Cognitive Dysfunction

During treatment, many people report thinking and memory problems, as if they are in a “mental fog.” They have trouble remembering information such as names, dates and telephone numbers. Many say they have memory lapses in the middle of tasks or conversations and have difficulty paying attention. These symptoms all represent cognitive dysfunction, which is commonly known as “chemo brain.” Originally thought to accompany chemotherapy only, research has shown that cognitive dysfunction is related to many types of cancer treatment, affecting attention, concentration, short-term memory, language skills, organizational ability and math skills. These problems are not typically serious but can certainly be frustrating and affect your quality of life.

What causes cognitive dysfunction?

The cause of cognitive dysfunction, commonly referred to as chemo brain, may be caused by the cancer itself or by its treatment, such as chemotherapy, radiation therapy, hormone therapy and surgery. Combination therapies further increase the risk. It may also be caused by conditions related to cancer treatment, such as anemia, fatigue, infection, pain, hormone changes, sleep problems, nutrition problems, stress, anxiety and depression.  

When does cognitive dysfunction typically occur?

Cognitive dysfunction often begins slowly. It can occur during treatment as well as months or years after the end of treatment. It is generally short-term, but how long it lasts varies from person to person.

How you can manage cognitive dysfunction

Research is underway to determine how to best manage cognitive dysfunction. Some people find the following helpful:

  • Track your symptoms so you and your health care team can see any patterns. Note when they occur, how soon after treatment they start and whether anything makes them better. Download a free symptom tracker at
  • Use a calendar or daily planner. Write down all appointments, activities, medication schedules, important dates (birthdays and anniversaries), “to do” lists, phone numbers and addresses, etc.
  • Keep important items, such as your keys, wallet, purse and phone, in a basket in the same place so they are always where they should be.
  • Exercise your brain. Read a book or magazine every day, do crossword puzzles or word or number games, do jigsaw puzzles, play card games, play a musical instrument or learn a new language.
  • Get physical exercise. Walk, swim, ride a bike, do aerobics, practice yoga or garden.
  • Avoid alcohol and other substances that can disrupt your cognitive function.
  • Follow a nutritious diet.
  • Stay rested. Fatigue can worsen cognitive dysfunction.
  • Don’t try to multi-task. Focus on one thing at a time.
  • Ask for support. Tell friends and family that you’re having cognitive problems.
  • Ask people to repeat information or to write down new information (phone numbers, dates, etc.). Take a caregiver or friend with you to medical appointments to help you keep track of what is said during the visit and share their opinion of your cognitive issues.

When to call your health care provider

Before treatment begins, if possible, ask about the possibility you may experience cognitive dysfunction. If you are at risk, consider your age, predisposition for cognitive decline or any other condition that may worsen if you begin a therapy that has cognitive dysfunction as a side effect. 

Contact your health care team when you first notice symptoms. Your health care provider may order blood tests and neuropsychological testing to see whether they are caused by a condition something other than your treatment, such as anemia, a chemical imbalance in your blood, dementia or Alzheimer’s disease.

If no underlying cause is found, your health care provider will suggest ways to cope and improve your mental processing. Additional treatment options are available for cognitive dysfunction that gets worse or continues for many months after treatment.

If you notice your symptoms suddenly get worse or you have new ones, contact your health care team right away. They can evaluate whether they are signs of metastasis or another medical issue. If you have any other neurological symptoms such as headaches, new balance problems or weakness/numbness in a body part, an MRI of the brain may be recommended.