Understanding Chemotherapy-Associated Cognitive Decline: A Review of “Chemobrain”

Greater emphasis should be given to formally defining chemobrain and oncology nurses may want to move it higher on their lists of priorities, according to researchers. The cognitive impairment experienced by many patients treated with chemotherapy, referred to as chemobrain, can be subtle yet persistent. Some patients report difficulties related to memory and attention even months after they have completed treatment. “I do believe that chemobrain/cognitive changes should be assessed at every visit, just like pain and neuropathies,” said Kelly Moore, RN, of the Moncrief Cancer Institute at the University of Texas (UT) Southwestern in Dallas.

Ms Moore and her colleagues conducted a pilot study to explore the onset of chemobrain in patients who recently began chemotherapy treatment and in patients who have been receiving chemotherapy for an extended period of time.¹ The prospective observational study produced rather disappointing findings, but highlighted how urgently diagnostic tools for cognitive decline are needed. “I thought that the patients’ cognitive testing tools would reflect greater cognitive decline in my patients, but it was minimal,” Ms Moore told Oncology Nurse Advisor.

A high percentage of participants were verbally reporting symptoms of cognitive decline at their clinic visits, but the cognitive assessments tools didn’t show that. “I didn’t feel my collection tools detected those changes,” Ms Moore said. “My biggest takeaway from the study is that larger studies need to be performed to specifically investigate how chemobrain happens and what interventions may be appropriate to treat it.”

Is Cognitive Decline a Bigger Concern Than Ever?

Catherine M. Bender, PhD, RN, professor and endowed chair in oncology nursing at the University of Pittsburgh School of Nursing in Pittsburgh, Pennsylvania, suggests that there needs to be caution when using the term “chemobrain.” Many factors contribute to the problem of deterioration in cognitive function in patients with cancer, only one of which is the treatment. “For example, we now know that some individuals with cancer — up to 35% — have poorer cognitive function than their healthy counterparts (matched by age and education) before they begin cancer treatment. Several factors including mood and characteristics of the disease itself may be contributing to this poorer, pretherapy cognitive function,” Dr Bender explained to Oncology Nurse Advisor.

Due to improved methods for diagnosing cancer early while it is still treatable and advancements in treatment, cancer survivors are living much longer. Subsequently, some are experiencing long-term effects of the disease and its treatment. Decline in cognitive function is one of those potential long-term consequences. “That factor alone is contributing to the increasing numbers of individuals experiencing the problem. There is also evidence that longer duration of therapy and higher doses of therapy are associated with greater risk for experiencing treatment-related changes in cognitive function,” she continued.

There also is evidence that suggests some newer forms of therapy, such as immunotherapies, may also be associated with deteriorations in cognitive function. Studies are needed to systematically evaluate this issue, noted Dr Bender. Older persons with cancer are more vulnerable to changes in cognitive function due to cancer and cancer therapy. In addition to their age, they are more likely to have comorbidities and to be taking medications for those comorbidities, which also may be associated with poorer cognitive function. “But not all older adults with cancer experience changes in cognitive function,” she said. Some evidence suggests that older adults who adapt healthy lifestyles that include physical activity and a healthy diet may be less vulnerable to these effects.

Interventions for Managing Cognitive Decline

Currently, no proven interventions are established for managing deteriorations in cognitive function in patients with cancer. However, Dr Bender reports that a great deal of research examining the efficacy of interventions to prevent or manage cognitive deterioration is ongoing. Some investigators are assessing behavioral interventions, such as teaching patients about the basis of the cognitive decline, how to recognize situations that exacerbate the problem, and methods for coping during times of high cognitive demand. “Some of these coping mechanisms include things like meditation techniques. Others are looking at the impact of physical activity on cognitive function,” Dr Bender said. “There is growing evidence that physical activity is associated with better cognitive function in healthy older adults. Some, including our group, are examining whether this extends to individuals with cancer as well,” she added.

Steven Morris, RN, a clinical nurse manager in oncology and bone marrow transplantation at Siteman Cancer Center and Barnes-Jewish Hospital in St Louis, Missouri, said there are more cancer survivors today, yet he is not seeing a big uptick in “chemobrain.” “I don’t feel we have seen a major increase or decrease either way. My perspective is from an inpatient point of contact.  We have always seen very sick patients,” said Mr Morris. 

Slight improvements in the tools for assessing cognitive function have been achieved, but this is an area that is lacking, noted Mr Moore. Anna C. Beck, MD, professor of internal medicine at the Huntsman Cancer Institute at the University of Utah School of Medicine in Salt Lake City, agrees that research is scare. She also believes that this issue will become a greater concern as baby boomers enter their 7th, 8th, and 9th decades of life.

“The problem may seem like it is becoming more prevalent because there are now more cancer survivors,” Dr Beck told Oncology Nurse Advisor. Currently, there are more than 15 million cancer survivors, and this number is expected to grow to 30 million. This is related to improvements in cancer screening and longer life expectancy, as well as more effective treatment options.