Memantine and Exercise to Improve Cognitive Function and Modulate Biological Pathways of Cognitive Decline During Chemotherapy in Breast Cancer

This study is testing whether a medication called memantine (commonly used for Alzheimer's) combined with an exercise program can protect and improve thinking and memory in women with breast cancer who are experiencing cognitive side effects from chemotherapy (sometimes called "chemo brain"). **You may be eligible if...** - You are a woman aged 50 or older - You have stage I-III breast cancer and are recommended to receive chemotherapy - You have had at least one cycle of standard chemotherapy and have not yet started your 3rd cycle - You are experiencing at least mild cognitive concerns (rated at least 3 out of 10) - You speak English **You may NOT be eligible if...** - You are allergic to memantine - You received chemotherapy before your current treatment - You have severe cognitive impairment - You had a heart attack within the last 6 months - You have heart or joint problems that prevent safe exercise - You have severe mental illness, active substance abuse, or cannot swallow capsules - You have significantly reduced kidney function Talk to your doctor to see if this trial is right for you.