Classification as a function of the degree of dementia

Primary dementias may be classified into dementia of Alzheimer type (DAT) and dementia of vascular type (DVT) which differ in morphological and clinical respects. Studies on cerebral blood flow (CBF) and metabolism may support the classification procedure provided the dementias are in their early phase and their symptoms are florid. Generally unchanged CBF and cerebral metabolic rate (CMR) oxygen are accompanied either by reduced CMR glucose (DAT) or by increased CMR glucose (DVT). In chronic dementias, these differences disappear and no classification of DAT and DVT by means of CBF and metabolism may be possible. As far as the degree of dementia is concerned, a close correlation between diminished CBF and metabolism and severity of dementia is generally found. However, in some cases of productive or hyperactive dementia without brain atrophy, this correlation is not evident.