Objectives: The aim of this study was to determine whether use of diuretics, angiotensin-1 receptor blockers (ARB), angiotensin-converting enzyme inhibitors (ACE-I), calcium channel blockers (CCB), or b-blockers (BB) was associated with a reduced risk of Alzheimer disease (AD) dementia in participants with normal cognition or mild cognitive impairment (MCI). Methods: Secondary longitudinal data analysis of the Ginkgo Evaluation of Memory Study in older adults at least 75 years of age with normal cognition (n 5 1,928) or MCI (n 5 320) over a median 6.1-year period using Cox proportional hazard models after adjusting for confounders. Results: Diuretic use was reported by 15.6%, ARB 6.1%, ACE-I 15.1%, CCB 14.8%, and BB 20.5%. Of the 2,248 participants, 290 (13%) developed AD dementia. Hazard ratio for incident AD dementia among participants with normal cognition was 0.51 in diuretic (95% confidence interval [CI] 0.31-0.82), 0.31 in ARB (95% CI 0.14-0.68), 0.50 in ACE-I (95% CI 0.29- 0.83), 0.62 in CCB (95% CI 0.35-1.09), and 0.58 in BB (95% CI 0.36-0.93) users and was not significantly altered when mean systolic blood pressure was above 140 mm Hg. In participants with MCI, only diuretic use was associated with decreased risk (hazard ratio 5 0.38, 95% CI 0.20-0.73). Conclusions: Diuretic, ARB, and ACE-I use was, in addition to and/or independently of mean systolic blood pressure, associated with reduced risk of AD dementia in participants with normal cognition, while only diuretic use was associated with reduced risk in participants with MCI. © 2013 American Academy of Neurology.