In a fog

On a recent social media post, we asked our followers to tell us about a topic they wanted to learn more about. The most popular response? Chemo brain, also called chemo fog.
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You asked, we answered. Read on for:

Five facts + twelve clinical takeaways about chemo brain

Written by: Grace Neubauer, MS, CCC-SLP
Edited by: Natalie Douglas, PhD, CCC-SLP
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“I lost the capacity to multitask and to hold a string of ideas in my head. I groped for the right word that I knew would express what I wanted to say, and lost the ability to hold a thought in my mind if I had to wait a few minutes for my turn to speak. It felt like a mental fog had descended over me; I might begin a sentence knowing what I wanted to say, but by mid sentence I’d lost the sense of it and stumbled finding the words or had to stop speaking altogether. I could no longer do crossword puzzles; I would remember that I used to know the word, it might sit just out of reach in my mind, but I could no longer reliably retrieve it. I used to always rely on a nimble mind and strong facility with language, but could no longer trust my mind or memory. I lost the ability to discuss a book. I’d struggle to remember something I’d just read. Some of this has improved over the years since my transplant, but much has remained.”  ~ On living with chemo brain, contributed by Susan Evans (mom of TISLP Editor Karen)

Fact #1: The term “chemo brain” refers to cognitive changes related to chemotherapy for non-central nervous system (CNS) cancer (i.e., not the brain or spinal cord).

This is true. But did you know that “chemo brain” is a misnomer? A common term found in the research is “cancer related cognitive impairment” (CRCI). This is because cognitive impairment in individuals with cancer* has been shown before, during, and after treatment, even in those who did not undergo chemotherapy. These patients commonly report changes in memory, processing speed, and executive functioning (Parsons & Dietrich, 2019). Horowitz et al. (2018) include language or verbal ability and visuospatial processing too. Importantly, deficits can be subtle. More on that later.
Ehrenstein et al. (2020) discuss how chemotherapy is a risk factor for CRCI, but cognitive changes have also been seen post-surgery, in other adjuvant therapies, and could be caused by the cancer itself. Radiation and hormonal therapy may also impact cognition (Janelsins et al., 2014). Horowitz et al. (2018) suggest that cognitive reserve and genetics likely influence who is most impacted by CRCI. They also discuss several proposed reasons why CRCI occurs, though there are several theories. Jia et al. (2020) suggest inflammation, genetics, and DNA damage may contribute. Lange et al. (2019) refer to several studies that have demonstrated evidence of CRCI with neuroimaging.
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Clinical takeaway 1: You hear colloquial terms like “chemo brain” and “chemo fog” to refer to cognitive changes + cancer. But if you only target individuals who actually received chemotherapy, you may not reach all those who need your services.

For the purposes of this blog post, “chemo brain” will now be referred to as CRCI.
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Fact #2: Much of what we know about CRCI is thanks to individuals with breast cancer.

Overwhelmingly, the articles reviewed for this blog post studied individuals with breast cancer. Janelsins et al. (2014) acknowledge how much we do not know about other types of non-CNS cancers and CRCI. This article also gives a great summary of the timing of CRCI seen in the research, but it is several years old. The same lead author published another article in 2018 and found cognitive changes can affect breast cancer survivors for at least six months post-treatment.

Clinical takeaway 2: We owe a lot to individuals with breast cancer for their participation in research. Until we have more robust research about CRCI in different types of patients with cancer, we are limited in our knowledge.
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Fact #3: The medical community has not always believed in the existence of CRCI, but now we know they were wrong.

When you do a deep-dive into the early literature about this topic, you will find that researchers questioned the validity of individual reports of changes in their cognition as being related to their cancer diagnosis and/or treatment. Researchers attributed patient complaints to other coexisting conditions such as depression, anxiety, or fatigue, which can also impact cognition and are prevalent among patients with cancer. Hutchinson et al. (2012) and O’Farrell et al. (2013) both explore these ideas.
As SLPs, we know our patients are not made up of discrete parts. It is not unreasonable to think that someone who has been going through cancer treatment might have depression and CRCI. Today, even though it continues to be difficult to measure (see below), CRCI is no longer disputed in the literature.

