Does endocrine therapy for the treatment and prevention of breast cancer affect memory and cognition?

Oestrogen receptors have been identified in several areas of the brain important in cognitive performance, including the prefrontal cortex (active during short-term working memory), the hippocampus and related cortical areas (learning and storage of information) and the amygdala (involved in the modulation of memory consolidation). There is much debate as to whether or not a reduction in oestrogen levels results in a corresponding decline in cognitive processing. Arguments for an effect are based on findings from laboratory and hormone replacement studies and the pharmacological actions of breast cancer drugs. However, there are few clinical data substantiating the claim that endocrine therapies used in the treatment and prevention of breast cancer could affect cognition. This paper examines the main evidence associated with this claim and discusses the importance of examining such issues within randomised trials.