Activity & Cognition After Treatment for Breast Cancer

Overview

This study addresses an important public health concern; impoverished cognitive function associated with treatment of breast cancer. Due to increased awareness of breast cancer combined with advances in medical care, there are over 2.8 million women living with a history of breast cancer in the U.S. alone. Chemotherapy and adjuvant therapy to remove cancerous tissue can result in deficits in attention, speed of processing, memory, and quality of life. Physical activity has been associated with a number of health benefits for breast cancer survivors including improvements in cognitive function. However, most of the literature is cross-sectional and it is unclear whether acute (single) bouts of physical activity affect cognition and, if they do, how long this effect lasts. This study will be the first, to the investigators' knowledge, to examine the effects of an acute bout of aerobic exercise on cognitive functioning in breast cancer survivors. Specifically, the investigators will determine the effects of a 30-minute moderate intensity aerobic exercise session (treadmill walking) on immediate and one hour follow up changes in measures of processing speed, memory, and executive function. Additionally, accelerometer cut-points for physical activity intensities in breast cancer survivors will be assessed. Finally, the investigators will examine the association of cardiorespiratory fitness and physical activity with changes in cognitive function. Findings from this study will allow researchers to determine whether any acute effects of exercise on cognition are retained over time and therefore have real meaning in the context of one's daily life.

This study addresses an important public health concern: impoverished cognitive function associated with treatment of breast cancer. Due to increased awareness of breast cancer combined with advances in medical care, the 5-year survival rate has climbed to 89.2% with over 2.8 million women living with a history of breast cancer in the U.S. alone. Unfortunately, the treatment of breast cancer is not without its consequences. Chemotherapy and adjuvant therapy to remove cancerous tissue can result in deficits in attention, speed of processing, memory, and quality of life. While past studies have identified memory and executive function as valuable, important determinants of long-term survival and quality of life in survivors of different types of cancer, it is unclear if standard care methods alone prove successful in attenuating declines in these variables. Previous research in breast cancer populations has found that executive function difficulties, namely in working memory, cognitive flexibility, and processing speed, as well as fatigue, are the most commonly described deficits. Furthermore, evidence suggests impairments in cognitive functioning may persist in up to 35% of breast cancer survivors years after treatment ends. A behavioral and lifestyle modality known to improve physical and mental health status and protect against health declines is physical activity. Not only is physical activity known to protect against a host of diseases, but it also has been shown to provide many health benefits to breast cancer survivors. While the extant literature suggests that physical activity can lead to improvements in varying cognitive domains in breast cancer survivors, another study concluded that only 32% of these survivors meet the recommended guidelines for physical activity. Additionally, while benefits from physical activity for breast cancer survivors are well known, there is currently no scientifically recognized physical activity training program aimed at improving cognitive function in this cohort. As such, a review chapter examining cognitive impairment in breast cancer survivors suggests more comprehensive studies examining the relationship between objective measures of physical activity, cardiorespiratory fitness, and cognitive performance are warranted to gain a better understanding of the potentially protective effects of fitness and physical activity on cognitive functioning in breast cancer survivors for better survival along the cancer continuum. In addition, other research has shown that subjective memory impairment, fatigue, and anxiety plague breast cancer survivors and suggests that breast cancer survivors may suffer from poorer quality of life as a result. Furthermore, it has been shown that breast cancer survivors have longer reaction time to working memory tasks compared to healthy, age-matched controls, and those survivors with higher levels of physical activity had shorter reaction times for more difficult tasks. A recent study also measured levels of objective physical activity and found those with higher levels displayed more positive measures of global cognition. Despite this evidence, it is unknown if acute (single) bouts of exercise can provide benefits in varying cognitive domains. Previous research has shown that acute bouts of aerobic physical activity, of both light and moderate intensity, decrease state anxiety in breast cancer survivors. However, it is not known if these benefits extend to cognitive functioning. Furthermore, most of these results are founded in cross-sectional research and it is unclear whether acute bouts of physical activity improve cognition and, if they do, how long this effect lasts. This has implications for real world contexts in that, if benefits are present, breast cancer survivors can find relief in cognitive symptoms quickly by simply engaging in a bout of physical activity. This study will be the first, to the investigators' knowledge, to examine the effects of an acute bout of aerobic exercise on cognitive functioning in breast cancer survivors.