[Epidemiology of mental retardation in Poland].

In 490 Polish school districts 260 heavily imbecile children (I.Q. from 0 to 49), i.e., 0.30 percent of all children aged 5 to 15, among them 151 boys and 109 girls, were found by twenty teams composed of neuropsychiatrists, psychologists, and statisticians. The Langdon-Down syndrome was found in 39 cases (0.51 per thousand). 40.7 percent of the children had brothers and sisters that were weak-minded or afflicted with other psychic disorders. For 93 children it was possible to establish birth asphyxia. The proportion of children who because of imbecility are unable to attend normal schools amounts to 2.0 percent.