Amyotrophic lateral sclerosis and environmental factors

Abstract

SummaryAmyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder that affects central and peripheral motor neuron cells. Its etiology is unknown, although a relationship between genetic background and environmental factors may play a major role in triggering the neurodegeneration. In this review, we analyze the role of environmental factors in ALS: heavy metals, electromagnetic fields and electric shocks, pesticides, β-N-methylamino-L-alanine, physical activity and the controversial role of sports. The literature on the single issues is analyzed in an attempt to clarify, as clearly as possible, whether each risk factor significantly contributes to the disease pathogenesis. After summarizing conflicting observations and data, the authors provide a final synthetic statement.

What causes amyotrophic lateral sclerosis?

“…Similarly, electric shock is not a risk factor in some analyses but is in others 97, 98 . There is mixed evidence for the involvement of chemicals, such as heavy metals, ambient aromatic hydrocarbons, pesticides, and cyanotoxins 99– 103 . Trauma, including head injury, also appears to be a risk factor in meta-analysis 104 .…”

Flavin-containing monooxygenases in aging and disease: Emerging roles for ancient enzymes

“…hFMO1 expression is consistently decreased in the spinal cord of ALS patients (62), and single nucleotide polymorphisms in the hFMO1 3Ј-untranslated region occur more frequently in female patients with sporadic ALS (62). Additionally, mFmo1 is up-regulated in a mouse model of ALS, which, although in the opposite direction of human findings, may be explained by different stages of the disease affecting expression differently (62).…”

Neuron-Microglia Interactions in Motor Neuron Degeneration. The Inflammatory Hypothesis in Amyotrophic Lateral Sclerosis Revisited

“…Until now, the higher ALS prevalence in specific groups of patients (football players [21][22][23], veterans of the Gulf War [24,25] or farmers with elevated pesticide and/or fertilizer exposure [26][27][28][29]) has not helped unravel the cascade of events or the driving force underlying the disease. Several pathological mechanisms such as genetic factors, environment, autoimmunity, oxidative stress, excitotoxicity, microglial activation, impairment in filament organization and neuronal transport, and misfolded proteins have been proposed as possible explanations of ALS heterogeneity [30,31].…”