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Chemo brain

What is chemo brain?


What chemo brain is

After cancer treatment, some people notice changes in their memory, concentration and the way they think. Women with breast cancer were the first to report these problems, which they linked to their chemotherapy treatment. So they called the changes chemo brain. Another name people use is chemo fog.

It is not clear exactly what causes these memory and concentration changes in people with cancer. So calling them chemo brain may not be accurate. Mild cognitive impairment (MCI) is a more accurate description used by doctors. Another name is cognitive dysfunction.

People use the word cognitive or cognition in different ways. It basically means thinking. In psychology, it means the way you process information or understand the world and how it works.

Most people who have cognitive changes are able to do everyday things. But they may notice they aren’t able to do some things quite as well as before they had cancer. Symptoms can include

  • Memory loss – forgetting things that you normally remember
  • Difficulty thinking of the right word for a particular object
  • Difficulty following the flow of a conversation
  • Trouble concentrating or focusing on one thing
  • Difficulty doing more than one thing at a time (multi tasking)
  • More difficulty doing things you used to do easily, such as adding up in your head
  • Fatigue (tiredness and lack of energy)
  • Confusion
  • Mental fogginess

The changes are often mild and very subtle. But if you have them they can reduce your quality of life. Doctors now know that people with different types of cancer may have these problems. So it’s not just breast cancer – and it may not just be chemotherapy that causes the problems.


Who gets chemo brain

It is not certain how many people have mild cognitive impairment after cancer. A review looked at women with breast cancer and suggested the number of women with cognitive impairment is somewhere between 17 out of every 100 (17%) and 50 out of every 100 (50%). We need more research to confirm how many women with breast cancer have these problems.

A review of studies in 2008 showed that some men having prostate cancer treatment to lower testosterone levels had cognitive impairment. Between about half and about two thirds of the men in these studies had these types of changes. The men showed difficulty in coping with problems that involved mentally rotating objects in space (spatial ability) and problems with multi tasking. But we need larger, more thorough studies that include brain scans so we can understand more about how prostate cancer treatment affects thought processes. We also need more research to find out how many people with other types of cancer are affected.


How chemo brain may affect you

The symptoms of cognitive impairment can come and go. How much you notice them seems to depend on what you are doing. For example, if you need to juggle a number of things as part of your normal day, you may notice it more than someone who doesn’t. People often notice it more when they go back to work. Tiredness usually makes the symptoms worse.

For most people, the symptoms have either gone or really improved within a year of ending treatment. But for some people the symptoms can be long term and may continue for years after treatment has finished.

Research suggests that people who have mild cognitive impairment are also more likely to have depression, anxiety, and fatigue. We don’t know whether the causes of these are the same as the causes of cognitive impairment, or whether one leads to the other.

One of the problems with testing for these changes is that current psychological tests are not always sensitive enough to pick up the sort of problems that people have after cancer. So people who say they are having problems tend to come out of the tests with results that the researchers would describe as a normal score.


Causes of chemo brain

We don’t know what causes mild cognitive impairment. Research suggests that there may be a number of factors that contribute to it, including


So far, research hasn’t clearly shown whether chemotherapy causes these thought and memory changes. Early studies only tested people after their chemotherapy. These tests showed that people had cognitive impairment. But more recent research has shown that some people with cancer have similar problems before they start any treatment and that the changes may even improve during treatment. This implies that it’s something to do with having cancer, rather than having cancer treatment.

German researchers looked at women with breast cancer before, during and after chemotherapy. Their research suggested that other unknown factors affect thought processes before chemotherapy, but that chemotherapy may make these problems worse in some women.

Research looking at other types of cancers has shown that chemo can cause thought and memory problems. In 2008, Swedish researchers found that men with testicular cancer who had 4 or more cycles of chemotherapy could be at risk. They tested men who had treatment between 4 and 21 years ago. The men had problems with some aspects of language. They were likely to say similar but incorrect words for things during the tests. About 36 of out every 100 men (36%) who had chemotherapy had problems, compared with about 17 out of every 100 men (17%) who hadn’t had any chemotherapy. But these men were only tested after treatment not before.

Researchers have also used MRI scans to look into whether the brain works differently in people who have had chemotherapy. People in the research study did a memory test. The test started simply and became more difficult. At the same time they had a brain MRI scan. In all groups of people, the researchers could see an increase in the activity in the brain during the test. But the activity was less in the people who’d had chemotherapy.

