April 2018 Ask the Expert: Chemobrain

April 2, 2018

If you’ve had trouble concentrating on a task, remembering words or directions, doing several things at once, or recalling a date or phone number, you may be experiencing cognitive changes after cancer treatment, often called “chemobrain.” It’s normal to feel frustrated or worried about these symptoms.

In April, Living Beyond Breast Cancer expert Arash Asher, MD, answered your questions about chemobrain, including how to recognize it, what may cause it, and how to manage it.

Remember: we cannot provide diagnoses, medical consultations or specific treatment recommendations. This service is designed for educational and informational purposes only. The information is general in nature. For specific healthcare questions or concerns, consult your healthcare provider because treatment varies with individual circumstances. The content is not intended in any way to substitute for professional counseling or medical advice.

What causes chemobrain?

The term “chemobrain” may not be the best word to describe this problem, although the assumption was that chemotherapyinfo-icon was the cause of these problems (therefore: “chemobrain”). However, many chemotherapy drugs do not readily cross the blood-brain barrierinfo-icon and affect the brain. Many scientists believe that symptoms develop from the body’s reaction to chemotherapy. The immune systeminfo-icon releases a number of chemicals (such as inflammatory cytokines) to counteract injury or disease, such as when someone comes down with the flu. Elevations in these chemicals can make one feel achy, foggy, fatigued – forcing one to rest: Think about how it feels to have the flu. One prevailing theory is that chemotherapy triggers the release of these chemicals and contributes to fuzzy or foggy thinking commonly called “chemobrain.” 

Recent research suggests factors other than chemotherapy may be playing a role in the cognitive symptoms reported by patients with cancer, including: 

  • Radiation therapyinfo-icon
  • The cancer itself
  • Hormonal changes from drugs that are used to treat some types of breast cancer by blocking estrogeninfo-icon, such as tamoxifeninfo-icon or anastrozoleinfo-icon (Arimidex), or by blocking testosterone for those treated for prostate cancer 
  • Poor sleep
  • Side effects from other medications (such as pain medications, some nauseainfo-icon medications, corticosteroids) that are often used during some cancer treatments 
  • Elevated stressinfo-icon, anxietyinfo-icon, or depressioninfo-icon

How long does chemobrain last? Will it eventually go away?

Nobody knows for sure how long it may last for each individual and it can depend on a number of factors, including your age, whether you may be on anti-estrogeninfo-icon therapyinfo-icon like tamoxifeninfo-icon or anastrozoleinfo-icon (Arimidex), other medical issues you may have that may be contributing, such as thyroid issues, insomniainfo-icon, etc. That said, it seems that about 80 percent of breast cancer survivors return to their cognitive baselineinfo-icon within 6-12 months of finishing treatment with chemotherapyinfo-icon, radiation therapyinfo-icon, or both.

Can chemobrain get worse as I age?

For all of us, there is a natural, expected gradual decline of cognitive functioning as we age. I would not expect the symptoms of chemobrain to get worse after treatment has ended. If you do notice worsening symptoms over time, it would be important to talk to your doctor to evaluate for other causes that may be contributing to your symptoms. 

I am a 15-year breast cancer survivor and my bad memory comes in waves. I have good memory days, where I can recall facts and figures. But I also have bad memory days, where finding the correct words and recalling memories are difficult. Is this normal?

Many patients report that symptoms may fluctuate. This may be related to a number of factors. I suspect the most important of these factors include:

  • Sleep: Almost everyone does more poorly with reaction time, word-finding, memory, and concentration with less than optimal sleep (for most adults this would be at least 7-8 hours).
  • Stressinfo-icon
  • Symptoms of depressioninfo-icon, anxietyinfo-icon or both

How do I tell the difference between chemobrain and the start of dementia/Alzheimer's disease?

