[citation needed] The onset of pervasive developmental disorders occurs during infancy, but the condition is usually not identified until the child is around three years old.
Parents may begin to question the health of their child when developmental milestones are not met, including age appropriate motor movement and speech production.
[5] The fifth edition of the DSM removed PDD as a category of diagnoses, and largely replaced it with ASD and a measure of the relative severity of the condition.
However, an editorial published in the October 2012 issue of American Journal of Psychiatry notes that, while some doctors argue that there is insufficient evidence to support the diagnostic distinction between ASD and PDD, multiple literature reviews found that studies showing significant differences between the two disorders significantly outnumbered those that found no difference.
[9] The World Health Organization’s International Classification of Diseases, 10th edition (ICD-10) categorized PDD into five distinct subtypes, each with their own diagnostic criteria.
[1] The disorders were primarily diagnosed based on behavioral features, although the presence of any other medical conditions is important, it is not taken into account when making a diagnosis.
[medical citation needed] Before the release of the DSM-5, some clinicians used PDD-NOS as a "temporary" diagnosis for children under the age of five when, for whatever reason, they are reluctant to diagnose autism.
Very young children have limited social interaction and communication skills to begin with, so it can be difficult to correctly diagnose milder cases of autism in toddlers.
Early intervention, including appropriate and specialized educational programs and support services, play a critical role in improving the outcome of individuals with PDD.