Prospective studies of cerebral perfusion and cognitive testing among elderly normal volunteers and patients with ischemic vascular dementia and Alzheimer's disease.

To compare longitudinal changes of cerebral perfusion (CBF) and cognitive status in two common forms of dementia in the elderly, 42 patients with ischemic vascular dementia (IVD), 44 patients with dementia of the Alzheimer type (DAT), and 120 elderly normal volunteers were evaluated prospectively over a mean interval of 3.35 years. Subjects were at least age sixty, (mean age 71.1). Mean bihemispheric cerebral blood flow and cognitive test scores of control subjects were significantly higher than those of both demented groups at entry and remained so. After adjustment for initial CBF, course over time was similar for all groups. Group variability was similar for CBF but not for cognition. Both IVD and DAT patients were more variable than controls but similar to each other. Throughout, DAT patients showed greater cognitive impairments than IVD patients. Cognitive impairments stabilized among IVD patients treated by control of risk factors, antiplatelet or anticoagulant therapy but declined progressively among DAT patients.