The researchers also found that the area of the brain dealing with emotions became more active in people who’d had chemo and then reported problems. Unfortunately this study looked at the patients at only one point in time, not before and after treatment. To find out how chemotherapy affects people over time, we need long term studies.

A Dutch trial looked at women with breast cancer and compared different types of chemotherapy. They looked at women before and after treatment and compared them with women not having chemotherapy and women who didn’t have breast cancer. The research found that women treated with high dose chemotherapy were more likely to have cognitive impairment than those treated with standard dose treatment.

Other cancer treatments

Many people have more than one type of treatment for cancer, which makes it difficult to work out what is causing a particular side effect. A small study looked at 31 women treated with the hormone therapies, tamoxifen and anastrozole. They found that women taking anastrozole had more thought and memory problems than women taking tamoxifen. Another study compared women taking tamoxifen with women taking exemestane and with women who hadn't had breast cancer. This study found that the women taking tamoxifen had more problems with memory and organisation skills than those taking exemestane and the women who hadn't had cancer. We need more research to find out what effects hormone therapy and other cancer treatments may have.

Anxiety, fatigue, old age, depression

From research, we know that people who report thought and memory problems after chemo are more likely to have anxiety and depression than people who don’t have these symptoms. But it isn’t clear whether one causes the other. There could be another factor that leads to thought and memory problems as well as anxiety and depression.

In 2008, researchers published the results of a trial with people who had breast or bowel cancer. People with bowel cancer did thought and memory tests before they had chemotherapy. They did the tests again after chemotherapy. The tests were below normal for 30 out of  every 100 people tested before chemo (33%). The problems improved after a while. After 2 years, only 10 out of every 100 people (10%) had below normal results. The researchers in this study suggest that other factors may contribute to cognitive impairment, including anxiety, the cancer itself or other treatments.

Changes in blood proteins called cytokines

Cytokines are proteins made by the body as part of the immune response. Researchers have looked at blood levels of cytokines in women who had treatment for breast cancer. The researchers compared them with cytokine levels in women who didn’t have breast cancer. They found that women with breast cancer had higher cytokine levels. They also found that women who reported thought and memory problems had the highest levels of cytokines. We need more research to find out what this actually means. The researchers are extending their study to include more women who have had breast cancer and also people with other types of cancer.


Future research

In 2006 a group of specialists and patients set up the International Cognition and Cancer Task Force (ICCTF). This group aims to guide future research and give information to patients and doctors about how to manage the symptoms of cognitive impairment.

In research comparing formal brain tests with symptoms reported by patients, more people reported problems than showed up on the formal tests. The researchers suggest that the formal tests aren’t able to pick up the kind of cognitive problems that people with cancer have. We need more research to look at the best way to test people for these slight changes in memory and thought processes.

There is a study trying to find out how chemotherapy can affect the memory of young adults. Many of the studies up till now haven't included this age group. The researchers want to compare the results of tests of young adults having chemotherapy with people of similar ages not having chemotherapy. This study has now closed and we are waiting for the results.


Preventing and treating chemo brain

Doctors have been looking into how to prevent and treat cancer related thought and memory problems. It is still too early to know how well these work but they include

  • Erythropoietin (EPO) – this drug may help by raising haemoglobin levels
  • Aspirin – which works as a mild blood thinning drug
  • Methylphenidate – a type of stimulant for chronic fatigue syndrome, daytime drowsiness and attention deficit disorder

The aim with EPO or aspirin treatment is to maintain or increase blood flow to the brain cells and so increase their oxygen supply. Understanding more about what causes chemo brain will help doctors to find ways of preventing and treating it.


Tips for coping with chemo brain

  • Try to keep your life as simple as possible
  • Avoid trying to do too many things at the same time
  • Think about writing lists about what you need to do, things you need to buy and where you left things
  • Writing people’s names down with a brief description to help you remember them may be helpful
  • Repeating things back to people, for example, the names of people you meet for the first time can help
  • When arranging to meet someone or organising an event it may be helpful to write the details down and repeat them back to someone
  • Try to talk to people somewhere quiet with few distractions
  • Many people find it useful to keep a calendar on your wall
  • It may be helpful to write yourself notes and stick them up where you can see them to remind you to do things
  • Try to follow a healthy diet, and get some exercise and plenty of rest – try to avoid becoming over tired
  • Keeping your mind active may help – for example, doing crosswords, sudoku and puzzles


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Updated: 22 January 2015