Methods: We used data from the Wisconsin Longitudinal Study, a community-based random sample of Wisconsin high school graduates in 1957 and their selected siblings. Our final sample included 6,792 aging parents (Mage=71) regarding 22,225 of their non-disabled adult children (Mage=44). To measure the relationship quality, we calculated ambivalence scores, indicating simultaneous and contradictory feelings of parents (i.e., solidarity and conflict) toward adult children. We estimated multi-level models to examine between- and within- family differences in feelings of ambivalence in the parent-adult child relationship: we tested (1) whether parents from families of adults with DD or SMI were more likely to report feelings of ambivalence toward their non-disabled children than those from families where none of children have a disability (i.e., between-family differences) and (2) whether or not parents of adults with the conditions were likely to report greater variability in the quality of their relationships with adult children (i.e., within-family variability).
Results: Parents of a child with SMI reported greater ambivalence in their relationships with their other adult children. However, levels of ambivalence in families of adults with DD did not differ from those in the comparison group. Compared with parents who did not have a disabled child, parents of a child with SMI reported higher levels of conflict with their other adult children whereas they did not differ with respect to feelings of solidarity. In addition, parents who had an adult child with SMI were more likely to report greater variability in the quality of the relationships with their children than the comparison group parents.
Conclusions and Implications: These findings suggest that siblings of the adult child with SMI were adversely affected by their brother or sister with the conditions in terms of the relationships with their parents. Attention to the needs and family interactions of siblings, as well as parents, can thus create a more holistic approach to intervention with these families and enhance their ability to provide support to their sibling with serious mental illnesses.