Does the efficacy of parent–child training depend on maternal symptom improvement?

Multimodal treatment of children with ADHD often includes parent–child training (PCT). However, due to the high heritability, parents of children with ADHD are frequently also affected by the disorder, which is likely to constitute a significant barrier to successful treatment of the child. This secondary analysis of our randomized controlled multicentre AIMAC trial (ADHD in mothers and children) investigates whether children’s outcomes following parent–child training in combination with maternal ADHD treatment depend on maternal symptom improvement. In a first step focusing on treatment of maternal ADHD, 144 mothers of mother–child dyads were randomized to multimodal ADHD treatment (group psychotherapy plus methylphenidate) or clinical management (mainly supportive counselling). After 12 weeks (T2), a 12-week PCT program (T2–T3) for all mother–child dyads was added to treat children’s ADHD. Maternal symptomatology (CAARS-O:L; SCL-90-R) and children’s externalizing symptoms (ADHD-ODD Scale, SDQ) were repeatedly assessed (T1 = baseline, T2, T3). Effects of changes in maternal symptomatology (T1–T2) on the change in children’s symptom scores (T1–T3) were analysed using a general linear model, controlling for baseline scores, study centre, and maternal treatment group. 125 mother–child dyads were analysed. Mothers showed significant improvements in ADHD symptoms and overall psychopathology [CAARS-O:L ADHD index: mean − 3.54, SE 0.74 p < 0.0001; SCL-90-R Global Severity (GS): mean − 11.03, SE 3.90, p = 0.0056]. Although children’s externalizing symptoms improved significantly (ADHD-ODD Scale: mean − 4.46, SE 0.58, p < 0.0001), maternal improvement had no effect on children’s outcomes after Bonferroni–Holm correction for multiple testing. The findings do not support our hypothesis that children’s outcomes following PCT for ADHD depend on maternal symptom improvements.