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Cognitive problems

Cognitive function refers to your mental skill or abilities. It includes thinking, reasoning, perception, judgment, learning, attention and memory. When someone has problems with cognitive function, they may have what is called cognition impairment or cognitive dysfunction.

Sometimes cancer or its treatments affect cognitive function. Cognitive rehabilitation is also called cognitive retraining. It may help you regain your cognitive function or cope with cognitive problems.


People with cancer can have cognitive problems for many different reasons. These problems may be caused by more than one factor.


Certain cancers, including a brain tumour or another cancer that has spread (metastasized) to the brain, can cause cognitive problems.

Cancer treatment

The type and dose of cancer treatment, along with the length of treatment, can affect cognitive function.

Chemotherapy may cause problems with memory or thinking. This is sometimes called chemo brain. Higher doses of chemotherapy are more likely to cause cognitive problems.

Radiation therapy to the head and neck or total body irradiation can damage brain cells or cause brain swelling.

Some biological therapies, such as interleukin-2 (Aldesleukin, Proleukin), can affect cognitive function. They are more likely to cause problems when you have to take them for a long period of time.

Hormonal therapies such as anti-estrogen drugs have been linked to cognitive problems, but the problems are less severe than with other therapies.

Brain surgery, such as for biopsy or to remove a tumour, can damage or disturb areas of the brain.

Conditions or symptoms related to cancer

Cognitive problems can also be caused by conditions or symptoms related to cancer or cancer treatment, including:

  • anemia (low red blood cell count)
  • sleep problems
  • fatigue
  • hypercalcemia (high blood calcium)
  • electrolyte imbalances

Other health problems

Other problems that can cause cognitive function issues include:

  • infections, especially of the brain and spinal cord or those that cause a high fever
  • other diseases or conditions that affect the brain or nervous system
  • not getting enough vitamins and minerals such as iron, vitamin B and folic acid
  • stress, anxiety or depression
  • older age
  • medicines used to manage medical problems related to cancer or its treatment


Medicines that can cause cognitive function problems include:

  • drugs used in stem cell transplants that cause immunosuppression
  • antibiotics
  • corticosteroids
  • pain relievers
  • antidepressants
  • anti-anxiety medicines
  • heart medicine
  • medicine to help sleep disorders
  • medicines used to manage nausea, vomiting or other symptoms related to cancer

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Cognitive function changes can be very mild and may lessen or go away in the days or months following treatment. Sometimes cognitive problems are more serious and may take more time to improve, or they may not improve at all.

Cognitive changes are different for everyone. They may include considerable changes in your mental skills and can cause difficulty with:

  • language skills, including expressing yourself in words, recalling words or naming objects, understanding words or conversations, and writing
  • math
  • memory, including forgetting things that you knew well such as names and important dates
  • learning new things
  • performing different tasks at once (multi-tasking) or switching between tasks
  • focusing attention, concentrating or organizing thoughts
  • judgment and reasoning
  • motor skills such as buttoning clothes or using cutlery
  • thinking quickly

Cognitive changes can also include changes in your behaviour or emotions, including:

  • disorientation or mental “fog”
  • mood swings
  • inappropriate anger or crying
  • irrational behaviour
  • confusion

Cognitive problems can affect your psychosocial well-being and overall quality of life, including your ability to work or perform daily activities. They may also interfere with your ability to understand or make decisions about your illness or treatment.

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The early signs of cognitive problems or impairment may be subtle and are easy to miss. Some of the changes associated with cognitive problems can also be confused with or made worse by depression or fatigue.

Family members are often the first people to notice a change in a loved one’s cognitive function or personality. You can ask a family member or caregiver to keep track of changes in your thinking, communication and memory. If you or someone else notices changes in your cognitive function, share your concerns with your doctor. Your doctor may do a simple evaluation or may refer you to a specialist for a more thorough assessment.

