ABSTRACT
This study was conducted to evaluate some factors that may affect the cognitive abilities of children with Down syndrome [DS] including hypothyroidism; zinc and selenium deficiency; and the oxidative five stress and additionally, to study the effect of zinc supplementation on the mental state of such cases. Sixty Down syndrome patients were enrolled together with 20 apparently healthy controls with matched age and sex. Estimation of the IQ scores, evaluation of the thyroid function tests, measurement of the serum levels of zinc and selenium, as well as plasma levels of superoxide dismutase activity [SOD] and hydrogen peroxide [H[2][O]2] were done to all cases and controls, Cases with severe mental retardation [IQ 25-39] were received oral zinc sulfate supplementation. A follow up study was done to reevaluate all the above-mentioned studied parameters after 3, and 6 months. Results showed that, in comparison with the controls, DS patients had significantly lower serum levels of both zinc and selenium and significantly higher serum level of TSH, as well as plasma levels of both SOD and H[2]O[2]. There were significant positive correlations between the IQ scores and each of T3, T[4], zinc and selenium serum levels, while significant negative correlations were found between the IQ scores and serum level of TSH, as well as plasma levels of both SOD and H[2]O[2]. The follow up study showed significant rise of serum zinc level after 3 months of zinc supplementation. Progressive improvement of the IQ scores and thyroid function tests were noticed. This improvement was significant after 6 months of zinc supplementation. In conclusion, cognitive abilities in DS patients may be affected by multiple factors as hypothyroidism, oxidative stress as well as zinc and selenium deficiency. Zinc supplementation for 6 mo may help these abilities to be improved