Aluminum Neurotoxicity — Potential Role in the Pathogenesis of Neurofibrillary Tangle Formation

Alzheimer's disease is a progressive neurodegenerative disease characterized neuropathologically by the development of large numbers of neurofibrillary tangles in certain neuronal populations of affected brains. This paper presents a review of the available evidence which suggests that aluminum is associated with Alzheimer's disease and specifically with the development of the neurofibrillary tangle. Aluminum salts innoculated into experimental animals produce neurofilamentous lesions which are similar, though not identical, to the neurofibrillary tangle of man. Although a few reports have suggested evidence of increased amounts of aluminum in the brains of Alzheimer's disease victims, such bulk analysis studies have been difficult to replicate. Using scanning electron microscopy with x-ray spectrometry, we have identified accumulations of aluminum in neurofibrillary tangle-bearing neurons of Alzheimer's disease. Similar accumulations have been identified in the neurofibrillary tangle-bearing neurons found in the brains of indigenous natives of Guam who suffer from parkinsonism with dementia and amyotrophic lateral sclerosis. This ongoing research still cannot ascribe a causal role of aluminum in the pathogenesis of neurofibrillary tangle formation; however, it does suggest that environmental factors may play an important part in the formation of this abnormality.