The accumulation of specific metals may trigger neuronal degeneration associated with Amyotrophic lateral sclerosis (ALS), according to a study conducted on residents of the Kii Peninsula in Japan. The study, titled, “Neutron Activation Analysis of Scalp Hair from ALS Patients and Residents in the Kii Peninsula, Japan” was recently published in the journal Biological Trace Element Research.
The team of researchers led by Tameko Kihira from the Department of Health Sciences, Kansai University of Health Sciences, Osaka, Japan examined the accumulation of transition metals in the scalp hair of amyotrophic lateral sclerosis (ALS) patients in the Koza/Kozagawa/Kushimoto (K) area (K-ALS) in the Kii Peninsula, Japan.
Amyotrophic lateral sclerosis (ALS) is a progressive degenerative disorder of the upper and lower motor neuron system. The pathogenesis of the condition remains unclear, however multiple mechanisms are thought to be involved. These include interactions between genetic and environmental factors, oxidative stress and dysfunctional protein aggregation.
The incidence of ALS has been found to be higher in the Koza/Kozagawa/Kushimoto (K) area in the Kii Peninsula of Japan, with evidence showing an association between ALS and consumption of water containing transition metals. Essentially, studies found low levels of Calcium (Ca) and high levels of Manganese (Mn) and Aluminum (Al). ALS patients from this specific area (called K-ALS) were revealed to be carrying high levels of urinary 8-hydroxydeoxyguanosine, a marker of oxidized DNA.
Evidence shows that metals such as Cadmium have toxic effects, which are enhanced when there is insufficient Ca in one’s diet. In this regard, the team of researchers found transition metals are easily absorbed when people have low levels of Ca, and thought that this could increase the oxidative stress in neurons, thus making a person more prone to ALS.
Using neutron activation analysis, the researchers measured the levels of metals Ca, Al, Cu, Mn, V, Br, I, Zn and S in hair samples of 132 K-residents, 29 controls, 7 K-LS and 10 ALS patients.
Results revealed that, compared to controls, K-ALS patients had higher levels of Zn, Mn and V, while S was lower. Furthermore, results showed that Mn was negatively correlated with clinical durations in K-ALS patients, and Al was higher in K-residents than in the controls.
Baeed on these findings, Tameko Kihira and colleagues strongly suggest that the accumulation of these transition metals can lead to metal-induced oxidative stress, that can trigger the neuronal degeneration associated with K-ALS.