International Meeting for Autism Research: Developmental Trajectories of Signs of Autism Spectrum Disorder (ASD) in Infants and Toddlers with ASD, Developmental Delay or Typical Development

Thursday, May 20, 2010

Franklin Hall B Level 4 (Philadelphia Marriott Downtown)

1:00 PM

M. Dereu , Department of Experimental Clinical and Health Psychology, Ghent University, Ghent, Belgium

M. Meirsschaut , Department of Experimental Clinical and Health Psychology, Ghent University, Gent, Belgium

R. Raymaekers , Department of Experimental Clinical and Health Psychology, Ghent University, Gent, Belgium

I. Schietecatte , Department of Experimental Clinical and Health Psychology, Ghent University, Gent, Belgium

S. Van der Paelt , Department of Experimental Clinical and Health Psychology, Ghent University, Gent, Belgium

P. Warreyn , Department of Experimental Clinical and Health Psychology, Ghent University, Gent, Belgium

H. Roeyers , Experimental-Clinical and Health Psychology, Ghent University, Ghent, Belgium

Background: Most research around early signs of ASD is retrospective in nature or based on high-risk populations, so little is known about the specificity of these early signs. However, some young children with other developmental disorders seem to show signs of ASD as well (many false positive screens in screening studies have other developmental disorders, e.g. Dietz et al., 2006) and at least in some children with ASD the signs only become apparent when they grow older (low sensitivity of population screening instruments, e.g. Baird et al., 2001).

Objectives: To examine the occurrence rate of these early signs over the first years of life in children with typical development (TD), in children with developmental delay (DD) and in children with ASD by comparing their developmental trajectories in amount of early signs of ASD.

Methods: Child care workers in day-care centres filled out the CESDD (Dereu et al., in preparation) for all children in their facility (N= 7007, age range 2 – 39 months). Children suspected of developmental problems, were assessed with the MSEL and ADOS and if necessary referred for clinical diagnosis and treatment. There were 43 children with ASD (M = 24 months, range 7 – 38) and 61 children with DD (M = 19 months, range 3 – 38).

Results: First, the occurrence of signs of ASD over time in typically developing children (n = 6909, M = 16 months, range 2 – 39) was analyzed. The total amount of early signs of ASD is very low but slightly increases over time (R² = .009, F(1, 6901) = 64.918, p < .0001; Total signs = 0.083 + 0.014*Age).
Secondary, the developmental trajectories of the amount of ASD symptoms was compared across diagnostic groups (TD, DD and ASD) using ANCOVA. Age was defined as ‘months from youngest ASD age’ (myda; see Thomas et al., 2009). The amount of early signs of ASD significantly differed at the youngest age across groups (F(2,7001) = 52.775, p < .001). Also, for the total sample the amount of signs increased over time (F(1,7001) = 165.125, p < .001). We also found a Group x Age interaction (F(2, 7001) = 74.863, p < .001) indicating that the increase in amount of signs of ASD significantly differed across diagnostic groups. The intercepts and slopes of the regression equations showed that at the youngest age children with DD had the most signs of ASD, but the increase in signs of ASD was about four times higher in the ASD group compared with the DD group.

Conclusions: Screening for ASD in young children should be done cautiously. The younger the children, the more likely it seems, based on the developmental trajectories found in this study, that cases of ASD will be missed and the more false positives will be generated by children with DD.

See more of: Developmental Stages
See more of: Autism Symptoms