[Environmental factors in western Pacific foci of ALS and a possible pathogenetic role of aluminum (Al) in motor neuron degeneration].

Recent decline in incidence rates of ALS in Guam and the Kii Peninsula of Japan strongly implicates environmental factors rather than inheritance in its causation. Environmental studies in Western Pacific foci showed identical mineral compositions in the soils and drinking water, i.e., extremely low calcium (Ca) and magnesium (Mg) and high aluminum (Al) and manganese (Mn). Series of trace-elemental analyses of the CNS tissue of ALS patients have revealed a high contents of Al and Ca with significant positive correlations between Al and Ca and/or between Ca and Mn, suggesting the prolonged exposure to these trace environment to cause abnormal mineral metabolism detrimental to neurons. Using electron energy loss spectrometry (EELS), Al was found to accumulate within DNA-containing chromatins and rRNA-containing cellular components, i.e., nucleolus, heterochromatin, rough endoplasmic reticulum, in lumbar motor neurons of ALS. Thus, Al may preferentially bind to nucleic acids and cause a progressive inhibition of the protein synthesis of rRNA and the transcription or gene modulation of DNA, leading to neuronal degeneration.