In murine breast cancer-bearing mice receiving chemotherapy, we found a greater than 40 ​% decline (P ​< ​0.0001) in DNM1 immunoreactivity in the hippocampal CA1 and CA3 subregions concurrent with a deterioration in spatial recognition memory (P ​< ​0.02), compared to control mice without exposure to cancer and chemotherapy. The gene discussed is DNM1; the disease is cancer.