The issue of ‘chemo-brain’ — cognitive impairment following chemotherapy — has been a controversial one. While it is now (I hope) accepted by most that it is, indeed, a real issue, there is still an ongoing debate over whether the main cause is really the chemotherapy. A new study adds to the debate.
The study involved 28 women who received adjuvant chemotherapy for breast cancer, 37 who received radiotherapy, and 32 age-matched healthy controls. Brain scans while doing a verbal working memory task were taken before treatment and one month after treatment.
Women who underwent chemotherapy performed less accurately on the working memory task both before treatment and one month after treatment. They also reported a significantly higher level of fatigue. Greater fatigue correlated with poorer test performance and more cognitive problems, across both patient groups and at both times (although the correlation was stronger after treatment).
Both patient groups showed reduced function in the left inferior frontal gyrus, before therapy, but those awaiting chemotherapy showed greater impairment than those in the radiotherapy group. Pre-treatment difficulty in recruiting this brain region in high demand situations was associated with greater fatigue after treatment.
In other words, reduced working memory function before treatment began predicted how tired people felt after treatment, and how much their cognitive performance suffered. All of which suggests it is not the treatment itself that is the main problem.
But the fact that reduced working memory function precedes the fatigue indicates it’s not the fatigue that’s the main problem either. The researchers suggest that the main driver is level of worry —worry interfered with the task; level of worry was related to fatigue. And worry, as we know, can reduce working memory capacity (because it uses up part of it).
All of which is to say that support for cancer patients aimed at combating stress and anxiety might do more for ‘chemo-brain’ than anything else. In this context, I note also that there have been suggestions that sleep problems have also been linked to chemo-brain — a not unrelated issue!
Cimprich, B. et al. 2012. Neurocognitive impact in adjuvant chemotherapy for breast cancer linked to fatigue: A Prospective functional MRI study. Presented at the 2012 CTRC-AACR San Antonio Breast Cancer Symposium, Dec. 4-8