Affective disorder in childhood: separating the familial component of risk from individual characteristics of children.

ABSTRACT

In studying the risk of affective disorder in children, the investigator must deal with the problem that there are two possible units of analysis: the child and the family. An analysis based on children must take account of the intercorrelation within a sibship to produce correct results, while a family-based analysis makes it difficult to investigate individual characteristics of children that help determine the net risk. A two-stage iterative approach to this problem is proposed, yielding estimates of the effect of family-based factors (parental illness, family social class, marital status of parents) and individual factors (age and sex of child, previous non-affective illness). This technique is applied to a sample of 275 children from 143 families representing a wide range of familial risk for affective disorder. The final family-based model (predicting at least one child with affective disorder in the sibship) indicates a six-fold increase in risk to the child associated with maternal affective disorder (P less than 0.001), a three-fold increase in risk associated with paternal affective disorder (P less than 0.05) and divorce or separation of the biological parents, and a suggestion of increased risk in the highest social class (P = 0.06). The excess sibship risk, due to child factors age, prior anxiety disorder, and prior childhood diagnosis, contributed significantly to the family prediction (P less than 0.001).