Wnuk and colleagues have recently presented a summary and review of research studies that address the impact of hormone therapy (HT) on the structure of the hippocampus . After first describing a robust basic science literature showing enhanced structure and function of the hippocampus, the review focuses on hippocampal volume measured in postmenopausal women using non-invasive structural magnetic resonance imaging. Hippocampal volume is a clinically relevant measure of brain structure, because reductions in hippocampal volume are associated with an increased risk of developing Alzheimer’s disease . According to the review, about half of the studies to date show increased hippocampal volume among women using HT, but the largest study – that from the Women’s Health Initiative Memory Study (WHIMS) – shows decreased hippocampal volume. Age, duration of treatment, timing of treatment, and amount of aerobic exercise are considered as possible modifiers of the impact of HT on hippocampal volume, but no firm conclusions are drawn. The conclusion from the review is that the findings on HT and hippocampal volume are equivocal and limited by cross-sectional designs. Further, without a randomized clinical trial of HT on hippocampal volume, it is unclear what effect, if any, HT has on this surrogate marker.
Associate Professor of Psychiatry and Psychology, Center for Cognitive Medicine, University of Illinois at Chicago, Chicago, USA