Mental dysfunction usually leads to impairment in the quality of life. Little of information is available about cognitive functions and changes in CBF in elderly Egyptian people.The aim of the present study is to evaluate CBF in elderly patient with cognitive dysfunction, either primary (Alzheimer), or secondary (vascular) with analysis of results in comparison to data of control.30 patients aged ≥ 65 years have been introduced. Assessment of cognitive functions, psychic status, LAB investigations and Duplex U/S of extracranial internal carotid artery and vertebral artery to measure CBF has been introduced.