Physical activity may improve cognition for pediatric cancer survivors
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Pediatric cancer survivors often experience neurocognitive dysfunction that may persist for years after successful treatment.
Survivors may struggle with impairments in memory, attention, executive function, processing speed and visuomotor integration. Additionally, they report less participation in physical activity than their healthy counterparts, which may impact psychosocial well-being and increase risk for chronic diseases.
“Over the past number of years, a growing body of research has shown benefits of physical activity for the brain. I was really inspired by this, as it suggested that people could have some control over their cognitive function — and through a means that is accessible to most,” Emily Barlow-Krelina, MA, PhD candidate at York University, said in an interview with Healio. “At the same time, I was working with survivors of childhood cancer who were struggling with cognitive difficulties in their everyday life. I wanted to understand whether physical activity could be an effective approach to managing these challenges.”
Barlow-Krelina and colleagues, including Kim Edelstein, PhD, CPsych, neuropsychologist and scientist in the department of supportive care at Princess Margaret Cancer Centre, studied the impact of physical activity on cognitive function among 12,123 cancer survivors enrolled in the Childhood Cancer Survivor Study.
Barlow-Krelina and Edelstein discussed the implications of their findings with Healio.
Question: What inspired you to conduct this study?
Edelstein: Survivors often ask about what they can do to improve their thinking abilities and often are surprised when we recommend exercise. The relationship between physical activity and cognition has been shown in many different patient groups, including among those with cancer, although less is known about this among pediatric cancer survivors. The time was right to ask this question, and the Childhood Cancer Survivor Study provides a great opportunity to learn more about these long-term outcomes because of the detailed diagnosis, treatment and other information that it makes accessible to researchers. The Childhood Cancer Survivor Study is an NCI-funded resource to promote and facilitate research among long-term survivors of cancer diagnosed during childhood and adolescence. Investigators interested in potential uses of this resource are encouraged to visit www.stjude.org/ccss.
Q: Why do you think cancer survivors are less physically active than their siblings?
Edelstein: Cancer can affect how we move, feel and think. This can be due to the cancer itself or adverse cancer treatment effects, such as fatigue or amputations. Cancer and cancer treatments also can affect how children develop, both physically and mentally. So, survivors of childhood cancer may be less active than their siblings because of direct effects of the cancer on their ability to move, or indirect effects of the treatment on other factors that are important for physical activity, such as stamina and motivation.
Q: Why were associations between physical activity and neurocognitive problems more consistently observed in cancer survivors vs. siblings?
Barlow-Krelina: I think that because survivors have a greater incidence of neurocognitive problems, there is more potential for physical activity to exert beneficial effects. Although siblings show some potential enhancement of cognitive function with more physical activity, they reported fewer problems to begin with. By contrast, for survivors, engagement in physical activity may also afford protection against cognitive problems that might otherwise be reported. This association was particularly strong among survivors of central nervous system cancers.
Q: Do you have any theories about the mechanism of this association?
Barlow-Krelina: Several mechanisms have been proposed to explain the relationship between physical activity and cognition, although one of the main theories points to brain growth factors. These compounds are released to a greater extent in people who are more active and have been tied to increases in blood flow to the brain, greater connectivity between neurons and enhanced repair mechanisms. Physical activity also has shown anti-inflammatory effects and is associated with reduced stress and better mood, so it is very possible that several of these mechanisms act together.
Q: Consistent physical activity appeared to have the greatest effect. Does this mean that physical activity must be maintained over time to be effective?
Barlow-Krelina: These findings suggest that to see the greatest benefits in cognitive function, one should work toward maintaining physical activity over time. However, physical activity at any point in time appear to have some cognitive impact, with more and higher-intensity physical activity showing stronger effects.
Q: What would you recommend to pediatric cancer survivors based on these findings?
Barlow-Krelina: It’s important to be mindful about how to take a sustainable approach to increasing activity. So, although you should think about what will get your heart rate up, also consider what will help to keep you engaged long term, such as building activity into your daily habits, coordinating with friends or doing things outdoors. Our results show some promising patterns of association between physical activity and cognitive function for survivors of childhood cancer, but it is important to note that our study primarily speaks to subjective information that was self-reported by participants. More research is needed to confirm these findings with physical activity interventions and direct measures of cognitive function.
For more information:
Emily Barlow-Krelina, MA, can be reached at 130 BSB, 4700 Keele St., Toronto, ON M3J 1P3; email: embarlow@yorku.ca.
Kim Edelstein, PhD, CPsych, can be reached at 610 University Ave. 18-716, Toronto, ON MSG 2M9; email: kim.edelstein@uhn.ca.
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