Diagnostic Indicators for ASD in 14-month-olds

Background: Diagnostic criteria for Autism Spectrum Disorders presented in the DSM-IV and ICD-10 have limited applicability for children under 3 years of age.  However, red flags for ASD have been identified in children as young as 14 months (Landa et al., 2007).  Thus, there is a need for diagnostic criteria for ASD in children younger than age 3 to improve early detection and access to early intervention.

Objectives: We propose preliminary diagnostic criteria for communication and social impairment in 14-month-olds, that also indicate high risk for an ASD diagnosis at 36 months of age.

Methods: 114 participants (95 younger siblings of children with autism and 19 low risk controls) were given the Mullen Scales of Early Learning, Communication and Symbolic Behavior Scales Developmental Profile, and Autism Diagnostic Observation Schedule at 14 months of age.  Outcome diagnoses were determined at 30 or 36 months of age by a blind expert coder.  Classification and Regression Trees (CART) were used to identify the variables and associated cutpoints at 14 months that best differentiated children with and without ASD diagnoses at outcome.  These predictors were then applied to the 14 month data to determine sensitivity and specificity.

Results: The identified variables and cutpoints included: CSBS Initiation of Joint Attention (<2) and Consonant Inventory (<4); ADOS Stereotyped Behaviors and Restricted Interests algorithm total (>0) and Response to Joint Attention (>1); and Mullen Receptive Language T Score (<33).  38 children met 3 or more of the criteria; 23 of these had ASD outcomes and 13 had outcomes of other impairments at 36 months of age.  All but one child had impairment at 14 months, usually language or social impairment, or ASD.

Conclusions: We identified five indicators that, at 14 months of age, predict 36-month diagnoses of ASD or other related impairment.