Adaptive Behavior Profiles in Girls with Autism: A Comparison to Previously Published Profiles in Boys

Background:

The vast majority of research on adaptive behavior profiles in individuals with autism spectrum disorders (ASD) has been conducted on boys. Studies using the Vineland Adaptive Behavior Scales have shown Socialization skills to be most impaired, followed by Communication and then Daily Living Skills (Bolte & Poustka, 2002; Carter et al., 1998). In boys with ASD without cognitive impairment, adaptive skills tend to fall substantially below both IQ and age, with age being negatively correlated with adaptive behavior, suggesting a widening gap with age (Klin et al., 2007; Kanne et al., 2010).

Objectives:

This study compares a sample of girls with ASD evaluated at the Yale Child Study Center with a sample of boys of the same age range evaluated at Yale and published by Klin et al. in 2007. In the Klin study, 84 boys ages 8 to 18 years (Mean=12.4) of average intelligence (FSIQ=99.8; VIQ=104.7; NVIQ=94.5) exhibited significant adaptive deficits, with their Socialization Standard Scores on the Vineland falling more than 3 standard deviations below chronological and mental age (Mean=52.0). Age was negatively correlated with adaptive functioning, with older boys exhibiting a greater gap between cognition and adaptive behavior than younger boys. With the current study, our aim is to examine if girls with ASD exhibit similar profiles.

Methods:

Participants included 48 girls with ASD that received diagnostic evaluations through the Yale Developmental Disabilities Clinic. The sample was restricted to girls between the ages of 8 and18 years to match the Klin et al. sample (Mean Age=11.47; SD=2.63). IQ measures included the Differential Ability Scales, Second Edition and a combination of the Wechsler Scales for children for adults. The Vineland Adaptive Behavior Scales, Expanded Formwas used to assess adaptive behavior. Similar to the boys in the 2007 paper, girls evidenced stronger Verbal IQ scores than Nonverbal (VIQ=94.76, SD=27.83; NVIQ=83.57, SD=23.95), with a Full Scale Mean of 85.94 (SD=25.25).

Results:

Results revealed significant delays in all adaptive areas with the following Vineland Mean Standard Scores: Communication=64.77 (SD=22.59); Daily Living Skills=53.02 (SD=21.66); and Socialization=56.65 (SD=15.0). Age Equivalent (AE) scores for Socialization were lowest, with a Mean Interpersonal AE=3.73 years (SD=2.25) – quite similar to the sample of boys in 2007 (Mean AE=3.2, SD=1.6). Pearson correlations indicated that Nonverbal IQ was related to more areas of adaptive functioning (Comm r=.56, p<.01; DLS r=.48, p<.01; Soc r=.34, p<.05) than Verbal IQ (Comm r=.62, p<.01). Age was negatively correlated with adaptive Socialization skills (r= -0.31, p<.05), consistent with results in boys.

Conclusions:

Results highlight the similarities in adaptive behavior profiles in girls compared to well-established profiles in boys. Though current studies are questioning if diagnostic profiles of girls could be qualitatively different than those in boys, our findings suggest that perhaps differences in symptomatology could be independent from more consistent cognitive and adaptive profiles. The substantial gap between cognition and adaptive functioning is similarly striking, as is the significant correlation between age and socialization skills suggesting that this gap widens with age. Implications for informing intervention will be discussed.