Trajectory of Irritability in Autistic and Typically Developing Youth From Early Childhood to Adolescence.

This study examines changes in irritability from early childhood to adolescence and differences by diagnostic group, sex, and early childhood nonverbal and verbal abilities. Participants included 243 autistic (AUT) and 194 typically developing (TD) children, with 20% of participants being female, 47% identifying as non-White, and 26% identifying as Hispanic. Data were drawn from the CHARGE (Childhood Autism Risks from Genetics and the Environment) Study, which evaluated children at ages 2-5 years and followed up during pre- (ages 8-12) or late (ages 15-19) adolescence through the ReCHARGE Study. Irritability was higher in the AUT group than in the TD group across all time points; participants overall experienced a decrease in irritability over time. A three-way interaction among sex, diagnosis, and time emerged in late adolescence but not in pre-adolescence, and this effect remained significant even after adjusting for early cognitive abilities. Specifically, TD males and females, and AUT males, showed reductions in irritability, while AUT females exhibited persistently high irritability. In pre-adolescence, higher early verbal and nonverbal cognitive abilities were linked to greater reductions in irritability regardless of diagnosis, whereas in late adolescence, only nonverbal ability predicted irritability change, with this effect specific to autistic youth. Higher levels of adolescent psychopathology were associated with less improvement in irritability, regardless of diagnostic group. Collectively, these findings reveal that while irritability generally decreases over time, its trajectory varies by diagnostic group, sex, and early cognitive ability-highlighting the importance of early identification and interventions, particularly in autistic females, targeting irritability to support positive long-term outcomes.