What developmental delays are suggestive of Autism Spectrum Disorder (ASD)?

Developmental Delays Suggestive of Autism Spectrum Disorder

The most significant developmental delays suggestive of Autism Spectrum Disorder include reduced social attention, impaired social communication, repetitive behaviors with objects, and atypical body movements between 12-24 months of age. 1

Key Early Markers (12-24 months)

Social Communication and Interaction

• Failure to respond to name - Highly specific marker at 12 months 1
• Reduced eye contact - Less frequent eye contact compared to typically developing children 1
• Fewer nonverbal behaviors to initiate shared experiences 1
• Decreased joint attention - Significant differences in initiation of joint attention 1
• Reduced gestures - Lower frequency of gesture use during the second year of life 1
• Decreased pointing to objects or pictures 2
• Limited or no use of meaningful words by 18 months 2
• Not following simple directions 2

Emotional and Temperament Regulation

• Lower positive affect - Distinguished from non-ASD siblings and controls 1
• Higher negative affect - More emotional dysregulation 1
• Difficulty controlling behavior - Problems with attention and behavioral regulation 1
• Lower sensitivity to social reward cues - Reduced effortful emotion regulation 1

Repetitive Behaviors and Object Use

• Atypical use of objects - Such as spinning, lining up, or rotating objects, evident as early as 12 months 1
• Repetitive motor actions - More frequent than in typically developing children 1
• Stereotyped behaviors - Repetitive actions or posturing of body, arms, hands, or fingers 1

Motor Development

• Atypical body movements - Including hand flapping, finger flicking, and unusual arm/foot movements 1
• Motor delays - Can be predictive of social communication delays 1, 3
• Head lag at 6 months - May predict subsequent ASD diagnosis at 30-36 months 1
• Asymmetric movements or persistent motor asymmetry 2

Age-Specific Warning Signs

Before 12 months

While reliable behavioral markers before 12 months have not been consistently identified 1, some potential early indicators include:

• Reduced positive affect and increased perceptual sensitivity at 7 months 1
• Emotional dysregulation and reduced attentional flexibility 1
• Motor delays at 6 months may predict later social communication delays 1

12-18 months

• No response to name when called 4
• Limited or no use of gestures in communication 4
• Lack of imaginative play 4
• Not transferring objects between hands 2
• Not showing interest in reaching objects 2
• Not vocalizing or imitating sounds 2

18-24 months

• Regression in previously acquired skills 2
• No eye contact or social engagement 2
• No pointing to objects or pictures 2
• Not following simple directions 2
• Decline in acquisition of new skills during the second year of life 2

Clinical Implications

Patterns of Onset

Three distinct patterns of ASD onset have been observed 5:

1. Developmental delay - More common in children with severe/profound intellectual disability
2. Developmental stagnation - More common in children without intellectual disability
3. Developmental regression - Less likely to show language signs at onset

Early Detection Considerations

• The first symptoms of ASD are evident between 7-12 months in 41.9% of cases and between 13-24 months in 27.6% of cases 5
• Social interaction/relationship problems (93.3%) and language issues (92.4%) are the most common early signs 5
• Delay in spoken language (both production and comprehension) is one of the most common symptoms prompting initial medical consultation 5

Common Pitfalls in Identification

• Focusing only on language delays - While common, language delays alone are not specific to ASD
• Overlooking subtle social communication deficits - These may be more predictive than general developmental delays
• Waiting for multiple clear signs - Early referral based on concerning behaviors is critical
• Attributing delays to other factors - Such as being "just a late bloomer" or "family history of late talking"
• Missing regression - Failure to identify loss of previously acquired skills

Action Steps

When developmental delays suggestive of ASD are identified:

• Refer for autism-specific screening using validated tools 6
• Initiate early intervention services without waiting for confirmatory testing 2
• Consider specialty referrals (developmental pediatrics, neurology) 2
• Early intensive behavioral intervention based on applied behavior analysis improves cognitive ability, language, and adaptive skills 6

Early identification is crucial as children who receive intervention within the first 6 months of diagnosis have significantly better outcomes in vocabulary development, receptive and expressive language, syntax, speech production, and socioemotional development 2.