AUTISM AND ASSOCIATED MEDICAL DISORDERS IN A FRENCH EPIDEMIOLOGIC SURVEY

Objective: To estimate the prevalence of autism, to assess the strengt h of its association with specific medical disorders, and to test for a secular increase in its incidence. Method: An epidemiological survey was conducted among 325,347 French children born between 1976 and 198 5 and living in three different French departements. Diagnosis, educat ional level, and associated medical conditions were abstracted from th e records of children known to local educational authorities. Data wer e also pooled with those from another similar survey Results: One hund red seventy-four children (mean age: 11.6 years) with autism were iden tified, The prevalence rate was 5.35/10,000 (16.3/10,000 if other perv asive developmental disorders are included), with no difference accord ing to geographical area or social class. Rates of medical conditions were as follows: 1.1% for tuberous sclerosis, 2.9% for chromosomal abn ormalities including fragile X, 2.9% for cerebral palsy, 4.6% for sens ory impairments, 0.6% for neurofibromatosis, 0.6% for congenital rubel la, and 1.7% for Down syndrome. In the combined sample of 328 children with autism, the level and pattern of medical correlates were compara ble, with tuberous sclerosis having a consistently strong association with autism. Prevalence rates were similar in successive birth cohorts . Conclusion: Medical disorders (excluding epilepsy and sensory impair ments) accounted for fewer than 10% of the cases of autism. No secular increase in the prevalence of autism was found.