Temperament and its relationship to autistic symptoms in a high-risk infant sib cohort.

The present study prospectively investigated early temperamental profiles and their associations with autistic symptoms in high-risk infants (N = 138) with an older sibling with autistic spectrum disorder (ASD) and low-risk infants (N = 73) with no family history of ASD. Children who were diagnosed with ASD at 36 months were distinguished from non-ASD sibs and controls by a temperament profile marked by lower positive affect, higher negative affect and difficulty controlling attention and behavior, which we labeled Effortful Emotion Regulation. This profile also distinguished the non-ASD sib group from the control group. Children with ASD were distinguished from both of the other two groups by a temperament profile of low Behavioral Approach (lower sensitivity to "social" reward cues). Low levels of Behavioral Approach were associated with a higher number of ASD symptoms, even after taking into account IQ, sex and group membership. Finally, a cluster analysis revealed two ASD subgroups distinguished by number of ASD symptoms, IQ, age of diagnosis and scores on the Behavioral Approach profile. These findings suggest that temperament may be a useful framework for understanding the emergence of ASD early in life.