Pervasive developmental disorder
Parents may begin to question the health of their child when developmental milestones are not met, including age appropriate motor movement and speech production.[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.