Reevaluating the incidence of pervasive developmental disorders: Impact of elevated rates of detection through implementation of an integrated system of screening in Toyota, Japan

An approximately 11-fold increase was noted in prevalence of PDD compared to a previous survey two decades ago, and two main factors were believed to account for this apparent sharp increase. First, inclusion of high-functioning subjects detected during infancy, and second, higher rates of diagnosis resulting from an integrated process of screening.