Written by Angeline A. De Leon, Staff Writer. A 2016 observational case-control comparative study demonstrates that autistic Egyptian children, relative to healthy controls, have significantly increased levels of urinary porphyrins which may serve as useful biomarkers for heavy metal exposure.

autism - brain healthThe last decade of research on Autism Spectrum Disorder (ASD) has revealed that the disorder is related not only to complex genetic characteristics, but also to a number of nutritional and environmental factors.1 Specifically, the etiology of ASD appears to be highly related to exposure to toxic heavy metals such as mercury (Hg) and lead (Pb) from various sources, including fertilizers, industrial paint, and chemical waste products.2,3 Studies have shown that even low levels of exposure to Pb may induce inflammation which can severely disrupt neural development in young children and trigger early markers of behavioral abnormality.4,5 Exposure to mercury is associated with changes in the urinary excretion of porphyrins (compounds essential to the function of hemoglobin), with higher levels correlating to greater Hg toxicity.6 In a clinical study conducted by researchers in Cairo, Egypt, investigators examined levels of urinary porphyrins (coproporphyrin, pentacarboxyporphyrin, precoproporphyrin) as biomarkers of Hg exposure, looking at its relation to severity of ASD in Egyptian children.

A total of 100 children, aged 3-6 years without any neuropsychiatric disorders, were enrolled as participants in an observational case-control comparative study. Children with ASD were diagnosed according to the Childhood Autism Rating Scale (CARS) and the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition and were divided into three groups: healthy controls, children with ASD, and healthy siblings of ASD children. Using blood and urine sampling, plasma levels of Hg, Pb, and urinary porphyrins were evaluated within the three groups.

Analyses revealed that mean values of Hg and Pb were significantly higher in children with ASD (Hg = 32.9 +/- 16.4 µg/L; Pb = 16.4 +/- 7.05 µg/L), relative to their healthy siblings (Hg = 12.08 +/- 4.5 µg/L; Pb = 10.8 +/- 3.4 µg/L) as well as healthy controls (Hg = 12.08 +/- 4.5 µg/L; Pb = 10.8 +/- 3.4 µg/L) (p < 0.01 for both). Urine excretion of children with ASD also contained significantly higher levels of coproporphyrin, pentacarboxyporphyrin, and precoproporphyrin as compared to both their healthy siblings (p < 0.01) as well as healthy controls (p < 0.001). A significant positive correlation was reported between levels of coproporphyrin and precoproporphyrin and autism severity based on CARS scores.

Findings confirm higher blood levels of Hg and Pb in autistic children, relative to their healthy peers. The use of urinary porphyrins was shown to be a useful biomarker for heavy metal exposure, with results indicating that increased levels of coproporphyrin and precoproporphyrin may be linked to greater severity of autism in children.

Source: Khaled EM, Meguid NA, Bjorklund G, et al. Altered urinary porphyrins and mercury exposure as biomarkers for autism severity in Egyptian children with autism spectrum disorder. Metab Brain Dis. 2016; 31: 1419-1426. DOI: 10.1007/s11011-016-9870-6.

© Springer Science+Business Media New York 2016

Posted November 28, 2017.

Angeline A. De Leon, MA, graduated from the University of Illinois at Urbana-Champaign in 2010, completing a bachelor’s degree in psychology, with a concentration in neuroscience. She received her master’s degree from The Ohio State University in 2013, where she studied clinical neuroscience within an integrative health program. Her specialized area of research involves the complementary use of neuroimaging and neuropsychology-based methodologies to examine how lifestyle factors, such as physical activity and meditation, can influence brain plasticity and enhance overall connectivity.

References:

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  4. Mostafa GA, Bjørklund G, Urbina MA, Al-Ayadhi LY. The positive association between elevated blood lead levels and brain-specific autoantibodies in autistic children from low lead-polluted areas. Metabolic brain disease. 2016;31(5):1047-1054.
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