Cancer and “Chemobrain”
The arduous search for words, misplaced keys or spectacles and an inability to concentrate: many cancer patients complain of these very burdensome cognitive problems even years after treatment, and most often blame chemotherapy. The research over the last ten years appears to confirm this assumption. After all, several studies have demonstrated an impairment of cognitive function in up to 75 percent of tested patients after chemotherapy. These disturbances were relatively mild, not reaching the degree of dementia by far, and were spread out over a wide range of cognitive domains.
“The validity of most of these studies, however, has been considerably limited“, says Dr. Kerstin Hermelink of the Clinic of Gynecology and Obstretrics of LMU Munich, “because the cognitive abilities of the patients were only tested after the chemotherapy. The first longitudinal studies that assessed the course of cognitive function by repeated assessments was published only in 2004.The largest of these methodologically far superior and more significant studies found little or even no difference between cancer patients with and without chemotherapy.”
Hermelink and colleagues at LMU have now conducted one of the largest studies in this field with their study COGITO, short for “Cognitive Impairment in Therapy of Breast Cancer”. This also had one decisive feature: COGITO is one of the very few prospective longitudinal studies that investigated cognitive abilities even before any cancer therapy began, i.e. even before any operation. The cognitive assessment was repeated twice within the first year following diagnosis. More than 100 breast cancer patients from five Bavarian clinics and hemato-oncological private practices took part in the study.
“Even before any cancer therapy started, about one third of our patients demonstrated poor cognitive test results,” reports Hermelink. “Towards the end of the chemotherapy, the changes all balanced out: while 27 percent of the women presented mainly a decline, 28 percent of the participants achieved mostly better test results. We conclude from this that there must be other factors that lead to a compromise of cognitive performance already before therapy. These factors continue to influence some of the patients during treatment, while other patients already recover from them.”
The consequences of hormonal changes on mental abilities were also investigated in this study, since most breast cancer patients undergo a drastic estrogen depletion due to the therapy. Many even abruptly go into premature menopause as a result of chemotherapy and hormone treatment. “The influence of estrogen on cognitive function is still not understood well,” says Hermelink. “In our study, however, we observed no significant effect of anti-estrogen therapy, and premature menopause even had a positive influence in a small part of the test.”
In summary, it can be said that cognitive impairment exists in many breast cancer patients already after diagnosis and before therapy. Even if in the COGITO study there is no evidence for additional impairment caused by chemotherapy it still cannot be ruled out. Estrogen depletion induced by breast cancer therapy had no negative influence on cognitive ability.
“We can therefore say with certainty that there must be factors other than chemo or hormone therapy that impair the cognitive abilities in some cancer patients,” stresses Hermelink. “The concept of so-called ‘chemobrain’ is too simplistic, and at most can only partially explain the cognitive problems of cancer patients. We assume that the stress of the diagnosis plays a central role. After all , it can act as a trauma, which can be aggravated by the treatment. We now intend to study this in more depth: possibly, we may have to exchange the term ‘chemobrain’ for ‘crisis brain’.”
“Short-term effects of treatment-induced hormonal changes on cognitive function in breast cancer patients: results of a multicenter, prospective, longitudinal study.” Kerstin Hermelink et al., Cancer, Vol. 113, Issue 9, p. 2431–2439, 1 November 2008
“Cognitive function during neoadjuvant chemotherapy for breast cancer: results of a prospective, multicenter, longitudinal study.” Kerstin Hermelink et al., Cancer; Vol. 109, Issue 9, p. 1905–1913, 1 Mai 2007
Dr. Kerstin Hermelink
Clinic of Gynecology and Obstretrics of LMU Munich
Tel.: ++49 (0)89 / 7095 - 7579