[Epidemiological investigation of tic disorders among pupils in the Shunde Longjiang area, and their relationship to trace elements].

Objective To investigate the epidemiological characteristics of tic disorders(TD) among pupils in the Shunde Longjiang area,and their relationship to trace elements.Methods A cross-sectional study of 4062 children aged 6-12 years,who were selected from the Shunde Longjiang area by stratified cluster sampling to investigate the epidemiological characteristics of TD,was conducted,and blood concentrations of trace elements in children with TD were determined.Forty normal children were selected as controls.Results The overall prevalence rate of TD was 2.98%;the prevalence rates of transient tic disorder,chronic motor or vocal tic disorder and Tourette's syndrome were 3.62%,2.39% and 1.21% respectively.Boys had a significantly higher prevalence rate of TD than girls(3.92% vs 1.96%;P0.05).There were no significant differences in blood copper,manganese and magnesium levels between children with TD and normal children(P0.05),however,children with TD had a significantly increased blood lead level and significantly decreased blood zinc and iron levels compared with the normal children(P0.05).No significant differences in trace elements were found between children with different subtypes of TD(P0.05).Conclusions TD is common in children aged 6-12 years and more prevalent in boys than in girls.High blood lead level and zinc and iron deficiencies may be one of the causes of TD,and thus should be considered during therapy.