Reliability of the Toddler Temperament Scale and Differences in Early Temperament Between High Risk Baby Siblings with and without Autism

Background:  Research has shown that baby siblings of children diagnosed with autism who go on to receive an ASD diagnosis at 36 months demonstrate unique early temperament trajectories in the first two years (Garon et al., 2009). This study builds upon this literature by looking at early temperament differences between high risk baby siblings with and without a diagnosis of ASD at age 2, using the Toddler Temperament Scale (TTS).  

Objectives:  To assess the internal reliability of the TTS subscales, and test for group differences in parent-rated temperament between baby siblings with and without an ASD diagnosis at age 2.

Methods:  Baby siblings were screened for autism using the M-CHAT or M-CHAT-R. Parents of children who screened positive completed the TTS when their child received a diagnostic evaluation including the ADOS, Mullen, Vineland, and parent interview (n=149, mean age of child = 22.6 months). Cronbach’s alphas were calculated for each of the nine subscales of the TTS.  Chi-square tests were used to compare demographics between children with an ASD diagnosis (n=80) and those with a non-ASD diagnosis (n=69; includes developmental delay, language disorder, and no diagnosis).  Subscale scores (average score across items within a subscale), as well as parent responses to general impression items on the TTS were compared between groups using t-tests. 

Results:  Several subscales of the TTS were found to have acceptable to good internal reliability: Activity (α=.748), Rhythmicity (α=.758), Approach (α=.849), and Distractibility (α=.873).  Other subscales were found to be less reliable: Mood (α=.693), Adaptability (α=.654), Persistence (α=.607), Intensity (α=.559), and Threshold (α=.573).  ASD and non-ASD groups did not differ significantly in terms of gender or ethnicity. Parents of children in the ASD group tended to rate their child’s behavioral style as significantly less distractible (p<.001, d= 1.00), less rhythmic (p=.004, d= .48), slower to adapt (p=.011, d= .43), more withdrawn (p=.009, d= .44), and having more negative mood (p=.004, d= .48), compared to parents with children in the non-ASD group. When asked directly for general impressions of their child’s temperament, parents in the ASD group described their child as being more irregular in bodily functioning (p=.037, d= .35), slower to adapt to socially acceptable behavior (p<.001, d= .87), and less manageable (p=.002, d= .52). 

Conclusions:  Certain subscales of the TTS appear to be reliable when used with a sample of children at high risk for autism. Within this high risk group, baby siblings who receive an ASD diagnosis around age 2 may demonstrate different temperament profiles than their peers without autism.  In particular, these children may be less able to remove themselves from ongoing behavior; less consistent in their eating, sleeping, and elimination routines; slower to change their behavior in response to novel people, events, and instructions; less likely to approach novel people or experiences; and present with more negative and less positive mood. Parents of these children may also describe their child as significantly harder to manage.  Temperament assessments may provide important information about parents’ experience of their child’s behavioral tendencies in this high-risk group.