Patterns of Early Skill Attainment and Loss In Young Children with Autism

Background: Recent emphasis on early diagnosis has led to focused attention on the development of symptoms of ASD, including “when” and “how” symptoms unfold (e.g. as overt symptoms, loss of previously gained skills). However, few studies examining onset and skill loss have provided systematic descriptions of pre-loss skill attainment, including specific ages of skill attainment for social-communicative skills.   

Objectives: The purpose of this study was to extend the literature on the ontogeny of ASD by examining the attainment and loss of specific socio-communicative skills in the early years.  Reports of ages for skill attainment and loss were used to answer the question: at what age do children with ASD diverge from children with developmental delays and typical development in attainment of early socio-communicative skills?

Methods: Participants included 244 children:  125 autism (AUT; mean age at parent interview = 48.6 months), 42 Pervasive Developmental Disorder-Not Otherwise Specified (PDD-NOS; 48.0 months), 46 non-spectrum Developmental Delay (DD; 43.3 months), and 31 typical development (TD; 52.4 months).  The Regression Validation Interview-Revised (RVI), a parent interview, was used to obtain precise ages of skill attainment and loss of 15 specific socio-communicative skills.  

Results: Kaplan-Meier survival analyses indicated that the TD group developed all skills significantly earlier than AUT, and all skills except smiling to mom/dad significantly earlier than PDD-NOS and DD. The AUT group had the largest percentage of children with any skill loss (63%), followed by PDD-NOS (60%), DD (24%), and TD (3%). Loss of eye contact, pointing to express interest and waving bye-bye were all reported in over 50% of children with AUT who had gained those skills. Only 5% of children in the AUT group attained all 15 skills, and only one child of the 125 in the AUT group acquired and then lost all 15 skills. 

A linear mixed model examining the pattern of skill acquisition and loss from birth to 30 months indicated significant main effects for group (F=920.92, df=3,3239, p<.001) and time (F=278.80, df=29,254, p<.001) as well as a significant interaction (F=21.39, df=87,257, p<.001).  Post hoc tests indicated that TD were reported to have significantly more skills compared to the AUT, PDD-NOS, and DD groups from 2-30 months.  In addition, the DD group began to have significantly more skills compared to AUT and PDD-NOS at 14 and 18 months, respectively, with significant differences remaining through 30 months.  The PDD-NOS group had significantly more skills than the AUT group at 21 months and from 24 to 30 months.

Conclusions:  This study contributes to answering the specific question of “when” divergence from typical development occurs in ASD, with findings indicating early in the first year of life. Results reveal that loss was quite common in ASD; however, the number and type of skills lost were variable. Children with varying degrees of skill attainment showed similarly varying degrees of skill loss, and children with even very few skills attained also were reported to lose skills. Findings indicate that symptom onset and regression in ASD may be best represented as a continuum.