PDD-NOS symptoms in adults with intellectual disability: toward an empirically oriented diagnostic model

Johnny L. Matson, Department of Psychology, Louisiana State University, 234 Audubon Hall, Baton Rouge, LA 70803, USA. Johnmatson@aol.com
Jonathan Wilkins
Kimberly Smith
Martin Ancona


PDD-NOS has been an illusive diagnostic category in Autism Spectrum Disorders (ASD). It is a frequently occurring ASD, but it has typically been defined by what it is not-autism. This latter condition has received the bulk of the attention in the development of diagnostic methods, while PDD-NOS has largely been ignored from a diagnostic standpoint. The symptoms that characterize PDD-NOS in adults with intellectual disability (ID), beyond the extrapolation of a few child studies, are largely unknown. This study is an attempt to provide systematic empirical data to describe the condition of PDD-NOS in adults with ID. The implication of these data for diagnosis and future research are discussed.