Part 1: Chemobrain – A Survivor's Guide to Cancer-Related Cognitive Impairment

Part 1: What is ‘Chemobrain’?

It’s a frustratingly common story for millions of cancer survivors. You walk into a room and forget why you’re there. You struggle to find a simple word that feels like it’s on the very tip of your tongue. The mental multitasking required to cook dinner while holding a conversation, once second nature, now feels like a monumental effort. For decades, patients who described this frustrating mental fog following treatment were often told it was simply the lingering effects of stress, fatigue, or depression.

But a growing body of scientific evidence has confirmed what survivors have known all along: the condition, often called “chemobrain,” is a real and measurable physiological side effect of cancer and its treatment.

Leading cancer research institutions, including the National Cancer Institute, now formally recognize the phenomenon as Cancer-Related Cognitive Impairment, or CRCI. The shift in terminology reflects a critical finding—that these cognitive changes are not caused by chemotherapy alone. Studies show they can also be linked to the cancer itself, as well as other treatments like radiation, hormone therapy, and targeted therapies. The experience is no longer an anecdote; it is a widely acknowledged medical condition affecting a significant portion of the survivor community.

The symptoms can vary from person to person but typically involve disruptions in executive function, the set of mental skills that includes managing time, paying attention, and switching focus. Survivors frequently report short-term memory lapses, a diminished ability to concentrate, trouble processing information quickly, and organizational challenges that were not present before their diagnosis. According to a comprehensive 2024 review in Frontiers in Oncology, this impairment can profoundly impact a person’s quality of life long after their cancer is in remission.

Understanding the prevalence of CRCI has been complex, as symptoms can be subtle and difficult to measure. However, a 2019 review published in the journal Cancers noted that estimates of affected patients range widely, from 20 percent to as high as 75 percent, depending on the type of cancer, the treatments received, and the methods used for assessment. What is clear is that a vast number of individuals are impacted.

The increased focus on chemobrain is, in many ways, a consequence of the remarkable success of modern cancer treatments. As more people live longer and fuller lives after a cancer diagnosis, the long-term side effects of their life-saving therapies have come into sharper focus. The conversation has shifted from purely survival to the quality of that survival. Acknowledging the reality of chemobrain is the essential first step for patients and families to begin understanding its sources and seeking effective strategies to manage it.

Validating this experience is crucial. For survivors who have felt dismissed or worried that they were somehow imagining their cognitive struggles, the scientific consensus is clear: you are not alone, and this is not in your head.

In Part 2 of our series, we will delve into the complex science behind why cancer and its treatments can affect the brain, exploring the leading theories that researchers are now pursuing.

This article is for informational purposes only and does not constitute medical advice. The content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or another qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read in this article.

National Cancer Institute. (2023, August 25). Cognitive Impairment in Adults with Cancer (PDQ®)–Patient Version. National Institutes of Health. Available at: https://www.cancer.gov/about-cancer/treatment/side-effects/memory/cognitive-impairment-pdq

D'Angelo G, Mandras G, Sapino AC, Piciucco R. Cancer-related cognitive impairment: an up-to-date review. Frontiers in Oncology. 2024;14:1387251. Published 2024 Feb 29. Available at: https://www.frontiersin.org/journals/oncology/articles/10.3389/fonc.2024.1387251/full

Prochazka M, Nagy Z, Czigler A, et al. “Chemobrain”: A Systematic Review of Structural and Functional Neuroimaging Studies. Cancers (Basel). 2019;11(5):709. Published 2019 May 22. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6562911/