Psychiatric disorders in individuals with co-occurring autism spectrum disorders (ASD) and intellectual disability (ID) are common, but diagnosis presents many challenges. The Psychopathology in Autism checklist (PAC) is among the very few instruments specifically developed for this group of individuals. The psychometric properties of the PAC…

Caretakers of adolescents and young adults with Down syndrome (DS) may report the onset of a depressive illness in previously mentally well individuals. However, the behavioral phenomenology of these conditions has not been well characterized. We ascertained a cohort of DS patient-subjects presenting to a specialty clinic with medical and/or…

Temperament is important for considering differences among diagnostic groups and for understanding individual differences that predict problematic behavior. Temperament characteristics, such as negative affectivity, effortful control, and surgency (highly active and impulsive), are predictive of externalizing behavior in typically developing…