Recently, the effects of aging on human brain tissue, mainly how structural changes may be related to functional changes, have been extensively discussed. However, there is still no agreement on which brain regions have altered perfusion and how it is related with dementia. Therefore, in the present study, we investigated regional changes in perfusion and gray matter concentration in healthy aging, Mild Cognitive Impairment and Alzheimer’s disease. The results indicate a significant age- and disease-related reduction of regional cerebral perfusion associated with brain atrophy. Therefore, these alterations may be important biomarkers for neurodegeneration.