Toxicity of manganese is more common than its deficiency (1), which unfortunately cause damage to the brain. Manganese appears to cause neurogeneration by activating microglia and causing them to release neurotoxins such as reactive oxygen and nitrogen species, which produce oxidative damage (2). The neurotoxins are also thought to possibly alter influence of neurotransmitters such as dopamine or gamma-aminobutyric acid (GABA) (1). According to a studies on non-human primates exposed to high doses of manganese, the mineral can lead to deficits in working memory performance and even induce an increase of beta-amyloid production linking manganese to Alzheimer's disease (3;4).
1. Anderson JG, Fordahl SC, Cooney PT, Weaver TL, Colyer CL, Erikson KM. Manganese exposure alters extracellular GABA, GABA receptor and transporter protein and mRNA levels in the developing rat brain. Neurotoxicology 2008;29:1044-53.
2. Zhang P, Wong TA, Lokuta KM, Turner DE, Vujisic K, Liu B. Microglia enhance manganese chloride-induced dopaminergic neurodegeneration: role of free radical generation. Exp Neurol 2009;217:219-30.
3. Schneider JS, Decamp E, Clark K, Bouquio C, Syversen T, Guilarte TR. Effects of chronic manganese exposure on working memory in non-human primates. Brain Res 2009;1258:86-95.
4. Burton NC, Guilarte TR. Manganese neurotoxicity: lessons learned from longitudinal studies in nonhuman primates. Environ Health Perspect 2009;117:325-32.