CD34 and Alzheimer disease: Using Cox proportional hazards regression models, we examined the relationships between the proportions of different circulating cell populations (log-transformed) with following EPC marker combinations, CD34+CD133+, CD34+CD133−, CD34+, CD34−CD133+, CD34−CD133−, or CD34+KDR+ (VEGFR2), and AD or all-cause dementia risk.