Brain changes in dementia of Alzheimer's type relevant to new imaging diagnostic methods

The aim of the article is to correlate grey and white matter changes and their topography to the results of modern methods for brain imaging such as CT, rCBF, PET, SPECT and NMR in Alzheimer's type of dementia. The findings are based on the study of a large material investigated thoroughly patho-anatomically. The findings are correlated with psychiatric and neurophysiologic follow-up studies. The degenerative grey matter process shows a regionally varying accent according to a pattern which is consistent and typical for the disease. This corresponds to metabolic changes on rCBF, PET and SPECT and thereby becomes of diagnostic value. This pattern is largely symmetric. Metabolic asymmetries have however been reported on PET scans. In this context individual variations of the topographic degenerative brain pattern and normal anatomical brain asymmetries are of interest. The white matter however also frequently shows changes, in particular loss of myelin and axons and a mild gliosis, slight in 1/3 of the cases and severe in an additional 1/3. These changes cause a decrease of density in the centrum semiovale correlating to lipid depletion. They may also influence the ventricular shape and size, of interest in CT or NMR studies. Also here variations in ventricular shape, normal and such due to pathological processes unrelated to the Alzheimer disease, may cause confusion, regarding degree of atrophy and even type of brain process. Such factors should be considered in the interpretation of non-invasive brain studies.