A Comparison Study of Inorganic and Organic Compounds in Children with Autism and Controls

Background: Recent literature supports the presence of a complex genetic/environmental interaction underlying at least some children's autism presentations.  The concentration of heavy metals and chemicals in the environment may be contributory to the etiology of autism.  The metalloprotein system, underlying heavy metal detoxification, and the methylation/sulfation system, underlying chemical transformation, may be altered in some children with autism.  Deficits in heavy metal detoxification are associated with changes in glutathione concentration and speciation.  Increased toxin concentrations can be associated with immunological abnormalities.  

Objectives: This study measured concentrations of elements, including heavy metals, total glutathione, and T and B cell subsets in children with autism and matched controls to determine whether there were significant differences present between the two groups that could contribute to the creation of a theoretical perspective that includes environmental toxicity.

Methods: Sixteen children, ages 2-9, with autism confirmed by Autism Diagnostic Observation Scale (ADOS), who were seen for their first visit to the Neurodevelopmental Service and not on exclusionary diets or nutrients, were eligible.  They were negative for genetic findings on chromosomes, fragile X, and oligoarray testing.  They were paired with 16 age, sex, and socioeconomically matched controls, found through a recruitment poster, who did not meet ADOS criteria for autism.  Blood was drawn from each child that measured plasma zinc/serum copper, T and B cell subsets, total glutathione, and plasma, serum, and red blood cell heavy metals, along with a large selection of elements including lead.  Hair samples were taken from all participants and heavy metal concentrations were measured.  Study analyses included t-test comparisons of all measures. 

Results: Children with autism had higher average serum antimony (13 pairs) than controls (p=0.005) and had higher average hair selenium, tin, and lead (9 pairs) than controls (p=0.002, p=0.014, p=0.030 respectively).  Children with autism (16 pairs) had lower mean total red blood cell glutathione than controls (p=0.006).  Children with autism had a higher average CD4 number (15 pairs) than controls (p=0.046). 

Conclusions: Children with autism may have had more difficulty eliminating antimony from their serum and may have had less ability to retain selenium, a micronutrient, than their matched controls.  Passive effluence of tin and lead through the hair may be increased in children with autism who did not have statistically higher blood levels of these elements than controls.  The increased amounts of tin and lead in the hair of children with autism versus controls is a finding that opposes recent literature.  Children with autism, who had significantly less red blood cell glutathione than controls, may have had decreased functioning of their metalloprotein system, affecting antimony elimination.  Detoxification differences in children with autism may have contributed to immune dysregulation, as evidenced by their significantly higher CD4 number than controls.  Overall, children with autism displayed mixed evidence of decreased heavy metal detoxification, clearly decreased total glutathione levels, and increased helper cell prevalence than controls.