Research Gives Insight on Cognitive Function in Patients With Cancer
Poor cognitive function can cause distress, impact quality of life, and contribute to treatment non-adherence, Catherine Bender, PhD, RN, FAAN, from the University of Pittsburgh, explained during the Distinguished Nurse Researcher session at the 42nd Annual Congress in Denver, CO (http://congress.ons.org/). She is the 2017 recipient of the Distinguished Nurse Research Award (https://www.ons.org/member-center/awards/distinguished/researcher), which recognizes the contributions of a member who has conducted or promoted research that has enhanced the science and practice of oncology nursing.
Cognitive function is related to mood, comorbidities, demographics, symptoms, cancer therapy, and concomitant medications. Cognitive domains include executive function, attention, language, perceptual-motor function, and learning and memory.
The prevalence of changes in cognitive function due to cancer treatment varies widely in the literature, with standard-dose chemotherapy reportedly related to 17%–75% of cognitive changes and immunotherapy with alpha-interferon related to 33%–70% of cognitive changes. “Higher rates and intensity of cognitive impairment increase with higher doses of medications,” Bender said. “Immunotherapy is also associated with more severe problems.”
Accelerated aging is related to inflammation, DNA damage, oxidative stress, genes, blood-brain barrier, telomeres, and senescence, and can lead to changes in the brain structure and cognitive function. “As we age, we are at an increased risk for cancer, and cancer therapy can contribute to the accelerated aging process,” Bender said.
Self-reported measures of perceived cognitive function are important, because they can demonstrate the patient experience and how it affects their ability carry on their daily lives and functional ability, Bender said, recommending self-reports on fatigue, depression, and anxiety. However, she cautioned that self-reported and objective measures of cognitive function are not correlated in most of the literature. Neuroimaging is helping to better understand cognitive function, she said.
She gave an example of a 2007 study published in the Journal of Clinical Oncology that looked at brain function in a set of twins, one of which had a history of breast cancer and the other did not. Although they scored similarly on a test, brains scans showed that the twin with a history of cancer had to work harder, based on activity levels monitored in the brain.
“We know there are some patients who do not experience cognitive changes. Why?” Bender asked. “They seem to be able to compensate for the influence of disease and treatment. I believe they have a reserve.” The theory of reserve suggests that some individuals are better able to compensate for insults related to disease and treatment, with expanded
- Cognitive reserve: the ability to efficiently use neural networks to compensate, which tends to be evaluated by proxy measures (e.g., age, IQ, education)
- Brain reserve: neuroplasticity, measured with biomarkers or neuroimaging techniques.
“Can we harness what we know about reserve theory and develop meaningful interventions to help patients who experience cognitive changes?” Bender said.
Bender and her team have been looking into exercise interventions to improve cognitive function. A 2003 study published in Psychological Science demonstrated that exercise improved executive, controlled, and spatial functions, as well as speed compared to a control group that did not engage in exercise.
“Physical activity is associated in reductions in proinflammatory cytokines and structural and functional brain changes, and it reduces other symptoms that influences changes (e.g., sleep issues, depression, anxiety). This could improve cognitive functioning.”
She launched a study to examine whether moderate-intensity aerobic exercise (over a six-month period) improves cognitive function in postmenopausal women with breast cancer who receive aromatase inhibitor therapy. The investigators are measuring cognitive levels, fitness levels, and cytokines. “We look forward to sharing results in a few years,” Bender said.
She also noted that future research is needed in the following areas.
- Long-term effects of disease and therapy on cognitive function
- Characteristic profile of patients at risk for cognitive changes
- Mechanisms underlying cognitive change
- Assessment for clinical and research setting
- Interventions to prevent or manage changes in cognitive function