What is Chemobrain:
"Chemobrain" is a term used to describe a number of thinking or memory problems that may occur in some individuals after they receive chemotherapy. While other long term side-effects of chemotherapy are well recognized (such as heart problems and fertility issues), an increasing amount of evidence now shows that many individuals may face problems related to the mind as well.
The Problems that May Occur:
From a few months after chemotherapy to many years later, some individuals may face a range of difficulties. Together they are termed cognitive defects – problems in perception, reasoning and learning. Here are some of the common complaints:
- Short-term memory lapses – forgetting where you put the TV remote, or what you came to buy at the store.
- Difficulty in finding the right word in a conversation.
- Doing multiple jobs at the same time – both at work as well as at home.
- Taking more time to learn new things
- Taking more time to perform tasks that were earlier completed easy and quickly.
Chemotherapy, Cancer, or Simply Fatigue:
The fact that cognitive issues do arise after chemotherapy is well established. However some researchers feel that the two may not be directly related. A number of studies now show that in some people at least, cognitive problems are occuring even before chemotherapy starts. Is it the cancer itself that causes these cognitive problems? There are others who suspect that it is the chemotherapy-related fatigue may be at the root of the problem. As more studies explore this issue, the exact extent of damage caused by chemotherapy itself will become clearer.
Chemotherapy's Effects on the Brain:
It is not completely understood how chemotherapy may damage the brain. The brain is protected from the effects of most chemotherapy drugs by a system known as the "blood-brain barrier" (BBB) that prevents most drugs from reaching the brain. Few of the chemotherapy agents used for cancers in which the cognitive defects have been identified can cross the BBB. It seems that drugs like adriamycin used for cancers like breast cancer and lymphoma may produce toxic agents called "free radicals" that may reach the brain and cause damage.
Not Everyone Experiences Cognitive Damage:
Even with the same disease and the same doses of chemotherapy drugs, the cognitive changes are not found in all individuals. It seems that certain people may be more susceptible to chemotherapy related changes. A number of studies have attempted to identify the factors, including a particular type of fat-carrying protein gene called Apo-E that has also been linked to Alzheimer's disease. Research on this issue is just starting and there may be a long way to go.
In general, the thinking and memory problems are mild and do not require any active treatment. However, the hunt has begun for a drug to improve the cognitive function. An agent called dexmethylphenidate (Focalin® or d-MPH) has been tested in a trial against fatigue and cognitive problems after chemotherapy. It is a drug used for a common childhood problem called attention deficit hyperactivity disorder (ADHD). It was found to definitely improve fatigue and may also have a beneficial effect on thinking and memory problems. If further trials confirm a benefit of this drug, it may be good news for many survivors.
Sources of Information:
'The relationship of APOE genotype to neuropsychological performance in long-term cancer survivors treated with standard dose chemotherapy.' Psychooncology. 2003 Sep;12(6):612-9.
National Cancer Institute - Clinical Trial Results - Dexmethylphenidate Reduces Some Symptoms of Chemobrain (url: http://www.cancer.gov/clinicaltrials/results/chemobrain0605)