The role of zinc and copper in autism spectrum disorders

Autism spectrum disorders (ASDs) are lifelong developmental disabilities. This group of disorders includes autistic disorder, Asperger syndrome, and pervasive developmental delay not otherwise specified. These disorders are presented from birth or very early during development and affect essential human behaviors such as social interaction, the ability to communicate ideas and feelings, imagination, and the establishment of relationships with others. Infantile autism and Asperger syndrome are two closely related forms of developmental disorders (Bjørklund 1998). ASDs are a group of systemic disorders with multiple etiology, including both genetic and environmental/ lifestyle factors. This article focuses on some of the changes in trace element metabolism commonly found in ASD patients. Bioelements play important roles in the central nervous system. The lack or excess of essential minerals and trace elements are known to cause a variety of health problems, and could contribute to the etiology of ASDs (Lakshmi Priya and Geetha 2011, BlaurockBusch et al. 2012). Similarly, mercury (Hg) and other toxins may play a role in the pathogenesis of ASDs (Bernard et al. 2001, Geier et al. 2009, 2010, 2012, Blanchard et al. 2011, Blaurock-Busch et al. 2012, Kern et al. 2012). Children are, due to their behavior, more exposed to environmental toxins than adults, but often also have higher intestinal absorption rates and lower detoxification ability (Grandjean and Landrigan 2006). Many studies show that autistic children have a higher body-burden of toxic metals compared to neurotypical controls (Desoto and Hitlan 2010, Geier et al. 2010, 2012, Lakshmi Priya and Geetha 2011, Obrenovich et al. 2011, Elsheshtawy et al. 2011, Adams et al. 2013, Al-Farsi et al. 2013). These studies indicate that children with autism have a decreased ability to excrete toxic metals, leading to a higher body burden. Moreover, studies show that Hg body-burden is associated with increased ASD severity (Lakshmi Priya and Geetha 2011, Elsheshtawy et al. 2011, Geier et al. 2012, Adams et al. 2013). Reduced activity of transketolase has been reported in some patients with ASDs (Lonsdale et al. 2011, Obrenovich et al. 2011). The level of transketolase is used as a diagnostic test of thiamine deficiency. Of 91 examined children with ASD, 19 (21%) suffered from lack of transketolase and thiamine, defined by enhancement of the activity of transketolase from blood samples by more than 18% after supplementation with thiamine (Obrenovich et al. 2011). It is an unresolved The role of zinc and copper in autism spectrum disorders