This is a case–control study. A total of 279 AD and 117 vascular dementia (VaD) patients were recruited from neurology clinics at three teaching hospitals in Taiwan from 2007 to 2010. Controls (n = 466) were recruited from the elderly health checkup program and volunteers in the hospital during the same time interval. Three common (frequency ≥ 5%) haplotype-tagging single nucleotide polymorphisms were selected from the lipid metabolism gene SAR1B to assess its association with AD and VaD.