This study seeks to assess the effects of lisdexamfetamine (trademark name: Vyvanse; LDX) on executive function and prefrontal cortex activation in menopausal women ages 45-57, who report subjective cognitive difficulties. This protocol will recruit women from Dr. Epperson's ongoing study, Protocol #812470, to examine the impact of LDX on brain activation during performance of cognitive tasks specifically probing prefrontal cortex function.