Longitudinal studies of autistic people show that the behavioral features of autism generally endure into adulthood. Yet the prognostic indicators remain far from certain, especially for cognitively able individuals. Here, we test the predictive power of specific cognitive skills, namely theory of mind and executive function, measured in childhood, on young people’s autistic features and adaptive behavior 12 years later. Twenty-eight young autistic people (2 female) were seen twice within the space of 12 years. At Time 1 (M = 5 years; 7 months, SD = 11 months), participants were assessed on components of executive function (planning, inhibition and cognitive flexibility) and theory of mind (false-belief understanding). At Time 2, 12 years later (M = 17 years 10 months, SD = 1 year; 2 months), we measured participants’ autistic features and adaptive behavior. Only Time 1 executive function skills predicted significant variance in autistic adolescents’ autistic features, over and above variance attributable to early age, intellectual ability and theory of mind skills. Furthermore, early EF skills, in addition to early verbal ability and nonverbal ability, predicted significant variance in young people’s adaptive behavior at the 12-year follow-up. These long-term longitudinal findings clearly demonstrate that executive function measured in early childhood has prognostic significance in a sample of young autistic people approaching emerging adulthood and underscore their importance as a key target for early intervention and support
