Aluminium and
silicon are incidentally found in
senile plaques (SP) and neurofibrillary tangles (NFT) of brains with
Alzheimer's disease (AD), and have been considered as one of the risk factors for
senile dementia. Since
lipofuscin granules were concentrated concomitantly with SP and NFT in the high density fraction in subcellular fractionation of autopsied brains and are solid in nature, it was suspected that
aluminum and
silicon are accumulated in
lipofuscin granules. Therefore, elemental analyses of partially purified
lipofuscin granules from autopsied brains with AD and those without
dementia, were attempted by energy dispersive X-ray spectrometry with a scanning electron microscope. It was demonstrated by a mapping method that
aluminum and
silicon were accumulated in some
lipofuscin granules, probably as
aluminosilicate. In addition, it was demonstrated by fluorescence microscopy of Bodian stained
paraffin sections, that many SP and NFT contained
lipofuscin granules, although
lipofuscin granules were not always specific to those neuropathological changes. These results imply that
aluminum detected in SP and NFT is due to
lipofuscin granules and can explain the cause of discrepancies in the reports on the presence of
aluminum in SP and NFT.