LAUSR

Dyadic interactions may be affected by the mental health of either partner; however, both partners’ symptoms are typically not considered simultaneously in observational studies of parent–child relationships. Using the actor–partner interdependence model (APIM), we examine how depression and posttraumatic stress disorder (PTSD) symptoms in mothers and adolescent daughters predict their own and each other’s relational behaviors (warmth, hostility, communication) during interactions, and whether partners’ relational behaviors predict changes in symptoms 1 month later. Participants include 150 mother (mean age = 41.6) and daughter (mean age = 15.1) dyads from diverse (57% Latina; 23% Black, 20% White), low-income families. Mothers and daughters reported on their symptoms and participated in a videotaped interaction task. A subset completed a follow-up interview 1 month later. For both depression and PTSD, mothers’ and daughters’ symptoms predicted their own relational behaviors (actor effects). In contrast, partner effects varied by symptom type and family role. Adolescents’ depressive symptoms predicted how their mothers acted toward them, beyond maternal symptoms (an additive partner effect); the converse was not true. Mother and daughter PTSD symptoms interactively predicted daughters’ relational behaviors (an Actor × Partner interaction), with buffering or exacerbating effects based on dyad symptom similarity. PTSD symptoms had unique effects beyond depression. In longitudinal analysis, mothers’ relational behaviors predicted changes in adolescents’ depressive symptoms, but adolescent behaviors were unrelated to subsequent maternal symptoms. Findings suggest that depression and PTSD symptoms may affect family relationships differently, and highlight the importance of considering both members’ symptoms during interactions. Implications for dyadic interventions are discussed.