Association between urinary BTEX metabolites and dyslexic odds among school-aged children.

Benzene, toluene, ethylbenzene, and xylene (BTEX) are ubiquitous in the environment, and all of them can cause neurotoxicity. However, the association between BTEX exposure and dyslexia, a disorder with language network-related regions in left hemisphere affected, remains unclear. We aimed to assess the relationship between BTEX exposure and dyslexic odds among school-aged children. A case-control study, including 355 dyslexics and 390 controls from three cities in China, was conducted. Six BTEX metabolites were measured in their urine samples. Logistic regression model was used to explore the association between the BTEX metabolites and the dyslexic odds. Urinary trans,trans-muconic acid (MU: a metabolite of benzene) was significantly associated with an increased dyslexic odds [odds ratio (OR) = 1.23, 95% confidence interval (CI): 1.01, 1.50], and the adjusted OR of the dyslexic odds in the third tertile was 1.72 (95% CI: 1.06, 2.77) compared to that in the lowest tertile regarding urinary MU concentration. Furthermore, the association between urinary MU level and the dyslexic odds was more pronounced among children from low-income families based on stratified analyses. Urinary metabolite levels of toluene, ethylbenzene, and xylene were not found to be associated with the dyslexic odds. In summary, elevated MU concentrations may be associated with an increased dyslexic odds. We should take measures to reduce MU related exposure among children, particularly those with low family income.

Urine patterns, peptide levels and IgA/IgG antibodies to food proteins in children with dyslexia.

There is an association between psychiatric disorders and dyslexia. In some psychiatric disorders abnormal urinary peptide patterns and peptide levels, and elevated levels of IgA antibodies to food proteins have been detected. These abnormalities are probably due to insufficient breakdown of the proteins gluten and casein. The aim of this study was to discover whether such abnormalities could be found in urine samples and serum of children with dyslexia. After screening 291 pupils in the fourth grade, 15 dyslexics and 15 controls were pairwise matched by gender, age, and cognitive level. Word decoding, spelling, and short-term memory tests were carried out, and information on handedness, immune and other disorders was obtained. Analyses of 24-h urine samples and of serum were performed. The reading abilities significantly differentiated the groups, and significant differences were found in frequency of left-handedness, immune disorders and other disorders. Three dyslexic children had elevated IgA antibodies. Two of these had positive endomycium tests, and coeliac disease was confirmed by biopsy. One had antibodies to proteins in milk. Our findings may suggest weak urinary peptide abnormalities in the dyslexic children, and they show significant differences in levels of IgA of antibodies to food proteins.