Background: The high rates of comorbid disorders in ADHD may be influenced by evoked negative parenting behaviours, which have been shown to increase risk for externalising and internalising psychopathology in children. Most family research on comorbidity in ADHD is cross-sectional and does not account for genetic confounds, precluding the assessment of the independent environmental influence of specific risk factors. We used a longitudinal adoption-at-birth design to investigate whether parental hostility and warmth in mid-childhood mediated relationships between children’s early ADHD symptoms and subsequent ODD and anxiety symptoms in early adolescence, after accounting for genetic confounds.
Methods: Phenotypic data on 294 adopted children, their adoptive parents and their birth parents were drawn from the Early Growth and Development Study (EGDS), a prospective adoption-at-birth cohort. A cross-rater approach was used to assess reciprocal relationships between adoptive mother and father self-reports of parental hostility and warmth, and partner ratings of children’s ADHD, ODD and anxiety symptoms at ages 6, 8 and 11. Birth mother ADHD symptoms were also included as predictors of all child and adoptive parent measures to assess evocative gene-environment correlation.
Results: Children’s ADHD symptoms did not evoke parental hostility nor warmth, and these in turn did not predict children’s subsequent ODD and anxiety symptoms. However, we found that parental hostility and warmth in early childhood did prospectively predict child ADHD symptoms up to several years later, in early adolescence.
Conclusions: While we did not find evidence that parental hostility or warmth mediated comorbidity between symptoms of ADHD, ODD and anxiety, our findings suggest that early parental warmth and hostility may have a long-term influence on core ADHD symptoms.