A Field Study of Mental Subnormality in Children

Abstract

Summary A description is given of a census investigation of imbecility and idiocy within a group of children comprising 10 one‐year classes in a population of altogether 265,000 individuals in Sweden. The incidence of mental subnormality of these degrees was 7.1 per 1,000 boys and 5.8 per 1,000 girls in the ages 2–11 years. The distribution of different clinical types in this material was studied and the educability in the different clinical groups is discussed. The occurrence of complications concerning pregnancy, delivery and birth weight, as well as of signs of cerebral injury during the first week of life, was investigated in certain groups of the material. Half of the cases in the sporadic idiopathic oligophrenic group had early potential injury or signs of cerebral injury of the type described above. In a control material of unselected newborns, the corresponding figure was only 20 per cent. A comparison with a special, unselected series of children with cerebral palsy seemed to show that abnormal conditions concerning pregnancy, child birth and birth weight can be traced in sporadic idiopathic imbecility and idiocy almost as often as in cerebral palsy. Etude de groupe du retard intellectuel chez l'enfant. Investigation statistique de l'imbecillité et de l'idiotie dans un groupe d'enfants, comprenant 10 classes d'un an, et issus de 265000 parents suédois. La fréquence de tels retards intellectuels entre 2 et 11 ans, peut être fixée à 7,1 pour mille chez les garcons, et 5,8 pour mille chez les filles. La répartition des divers types cliniques, ainsi que les possibilités éducatives de chaque groupe ont étéétudiées. L'existence de facteurs étiologiques a été recherchée, notamment au cours de la grossesse ou de l'accouchement, le poids de naissance, et les signes de traumatisme cérébral observés dans la première semaine. Dans 50 % des cas d'oligophrénie essentielle, on retrouvait des signes de maladie cérébrale précoces. Ce pourcentage dans un groupe de nouveauxnés témoins n'était que de 20 %. La comparaison avec un groupe d'enfants atteints de «paralysies cérébrales» semble montrer que de sfacteurs anormales en connection avec la grossesse et l'accouchement pathologique ou la prématurité peuvent étre trouvés presque aussi frequents dans l'imbécillité et l'idiotie sporadiqvie que dans la paralysie cérébrale. Eine Übersichtsstudie über die geistige Unterentwicklung bei Kindern. Beschrieben wird eine statistische Untersuchung über das Vorkommen von Imbezilität und Idiotie unter einer Gruppe von Kindern, welche 10 Ein‐Jahr Klassen einer Bevölkerung von insgesamt 265000 Menschen in Schweden umfasst. Die Häufigkeit geistiger Unterentwicklung dieser Schweregrade betrug 7,1 auf 1000 Jungen und 5,8 auf 1000 Mädchen in den Altersstufen zwischen 2. bis 11. Lebensjahr. Die Verteilung der verschiedenen klinischen Gruppen in dieser Serie wurde studiert vind die Erziehungsmöglichkeiten der verschiedenen klinischen Gruppen diskutiert. Bei gewissen Gruppen dieser Untersuchungsreihe wurde das Vorliegen von Komplikationen in der...

Relative importance of genetic and nongenetic etiologies in idiopathic mental retardation: estimates based on analysis of medical histories

“…This may be taken as the base rate of such disturbances in groups with no retardation caused by nongenetic brain damage. This rate is quite similar to the rate of prenatal and perinatal disturbances reported in two normal white control groups (Pasamanick & Lilienfeld, 1955;Herlitz & Redin, 1955).…”

“…Medical history analysis may be difficult to replicate precisely as we performed it, since a genetic control group of severe retardates of multiplex families and consanguineous parentage is already hard to find in scientifically advanced countries. However, it may be feasible to use normal population samples as control groups, in view of the similar prevalences of recorded disturbances of pregnancy and delivery in our genetic control group and in two white control groups previously reported (Pasamanick & Lilienfeld, 1955;Herlitz & Redin, 1955). The use of normal populations as control groups is subject to two conditions:…”

Estimated Frequency of Genetic and Nongenetic Causes of Congenital Idiopathic Cerebral Palsy in West Sweden

“…The validity of the above conclusions depends on the accuracy of the estimate of the proportions of risk factors in the control group and the study groups. An earlier study (Herlitz & Redin, 1955) found in a normal control group the same 0.25 proportion of non‐neuropathic risk factors as in the Goeteborg dataset, lending support to the credibility of the present analysis. Similarly, the wide range of estimated genetic causation of the different CP syndromes, from 3% in dyskinesia to 60% in hemiplegia and 100% in pure ataxia, seems incompatible with systematic under‐reporting or over‐reporting of risk factors.…”

Biological Factors in Mild Mental Retardation

“…Since only multiplex families were included in our comparison group, we would expect the likelihood of homozygosity among them to be much higher, probably approaching Since this group is essentially one of genetic retardation, it can be expected to show a prevalence of prenatal, perinatal and infantile biological disturbances similar to that of the normal population. This supposition is supported by two semiretrospective studies of 28 years ago, in which normal white populations in Sweden (Herlitz and Redin 1955) and the lJSA (Pasamanick and Lilienfeld 1955) showed prevalences of 20 to 30 per cent, compared with 23 per cent in our control group. Complications of pregnancy alone were observed in Edinburgh in 1 4 .…”