Idiopathic Retardation Research Articles

A study of institutionalized mentally retarded patients in Manitoba: over-representation by Canadian Indian children.

During analysis of data on 406 severely and profoundly mentally retarded children and their families in Manitoba a marked excess of Canadian Indian children was observed. There was no evidence to suggest that the over-representation by native children was due to an increased propensity of Indian families to institutionalize their children nor were these patients more profoundly retarded or more physically handicapped than the non-Indian children studied. Further analysis showed that Indian children were primarily over-represented in the groups with acquired retardation, autosomal recessive genetic disorders, idiopathic retardation with seizures and idiopathic retardation with malformations or dysmorphic signs. Review of other demographic findings indicated that other factors potentially predisposing to retardation, including low socioeconomic status, illegitimacy, high birth order, poor maternal reproductive history and increased consanguinity, were more common in the histories of native children. Severe and profound mental retardation has been said to occur equally in all strata of society. This evidently was not so in this Canadian population and the Indian child may be at special risk. Health care workers should be aware of possible predisposing factors for retardation in this group if reduction of the incidence of this major problem is to be achieved.

Pathogenic Factors in Idiopathic Mental Retardation

Pathogenic factors in a mentally retarded population were evaluated by comparing their frequency among three groups of patients: a control group with predominantly genetic retardation and consanguineous parents; a group with severe idiopathic retardation and unrelated parents; and a group with mild idiopathic retardation and unrelated parents. Seven factors were found to be significantly more common among the patients with idiopathic retardation than in the genetic control group: a history of maternal reproductive inefficiency; bleeding during pregnancy; toxemia during pregnancy; signs of perinatal stress; neonatal anoxia; neonatal jaundice; and seizures during the first year of life. A history of repeated maternal abortions was particularly associated with mild retardation, and infantile seizures were particularly associated with severe retardation. The latter association remained significant even after exclusion of all infantile spasms, neonatal seizures and symptomatic seizures. Since the control group in this study was composed mainly of genetically retarded patients, the associations observed seem likely to be related to the causes of retardation rather than simply being the effects of a damaged fetus.

Dermatoglyphics in idiopathic mental retardation.

EPIDERMAL RIDGE configurations (dermatoglyphics) have been of value in diagnosing a variety of disorders associated with chromosomal aberrations1and other genetically determined disorders.2In addition, dermatoglyphics have been abnormal in a high percentage of patients with prenatal rubella.3,4Most of the snydromes reported to be associated with dermatoglyphic abnormalities also include retardation as a feature. However, most mentally retarded individuals cannot be classified as yet into easily separable syndromes. Most are listed as having idiopathic retardation or retardation of unknown etiology. Where more than one retarded individual in a family is recognized, the term cultural-familial retardation is applied and partly glosses over medical ignorance. If the idiopathic group of retarded could be subdivided further on the basis of dermatoglyphic characteristics, a useful diagnostic tool would be available to the clinician. Studies of dermatoglyphics in mentally retarded groups have been carried out previously but the groups of retarded