[Amyotrophic lateral sclerosis--causative role of trace elements].

Although numerous hypotheses have been proposed for the cause of amyotrophic lateral sclerosis (ALS), conclusive decision still remains vague. Recent epidemiological investigation disclosed an aggregation of ALS cases in the Western Pacific, including the Kii Peninsula of Japan, the island of Guam in Marianas and West New Guinea. Extensive environmental studies in these foci indicated an important role of trace elements in ALS etiology. It is postulated that chronic environment deficiencies of calcium and magnesium may provoke secondary hyperparathyroidism, resulting in increased intestinal absorption of toxic metals under the presence of excess levels of divalent or trivalent cations and lead to the mobilization of calcium and metals from the bone and deposition of these elements in nervous tissue. This hypothesis, called metal-induced calcifying degeneration of CNS, has been supported by experimental studies using several animal species.