Early Characteristics of Children Who Lose Their Autism Diagnosis Between Age 2 and 4

Background:  

Emerging literature has indicated that a subset of children with a documented ASD lose their diagnosis and function in the average range of cognition and behavior. Multiple factors including intervention, symptom severity, adaptive functioning, motor skills and language abilities may help to predict positive outcomes. Prospective research will help to increase our understanding of the rate of optimal outcomes and the early characteristics of children who attain them.

Objectives:  

To explore child-level factors at age two that differentiate children who attain an optimal outcome from those who retain their ASD diagnosis at age four in a prospective study.

Methods:  

214 children were diagnosed with an ASD, by clinical best estimate, at an average age of 26 months (Time- 1) following positive screening on an autism-specific screener (M-CHAT(-R)). The Autism Diagnostic Observation Schedule (ADOS), Mullen Scales of Early Learning, Vineland Adaptive Behavior Scales (VABS-II), and Childhood Autism Rating Scale (CARS) were completed.

At an average age of 53 months (Time-2), children were re-evaluated; 171 (80%) children retained an ASD diagnosis (ASD-ASD). Of these, 33 have older or same-aged siblings on the spectrum. 19 children (9%) were determined to meet the following criteria for an “optimal outcome”(OO): no longer met criteria for any ASD, and functioning in the average range (within 1.5 SD of the mean) on standardized measures of cognition, language, social and communication skills. Of these 19 children, 3 have older or same-aged siblings on the spectrum. 24 children moved to a different diagnosis (e.g., Global Delay) and will not be considered further here.

Results:  

A Chi-square test for independence indicated that children initially diagnosed with PDD-NOS were more likely to attain an optimal outcome (13.8%) than children initially diagnosed with AD (7.0%)(p=.046). Independent groups t-tests compared ADOS, Mullen, VABS-II, CARS and DSM-IV symptoms of the OO group (N=19) to the ASD-ASD group (N=171) at Time-1. No significant group differences were found in Time-1 ADOS scores, providing evidence against simple misdiagnosis at age two. For DSM-IV symptoms, the OO group had fewer restricted/repetitive behaviors (RRBs) than the ASD-ASD group (p=.01). In addition, the OO group had less severe autism as measured by the CARS (M=28.7 vs. M=33.02, p=.001). The OO group was higher on Daily Living (p=.03) and Motor Skills (p=.01) on the VABS-II. No significant group differences were found in the areas of cognitive or language skills.

Conclusions:

Nine percent of children diagnosed with an ASD attained optimal outcome by age four. At age two, these children showed fewer RRBs, lower symptom severity, more diagnoses of PDD-NOS as opposed to Autistic Disorder, and higher daily living and motor skills than those who retained their diagnosis. RRBs have been found in other studies to be a negative prognostic factor, and may reflect the fact that these children are less attentive to intervention and natural social interactions. Early motor skills have also previously been found to predict outcome and may function as a better indication of CNS integrity than social or language skills in children with impaired motivation to interact.