Who is affected by pervasive developmental disorders?
Pervasive developmental disorders are very rare. Information regarding how many people have a PDD is inconsistent. Many sources state that for every 10,000 births, five to 20 children are diagnosed with a PDD, including autism. However, other sources state these are very conservative estimates. There have been concerns that the incidence of autism is increasing, but it’s not clear if this is the case or there have been shifts in diagnostic criteria and patterns of diagnosis, and better detection. With the exception of Rett’s disorder, a PDD is more frequently found in boys. Rett’s disorder is almost always found exclusively in girls.
