Breast cancer patients often display mild cognitive defects even before the initiation of chemotherapy. A new study now attributes the syndrome to posttraumatic stress induced by diagnosis of the disease. These findings were published in the Journal of the National Cancer Institute (2015; doi:10.1093/jnci/djv099).
A large number of studies have shown that cancer patients very often exhibit mild deficits of attention, memory, and other basic cognitive functions. The phenomenon has generally been attributed to putative side effects of chemotherapeutic drugs on the brain, and the condition is therefore popularly referred to as chemobrain.
However, more recent investigations have detected symptoms of chemobrain in patients who had not yet embarked on a course of chemotherapy. Now a research team led by LMU’s Kerstin Hermelink, PhD, of the Breast Center in the Department of Gynecology and Obstetrics at Munich University Hospital and Ludwig-Maximilians-Universitaet (LMU) in Munich, Germany, has shown that, in breast cancer patients, pretreatment cognitive impairment is most probably due to posttraumatic stress induced by diagnosis of the malignancy itself.
This research used data from a multicenter study called Cognicares (Cognition in Breast Cancer Patients – the Impact of Cancer-related Stress).
“Cancer patients can perceive and experience their condition as a severe trauma. Indeed, many of them develop symptoms of posttraumatic stress disorder, particularly in the early phase after they receive the diagnosis,” said Hermelink. “Stress has a very considerable influence on cognitive performance and definitely impacts on brain function, so it was quite natural for us to ask whether the cognitive deficiencies displayed by many breast cancer patients might not be attributable to the stress that is inevitably associated with malignant disease.”
Hermelink and her colleagues studied 166 women with a breast cancer diagnosis and 60 others in whom screening of the breast had revealed no signs of disease. The participants were assessed at three times during the first year following the diagnosis.
Prior to the first course of treatment, the patients and the healthy controls exhibited very similar levels of performance on standard cognitive tests. However, in one specific test of attention, members of the patient group had a significantly higher error rate.
“And as we suspected at the outset, the higher failure rate in this test could be linked to posttraumatic stress. The greater the level of stress, the more errors they made, and statistical analysis confirmed that the correlation was highly significant,” explained Hermelink.
Interestingly, the extent of pretreatment cognitive impairment detected in the Cognicares study was considerably lower than that reported in several earlier investigations. “This is probably because we took great pains to control effectively for the possible impact of factors that could have distorted the interpretation of the results,” said Hermelink. “In particular, we made sure that differences in the composition of the two groups were minimized as far as possible.”
This is important because even slight differences in age structure, level of education, or intelligence between the patients and the control group can result in discrepancies in cognitive performance on standardized tests, which could mask or amplify the extent of cognitive impairment displayed by the patients.