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Risk factors for mental retardation
Insights
Identifying risk factors for intellectual disability is crucial. This study found identifiable risk factors in over half of children with intellectual disability, with prenatal factors linked to severe cases.
Area of Science:
- Medical Science
- Developmental Psychology
- Epidemiology
Background:
- Intellectual disability (ID) presents a significant public health challenge.
- Understanding the etiology of ID is essential for prevention and intervention strategies.
- Previous research has identified various potential risk factors, but comprehensive prospective studies are limited.
Purpose of the Study:
- To prospectively identify risk factors associated with intellectual disability in a large cohort of children.
- To determine the incidence of intellectual disability and its severity in relation to identified risk factors.
- To investigate the association between prenatal and perinatal conditions and different levels of intellectual disability.
Main Methods:
- A prospective cohort study of 12,000 children born in northern Finland in 1966, followed to age 14.
- Assessment of intellectual functioning using IQ scores, with a threshold of <86 for intellectual disability and <50 for severe intellectual disability.
- Analysis of identified risk factors, including prenatal and perinatal conditions, and their correlation with ID severity.
Main Results:
- A risk factor was identified in 50.6% of children with intellectual disability, with higher percentages for severe ID (86.7%).
- Prenatal conditions were most strongly associated with severe ID (64%), while perinatal conditions were linked to mild ID and subnormality.
- Cases without a known risk factor were more prevalent in boys than girls.
Conclusions:
- A significant proportion of intellectual disability cases have identifiable risk factors, particularly prenatal ones for severe forms.
- The study highlights the importance of considering both prenatal and perinatal factors in the etiology of intellectual disability.
- Further research is warranted to explore unknown risk factors and develop targeted preventive measures.
Abstract:
Risk factors for mental retardation were studied prospectively in 12 000 children born in northern Finland in 1966 and followed to the age of 14 years. The number of untraced children was less than 2 per 1000. Altogether 326 children had an IQ less than 86, and the incidence of severe retardation (IQ less than 50) was especially high. An incidence figure for children with mental retardation, a separate figure for healthy children, and also the death rate were calculated for each disease. Only in the cases of Down's syndrome and some hereditary diseases were all the exposed children mentally retarded; in other diseases some children did not seem to suffer any sequelae. A risk factor could be found for 50.6% of the total number of children with mental retardation, the percentage decreasing from the severest to the mildest form (86.7%, 45.4%, and 30.9%). Some 9.4% of the healthy children and 77.7% of those who died had had one or more of these conditions. Prenatal conditions were most often associated with severe mental retardation (64%), and perinatal conditions with mild retardation, (IQ 50 to 70; 27%) and mental subnormality (IQ 71 to 85; 18%). Cases with no known risk factor were more common among boys than girls.