Prevalence of Autism Spectrum Disorders Among Young Adults in Union County, New Jersey
Minimal data currently exist regarding the prevalence of Autism Spectrum Disorders (ASD) in young adults, rendering planning for, access to, and implementation of medical and daily living services for adults with ASD both inefficient and ineffective, at best. A study of ASD prevalence in a community sample of adults in the United Kingdom (UK) identified an ASD rate of 1% across all ages of adults, consistent with the rate in children (Brugha et al., 2011). Additional epidemiologic studies of ASD in adults are needed, especially in the United States, where ASD rates have increased significantly among children.
To estimate ASD prevalence and to describe the expression of ASD in a cohort of young adults born in 1988 and residing in Union County, New Jersey (NJ) in 2006, using the Centers for Disease Control and Prevention (CDC) Autism and Developmental Disabilities Monitoring (ADDM) Network population-based method of prevalence determination.
This study used the ASD ascertainment strategy of the CDC ADDM Network, described previously in the Morbidity and Mortality Weekly Report (MMWR) Series (Rice, 2007) and replicated repeatedly in biannual surveillance cycles. The ADDM Network methodology uses an active, multi-phase method, consisting of independent review, abstraction and analysis of medical and educational records. The study used consistent DSM-IV-TR definitions of ASD.
In a population of 6,865 young adults born in 1988 and residing in Union County NJ, in 2006, 40 individuals with ASD were identified, indicating ASD prevalence of 5.8 per 1,000 (95% confidence interval [CI] = 4.27-7.94). Significant differences were found in prevalence between males, 9.23 per 1,000 (CI=6.56-12.98) and females, 2.13 per 1,000 (CI=1.01-4.47). ASD prevalence was lower in Hispanic individuals than in Whites or Blacks: White, non-Hispanic 6.7 per 1,000 (CI=4.37-10.27); Black, non-Hispanic 5.6 per 1,000 (CI=3.01-10.4); Hispanic 1.8 per 1,000 (CI= 0.58-5.59). Nineteen of 40 (47.5%) cases had a documented ASD diagnosis by a community provider. Six of 40 (15%) cases received special education services under the Autism Classification. Among the young adults identified with ASD at age 18, 45% (n=18) had a co-morbid psychiatric or neurological disorder.
ASD prevalence among 18-year olds was consistent with the two epidemiologic estimates for the cohort and period, but lower than expected, when compared to ASD estimates from later NJ cohorts, for example: 9.9 per 1,000 and 10.6 per 1,000 for cohorts born in 1992 and 1994. The findings suggest increasing ASD prevalence over time. Study findings also indicate the possibility of sex and race-based disparities and a significant proportion of undiagnosed/unrecognized young adults with ASD.