A population-based sample of 900 school-age children attending the following full-time SE groups: at level 1, children had isolated neurodevelopmental, physical, or other impairments; at level 2, borderline to mild intellectual disability (ID); and at level 3, moderate to severe ID. Three hundred and one children enrolled in mainstream education formed the control group (level 0). For all children with siblings, we defined familiar forms of learning disorders as having a sibling in one of the SE groupings. We performed our analysis for the entire cohort as well as comparing risk factors within the familial and non-familial types of SE groupings.
In multinomial logistic regression analysis, age of father 40 years, low BW (<2500 g or <−2 SD), male sex, and parent's lower SES, all increased the probability of SE placement. In the familial forms of levels 2 and 3, the parental SES was lower and, in addition, in the level 2, the family size was bigger. Furthermore, in the non-familial form of level 2, both the low and the high (
4000 g) BW were more common.
Among the known risk factors for learning disabilities (LD), our study highlighted the importance of a higher paternal age and a lower SES especially in the familial forms of LD.