Mentally retarded

Data of mentally retarded (IQ below 85), recorded at the age of 14-years.

Number of cases
Data obtained: N = 326

Data collection
Collected from schools, institutions for mentally retarded and child wefare clinics for those persons who were not at classlevel apropriated for age.

Follow-up data on the mental and physical development of the children were collected at various ages; the last follow-up was in 1980 and 1981, when the children were 14 years old. Only 14 children, 1.2 per 1,000, could not be traced at that age; these children had emigrated to other countries. Of the original cohort, 82.9% were still living in northern Finland in 1980, 10.7% were living in other parts of Finland, and 6.5% had emigrated to other countries, mainly Sweden.

Follow-up data were collected during the period 1966 to 1983 in the following ways: (a) guestionnaires on the pregnancy and on morbidity and mortality among the infants during the perinatal period were filled in by the midwives at the antenatal and postnatal clinics (Rantakallio, 1969); (b) guestionnaires on the children's health and development at the age of one year were filled in by the public health nurses at the children's welfare centers (Rantakallio & Mäkinen, 1983); (c) hospital records and special forms were filled in for those children who visited neurological out-patient clinics in the area either because of their symptoms or when reguested to do so for study purposes; (d) data on admissions to the four children's hospitals in the area from 1966 to 1972 were collected by the research group (Rantakallio, 1978); and information was taken from national registers, namely, death certificates (since 1965); hospital discharge register (since 1972), medicine reimbursable in full (sincce 1967), child subsidies for chronically sick children (since 1967), and mentally retarded children (since 1979).

The latest guestionnaire on the child's health and development and school performance at the age of 14 years was filled in by the child and family. The response rate was 97%. In the remaining cases, school health nurses were interviewed concerning the health of the child and school social workers were gueried concerning school performance. This method was also used if the data on school performance received from the child and family were inadeguate or doubtful.

Main articles
Rantakallio P., von Wendt L.: Mental retardation and subnormality in a birth cohort of 12,000 children in Northern Finland. Am. J. Ment. Defic. 1986, 90: 380-387.

Last updated: 10.7.2020