Vascular dementia: perfusional and metabolic disturbances and effects of therapy.

Positron emission tomography (PET) has elucidated basic pathophysiological mechanism that produce the cognitive decline in vascular dementia (VD). The typical pattern of glucose metabolism seen in VD with scattered areas of focal cortical and subcortical hypometabolism differs from that in AD with marked hypometabolism affecting the association areas. The total volume of metabolically inactive tissue is significantly related to severity of dementia. Rather than the quantity of tissue destruction, the critical effect may be the quantity of cortical hypometabolism caused by subcortically induced disconnection. Studies with HMPAO SPECT have shown focal deficits in VD and AD patients that are comparable to those seen with FDG PET. In mildly demented patients performance for the classification AD versus VD is much better by PET because it might be more sensitive for imaging small functional pathological changes. A longitudinal analysis of rCMRGl in VD showed that the progression of dementia can be delayed by the adenosine uptake blocker propentofylline and that neuropsychological and metabolic changes are closely related.