Among the five pervasive developmental disorders previously categorized under PDD, Autism Spectrum Disorder (ASD) is the most common form. ASD is a complex neurodevelopmental condition characterized by a wide range of symptoms, including social communication challenges, repetitive behaviors, and restricted interests. Its prevalence has increased in recent years, and it is estimated to affect around 1 in 54 children in the United States, making it the most frequently diagnosed PDD/ASD condition.
Please note that diagnostic criteria and classifications may change over time, and it's essential to refer to the most recent edition of diagnostic manuals for the latest information.