Reduced Curiosity and Exploration As an Early Warning Sign of ASD

Background: Researchers and clinicians have sought to diagnose children with ASD at the youngest ages possible, but the slow emergence of symptoms during the first two years of life makes this a challenge.  Ideally, novel behavioral markers of ASD would be discovered that are found in both early and late-onset ASD.  Exploring the environment is one mechanism that typically developing toddlers use to bootstrap sensor-motor development and joint attention skills.  Restricted interests in ASD toddlers may interfere with this important early behavior, and be observable during free play situations.

Objectives: Examine behavioral markers associated with both early and late-onset cases of ASD.

Methods:  255 participants (mean age = 15 months) were recruited from a large scale longitudinal study examining early development of ASD in toddlers. Participants were evaluated every 6-12 months until age three on several diagnostic (e.g., ADOS) and experimental measures (e.g., exploration). Four diagnostic comparison groups were included; early-onset ASD (mean age of diagnosis =17.73 months; n=55), late-onset ASD (no ASD diagnosis at initial assessment, mean age of ASD diagnosis= 24.94 months; n=37), language delay (LD, n=55), and typically developing children (TD, n=108).

To measure exploration, toddlers were observed in a room with functional (e.g., ball) and nonfunctional (e.g., piece of string) toys placed in standardized locations (Pierce & Courchesne, 2001). Some toys were inside difficult to open containers and some were on the floor. Videos from the participants’ initial evaluation were coded to evaluate exploration including the number of toys and containers explored, amount of time exploring, and movement about the room.

Results: Data have been analyzed for 190 participants; ASD early-onset (n=42), ASD late-onset (n=32), LD (n=38), TD (n=78). A MANOVA revealed a significant effect of diagnosis on for both the number of items explored (F(3, 186)=7.872, p<.000) and the number of containers explored (F(3,186)=4.656, p=.004). The TD group explored significantly more items (M=12.12) than either the early-onset ASD (M=8.6, p<.000) or late-onset ASD groups (M=9.28, p=.008). The TD group also explored more containers (M=4.79) than either the early-onset ASD (M=2.83, p<.010) or late-onset ASD group (M=2.66, p<.013).  The LD group also explored more items (M=10.34) and containers (M=3.32) than either ASD group, but these differences were not significant.

Conclusions: Children with early-onset ASD and late-onset ASD explored fewer items and containers than TD children. These data suggest exploration is an observable behavioral feature associated with ASD and identifies an easy-to-implement assessment that can capture these features in a young population. Notably, children with late-onset ASD performed similarly to children with early-onset ASD on their initial assessment, prior to their diagnosis of ASD, suggesting late-onset ASD cases may show measureable characteristics associated with ASD before showing enough clear symptoms to receive a diagnosis. Although not significant, both ASD groups also showed reduced exploration in comparison to the LD group. Further research comparing ASD from other developmental delays is needed to identify early behaviors highly specific to ASD.  Further analyses of the quality of exploration and play are currently being examined and will be presented.