Development in infants with autism spectrum disorders: a prospective study
Rebecca Landa1, Elizabeth Garrett-Mayer
1The Kennedy Krieger Institute, Center for Autism and Related Disorders, The Johns Hopkins School of Medicine, MD 21211, USA. landa@kennedykrieger.org
Insights
Early signs of autism spectrum disorder (ASD) emerge by 14 months, with significant developmental delays and slowing noted between 14-24 months in affected infants. Early detection is crucial for intervention.
Area of Science:
- Neurodevelopmental disorders
- Pediatric psychology
- Early childhood development
Background:
- Autism spectrum disorder (ASD) diagnosis often occurs after age three, despite prenatal neurobiological disruptions.
- Understanding early developmental trajectories in the first two years is critical for timely intervention.
- Limited research exists on developmental changes in infants at high risk for ASD.
Purpose of the Study:
- To examine early developmental patterns in infants at high and low risk for ASD.
- To identify when developmental differences become apparent in autism spectrum disorder.
- To inform early detection and intervention strategies for autism.
Main Methods:
- Prospective study of 87 infants assessed at 6, 14, and 24 months using the Mullen Scales of Early Learning (MSEL).
- Participants included high-risk (siblings of children with autism) and low-risk infants.
- Diagnostic groups (unaffected, ASD, language delayed) determined at 24 months via standardized assessments and clinical judgment.
Main Results:
- No significant group differences at 6 months.
- By 14 months, the ASD group showed significant delays compared to unaffected infants in most domains.
- By 24 months, the ASD group lagged behind unaffected and language-delayed groups in multiple developmental areas, with a notable performance decline between ages 14 and 24 months.
Conclusions:
- Developmental variations in autism spectrum disorder are detectable by 24 months using general developmental assessments.
- A significant slowing of development between 14 and 24 months is characteristic of autism spectrum disorder.
- These findings highlight the potential for earlier identification of autism spectrum disorder through developmental monitoring.
Background:
Autism is rarely diagnosed before three years of age despite evidence suggesting prenatal abnormalities in neurobiological processes. Little is known about when or how development becomes disrupted in the first two years of life in autism. Such information is needed to facilitate early detection and early intervention.
Methods:
This prospective study of autism spectrum disorders (ASD) examined development using the Mullen Scales of Early Learning (MSEL) in 87 infants tested at target ages 6, 14, and 24 months. Participants came from infants at high risk (siblings of children with autism) and low risk (no family history of autism) groups. Based on language test scores, Autism Diagnostic Observation Schedule, and clinical judgment at 24 months of age, participants were categorized as: unaffected, ASD, or language delayed (LD). Longitudinal linear regression and ANOVA models were applied to MSEL raw scores, and estimates were compared between the three diagnostic groups.
Results:
No statistically significant group differences were detected at 6 months. By 14 months of age, the ASD group performed significantly worse than the unaffected group on all scales except Visual Reception. By 24 months of age, the ASD group performed significantly worse than the unaffected group in all domains, and worse than the language delayed group in Gross Motor, Fine Motor, and Receptive Language. The developmental trajectory of the ASD group was slower than the other groups', and showed a significant decrease in development between the first and second birthdays.
Conclusions:
Variations from typical and language delayed development are detectable in many children with ASD using a measure of general development by 24 months of age. Unusual slowing in performance occurred between 14 and 24 months of age in ASD.
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