Abstract Defining the vascular component(s) of the clinical diagnosis of vascular cognitive impairment (VCI) and vascular dementia (VaD) continues to be problematic. The goal of this study was to determine whether vascular stiffness, measured by pulse wave velocity (PWV), is altered in VaD, to study the utility of PWV in differentiating VaD from Alzheimer dementia (AD) and the relationship between PWV and cognitive function. A qualitative and quantitative structured analysis of the literature was conducted until September 2010, using a search strategy based on the key words: dementia, vascular dementia, dementia of vascular origin, cognitive function and arterial stiffness or pulse wave velocity. Seventeen studies assessed large vessel vascular stiff by PWV and related it to cognitive function or dementia. Six of these studies compared PWV in 154 persons with VaD, 207 with AD and 197 controls without dementia. Mean PWV was significantly (p < 0.0001) higher in VaD compared with controls. Mean PWV was significantly (p = 0.002) higher in VaD compared with AD. Fourteen studies examined the relationship between PWV and cognitive function. The majority of studies (nine of 14) reported a significant correlation between PWV and cognitive function. Four of eight studies that evaluated the relation using univariate analysis reported a significant correlation of PWV with the Mini Mental State Exam (MMSE) or Hasegawa Dementia Scale, and the correlation with MMSE between studies showed a close agreement of correlation coefficients (0.206 to 0.27). In multivariate analysis, adjusted for a wide range of possible confounding factors, the majority or 80% (eight out of 10) studies comprising a population of 6,034 individuals found a significant inverse relationship between PWV and cognitive function. In summary, vascular stiffness is inversely related to cognitive function. Vascular stiffness is greater in VaD compared with AD, suggesting PWV may be useful in identifying VaD.