Aluminum and Alzheimer Disease

To the Editor.—  I read with interest the editorial on Alzheimer disease by Katzman in the April issue of the Archives (33:217, 1976). A colleague and I¹ recently reported localization of aluminum and silicon in senile plaques in six patients with Alzheimer disease by using a Castaing electron microprobe. We did not identify aluminum in the comparatively few neurofibrillary tangles available for examination. Crapper et al² studied with an atomic absorption spectrophotometer the amount of aluminum in samples of brain from 18 patients with Alzheimer disease. This technique measures the total aluminum concentration in a given brain sample. In two of their cases these authors reported a significant association between abnormal quantities of aluminum and neurofibrillary tangles, but not of senile plaques. This was surprising because the tissue in question apparently contained both senile plaques and tangles. Terry and Pena,³ using an electron microprobe, were unable to