Co-occurring autism and attention-deficit/hyperactivity disorder (ADHD) have been associated with poorer social skills. Most studies examining the association of ADHD symptoms and social skills in autism employ categorical and cross-sectional designs, which provide a narrow view of the development of ADHD symptoms. Using group-based trajectory modeling, we identified five trajectories of caregiver-reported attention problems in an inception cohort of autistic children (N = 393) followed from age 2–5 years (T1) to age 10.5–11 years (T8): Low-Stable (LS; 15.5% of participants), Low-Decreasing (LD; 25.2%), Low-Increasing (LI; 19.2%), Moderate-Decreasing (MD; 32.9%), and High-Stable (HS; 7.2%). Child FSIQ and caregiver age at baseline were lower and caregiver depression at baseline was higher for participants in the MD group than the LS group. Psychotropic medication use was associated with higher attention problems. The MD and HS groups had similar mean Vineland Adaptive Behavior Scales, Second Edition (VABS-II) Socialization standard scores at T8, which were lower than other groups. The LI group had lower Socialization scores than the LS group. Results support that a decline in caregiver-reported attention problems is common but not universal in autistic children and that even moderate/subclinical attention problems may relate to social skills outcomes in autism.

In the general population, irritability is associated with later depression. Despite irritability being more prevalent in autistic children, the long-term sequelae are not well explored. We tested whether irritability in early childhood predicted depression symptoms in autistic adolescents, and whether associations could be explained by difficulties in peer relationships and lower educational engagement. Analyses tested the longitudinal associations between early childhood irritability (ages 3–5) and adolescent depression symptoms (age 14) in a prospective inception cohort of autistic children (N = 390), followed from early in development shortly after they received a clinical diagnosis. Mediators were measured in mid-childhood (age 10) by a combination of measures, from which latent factors for peer relationships and educational engagement were estimated. Results showed early childhood irritability was positively associated with adolescent depression symptoms, and this association remained when adjusting for baseline depression. A significant indirect pathway through peer relationships was found, which accounted for around 13% of the association between early childhood irritability and adolescent depression, suggesting peer problems may partially mediate the association between irritability and later depression. No mediation effects were found for education engagement. Results highlight the importance of early screening and intervention for co-occurring irritability and peer problems in young autistic children.