamed of asking for help because it’s not your fault.
NAVEENA
Podcast: Brain Fog and Cancer
Host Julie McCrossin talks with Prof Janette Vardy, a medical oncologist, who has been studying brain fog and cancer.
Listen to more episodes from our podcast for people affected by cancer
Key resource
Download a PDF booklet on this topic.
More resources
This information has been clinically reviewed by Prof Janette Vardy, Medical Oncologist, Sydney Cancer Survivorship Centre, Concord Repatriation General Hospital, University of Sydney, NSW. This edition is based on the previous edition, which was reviewed by Prof Janette Vardy (see above); Dr Heather Green, Clinical Psychologist and Health Psychologist, Griffith University, Gold Coast, QLD; Johanna Jordaan, Consumer; Lesley, 13 11 20 Consultant, Cancer Council, WA; Sarah Ramsdale, Cancer Survivorship Nurse, ICON Cancer Centre Warrnambool, VIC; Brooke Russell, Principal Occupational Therapist, WA Cancer Occupational Therapy, WA; Dr Adam Walker, Director, Laboratory of ImmunoPsychiatry, Neuroscience Research Australia and University of New South Wales, NSW.
View the Cancer Council NSW editorial policy.
