Multi-Trajectories of Conduct Problems, Hyperactivity/Inattention, and Peer Problems Across Childhood: Results from the Growing Up in Scotland Birth Cohort.

Using a person-centred approach, this study inspected multi-trajectories of conduct problems, hyperactivity/inattention and peer problems, and associated risk factors for group membership. The sample included 3,578 children (50.8% males) from a population birth cohort in Scotland (Growing Up in Scotland). The parental version of the Strengths and Difficulties Questionnaire (SDQ) was used when children were 4, 5, 6, 7, and 10 years old. Antecedent factors at the perinatal, child, and family levels were collected using parental reports, observation, and standardised assessments at 10, 24, and 36 months. A group-based multi-trajectory analysis was employed. Findings showed that a six-group model best fit the data. Identified groups included non-engagers, normative, decreasing externalising/low peer problems, low externalising/moderate peer problems, moderate externalising/increasing peer problems and multimorbid moderate-high chronic. Findings suggest multimorbidity between externalising behaviours and peer problems in the more elevated groups. Two common protective factors emerged across all groups: caregiver mental health and parent-infant attachment. Identified risk factors were specific to group membership. Risk factors for the most elevated group included single-parent status, social deprivation, previous neonatal intensive care unit admission, child sex, whilst children's expressive language was a protective factor. Taken together, findings contribute to the emerging literature modelling trajectories of externalising behaviours and peer problems simultaneously and have important practical implications for prevention of problems in childhood, by identifying targets at the perinatal, child, and family levels.