Researchers have found a link between small amounts of metals in the blood in a group of patients with amyotrophic lateral sclerosis (ALS), and the occurrence of the disease in a geographical area that has a higher rate of ALS. While this occurrence cannot be considered to be the sole cause of ALS, the study opens new approaches to understand its causes.
The study, “Blood trace metals in a sporadic amyotrophic lateral sclerosis geographical cluster,” was published in the journal Biometals.
Amyotrophic lateral sclerosis (ALS) is a fatal disorder for which the cause is unknown. It is thought that both heritable traits and factors in the environment contribute to its development and progression.
The study involved six patients (three men and three women) and five controls (two men and three women), of roughly the same age, all living in the same geographical area in Italy. Among the 11 subjects, eight were born and lived in this area, one patient moved there in 1970, another patient moved there in 1988, and one control moved in at the age of 12.
Acid mine drainage has been reported in this area, which can lead to the release of inorganic contaminants, such as trace metals, into soil and water. Importantly, the incidence of ALS in this area is higher than the rest of Italy.
The levels of manganese (Mn), zinc (Zn), cobalt (Co), and chromium (Cr) were found to be higher both in patients and controls, in comparison with the reference values for the Italian population.
DNA damage was assessed and was found to be similar in both patients and controls.
The most striking finding was the lower concentrations of arsenic serum (As) in the ALS group, compared to the controls. Levels of As and Cr were found to correlate with disease progression.
High concentrations of metals were associated with the disease group, such as Selenium (Se) and Aluminum (Al).
Also, more of the ALS patients drank tap water than the controls.
“From the results of this survey it must be stressed that single metal evaluations may underestimate their relevance for health risks. It is more likely that all these metals interact with one another with an additive or even a synergistic effect,” the authors note. Moreover, they stated that more studies are needed to investigate the role of environmental factors on the development of ALS.