We assessed the clinical utility of the parent-reported Strengths and Difficulties Questionnaire (SDQ) as a screen for emotional and behavioural difficulties in 626 children and young people with intellectual disability. Using the Developmental Behavior Checklist (DBC2-P) to determine clinical caseness, the area under the curve for the SDQ total difficulties score was 0.876 (95% CI 0.841–0.911), indicating that it is a good measure for identifying significant emotional and behavioural difficulties requiring further investigation. Analyses supported the use of the same SDQ cut-off for those with and without intellectual disability, which may assist with consistent and comparable assessment in clinical practice.

The current study used developmental trajectories to examine the relationship between internalising and externalising behaviours and victimisation over the transition period from primary to secondary school. Data were collected using a self-completion questionnaire four times over 3 years from 3,459 students aged 11–14 years. Students were tracked longitudinally to assess their knowledge, attitudes, mental health and bullying experiences during the transition period. Multilevel modelling was used to examine the relationship between developmental victimisation trajectories and behavioural and emotional difficulties over time of students’ transitioning from primary to secondary school. Males who experienced low, but increasing, levels of victimisation over secondary school had greater emotional symptoms, conduct problems, hyperactivity, peer problems and lower pro-social behaviour than those who had not been victimised. Whereas females who experienced low, but increasing, levels of victimisation over secondary school had greater emotional symptoms and peer problems than those who had not been victimised. The current results highlight the need to prevent the continuation or escalation of chronic victimisation from primary to secondary school and to improve the emotional wellbeing of adolescents. It is recommended that whole-school bullying prevention and intervention programs and social wellbeing programs are implemented during primary school and the transition to secondary school.