Breast cancer survivors who suffer fatigue may be affected in the autonomic nervous system.
A new study says survivors with persistent fatigue had high levels of the stress hormone norepinephrine.
Researchers asked 109 women to give a speech and do a math problem. Half of these women had fatigue and half did not. Blood tests found that norepinephrine rose in both test subjects. However, the women with fatigue had higher levels of the stress hormone.
Christopher Fagundes, the study co-author and a postdoctoral fellow at Ohio State University's Institute of Behavioral Medicine Research, said in a person with persistent fatigue the two parts of the autonomic nervous system might go out of balance.
"They had higher sympathetic activity and lower parasympathetic activity," Fagundes said of the women in the study.
A 2006 review of studies in the European Journal of Cancer found that as many as 19 to 38 percent of cancer patients experience "disabling fatigue." Women receiving chemotherapy or chemo plus radiation therapy are more likely to experience fatigue than those who only undergo radiation.
"Sick people with inflammation become tired and lethargic, which makes sense since their bodies are using energy to fight off infections," the researchers said "You can imagine that a long-term, systemic inflammation, year-in and year-out, might produce this fatigue."
