(Seoul = Yonhap News) Reporter Kim Gil-won = After cancer treatment is over, many patients mainly focus on whether it will recur or manage aftereffects. However, one of the health issues that must be taken care of in the long term after overcoming cancer is cognitive function.
In particular, some patients who have received chemotherapy complain of symptoms such as loss of memory and concentration and a feeling of blurry thoughts before and after treatment. It is a cancer-related decline in cognitive function, commonly referred to as ‘chemo brain’.
However, a study showed that people who decreased their amount of exercise after being diagnosed with cancer had a higher risk of developing dementia later in life than people who continued to maintain physical activity.
According to the latest issue of the international academic journal 'Cancer Research and Treatment', a joint research team (Sang-min Park, Soo-kyung Lee, and Min-ji Han) from the Department of Family Medicine at Seoul National University College of Medicine, Department of Health Care Management at Daejeon University, and Big Data Center at Seoul National University Bundang Hospital analyzed the relationship between changes in physical activity before and after cancer diagnosis and the subsequent occurrence of dementia using data from the National Health Insurance Service.
The subjects of the study were 260,659 adults who survived for more than three years after being diagnosed with cancer between 2009 and 2015 and who underwent national health checkups before and after their cancer diagnosis. People who had previously been diagnosed with dementia or who lacked the data needed for analysis were excluded.
The research team calculated the amount of physical activity (MET-min/week) before and after cancer diagnosis using the exercise frequency and intensity recorded in the health checkup questionnaire and compared the risk of developing dementia. MET is an indicator that indicates how many times the energy consumed during exercise is at rest.
As a result, it was estimated that people who decreased their physical activity after a cancer diagnosis had a 46% higher overall risk of developing dementia than people who continued to maintain a high level of physical activity. On the other hand, people who maintained or increased physical activity had an 18% lower risk of dementia.
This association was more pronounced in cancer survivors who received chemotherapy. Among people who received chemotherapy, if they maintained or increased physical activity, the risk of dementia decreased by 20%.
On the other hand, in cancer survivors who did not receive chemotherapy, the association between changes in exercise amount and risk of dementia was not statistically clear.
What is noteworthy about this study is not simply whether cancer patients exercise a lot, but that it looked at how exercise habits changed before and after the major event of a cancer diagnosis.
Cancer patients tend to experience fatigue, pain, and muscle weakness during surgery, chemotherapy, and radiation treatment, which reduces their activity level. There are many cases where a decrease in physical activity continues for a long time even after treatment is completed.
Deterioration of cognitive function after cancer treatment is also considered a major problem that reduces the quality of life of cancer survivors.
Among these, cognitive decline related to chemotherapy can manifest itself in the form of decreased memory, attention, concentration, and information processing speed. However, it is known that these cognitive changes are complexly involved not only in anticancer drugs but also in the cancer itself, inflammatory response, fatigue, sleep disorders, depression, and anxiety.
Exercise has the potential to affect this process in several ways.
Regular physical activity can help improve cerebral blood flow, cardiovascular health, and reduce inflammation. Additionally, the research team explains that promoting the secretion of substances involved in the growth and function of brain nerve cells and improving metabolic health can be linked to protecting cognitive function.
In a previous study, the research team followed 344,152 domestic cancer survivors for an average of 5.8 years and confirmed that the risk of dementia decreases as the amount of physical activity increases after cancer diagnosis.
Compared to cancer survivors who did not exercise at the time, the risk of dementia gradually decreased by 11%, 15%, and 21% depending on the level of physical activity. The same trend was observed in patients who received chemotherapy.
Professor Park Sang-min of the Department of Family Medicine at Seoul National University said, "This study is meaningful in that it analyzed the relationship between the change in an individual's exercise amount before and after cancer diagnosis and the risk of dementia, rather than the amount of exercise at one point in time," and added, "Strategies to help cancer survivors maintain physical activity may be important for long-term cognitive health management."
