Exploring the Characteristics of Children with a Diagnosis of PDD - NOS

The purpose of this study was to examine the diagnostic and developmental profiles of 105 children given a PDD-NOS diagnosis. Four subgroups were formed based on the reason for the PDD-NOS diagnosis (fewer than 6 criteria, fewer than 2 social criteria, no repetitive behaviours, and other). Cognitive level, adaptive functioning, autism severity, and the number of DSMIV autism criteria were examined, but the four subgroups did not differ on any developmental or diagnostic variables. Results suggest that the PDD-NOS group is very heterogeneous. The Pervasive Developmental Disorders (PDD) category of the Diagnostic and Statistical Manual (DSM-IV) includes four specific diagnoses: Autistic Disorder (AD), Asperger syndrome (AS), Rett Disorder, and Childhood Disintegrative Disorder; all of which are characterized by impairments in reciprocal social interactions, communication, and the presence of stereotyped behaviours, interests, and activities (American Psychiatric Association [APA], 2000). In addition, like other categories in the DSM-IV, there is a “not otherwise specified” diagnosis, PDD-NOS, for children who do not meet criteria for one of the specific PDD diagnoses. Considering the high prevalence rate of PDD-NOS (15/10,000; Fombonne, 2003), it is important that we gain a clearer understanding of this diagnosis, which is often confusing for parents and service providers alike. Efforts have been made to better understand PDD-NOS by comparing it to AD and AS. Buitelaar, Vander Gaag, Kiln, and Volkmar (1999) reported that PDD-NOS is a more heterogeneous category than AD. Matson, Dempsey, and Fodstad (2009) found better verbal communication and social relationships in the PDD-NOS group as compared to the AD group. Perry, Condillac, Freeman, Dunn-Geier, and Belair (2005) showed that children with PDD-NOS have significantly lower autism severity (as measured by the Childhood Autism Rating Scale, or CARS) than children with AD. Walker et al. (2004) reported that children with PDD-NOS have more delayed language than children with AS, fewer repetitive behaviours than both children with AD and AS, and fewer social difficulties than children with Asperger’s. The cognitive functioning of the PDD-NOS group was between that of the AD and AS groups. Walker et al. (2004) also identified three subgroups within their sample of 20 children with PDD-NOS: 1) children with good language functioning and many repetitive behaviours; 2) children with little or no repetitive behaviour; and 3) children who had a late age of onset, were too young, or too delayed to diagnose conclusively. © Ontario Association on Developmental Disabilities