At what age should children be screened for Autism Spectrum Disorder (ASD)?

Autism Screening Age Criteria

Children should be screened for Autism Spectrum Disorder (ASD) at 18 and 24 months of age, as recommended by the American Academy of Pediatrics. 1

Screening Recommendations

Standard Screening Schedule

• Screen all children at 18 months of age
• Screen all children again at 24 months of age
• For children with elevated risk factors, continuous developmental surveillance is required

High-Risk Children Requiring Enhanced Surveillance

• Siblings of children with ASD (risk of 7-18% compared to general population) 1
• Children with developmental concerns raised by parents or healthcare providers
• Children with other developmental delays

Evidence Supporting Early Screening

The recommendation for screening at 18 and 24 months is based on several factors:

• Evidence supports the usefulness of ASD-specific screening at these ages 1
• Early identification leads to earlier intervention, which improves outcomes
• ASD diagnoses made before 24 months have shown good stability in follow-up studies 1
• Screening at 18 months may identify many cases, though with higher false-positive rates than at 24 months 1

Screening Tools

Several validated screening tools exist for this age range:

1. M-CHAT (Modified Checklist for Autism in Toddlers):

   • Strong evidence for use as both level 1 (general population) and level 2 (high-risk population) screening tool 1
   • Follow-up interview (M-CHAT/F) improves positive predictive value
   • May have lower sensitivity at 18 months compared to 24 months 2

2. Q-CHAT-10 (Quantitative Checklist for Autism in Toddlers):

   • Promising tool with preliminary data showing good discrimination between ASD and non-ASD children 1
   • Ordinal scoring version (Q-CHAT-10-O) may have advantages for 18-month screening 2

3. Early Screening for Autism and Communication Disorders (ESAC):

   • Newer tool designed for children 12-36 months 3
   • Shows preliminary support for accuracy in high-risk populations

Clinical Considerations and Potential Barriers

Diagnostic Stability

• Studies show high diagnostic stability (85-100%) for children diagnosed with autistic disorder before 24 months 1
• Stability is more modest (47-62%) for children diagnosed with pervasive developmental disorder not otherwise specified 1

Implementation Barriers

Several barriers to implementing routine screening exist:

• Lack of time during well-child visits
• Inadequate reimbursement
• Workflow disruptions
• Limited familiarity with screening tools
• Lack of systems for referral and follow-up 1

Early Signs to Monitor

Between 12-24 months, key markers of ASD include:

• Reduced social attention
• Reduced social communication
• Increased repetitive behavior with objects
• Abnormal body movements
• Temperament dysregulation 1

Action Steps After Positive Screening

When a child screens positive for ASD:

1. Immediately refer for comprehensive diagnostic evaluation 1
2. Concurrently refer to appropriate early intervention services 1
3. Do not wait for formal diagnosis before initiating intervention

Importance of Early Intervention

Early identification and intervention are critical because:

• Early intensive behavioral intervention improves cognitive ability, language, and adaptive skills 4
• Presence of communicative speech by age 5 is a key predictor of long-term outcomes 5
• Children who receive intervention within the first 6 months of diagnosis show significantly better language development 5

While current evidence supports screening at 18 and 24 months, research on even earlier screening (9-15 months) is ongoing but not yet sufficient to recommend universal implementation 6.