Study Examines Behavioral Traits of Fragile X Patients Without Autism

Patients with fragile X syndrome who don’t meet the cut-off for a diagnosis of autism show a decrease in impulsivity and repetitive questioning over time, when compared with patients who do, a new study shows.

The study, “Overactivity, impulsivity and repetitive behaviour in males with fragile X syndrome: contrasting developmental trajectories in those with and without elevated autism symptoms,” was published in the Journal of Intellectual Disability Research.

Approximately 30 percent of patients with fragile X syndrome (FXS) meet the criteria for a diagnosis of autism spectrum disorder (ASD). Interestingly, individuals with both fragile X and ASD typically have milder ASD symptoms compared to those with ASD alone.

However, little is known about how characteristics associated autism develop over time in fragile X patients.

Researchers investigated the profiles and developmental patterns of three common characteristics in patients with intellectual disabilities — overactivity, impulsivity and repetitive behavior — in fragile X males over the course of 8 years at three time intervals.

Fragile X patients were categorized into two subgroups based on the suggested cut-off scores for autism. One group included patients who displayed elevated symptoms of autism at time 1 (FXS+ASD) and the second group included patients who did not (FXS-ASD).

Hyperactivity and impulsivity were assessed using the Activity Questionnaire and repetitive behavior was assessed using the Repetitive Behavior Questionnaire.

While there were no inter-group differences at any time point, researchers discovered that impulsivity scores decreased over time in the FXS-ASD group. This was true especially of children aged 12-18.

Additionally, while most repetitive behaviors were similar across both subgroups, repetitive questioning decreased over time only in the FXS-ASD group. This, however, was true only for patients who were in the 19-plus age group.

“Impulsivity improved over time in a group of males with FXS without elevated symptoms of autism but remained persistent in those with elevated symptoms of autism. In addition, subtle differences in the profile of repetitive behaviors emerged over time between these two subgroups,” the authors wrote.

Repetitive behavior and impulsive behavior have been associated with self-injurious behavior in fragile X males. These study results highlight the critical importance of further understanding such behaviors and demonstrates the need to develop early and targeted therapies.