Clinical takeaway 3: It is important to acknowledge to your patients that CRCI is real. They are not alone in this experience, and although there is a lot more to learn about CRCI, validate them. Cognitive change is a known effect of non-CNS cancer and its treatment.

Clinical takeaway 4: If you suspect your patient to be dealing with depression, anxiety or fatigue, it is important to communicate these concerns to the referring provider as these conditions may exacerbate cognitive impairments.

Clinical takeaway 5: You may encounter a provider who does not think CRCI exists (but hopefully not). The references listed at the end of this post offer up-to-date evidence.
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Fact #4: When you go looking for evidence, you will find over and over again that subjective reports do not match objective neuropsychological measures.

Remember how deficits can be subtle? Typically, the patient will report significant changes to their everyday functioning using a patient rated scale such as the FACT-Cog (see other outcome measures here), but then test in the “low range of normal” on objective testing (Horowitz et al., 2018). These patients often report that tasks take them longer or require more effort than usual. To this writer, this suggests a problem with the test, rather than the patient report.
The International Cognition and Cancer Task Force recommends three objective tests in hopes of standardizing research design in this population in this article. They are: Hopkins Verbal Learning Test-Revised (HVLT-R), Trail Making Test (TMT), and the Controlled Oral Word Association (COWA) of the Multilingual Aphasia Examination. Authors also recommend considering an assessment of working memory. These seem to be recommendations for researchers rather than clinicians. As you can probably guess, you’ll need to use your best clinical judgment in selecting assessment tools for your patients with CRCI. 
Cheung et al. (2012) is an older article but Tables 3, 4, and 5 outline commonly used measures in CRCI research. Several studies (Janelsins et al. 2014 and Parsons & Dietrich, 2019) suggest that taking baseline data prior to cancer treatment may assist in capturing subtle changes. This would require some teamwork with the cancer team for an early referral.

Clinical takeaway 6: You should use both subjective and objective measures to get the full picture. But be mindful that they might not “match.”

Clinical takeaway 7: There is no one objective measure recommended to identify CRCI. The three objective measures listed above have been recommended to researchers, but this seems to be a starting place. Authors recommend supplementing additional assessments as needed.

Clinical takeaway 8: One proposed solution to more accurately measure subtle cognitive changes is to obtain baseline data for comparison, if possible.
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Fact #5: Our role is to treat CRCI as it relates to improving communication, and we wish we could tell you exactly how to do it.

A lot of the research assumes that a neuropsychologist will evaluate CRCI. There is not much SLP-specific research about treatment for this population (yet). Interventions discussed in the literature include both cognitive training and cognitive rehabilitation approaches:

• Cognitive training commonly uses computer-based activities focused on improving specific cognitive skills.
• Cognitive rehabilitation incorporates compensatory strategy training and targets metacognitive skills using more functional tasks.

This review by Wefel et al. (2014), summarizes some published CRCI interventions and their outcomes in Table 1, which is worth checking out. Unfortunately, the current level of evidence for these interventions is low, and there are no set guidelines for treatment dosage, either.
Also, we highly recommend that you check out this article by Mary Ann Eller, MA, CCC-SLP about her personal experiences with “chemo brain” as an SLP.

Clinical takeaway 9: If you are trying to treat this population, you may want to involve neuropsychology. We have distinct roles, and a person may benefit from one or both services.

Clinical takeaway 10: Consider incorporating both a cognitive skill training and cognitive rehabilitation approach.

Clinical takeaway 11: You might have difficulty getting insurance to cover this. It will take some research.

Clinical takeaway 12: Consider tracking your own data and success with these patients. Research is definitely needed in this area!

