The relationship between formation of senile plaques and neurofibrillary tangles and changes in nerve cell metabolism in Alzheimer type dementia.

Nerve cell nucleolar volume in reduced, in senile dementia of Alzheimer type, by 15 - 25% in nerve cells not containing neurofibrillary tangles and by over 35% in those which do contain such changes, in a wide variety of brain regions, when compared to similar cells from non-demented control cases, suggesting that interference with production of proteins may be an early consequence of the pathogenic process. The extent to which nucleolar volume is decreased in the non-tangle-bearing cells is related to frequencies of both neurofibrillary tangle and senile-plaque formation within that region, but the reduction in volume in the tangle-bearing cells correlated with neurofibrillary changes only. It seems, therefore, that the severity with which the dementing process affects an area of brain is initially shown by alterations in cell metabolism, which may invoke reductions in protein synthesis in non-tangle-bearing cells, and is later marked by the proportion of these affected cells which go to form neurofibrillary tangles. Changes in nerve cell function do not seem to be as well indicated by the density of senile plaques within that area.