It’s common knowledge that many cancer survivors experience persistent fatigue. Why they experience this fatigue has been the focus of several research studies. We now know that the persistent fatigue experienced by about a third of breast cancer survivors may be caused by higher levels of norepinephrine.
Researchers from Ohio State University studied 109 women who had completed breast cancer treatment up to two years earlier. Half of the women were breast cancer survivors who reported persistent fatigue and the other half were non-fatigued breast cancer survivors. All of the women had baseline levels of the stress hormone norepinephrine drawn. They then had to give a speech and verbally answer math questions to increase their stress levels.
Subsequent norepinephrine levels rose in both groups of women; however, the women who reported persistent fatigue had significantly higher levels of norepinephrine. This suggests that high circulating stress hormone levels can and does cause persistent fatigue.
The report of the study was released online on March 9, 2011 in advance of publication in an upcoming print issue of the journal Psychoneuroendocrinology. Although the researchers acknowledge that more research is needed and that it is possible that some breast cancer survivors are persistently fatigued because of inactivity or deconditioning, the study findings add to the body of knowledge of biomarkers for fatigue. The findings also support other research studies that have found that exercise has a beneficial effect in reducing fatigue.