*It is important to note that chemotherapy is sometimes used to treat conditions other than cancer, so not everyone experiencing “chemo brain” will be a cancer patient, specifically.​
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Comments welcome below! What objective tests do you use? How are you doing this type of therapy? What is your experience with insurance covering it? 

Cheung, Y.T., Hsien-Jie Tan, E., & Chan, A. (2012). An evaluation on the neuropsychological tests used in the assessment and post-chemotherapy cognitive changes in breast cancer survivors. Supportive Care in Cancer. https://doi.org/10.1007/s00520-012-1445-4
 
Ehrenstein, J.K., van Zon, S.K.R., Duijts, S.F.A., van Dijk, B.A.C., Dorland, H.F., Schagen, S.B., & Bültmann, U. (2020). Type of cancer treatment and cognitive symptoms in working cancer survivors: an 18-month follow-up study. Journal of Cancer Survivorship. https://doi.org/10.1007%2Fs11764-019-00839-w
 
Horowitz, T.S, Suls, J., & Treviño, M. (2018). A call for a neuroscience approach to cancer-related cognitive impairment. Trends in Neurosciences. https://doi.org/10.1016/j.tins.2018.05.001.
 
Hutchinson, A.D., Hosking, J.R., Kichenadasse, G., Mattiske, J.K., & Wilson, C. (2012). Objective and subjective cognitive impairment following chemotherapy for cancer: a systematic review. Cancer Treatment Reviews. https://doi.org/10.1016/j.ctrv.2012.05.002.
 
Janelsins, M.C., Heckler, C.E., Peppone, L.J., Ahles, T.A., Mohile, S.G., Mustian, K.M., Palesh, O., O'Mara, A.M., Minasian, L.M., Williams, A.M., Magnuson, A., Geer, J., Dakhil, S.R., Hopkins, J.O., & Morrow, G.R. (2018). Longitudinal trajectory and characterization of cancer-related cognitive impairment in a nationwide cohort study. Journal of Clinical Oncology. https://doi.org/10.1200/JCO.2018.78.662.
 
Janelsins, M.C., Kesler, S.R., Ahles, T.A., and Morrow, G.R. (2014). Prevalence, mechanisms, and management of cancer-related cognitive impairment. International Review of Psychiatry.  https://doi.org/10.3109/09540261.2013.864260
 
Jia, M., Zhang, X., Wei, L., & Gao, J. (2020). Measurement, outcomes and interventions of cognitive function after breast cancer treatment: a narrative review. Asia-Pacific Journal of Clinical Oncology. https://doi.org/10.1111/ajco.13484
 
Lange, M., Joly, F., Vardy, J., Ahles, T., Dubois, M., Tron, L., Winocur, G., De Ruiter, M.B., & Castel, H. (2019). Cancer-related cognitive impairment: an update on state of the art, detection, and management strategies in cancer survivors. Annals of Oncology. https://doi.org/10.1093/annonc/mdz410
 
Parsons, M.W. & Dietrich, J. (2019). Assessment and management of cognitive changes in patients with cancer. Cancer. https://doi.org/1.0.1002/cncr.31905
 
Treanor C.J., McMenamin, U.C., O'Neill, R.F., Cardwell, C.R., Clarke, M.J., Cantwell, M., & Donnelly, M. (2016). Non-pharmacological interventions for cognitive impairment due to systemic cancer treatment. Cochrane Database of Systematic Reviews. https://doi.org/10.1002/14651858.CD011325.pub2  [open access]
 
Wefel, J.S., Kesler, S.R., Noll, K.R., & Schagen, S.B. (2014). Clinical characteristics, pathophysiology, and management of noncentral nervous system cancer-related cognitive impairment in adults. CA: A Cancer Journal for Clinicians. https://doi.org/10.3322/caac.21258 [open access]
 
Wefel, J.S., Vardy, J., Ahles, T., & Schagen, S.B. (2011). International Cognition and Cancer Task Force recommendations to harmonize studies of cognitive function in patients with cancer. The Lancet Oncology. https://doi.org/10.1016/S1470-2045(10)70294-1