Early Intervention for Toddlers with Autism Spectrum Disorder Affects Outcome at Adolescence: A Long-Term Follow-up Study

Background:

Most studies in autism spectrum disorder (ASD) have examined short-term intervention outcomes after 1-4 years, and showed positive gains in cognitive and adaptive skills. Studies have suggested that individuals with 'optimal outcome' generally received earlier and more intense interventions before three years of age. The current study focused on outcome in young adolescents diagnosed with ASD at a very early age.

Objectives:

To examine long-term outcomes 8-15 years after an early childhood ASD diagnosis (<3 years). The study compared outcomes in autism severity and adaptive skills of children who were enrolled in center-based early intensive intervention programs for ASD to those who were not.

Methods:

The study included 53 participants, 49 males and 4 females, with an age range of 11:0 – 17:10 years (M=13:8, SD=1:10 years). All the participants were diagnosed with ASD (T1) in the age range of 1:3-3:1 years (M=2:2, SD=0:5 years) and were reassessed after 8:7-15:7 years (M=11:7 (SD=1:10) years (T2). The diagnosis of ASD at baseline was obtained using two standardized tests, the Autism Diagnosis Interview-Revised (ADI-R) and the Autism Diagnosis Observation Schedule (ADOS). Outcome measures included adaptive skills using the Vineland adaptive behavior scales (VABS), and autism severity using the ADOS social affect calibrated severity scale (SA-CSS) and restrictive and repetitive behaviors severity scale (RRB-CSS) at T1 and T2.

The study population was divided into two groups based on the toddlers' educational placement after the ASD diagnosis. One group (n=29) received early intervention in an ASD-specific center-based program for six days per week (total of 40h/w) for at least one year. The second group (n=23) was enrolled in regular day care centers or stayed at home at least until the age of 36 months.

Results:

To examine the outcome at T2, two 2X2 MANOVAS (2 GroupsX2 Times) for ADOS-CSS and VABS scores and 2X2 ANOVA with repeated measures for time were performed.

Autism severity: A significant Time X Group interaction was observed [F(2,48)=4.03, p=.024, h² =.144]. The interaction was significant for ADOS-SA-CSS, but not for ADOS-RRB-CSS. While the group of early ASD-specific intervention showed a decrease in SA severity [T1: 7.18(2.19); T2: 6.82(2.98)] the non-ASD-specific placement group showed an increase [T1: 6.74(2.28); T2: 8.65(1.11)] in this measure.

Adaptive behaviors: The analysis showed a significant Time main effect [F(3,35)=3.39, p=.029, h² =.225]. A significant increase in the VABS communication scores [T1: 68.79(9.47); T2: 76.95(18.75)] and in the daily living skill scores [T1: 67.92(6.97); T2: 77.46(18.35)] was noted (p=.016, .005 respectively), but not in the socialization subdomain. No significant Time X Group interaction was found.

Conclusions:

Outcome in social communication abilities in adolescents who received ASD-specific intensive early intervention in a center-based setting is more favorable than in those who were not enrolled in these types of centers. Communication and daily living, but not socialization adaptive skills, significantly improved with time and intervention in adolescents with ASD. This study emphasizes the importance of early intensive ASD-specific intervention and indicates improved functioning over time.