Abstract
Brains came to autopsy from elderly cases that were psychometrically tested and were shown to be either intellectually normal (n = 48) or suffering from dementia of the Alzheimer-type (n = 56), as well as elderly cases that were not tested (n = 32). Cortical senile plaques, impregnated by von Braunmuhl''s Ag method, were found to range in structure from amorphous (neuritic) through to discrete (amyloid). Large numbers of the amorphous plaques were most frequently found in the outer half of the cortex of the demented cases, aged 60-75, whereas small numbers of the discrete plaques were most frequently found in the inner half of the intellectually normal cases, aged 75 onwards. The distribution of the senile plaques per se was found for 4 different regions of the cortex as well as the correlation of their numbers with the ages of the cases. The pathogenesis of the plaques is discussed.