Temperament in Infants At Heightened Risk for Autism

Background:  

Much recent research effort has been put toward identifying early behavioral manifestations of a later ASD diagnosis. Temperament is a potential early sign of ASD because it is viewed as being inherited or at least constitutional in nature, evident early in life, and stable across development. The few studies that have examined temperament as an early indicator of ASD have used parent report only.

Objectives:  

The goal of this “baby sib” study was to compare infants who later received an ASD diagnosis (HR-D infants) with infants at no known risk for developing ASD (LR infants) using a parent-report measure as well as an observational measure of temperament.

Methods:  

Temperamental variables were coded using the Minnesota Preschool Affect Rating Scales (MN-PARS; McPhee & Shapiro, 2004), while parent report was collected using the Infant Behavior Questionnaire - Revised (IBQ-R; Gartstein & Rothbart, 2003). These measures were collected at the 6- and 12-month time points for 31 infants at heighted risk for ASD (HR-D = 8) and 15 age-matched LR infants. The Child Behavior Checklist/1½ to 5 (CBCL; Achenbach & Rescorla, 2000) was collected at 24 months. Autism diagnostic status was determined at 24 months by trained clinicians.

Results:  

LR infants displayed more negative affect at 6 months and less negative affect at 12 months than HR-D infants, who showed the opposite pattern, as indicated by significant and large the age x group interaction for MN-PARS Negative Affect was, F(1, 21) = 5.37, p = .031, h_p² = .20. On IBQ Negative Affectivity, HR-D infants displayed significantly more negative affect at 12 (t = -2.193, df = 20, p = .040) but not 6 months (t = .277, df = 21, ns) than LR infants. Although many significant correlations were found within each temperament measure, there were virtually no significant correlations between IRQ-R temperament dimensions and conceptually similar MN-PARS ratings at 6 or 12 months. Qualitative inspection of MN-PARS temperament profiles suggested that 6 months HR-D infants appeared more passive and dull than the LR infants with a switch at 12 months towards more irritability and less adaptability. The measure that best differentiated the HR-D and LR infants was the Pervasive Developmental Problems Scale on the CBCL/1½ to 5, which was administered at 24 months.   

Conclusions:  

While the agreement between the measures was not found at 6 and 12 months, some insights on the early temperament of infants at heightened risk for ASD were revealed. In particular, negative affect emerged as an area of temperamental interest and qualitative temperamental profiles emerged that suggest a change in temperament from 6 to 12 months for the infants who later receive a diagnosis.