Cluttering in the Speech of Young Men With Fragile X Syndrome

Cluttering is a fluency disorder that has been noted clinically in individuals with fragile X syndrome (FXS). Yet, cluttering has not been systematically characterized in this population, hindering identification and intervention efforts. This study examined the rates of cluttering in male young adults with FXS using expert clinical opinion, the alignment between expert clinical opinion and objectively quantified features of cluttering from language transcripts, and the association between cluttering and aspects of the FXS phenotype.

Thirty-six men with FXS (aged 18-26 years; M = 22, SD = 2.35) contributed language samples and completed measures of nonverbal cognition, autism symptoms, anxiety, and symptoms of attention-deficit/hyperactivity disorder (ADHD). The presence of cluttering was determined by the consensus of two clinical experts in fluency disorders based on characteristics exhibited in the language sample. Cluttering features (speech rate, disfluencies, etc.) were also objectively quantified from the language transcripts.

Clinical experts determined that 50% of participants met the criteria for a cluttering diagnosis. Phrase repetitions were the most salient feature that distinguished individuals who cluttered. Although the presence of cluttering was not associated with autism symptoms or mean length of utterance, cluttering was more likely to occur when nonverbal cognitive ability was higher, ADHD symptoms were elevated, and anxiety symptoms were low.

Half of the male young adults with FXS exhibited cluttering, which supports FXS as a genetic diagnosis that is highly enriched for risk of cluttering. Cluttering was associated with increased ADHD symptoms and cognitive ability and reduced anxiety symptoms. This study contributes a new description of the clinical presentation of cluttering in men with FXS and may lead to improved understanding of the potential underlying mechanisms of cluttering and eventual refinements to treatment and diagnosis.