Gender Comparison of Repetitive Behavior Profiles Among Two Age Cohorts

Background:

ASD is identified more often in boys than girls, at a ratio of 4.5:1 (Christensen et al., 2016). Research suggests that a possible gender bias leads to under diagnosis of girls (Dworzynski et al., 2012), particularly for those with higher cognitive abilities (Frazier et al., 2014). More research is needed to better understand differences in core symptom presentation, including repetitive behavior profiles (Halladay et al., 2015). In general, boys tend to demonstrate more repetitive behaviors than girls (Szatmari et al., 2012) although the repertoire may be similar under age 5 (Harrop et al., 2015). Qualitative differences in repetitive behavior presentations have been suggested, which may be contingent on higher social proficiency, making repetitive behavior difficult to classify as diagnostically relevant in girls (Halladay et al., 2015; Hiller et al., 2015). Therefore, the female ASD phenotype should be reevaluated in order to improve diagnostic precision (Van Winjngaarden-Cremers et al., 2014).

Objectives:

The purpose of this study is to describe and compare repetitive behavior profiles and frequencies in two age cohorts of girls and boys with ASD measured by the Repetitive Behavior Scale-Revised (RBS-R; Bodfish et al., 2000).

Methods:

Participants included 214 children with ASD (42 girls; 172 boys) ranging from 16 months to 10 years of age (mean = 46.1 months). Participants were recruited from a university based ASD Clinic research database. Each participant met the following criteria: (1) a clinical diagnosis of ASD (2) 10 years of age or younger at the time of their evaluation; and (3) no co-morbid medical diagnosis that could attribute to repetitive behavior. Repetitive behaviors demonstrated by children in two age cohorts (1-3 years; 4-10 years) were compared using the RBS-R, a 43-item parent report measure which assesses frequency and repertoire of repetitive behaviors across 6 categories.

Results:

Preliminary analyses indicated that prior to 3 years of age, girls demonstrated a significantly higher overall number of repetitive behaviors (t = -1.66; p = .03) and significantly more ritualistic behaviors (t = -.12; p = .004) and sameness behaviors (t = -1.9; p = .002). A different profile emerged in older children indicating that girls demonstrated more stereotyped behaviors than boys (t = -2.2; p = .001). The younger cohort of girls (n = 23) demonstrated more stereotyped behaviors (62.7% of the total number of stereotypical behaviors assessed were endorsed), followed by restricted interests (58%), sameness (41%), compulsive (46%), ritualistic (36%) and self-injurious behavior (27%). This profile remained fairly consistent among the older cohort of girls (n = 19) with one exception. Ritualistic behaviors were endorsed more often than compulsive behaviors in the older female cohort. Both cohorts of boys demonstrated restricted behaviors most often, followed by stereotypical behaviors. Repetitive behavior profiles will be discussed relative to developmental level and social skills.

Conclusions:

In opposition to previous findings, results indicated that girls demonstrate more repetitive behaviors than boys, which may be reflective of methodological differences (parent report vs. direct observation). These findings contribute the understanding of the female ASD phenotype. Diagnostic implications will be suggested.