Vascular disease increases the risk of Alzheimer's disease. The assessment of vascular dysfunction in subjects at risk for AD has the potential to contribute to the disease early diagnosis and management. In this work, the phase-contrast velocity mapping MRI technique was used to evaluate cerebral hemodynamics in patients with cognitive dysfunction and healthy controls. Results showed significant differences in hemodynamic parameters (velocity and flow) across groups with lower mean values in the AD and MCI groups compared to the CO group. PC-MRI can be used to assess hypoperfusion in an early stage of AD.