Apathy in Dementia Methylphenidate Trial 2 (ADMET 2) is a Phase III, placebo-controlled, masked, 6 month, 10-center randomized clinical trial sponsored by National Institutes of Aging involving 200 participants with Alzheimer's disease (AD). ADMET 2 is designed to examine the efficacy and safety of methylphenidate as treatment for clinically significant apathy in AD participants. ADMET 2 will enroll participants from real world settings such as outpatient, nursing home, and assisted living facilities and will examine the effects of methylphenidate on apathy and cognition. ADMET 2 will also conduct careful safety monitoring.