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Age at first autism spectrum disorder diagnosis: the role of birth cohort, demographic factors, and clinical features.

TitleAge at first autism spectrum disorder diagnosis: the role of birth cohort, demographic factors, and clinical features.
Publication TypeJournal Article
Year of Publication2014
AuthorsMazurek, MO, Handen, BL, Wodka, EL, Nowinski, LA, Butter, E, Engelhardt, CR
JournalJournal of Developmental & Behavioral Pediatrics
Date Published2014 Nov-Dec
KeywordsAdolescent, Age Factors, Autism Spectrum Disorder, Child, Child, Preschool, Female, Humans, Intelligence, Male, Severity of Illness Index, Social Class, Time Factors

OBJECTIVE: This study sought to identify factors that may be associated with delays in autism spectrum disorder (ASD) diagnosis, including birth cohort, sociodemographic characteristics, and clinical features.

METHODS: Participants included 1716 children and adolescents with ASD enrolled in the Autism Speaks Autism Treatment Network (AS-ATN) between the years 2008 and 2011. Data were collected at enrollment using AS-ATN parent- and clinician-report forms and standardized measures of I.Q., ASD symptoms, adaptive function, and psychiatric symptoms.

RESULTS: Age at first ASD diagnosis was positively correlated with current age, suggesting a birth cohort effect. Sociodemographic and clinical features were also associated with age at diagnosis, even after controlling for current age. Hierarchical linear regression results showed that older current age, lower socioeconomic status (SES), higher I.Q. score, and lower levels of autism symptoms were associated with later age at initial diagnosis. There was also a significant interaction between current age and I.Q., with higher functioning children being diagnosed at younger ages than in previous years.

CONCLUSIONS: Early diagnosis of ASD is critically important for improving access to interventions; however, many children experience diagnostic delays. In this sample, children from the most recent birth cohorts were diagnosed earlier, suggesting that early signs of ASD are being increasingly recognized. However, socioeconomic barriers to diagnosis still seem to exist. Children with less severe ASD symptoms and with higher I.Q. are also diagnosed at later ages. Efforts are still needed to reduce diagnostic disparities for families of low SES and to improve early recognition of more subtle symptoms.


Lead Author
Micah Mazurek

Study Aims and Objectives
To discuss the factors contributing to age of first diagnosis for children with autism spectrum disorder.

Methods- Sample, Procedure, Study Measures, Analysis
The study included 1716 children and adolescents enrolled in the Autism Speaks Autism Treatment Network Registry. Researchers examined whether age of diagnosis was related to other factors, including intellectual functioning, severity of autism symptoms, behavioral and emotional problems, medication use, and child and family characteristics.

Results- Main Findings
The results indicated that younger children in the registry were diagnosed earlier, indicating improvements in diagnostic practices over time. Although factors like sex, race, and ethnicity were not related to age of diagnosis, children whose parents had less education were diagnosed later. Children with less severe autism symptoms and higher IQ scores were also diagnosed later, suggesting that subtle symptoms may be more difficult to recognize in young children, especially in those with strong cognitive abilities.

Conclusion- Summary Statement
Early diagnosis of autism allows children to receive interventions as early as possible; however, many children are diagnosed much later than they should be. This study found that children whose parents have less education, children with less severe symptoms, and children with higher IQ are diagnosed at later ages. More work is needed to improve access to early diagnosis for all families, and to improve early recognition of more subtle symptoms.

Alternate JournalJ Dev Behav Pediatr
PubMed ID25211371
Grant ListUA3 MC 11054 / / PHS HHS / United States