What is 'Chemo Brain'?

Chemo brain is the term often used to describe the mental cloudiness or fog that cancer patients sometimes notice associated with treatment for cancer. This cognitive impairment can occur at any time before, during, or after treatment.

Chemo brain is also sometimes referred to as cancer treatment-related cognitive impairment, cancer-therapy associated cognitive change, or post-chemotherapy cognitive impairment.

Chemo brain after cancer treatment - Dana-Farber Cancer Institute

Symptoms and Effects

Most people who are affected by chemo brain describe it as a decrease in mental sharpness. They may report various signs or symptoms such as:

  • Memory lapses: forgetting things they usually remember (e.g. names, dates, events)
  • Difficulty concentration: lack of focus or short attention span
  • Trouble multi-tasking: difficulty in keeping track of two tasks at once (e.g. answering phone while cooking)
  • Linguistic challenges: difficulty in remembering words to finish sentences
  • Delayed completing: taking longer to finish tasks due to slower or disorganized thinking

These changes are usually subtle and, in many cases, the people around the person will not notice the changes. However, the affected individuals are aware of the changes and may be frustrated by their lack of focus.

Coping with 'chemo brain'

The mental changes associated with chemo brain vary in length for each patient. Most people notice changes that present quickly and last a short time, whereas other will experience ongoing changes that may continue for several years.

Chemo brain can have a significant impact on an individual’s quality of life. They may affect performance at school or work or inhibit the individual’s ability to participate in social activities. In some cases, this can also contribute to depression or other mental health difficulties, particularly as cancer patients may be dealing with other psychological challenges related to the condition.


The exact cause of chemo brain is not known but the changes in mental function are real and not imagined. The symptoms usually begin during or shortly after chemotherapy, although some patients report a delayed onset of symptoms and may notice a decline in cognitive function some time after treatment has concluded.

Current research suggests that there are several factors that may contribute to causing chemo brain. Some patients experience symptoms even though they haven’t had chemotherapy and others notice symptoms that appear to be linked to hormonal therapies.

The following factors may contribute to chemo brain:

  • Cancerous growth
  • Chemotherapy treatment
  • Radiotherapy treatment
  • Other medications used in treatment (e.g. analgesics, steroids, antiemetics)
  • Hormonal changes and treatments
  • Surgery and anesthetic drugs
  • Low blood counts
  • Insomnia or fatigue
  • Other health conditions (e.g. diabetes, hypertension, infections)
  • Nutritional deficiencies
  • Individual patient characteristics (e.g. age, family, medical history)

Management Techniques

There are several things that patients affected by chemo brain can do to improve mental focus and reduce the symptoms of the condition. Patients may find it useful to:

  • Record important dates, events, to-dos, phone numbers, addresses, and notes in a planner.
  • Keep the brain active by taking a class, doing word puzzles or learning a new skill.
  • Decide on a place to keep objects that frequently become lost.
  • Make an effort to focus on one task at a time and avoid multi-tasking.
  • Follow a routine and keep a daily schedule.
  • Allow enough time to rest and sleep.
  • Stay physically fit to improve mood and mental alertness.
  • Consume a nutritious diet with high intake of fresh vegetables.
  • Reach out for support from family and friends if needed.

It is useful for patients to keep a diary of memory problems to record what problems they are experiencing and what else is going on in their life at that time. This can be useful to find associated links, which can then be adjusted so that mental clarity can be increased.


Further Reading

Last Updated: Feb 27, 2019

Yolanda Smith

Written by

Yolanda Smith

Yolanda graduated with a Bachelor of Pharmacy at the University of South Australia and has experience working in both Australia and Italy. She is passionate about how medicine, diet and lifestyle affect our health and enjoys helping people understand this. In her spare time she loves to explore the world and learn about new cultures and languages.


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