Ahmed IbrahimAhmed IbrahimHuman Reproductive EpidemiologyHuman Reproductive Epidemiology

December 2, 2007December 2, 2007

Autism Spectrum Disorders and Autism Spectrum Disorders and Socioeconomic Status: A tale of two spectraSocioeconomic Status: A tale of two spectra

1. Background: Autism Spectrum Disorders

2. Factors Affecting Demographic Studies of ASD

3. Review Objectives

4. Comparative Studies

5. Conclusions

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1.Background: Autism Spectrum Disorders

Autism Spectrum Disorder: Clinical Definition

1. Set of neurodevelopmental disorders

2. Deficits fall into three categories

-Social Interaction

-Communication/Linguistic Development

-Repetitive stereotyped behavior

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

Autism Spectrum Disorder: Etiology

GENETICENVIRONMENTAL

COOPERATIVE

Del. Epigenesis

Hoxa-1:Valproic AcidNon-mutagenic

Teratogenesis-Rubella

-Mercury Exposure

Chromosomal AberrationsFragile X syndrome

Single-gene mutations RELN

Mutagenesis

2. Factors Impacting Demographic Studies of ASD

Factors affecting ASD and Social Class studies

1.Ascertainment

2. Case definition variability

3. Small sample size

4. Inadequate control group

5. Limited measures of social class 6. Social class fluctuation (over time)

3. Review Objectives

Citation Year AssociationCreak and Ini 1960 Yes

Lotter 1966 Yes

Rutter and Lockyer 1967 Yes

Treffert 1970 Yes

Cuccaro 1996 Yes

Fombonne 2001 Yes

Croen et al 2002 Yes

Citation Year AssociationRitvo et. Al 1971 No

Fombonne 1992 No

Arvidsson 1997 No

Fombonne 1997 No

Oliviera 2007 No

Ritvo et. Al 1971 No

Fombonne 1992 No

Arvidsson 1997 No

Fombonne 1997 No

Oliviera 2007 No

Review Objectives

1. Investigate the distribution of autism among social class

2. Compare studies which used active and passive surveillance of autism among social class.

Hypothesis: There is no association between Autism and social class. Furthermore, passive surveillance is not an accurate approach of predicting the distribution of autism and social class.

4. Comparative Studies

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

Lotter et. Al, 1966-Middlesex County, London England

-Population: Public/private and handicapped children (8-10) in 9 schools in Middlesex county

-Ascertainment: Surveys mailed to public/private school administrators/teachers

Stage I: 75,930 children screened through school administrators

-Cases: Multi-stage screening involving evaluation by investigators and child behavior psychologists, medical records, parent interviews to determine case definition.

-35 were diagnosed as and 26 showing autistic behavior

-15 were diagnosed with nuclear autism (severe autism)

-20 were diagnosed with mild “non-nuclear” autism

-Remaining 26 were retained for comparison

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 occupationsII Managerial and technical occupationsIIIN Skilled non-manual occupationsIIIM Skilled manual occupationsIV Partly-skilled occupationsV Unskilled occupationsVI Armed forces

Registrar General Social Class Identification

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, clinicalcharacterization, and medical conditions (2007)Guiomar Oliveira* MD PhD, et al.

Maternal and Paternal Age and Risk of Autism Spectrum Disorders Lisa A. Croen, PhD; Daniel V. Najjar, MS; Bruce Fireman, MA; Judith K. Grether, PhD

1. Retrospective Cohort Study

2. All singleton births at Kaiser Permanente (N. California) 1995-1999

3. Cases were identified as diagnosed twice during outpatient visits at KP

4. Of 132 844 births, 593 were diagnosed as autistic.

5. Maternal age, paternal age, and income level among other covariates were investigated.

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

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

1. Case Control Study

2. All singleton births at Kaiser Permanente (N. California) 1995-1999

3. Cases were identified as diagnosed by Metropolitan Atlanta Developmental Disabilities Surveillance Program (MADDSP) born between 1983-1993

4. Controls were healthy Atlanta children (3-10 years of age) n=617

5. Maternal age, paternal age, and income level among other covariates were investigated.

6. Conclusions

1. There is likely no association between social class and ASD.

2. This association may not be consistent across all syndromes of ASD.

3. Educational level is more closely associated with ASD than median family income.

4. Educational level likely is correlated with both parental age

6. Conclusions