This document summarizes and reviews several studies that investigated the potential association between autism spectrum disorders (ASD) and socioeconomic status. The review found inconsistent results across studies, with some finding a higher prevalence of ASD among higher social classes and others finding no association. The review concludes that there is likely no consistent association between social class and ASD, though parental education level may be more closely associated with ASD than median family income alone. Ascertainment methods, small sample sizes, and variability in case definitions across studies make drawing definitive conclusions difficult.

1. Ahmed Ibrahim Human Reproductive Epidemiology December 2, 2007 Autism Spectrum Disorders and Socioeconomic Status: A tale of two spectra

5. 3. ASD is is organized into five pervasive developmental disorders (PDD’s) Prevalent -Autism (Dr. Leo Kanner, Johns Hopkins Hospital, 1943) -Asperger Syndrome (Dr. Hans Asperger, Germany, 1943) Rare -PDD-NOS (aka miscellaneous) -Rett Syndrome (primarily female cases) -Child Disintegrative Disorder. Autism Spectrum Disorder: Historical

6. Autism Spectrum Disorder: Etiology GENETIC ENVIRONMENTAL COOPERATIVE Del. Epigenesis Hoxa-1:Valproic Acid Non-mutagenic Teratogenesis -Rubella -Mercury Exposure Chromosomal Aberrations Fragile X syndrome Single-gene mutations RELN Mutagenesis

7. 2. Factors Impacting Demographic Studies of ASD

9. 3. Review Objectives

10. Yes 2002 Croen et al Yes 2001 Fombonne Yes 1996 Cuccaro Yes 1970 Treffert Yes 1967 Rutter and Lockyer Yes 1966 Lotter Yes 1960 Creak and Ini Association Year Citation

11. No 2007 Oliviera No 1997 Fombonne No 1997 Arvidsson No 1992 Fombonne No 1971 Ritvo et. Al Association Year Citation No 2007 Oliviera No 1997 Fombonne No 1997 Arvidsson No 1992 Fombonne No 1971 Ritvo et. Al

13. 4. Comparative Studies

14. Ritvo et. Al, 1971 : Los Angeles Metropolitan Area Population: Hospitalized children (12 years or younger) at the UCLA Neuropsychiatric Institute. -Time period: 1961-1970 -Total Sample: 148 patients -Cases: 74 patients diagnosed with autism -Control group: sex, age, and TOA matched 74 patients with other disorders

16. Results: Lotter et al. According to the Registrar General Social Class Identification Nuclear Autistic Children: 61% social class I, II Non-nuclear Autistic children: 31% social class I, II Children with autistic behavior: 24% social class I, II Note: 24% of all active males in Middlesex were in the upper two social class levels. I Professional etc occupations II Managerial and technical occupations IIIN Skilled non-manual occupations IIIM Skilled manual occupations IV Partly-skilled occupations V Unskilled occupations VI Armed forces Registrar General Social Class Identification

17. The distribution of the children with autism by social class: dev. Delay controls (Graffar class I: 18%:2% ; class II: 6.7%: 6%; class III: 24.8%:22% ; class IV: 41%:63%; class V: 9.5%:7%) Epidemiology of autism spectrum disorder in Portugal: prevalence, clinical characterization, and medical conditions (2007) Guiomar Oliveira* MD PhD, et al.

20. Copyright restrictions may apply. Croen, L. A. et al. Arch Pediatr Adolesc Med 2007;161:334-340. Parental Age Modeled as a Categorical Variable for Autism Spectrum Disorders

21. Copyright restrictions may apply. Croen, L. A. et al. Arch Pediatr Adolesc Med 2007;161:334-340. Parental Age Modeled as a Continuous Variable for ASDs

24. 6. Conclusions