Hierarchical cluster analyses were used to detect three subgroups in a sample of children with pervasive developmental disorder—not otherwise specified (PDD-NOS) evaluated at ages 2 and 4. At age 2, Cluster 1 demonstrated few autism symptoms and high cognitive scores; 60 % no longer met criteria for PDD at 4. Cluster 2 exhibited more autism symptoms and lower cognitive scores at 2; 89.5 % met criteria for ASD at 4. Cluster 3 had the lowest cognitive scores and most impaired social/communication skills at 2, but no repetitive behaviors; 60 % diagnosed with Autistic Disorder at 4. Results shed light on outcomes for different PDD-NOS types and raise questions regarding the increased importance of repetitive behaviors in DSM-5.
