Restricted and Repetitive Behaviors in Males and Females with Fragile X Syndrome: Developmental Trajectories in Toddlers Through Young Adults.
Lauren J Moskowitz, Elizabeth A Will, Conner J Black and 1 others
PMID 32221748WHAT IT FOUND
In Fragile X syndrome, sensory-motor behaviors decreased with age for both sexes, but higher-order behaviors like restricted interests and compulsions remained stable.
Males consistently showed more severe repetitive behaviors than females, except for compulsions. Higher nonverbal IQ was linked to increased compulsive behavior.
Key findings
01Sensory-motor behaviors decreased over time for both males and females, though males consistently displayed higher levels than females.
02Higher-order behaviors, including restricted interests, compulsive behaviors, and ritualistic/sameness behaviors, did not show significant improvement over time.
03Males showed stable or slightly increasing self-injurious behavior over time, whereas females showed a sharp decrease.
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTsWhat it means for SLPs
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What it does not show
Reliance on parent-report questionnaires (RBS-R) which may miss subtle behaviors in higher-functioning individuals or young children. Inclusion of infants (12 months) for whom the RBS-R is not validated, potentially affecting data accuracy in the youngest group. Use of multiple cognitive tests (Mullen, DAS, Leiter-R) with unknown convergent validity, though Z-scores were used to standardize. Lack of data on comorbid ASD diagnoses for many participants, preventing analysis of how ASD status influences RRB trajectories. No comparison group with other developmental disabilities, so findings are specific to FXS but not necessarily distinct from other conditions without further study.
Declared interests
None reported.
The easy way to misread this
Do not assume that higher-order repetitive behaviors like restricted interests or compulsions will resolve as the child matures. The study found these behaviors remained stable over time, unlike sensory-motor behaviors which decreased. Intervention should not be delayed or discontinued for these specific subtypes based on age alone.