To assess cognitive function, your doctor may:

  • talk to you about any cognitive changes you’ve noticed
  • do a physical exam
  • order diagnostic tests
  • do a neurological exam to check your:
    • reflexes
    • balance and coordination
    • motor skills
    • muscle strength
    • response to pain
    • awareness of surroundings
    • judgment and reasoning
    • memory
    • ability to calculate
    • language skills

Your doctor may order a CT scan or MRI of the head to check for tumours, damage to the brain caused by therapy or changes in the brain matter.

Find out more about tests and procedures, including physical exam, CT scan and MRI.

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Managing cognitive problems

Cognitive rehabilitation means teaching or re-teaching thinking, reasoning or memory skills. While these skills may not be exactly the same as they were before cancer or cancer treatment, cognitive rehabilitation can have positive effects that will help improve your confidence and quality of life.

If cognitive problems are caused by a condition, such as anemia or infection, they will usually go away after the condition or cancer is treated. Cognitive problems caused by medicine should also go away after you stop taking it.

Cognitive problems caused by cancer or its treatment may go away after treatment is finished, continue for a long time or become permanent. Managing long-term cognitive problems may include:

  • stimulants to improve concentration and memory
  • cognition-enhancing drugs, such as those used to treat Alzheimer’s disease
  • antidepressants, if cognitive problems are due to or made worse by depression
  • opiate antagonists (drugs that work against opioids such as morphine) to make you less drowsy
  • cognitive training to help improve cognitive skills and help you cope with cognitive problems
  • occupational therapy to help you with daily activities
  • vocational rehabilitation to help with job-related skills
  • psychosocial counselling and support for both you and your family

Talk to your healthcare team about how they can help you manage cognitive problems. A counsellor trained in neuropsychology can help support you during cognitive rehabilitation and adapt the rehabilitation as your needs may change over time.

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Coping strategies

Many people with cognitive problems feel frustrated, defensive and embarrassed about their reduced abilities. It is also common for caregivers to feel frustrated and helpless. Recovery from cognitive problems is different for each person. It will depend on the extent of the disease, the type of treatment and other factors.

You can try the following strategies to help you cope with thinking, memory and attention problems.

Use different tools to help you remember

Keep a record of your symptoms. This record might help you figure out when you become more distracted. It can also show if your memory is worse when you are tired or hungry or at other times. Knowing when your cognitive function is at its best or worst can help you plan your day so that you do more difficult tasks when you feel the best.

Keep a checklist of daily reminders in a handy location at home and a copy at work so you can look at it throughout the day. Have a notepad and pen with you so you can easily write down notes and reminders. You can also use a note-making app on your smartphone or tablet.

Use a calendar or daily organizer to remember appointments, activities and important dates. Set reminders on your phone or email calendar. You can also place sticky notes around the house to remind you of important tasks.

Try to take on one task at a time and avoid distractions.

Take care of yourself

Physical activity, such as walking, swimming or gardening, can help make you mentally alert. It is also important to get plenty of rest and try to reduce your stress. Yoga or meditation can help you relax and think clearer.

Exercise your brain. Try different activities, such as doing jigsaw or crossword puzzles, painting, playing a musical instrument or learning a new hobby. Word play, such as rhyming, can also help you remember things.

Talk to your family and friends about how you feel and how changes to your cognitive function affect you. They can better support you if they understand how you feel. They may also have some suggestions about how they can help.

Talk to your employer about getting support if you have problems at work, such as managing your workload or meeting deadlines.

Talk to your healthcare team

Ask questions at your appointments. You can also take a friend or family member with you to take notes so that you can go over what was said after the appointment.

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Suppression of the body’s immune system so it is less able to fight infections or diseases.

Immunosuppression can be caused by certain diseases, such as AIDS or lymphoma. It may also be a side effect of certain chemotherapy drugs. Doctors may also deliberately suppress the immune system before organ or stem cell transplants to prevent rejection.

Also called immunocompromised.


A drug that fights infections caused by bacteria and other micro-organisms.


Any steroid hormone that acts as an anti-inflammatory by reducing swelling and lowering the body’s immune response (the immune system’s reaction to the presence of foreign substances).

Corticosteroids are made by the adrenal gland. They can also be produced in the lab.


Dr Connie Eaves Tracking how stem cells grow

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