Forgetfulness. One of the most notorious side effects of chemotherapy. Chemotherapy treatment has been known to negatively affect thinking and memory in cancer patients, and may reduce quality of life for many. These symptoms of cognitive impairment are collectively referred to as “chemo brain” or ”chemo fog.” It can be short term, but for many, chemo brain lasts for years.

Why Does Chemo Brain Happen?

Researchers are still trying to figure that out. However, it is likely that chemo brain is the result of many factors, including, but not limited to:

• Cancer treatments (chemotherapy and radiation, for example)
• Stress and anxiety resulting from diagnosis
• Nutritional deficiencies (or other complication due to treatment)

As research continues to provide greater insight and explanation for this side effect, more light is being shed on possible contributing factors. Recent studies funded by the National Cancer Institute had some interesting perspectives.

In one study’s results, women who were carriers of the E4 allele of the APOE gene were more likely to experience cognitive impairment after chemotherapy than women who were not carriers of the E4 allele. While the study focused on breast cancer patients, the results are of interest because the E4 allele is a risk factor for late-onset Alzheimer’s disease.

An additional study published in Neurotoxicity Research used mice with the E4 allele of the APOE gene to show that they, too, developed chemo brain – specifically changes in learning and memory.

According to The Dana Farber, it’s important to note that chemo brain is very different from Alzheimer’s disease and dementia, and does not increase one’s risk of developing Alzheimer’s or dementia. 

While this research is intriguing – it is still new and unclear how it could affect cancer patients, including colorectal cancer patients (who are often treated with 5-FU, a well-known culprit of chemo brain). Only a quarter of the population has the specific E4 allele, and while future studies may support the notion that these people are at an increased risk for chemotherapy-related cognitive impairments, there is still no “cure” for the side effect. 

As research continues, it is incredibly important for patients to be armed with knowledge about how to manage chemo brain. Here are some practical tips:

• Get regular exercise: 150 minutes of moderate aerobic activity or 75 minutes of vigorous aerobic activity a week
• Get good sleep: Get into a regular bedtime routine 
• Talk to your doctor: they may be able to help with an additional prescription or with resources to help you manage
• Write it down: Keep a notepad with you and write things down that you need to remember
• Use labels: Label things around the house to minimize time spent looking for lost items (like car keys!)
• Use a checklist: Write down a list of daily reminders
• Playback on repeat: Repeat to others what they have told you as this can help you remember

---

Sources

http://ascopubs.org/doi/full/10.1200/JCO.18.00140 

https://www.cancer.gov/news-events/cancer-currents-blog/2018/chemobrain-cancer-survivors-alzheimers-gene?cid=eb_govdel