This is an excellent question and I realize an important worry for many patients. First, it should be pointed out that there are many types of dementia and that they may have different symptoms associated with them. Alzheimer’s dementia is the most common and often the fear for many patients if they experience cognitive symptoms after cancer treatment. For example, declarative episodic memory is a type of memory often impacted by Alzheimer’s dementia. Declarative episodic memory is the memory of events occurring at a particular time and place and is usually profoundly affected in Alzehimer’s dementia. Examples of this include remembering the name of your pet dog growing up, the name of your fourth gradeinfo-icon teacher, or where you were when you heard about the 9/11 terrorist attacks. These types of memories generally aren’t impacted by chemobrain but are usually profoundly affected in Alzheimer’s dementia. Furthermore, with Alzheimer’s dementia, other patterns emerge that don’t often occur with chemobrain. This includes the gradual progressioninfo-icon of cognitive symptoms and visual-spatial skills being affected (such as being able to drive a car). With more advanced Alzheimer’s dementia other problems emerge, such as behavior issues like becoming agitated, or having hallucinations, or problems with motor tasks, such as not being able to show how you would use a comb. None of these problems occur in chemobrain.

Are there any studies showing whether chemobrain relates to Alzheimer's in any way? Can chemobrain cause Alzheimer's or make it happen earlier?

There is no evidence that chemobrain relates to Alzheimer’s dementia, which is reassuring! That said, there are concerns that some patients who already have early dementia may have some of their dementia symptoms “unmasked” or sped up by cancer treatment. If there are concerns that your symptoms may be related to something more serious than chemobrain, it would be a good idea to talk to your doctor, or consider seeing a neurologist for an evaluation for this. This evaluation may include imaginginfo-icon tests (such as an MRIinfo-icon or some specialized types of PET scans), neuro-psychologicalinfo-icon testing, and blood tests to rule out other problems. It should be pointed out that among patients with chemobrain, the results of neuro-psychological testing (comprehensive testing that tests various aspects of cognitioninfo-icon) are often normal. I don’t believe that this means that the symptoms are not real, but that often the symptoms of chemobrain are subtle, and that often memory testing in idealized environments (no noises, no distractions, etc) does not simulate the often chaotic experience of “real life” and therefore may not always pick up on the cognitive concerns that patients describe. 

How common is chemobrain?

Researchers are not sure exactly how common chemobrain is because of a variety of challenges of research in this arena. These challenges include:

  1. The fact that many studies historically did not test cognitioninfo-icon before the start of chemotherapyinfo-icon and other cancer treatment.
  2. There is research showing that up to one out of every three or so patients with “chemobrain” may actually demonstrate some cognitive challenges BEFORE they start any chemotherapy and cancer treatment. The reasons for this are not clear, but one theory is that the risk factors for developing cancer may be similar to the risk factors for developing mild cognitive issues.
  3. It’s hard to compare how common chemobrain is within the different chemotherapy types, different cancer types, varying lengths of treatment, different ages of patients in studies, etc.

All of these complexities aside, the most recent evidence suggests that up to 75 percent of patients may experience chemobrain symptoms DURING active treatment (chemotherapy, surgeryinfo-icon, radiationinfo-icon, etc.). In my experience these symptoms aren’t very troublesome because our patients often are not focused on this issue when going through the rigors of active treatment. But, about 20 to 30 percent of patients continue to experience chemobrain symptoms after treatment has ended. I believe it is these patients that would benefit from more research to figure out the best ways to improve chemobrain symptoms. As you can see, for many patients, thankfully, the symptoms improve (typically within 6 to 12 months after treatment has ended).

Can chemobrain be prevented?

I don’t think anybody has an answer for this, yet. There is some preliminary research that moderate-intensity aerobic exerciseinfo-icon (e.g. brisk walking, cycling, dancing, etc.) during active treatment with chemotherapyinfo-icon can minimize chemobrain symptoms. More research is needed. That said, given the clear evidence that exercise helps with fatigueinfo-icon, bone health, anxietyinfo-icon, muscle strength, etc., I do believe strongly we should encourage all our patients to participate in an exercise program that is safe, even during active treatment.

Is there anything I can do to stop or improve the symptoms of chemobrain?

There is some early evidence that aerobic exerciseinfo-icon can help with the resolution of chemobrain symptoms (although, again, more research is needed). Most of the small studies in this arena have looked at aerobic exercise and mind-body exercises such as yogainfo-icon or tai chiinfo-icon. These exercises might be helpful not only because aerobic exercise seems to help optimize brain health (by decreasing inflammationinfo-icon, stimulating brain-derived neurotrophic factor — which helps act as a “fertilizer” for supporting brain cells — improving blood flow to the brain, etc.) but also by reducing distressinfo-icon and symptoms of depressioninfo-icon.

