Summary: A new analysis of CDC surveillance data with Rutgers University research shows a marked rise in autism spectrum disorder (ASD) among 4-year-old children in New Jersey. Between 2010 and 2014 the measured prevalence increased by 43 percent, with New Jersey reaching about one in 35 children.
Source: Rutgers University
Increase in ASD Prevalence Among Young Children in New Jersey
A recent report from the Centers for Disease Control and Prevention (CDC), using data collected and analyzed with Rutgers University researchers, found that autism spectrum disorder (ASD) prevalence among 4-year-old children rose notably in New Jersey between 2010 and 2014. Overall, the Early Autism and Developmental Disabilities Monitoring (Early ADDM) Network reported that roughly one in 59 children across participating sites was identified with ASD during the study period, but New Jersey’s prevalence was the highest among the seven sites studied—about one in 35, or approximately 3 percent of children in the state.
The increase observed in New Jersey represents a 43 percent rise over the four-year span. Researchers caution that higher rates in New Jersey likely reflect more complete case identification through the combined use of health and education records and a strong statewide system of clinical and educational services for children with developmental concerns.
“These findings are consistent, broad and startling,” said Walter Zahorodny, associate professor of pediatrics at Rutgers New Jersey Medical School and director of the New Jersey portion of the study. “Analysis of this young group shows U.S. autism rates continuing to rise without plateauing.”
How the Study Was Conducted
The Early ADDM Network conducted active surveillance in seven sites—Arizona, Colorado, Missouri, New Jersey, North Carolina, Utah, and Wisconsin—for children who were 4 years old in 2010, 2012, and 2014. Investigators reviewed health records and, where available, special education and early intervention records to identify children with developmental evaluations documenting behaviors consistent with DSM-IV-TR criteria for autistic disorder, pervasive developmental disorder–not otherwise specified (PDD-NOS), or Asperger disorder. Trained clinicians reviewed abstracted records using a standardized case definition.
Across the network, ASD prevalence among 4-year-olds varied by site, from about 8 per 1,000 in Missouri to 28 per 1,000 in New Jersey, with an average near 13 per 1,000 in the participating sites. Boys were identified with ASD at roughly twice the rate of girls. White children were identified more often than black or Hispanic children in some sites, a pattern that suggests differences in access to evaluation and documentation rather than clear biological differences alone.
Age of Evaluation and Diagnosis
The age at first developmental evaluation and at ASD diagnosis showed considerable variation across sites. First evaluations occurred as early as a median of 28 months in some sites and as late as 39 months in others. Children with co-occurring intellectual disability or other developmental conditions were more likely to be evaluated earlier than children without such conditions. The median age of ASD diagnosis reported in the study was about 53 months, a figure that has not shifted substantially in the past 15 years.
Researchers emphasized the importance of earlier evaluation and diagnosis. Early identification—ideally beginning with routine developmental screening by pediatricians around 18 months— can allow evidence-based interventions to start sooner, improving long-term outcomes. However, the study found that often only children with more severe symptoms are being identified and evaluated at the earliest ages, delaying care for many children who could benefit from early services.
Possible Factors and Research Needs
The study team noted several risk factors associated with higher ASD prevalence, including advanced parental age, certain maternal illnesses during pregnancy, genetic mutations, preterm birth (before 37 weeks), and multiple births. While these factors likely contribute, investigators stressed that they do not fully explain the rising prevalence observed. Researchers called for more study of non-genetic and environmental influences that may affect fetal and newborn development and contribute to increasing ASD rates.
Key Findings and Public Health Implications
Summary findings from the Early ADDM Network for 2010–2014 include:
- ASD prevalence among 4-year-olds increased in New Jersey from 2010 to 2014 but was stable in some other sites.
- Prevalence estimates were higher in sites that reviewed both education and health records versus health records alone.
- ASD affected boys more commonly than girls, with site-specific male-to-female ratios ranging from about 2.6:1 to over 5:1.
- Children with co-occurring intellectual disability were more often identified at younger ages, suggesting surveillance at age 4 may capture children with more severe or additional disabilities.
- Despite increased awareness, the median age at diagnosis has not decreased, indicating a need for improved, systematic early screening and faster referral to diagnostic evaluations and services.
Source: Rutgers University
Media Contact: Patti Verbanas – Rutgers University
Image Source: Nick Romanenko / Rutgers University
Original Research: Christensen DL, Maenner MJ, Bilder D, et al. “Prevalence and Characteristics of Autism Spectrum Disorder Among Children Aged 4 Years — Early Autism and Developmental Disabilities Monitoring Network, Seven Sites, United States, 2010, 2012, and 2014.” MMWR Surveillance Summaries, 2019;68(SS-2):1–19. The study provides open access surveillance estimates and compares DSM-IV-TR and DSM-5 case definitions for 2014.