A study led by communications sciences and disorders assistant professor Dr. Jessica Klusek (University of South Carolina, Arnold School of Public Health) recently examined vagal tone as a putative mechanism for pragmatic competence. The resulting paper, published in the Journal of Autism and Developmental Disorders, discusses the researchers’ investigation of carriers of the FMR1 premutation as a genetic model for pragmatic language impairment.
Pragmatic language, or “social language” encompasses conversational skills, such as knowing what to say, and how and when to say it. These skills are essential for successful communication with others. Pragmatic skills exist across a continuum in typical and clinical populations and are impaired in many neurodevelopmental disorders, particularly autism. The mechanisms underlying pragmatic impairment are poorly understood due to limited research on the topic.
Scientific theory suggests that vagal tone plays a role in pragmatic language skills. Vagal tone is characterized as activity of the vague nerve, which is one of a dozen cranial nerves and is the longest nerve of the autonomic nervous system in the human body. High levels of vagal tone are associated with autonomic health and enhanced ability to respond flexibly and adaptively in social situations. The researchers hypothesized that low levels of vagal tone would relate to increased difficulty with pragmatic language skills.
In the present study, Dr. Klusek and University of South Carolina psychology researchers Amanda Fairchild and Jane Roberts examined the relationship between vagal function and pragmatic ability, using carriers of the FMR1 premutation as a genetic model for vagal dysfunction. Carriers of the FMR1 premutation, also known as “fragile X carriers”, carry a mild genetic mutation on the FMR1 gene that is associated with impaired vagal function. Participants included 38 women with FMR1 premutation and 23 women without the premutation. Vagal tone was evaluated via analysis of ECG recordings and pragmatic language skills were rated from conversational samples.
The authors found that vagal tone accounted for significant variance in pragmatic competence across both groups and statistically mediated the effect of FMR1 premutation status on pragmatic ability. These results support a link between healthy vagal function and social communication competence, which informs potential mechanistic underpinnings of pragmatic impairment. These findings could have implications for designing targeted treatments for autism and other clinical populations that are characterized by pragmatic deficits.
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