What is “Chemo Brain?”

Image courtesy Salvatore Vuono at http://www.freedigitalphotos.netIn the last year, I’ve spoken to quite a few cancer survivors, and many of them have used the term “chemo brain.”  They do so half-jokingly, but also with some seriousness, to describe the cognitive changes that take place when a person is receiving chemotherapy — and also for some time after treatment is over.  After doing some research, I found that this is a very real and measurable phenomena that is being studied by a number of scientists.  It is not classified as a dementia, per se, but is notable for the purposes of this site due to the very nature of the symptoms associated with it.

The condition commonly called “chemo brain” or “chemo fog” is also known by the slightly more scientific names of post-chemotherapy cognitive impairment or chemotherapy-induced cognitive dysfunction.  Attention was brought to the condition, at least partly, due to the large numbers of breast cancer survivors who reported experiencing problems with memory, fluency, and other cognitive functions after completing chemotherapy.  But any cancer patient, especially those undergoing aggressive chemotherapy, may have varying degrees of difficulty both while undergoing treatment and for as long as several years afterward.

The significance of PCCI goes far beyond just the functional problems encountered by those who experience it.  There are an increasing number of cancer survivors in the population, in part due to the development of more effective forms of treatment.  However, many of these treatments are aggressive in nature, and while they are wonderfully effective in eradicating the cancer, they also often produce numerous unpleasant side effects.  There are times when fear of these side effects can negatively influence patients’ decisions.

The most common symptoms associated with PCCI include those affecting visual and semantic memory, as well as attention and motor coordination.  Quality of life can be quite significantly impaired, especially when it comes to making decisions with regards to treatment as well as work or school.  Many persons complain of difficulty with divided and alternating attention, comprehending what they have just read, paying attention to and understanding a conversation, and word-finding problems.  Other symptoms that have been reported include being unusually disorganized, confusion, difficulty concentrating, difficulty learning new skills, fatigue, feeling of mental fogginess, short-term memory problems, and taking longer than usual to complete routine tasks.  Factors that have been noted to increase risk that a person will develop PCCI include brain cancer, chemotherapy given directly into the nervous system, chemotherapy combined with whole-body radiation, higher doses of chemotherapy or radiation, and a younger age at time of diagnosis and treatment.

Something that I have noticed, when speaking with cancer survivors, has been supported in the research.  Many of these people go into treatment with the expectation that their lives will return to normal once treatment is completed and the cancer has been eradicated.  However, they find themselves surprised and dismayed to discover that some effects can linger for some time afterward.  While these impairments are temporary in nature, they can at times last for as long as 10 years after a person is declared to be in remission.  (Most patients report full return of function after about 4 years or less.)

Much research is still on-going with regards to what causes PCCI, as well as the mechanisms involved.  Theories include a direct effect of chemotherapy drugs on the brain, and also the role that hormones play in the health of the nervous system.  A number of factors, apart from the actual chemotherapy, have been found to enter into the condition’s development and severity.  These include menopause (especially that triggered by surgical removal of the reproductive organs), anesthesia, medications prescribed in addition to the actual chemotherapy, genetic predisposition, hormonal therapy, infection, fatigue, nutritional deficiencies, problems sleeping, emotional factors, co-morbid conditions, and paraneoplastic syndromes.  (Paraneoplastic syndromes can be related to hormones and other substances secreted by tumor cells, or by an immune response to the tumor, and can include conditions such as hypoglycemia and anemia — as well as others.)

Since the exact mechanism of PCCI is still unknown, treatment options are still relatively theoretical.  Some that have been suggested include the use of antioxidants, cognitive behavior therapy, erythropoietin and stimulant drugs such as methylphenidate.  A wakefulness-producing agent used for the treatment of narcolepsy, Modafinil, has been used in off-label trials, and has shown some benefit for breast cancer patients.  Estrogen replacement therapy has also shown some improvement in symptoms, although this regimen has been associated with other possible problems.

Most of the research that has been done into PCCI have utilized small samples, and have focused on younger patients.  This has led to some difficulty quantifying and generalizing results.  One study used neuroimaging, via MIR, to compare brain volumes in breast cancer patients who had undergone chemotherapy with those who had not.  One year after completion of treatment, chemotherapy patients were found to have smaller brain volumes, however at three years the differences in brain volume was no longer significant.  In another study using PET scans, chemotherapy patients were found to have significantly altered blood flow in the brain, particularly in the frontal cortex and cerebellum.

The severity and duration of symptoms of PCCI vary greatly from person to person.  Some may be able to go about their daily activities with only minimal disruption of function.  Others may be unable to work.  Those who experience significant difficulties may find it helpful to consult with a speech-language pathologist or occupational therapist, who can suggest compensatory strategies to aid function.  It is only rarely that people are unable to return to work at all.  It may be helpful to keep a journal of when problems occur, and see if there is any detectable pattern that may assist in dealing with it.  One thing that has been found to be successful is to attempt to eliminate other factors that may be influencing the cognitive difficulties.  These can include making sure that you get enough sleep, eat right, and do whatever you can to minimize problems such as anemia and those difficulties associated with menopause.  Stress relief techniques, organizational strategies, exercises to increase concentration and memory, and physical exercise, can also be of help.



Mayo Clinic


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