Following a medically induced menopause, many women report difficulty in remembering things, focusing and concentrating. The purpose of this study is to examine the effects of a stimulant medication called Vyvanse® (lisdexamfetamine; LDX) on executive functioning, such as attention, processing, organization, and memory, in women who are experiencing executive functioning difficulties after having undergone a risk-reducing bilateral salpingo-oophorectomy (RRSO). This study involves magnetic resonance imaging (MRI) to see how LDX affects brain chemistry while undergoing two 6-week trials of the study drug and placebo capsules.