Chemobrain: When cancer treatment disrupts your thinking and memory

For years people undergoing cancer treatment have described their minds as being in a fog — unable to concentrate and remember details about their everyday lives. Doctors and researchers knew something was wrong, but they couldn't pinpoint what it was.

Research now shows that what these people are experiencing is called mild cognitive impairment — the loss of the ability to remember certain things, learn new skills and complete certain tasks. The cause of mild cognitive impairment during cancer treatment still isn't clear, nor is it clear how often it happens or what may trigger it. Doctors aren't sure what they can do about it.

But that doesn't mean there isn't any hope. Recognize mild cognitive impairment and its association with cancer treatment, and talk to your doctor about your symptoms or concerns. Taking small steps can help you cope with changes in your memory during treatment.

What is chemobrain?

The terms "chemobrain" and "chemofog" refer to cognitive changes during and after cancer diagnosis and treatment. Though these terms imply a relation to chemotherapy, it isn't clear that chemotherapy is responsible. Women with breast cancer who underwent chemotherapy were the first group to bring these symptoms to light, as more started mentioning their symptoms to their doctors. It isn't clear whether chemotherapy, or other factors such as stress and hormonal fluctuations, cause the changes in memory and thinking. What is clear is that some people with cancer do notice increased difficulties with certain mental tasks during and after cancer treatment.

In general, researchers have found that chemotherapy can affect your cognitive abilities in the following ways:

• Word finding. You might find yourself reaching for the right word in conversation.
• Memory. You might experience short-term memory lapses, such as not remembering where you put your keys or what you were supposed to buy at the store.
• Multitasking. Many jobs require you to manage multiple tasks during the day. Multitasking is important at work as well as at home — for example, talking with your kids and making dinner at the same time. Chemotherapy may affect how well you're able to perform multiple tasks at once.
• Learning. It might take longer to learn new things. For example, you might find you need to read paragraphs over a few times before you get the meaning.
• Processing speed. It might take you longer to do tasks that were once quick and easy for you.

About 20 percent to 30 percent of people undergoing chemotherapy will experience cognitive impairment, though some studies report that at least half the participants had memory problems. One study found 35 percent of women with breast cancer had memory problems before beginning chemotherapy, so it's not clear how or if memory changes are related to cancer treatment. Signs and symptoms of these memory changes can last for a year or two after your treatment.

Changes in memory during and after treatment may be very subtle. You might notice changes during your everyday tasks and as you start working again after treatment. The memory changes are often so subtle, in fact, that researchers find that people who report having memory difficulties tend to score in the normal ranges on tests of their cognitive ability. That makes it more difficult to understand, diagnose and treat the memory changes.

What causes the memory changes?

Doctors don't know what causes the cognitive changes associated with chemotherapy. It was previously thought that chemotherapy drugs didn't enter your brain, but were kept out by the blood-brain barrier, which separates chemicals that should be in your brain from those that shouldn't. But some researchers now suspect some chemotherapy drugs may be able to slip past the blood-brain barrier. This could potentially affect your brain and your memory.

It isn't clear which chemotherapy drugs are more likely to cause memory changes or if higher doses pose a bigger risk than do smaller ones. And it isn't possible to predict who's more likely to have cognitive impairment after chemotherapy.

A number of factors can cause temporary memory problems in people undergoing chemotherapy — making it difficult to identify the so-called chemobrain from the normal stresses of treatment. Temporary memory problems can, for the most part, be treated. Causes include:

• Low blood counts. If your blood counts are low, you might feel tired, making it difficult to concentrate.
• Stress. Being diagnosed with cancer and starting treatment is stressful. Stress also makes concentrating difficult.
• Medication to treat side effects. Certain medications for treating side effects including nausea and vomiting may cause drowsiness. When you're tired, it may take longer to complete tasks.
• Lingering depression. Depression is common in people with cancer. If your depression continues after your treatment, you might find it difficult to pay attention.
• Lingering fatigue. Fatigue is a side effect of several types of cancer treatment, including chemotherapy. Your fatigue might end when your cancer treatment ends, though it also can continue after treatment.
• Hormonal changes. Many cancer treatments may alter the normal hormonal balance in your body, causing cognitive changes. Hormonal changes are a side effect of some treatments and, with other treatments, are the intended way to treat your cancer.
• Pain medications. Some pain medications cause drowsiness and difficulty concentrating. For most people, these side effects diminish or disappear once a proper dose of pain medication is established.

Talk to your doctor about your memory problems. If your symptoms are caused by medications or stress, your doctor can treat those symptoms and help get your mind back on track.

How are memory changes treated?

If you have impaired memory, your doctor may first try to rule out other causes of memory problems, such as stress and depression. Currently no medications exist to treat cognitive impairment associated with cancer and its treatment. Researchers are investigating whether medications for such disorders as depression, attention-deficit hyperactivity disorder (ADHD) and dementia could prove effective.

You can help yourself cope with the changes in your memory by taking a few simple steps. You might want to:

• Exercise your body. Aerobic exercise helps your mood and can make you feel more alert. Both can help you when it comes to concentrating.
• Exercise your mind. Give your mind a workout by learning a new skill, such as a new language. Take a class, participate in a book club or try crossword puzzles.
• Track your memory problems. Keep a detailed diary of your memory problems throughout your day. Carry your diary with you and take quick notes on what medications you take and when. Note the time of day your memory problems occur and the situation.
• Target specific problems. Use your daily diary to determine what influences your memory problems. If they tend to crop up in the early afternoon, you may be able to prepare yourself by not scheduling meetings or deadlines at that time of day.
• Take notes. Make a list of everything you need to accomplish today and use it as a guide. Take detailed notes of things you need to remember.
• Start a routine. Put your keys or other commonly misplaced objects in the same place every time you set them down. Try to keep the same schedule every day.
• Talk about your problems. Be open with your friends and family about what you're experiencing. Let them know your mind is moving a little slower these days and explain how they can help you. This can help you relax and make it easier for you to think and process information.

Find the coping method that's best for you and stick to it. Talk to your doctor about your concerns. He or she might have some other suggestions.

What other types of cancer treatment might cause cognitive impairment?

Chemotherapy isn't the only cancer treatment that may cause memory and thinking problems. Other treatments that might affect your brain include:

• Hormone therapy. It isn't clear whether women undergoing hormone therapy that alters the amount of estrogen in their bodies experience memory problems. Some studies link memory function to the amount of estrogen in the brain. Other studies haven't found this link.
• Immunotherapy. This experimental therapy stimulates your body's own defenses to fight your cancer. Treatment with cytokines — a type of protein that causes inflammation in your body — may cause problems with memory, multitasking and processing information.
• Radiation therapy. Radiation to your brain can impair your memory and your motor function, as well as your ability to learn new things and to multitask. Older adults and people receiving high doses of radiation are at a greater risk of memory problems. If you receive both chemotherapy and brain radiation, your risk is also higher.

As research continues, doctors expect to better understand which cancer treatments cause cognitive impairment and what they can do to limit their side effects.

Take note of any memory problems

If you're currently undergoing cancer treatment or you've already been through treatment, take note of any problems you have remembering certain things or concentrating during certain tasks. Talk to your doctor about your signs and symptoms.

If you've yet to start your treatment, talk to your doctor about the risks of treatment, including cognitive impairment. Understanding your risks can help you make more informed decisions about your treatment.

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