The Changing Prevalence of Autism in California

  • Lisa A. Croen
  • Judith K. Grether
  • Jenny Hoogstrate
  • Steve Selvin
Article

Abstract

We conducted a population-based study of eight successive California births cohorts to examine the degree to which improvements in detection and changes in diagnosis contribute to the observed increase in autism prevalence. Children born in 1987-1994 who had autism were identified from the statewide agency responsible for coordinating services for individuals with developmental disabilities. To evaluate the role of diagnostic substitution, trends in prevalence of mental retardation without autism were also investigated. A total of 5038 children with full syndrome autism were identified from 4,590,333 California births, a prevalence of 11.0 per 10,000. During the study period, prevalence increased from 5.8 to 14.9 per 10,000, for an absolute change of 9.1 per 10,000. The pattern of increase was not influenced by maternal age, race/ethnicity, education, child gender, or plurality. During the same period, the prevalence of mental retardation without autism decreased from 28.8 to 19.5 per 10,000, for an absolute change of 9.3 per 10,000. These data suggest that improvements in detection and changes in diagnosis account for the observed increase in autism; whether there has also been a true increase in incidence is not known.

Autistic spectrum disorders epidemiology prevalence mental retardation 

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Copyright information

© Plenum Publishing Corporation 2002

Authors and Affiliations

  • Lisa A. Croen
    • 1
  • Judith K. Grether
    • 1
  • Jenny Hoogstrate
    • 1
  • Steve Selvin
    • 2
  1. 1.March of Dimes Birth Defects Foundation/California Department of Health ServicesCalifornia Birth Defects Monitoring ProgramOakland
  2. 2.Biostatistics, School of Public HealthUniversity of California at BerkeleyBerkeley

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