It should be emphasized that although chemobrain and depression are different entities, there is a significant amount of overlap between the two processes. It would be important to work with your physicianinfo-icon to look for symptoms of depression and treat it, if present, because treating depression may improve cognitive symptoms as well. Treatment for depression may include therapyinfo-icon and medications. Other recent, evolving research has shown some benefit from meditation practices such as mindfulness-based stress reduction (MBSR) programs, which can be incredibly helpful, not just for stressinfo-icon and anxietyinfo-icon but also with providing a sense of control and improving cognitive symptoms.

Would taking hormonal therapy for 10 years make chemobrain more likely than taking it for 5 years?

The research has not clearly answered this important question either. One recent study following women taking hormonal therapyinfo-icon found they had an increased likelihood of having cognitive symptoms compared to women who were not on hormonal therapy (e.g. tamoxifeninfo-icon, anastozole (Arimidex), etc.) at 6 months and 1 year after the start of this treatment. We need more research to see how women do over 5 and 10 years. Pragmatically, I believe the answer rests on how you are doing with the hormonal therapy. Some women experience no symptoms and I suspect for these women, continuing hormonal therapy for 10 years instead of 5 years will not add to the toxicityinfo-icon. If you are one of the women experiencing cognitive symptoms with hormonal therapy, it might be reasonable to assume that these symptoms would last longer with the longer 10 year course.

That said, again, more research is needed. It should be noted that based on my experience and some research, women who were taking estrogeninfo-icon therapyinfo-icon prior to their breast cancer diagnosisinfo-icon and then start on anti-estrogen hormonal therapy seem to have more trouble than women who were not on estrogen replacement therapyinfo-icon. This may be because the brain has already been “primed,” or accustomed to, the supplemental estrogen and may have more trouble when they are given a drug to block estrogen production. 

Are people with metastatic breast cancer more likely to get chemobrain or to get it worse than people whose treatment ends?

Learning about the pervasiveness of chemobrain in metastaticinfo-icon breast cancer certainly deserves much more research and attention as well. I am not aware of any research looking specifically at this question. My experience would say that the symptoms are not necessarily “worse” but may be longer lasting because the treatments may be longer lasting. It is also worth pointing out that some recent research is suggesting that a significant degree of the “chemobrain” symptoms are not from chemotherapyinfo-icon but rather post-traumatic stressinfo-icon-type symptoms. If this is true, this underscores the importance of resiliency, strategies for coping with stress, support systems to endure and rise above the challenges with the more prolonged (and sometimes indefinite) treatments needed for women with metastatic breast cancer.

What is your opinion on taking nootropics [sometimes called “smart drugs” or “cognitive enhancers”] for chemobrain?

Many classes of medications and supplements can be considered nootropics. The ones studied to a greater degree include “stimulants,” drugs such as methylphenidate or modafinil (Provigil). Unfortunately, there is not clear evidence that they are helpful for symptoms of chemobrain (although some studies showed some benefit for some individuals). In addition, these medications can sometimes be habit forming and may have side effects. In my own practice, I use a stimulant occasionally for patients when

  1. there is evidence of impaired concentration/attention on neuro-psychologicalinfo-icon testing
  2. non-medication options (such as exercise, mindfulness, therapyinfo-icon) have not helped adequately or
  3. in situations when there are high levels of fatigueinfo-icon and the requirement for chemotherapyinfo-icon continued indefinitely (such as in the situation of metastaticinfo-icon breast cancer)

Supplements included in the nootropic category may include things such as omega-3 fatty acids, ginkgo biloba, ginseng, etc. Again, unfortunately, more research is required to answer whether any of these would be useful for chemobrain. There already is reasonable evidence that American ginseng may be useful for cancer-related fatigue. Since there is so much overlap with the symptoms of fatigue and chemobrain, I do occasionally use this supplement as a trial to see if this helps.

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