Immune response and stuttering: the potential link between cytokines and stutter

OBJECTIVE: Stuttering is a common speech disorder among the general population, characterized by disruptions in the fluency of speech. Even if many studies have been managed on stuttering, the etiology has not yet been exactly explained. This article aims to assess the level of cytokines in patients who stutter to provide evidence-based guidelines for clinicians. METHODS: A total of 74 children, including 34 who were stutterers and 40 who were controls, aged 4-15 years were included. The children with stuttering completed the Stuttering Severity Instrument-3 (SSI-3) form. Serum concentrations of IL-1, IL-6, IL-8, and TNF-α were analyzed in blood samples obtained from the subjects. RESULTS: Of the stuttering children we included in the study, 3 (8.8%) had very mild, 13 (38.2%) had mild, (35.2%) had moderate, 4 (11.7%) had severe, and 2 (5.8%) had very severe stuttering. IL-1, IL-8, and TNF-α levels in stuttering patients were significantly higher compared to the control group (p = 0.028, p = 0.031, p < 0.001, respectively). The IL-6 level did not show a statistically significant difference between the groups (p = 0.461). Regarding the diagnostic performance of stuttering, IL-1, IL-6, IL-8, and TNF-α all demonstrated statistically significant ability to distinguish between patients and the control group (p = 0.025, p = 0.021, p = 0.004, p = 0.003, respectively). CONCLUSIONS: These results suggest an increase in circulating levels of cytokines known to be regulatory and that stuttering is associated with a proinflammatory state. These results may be well-considered important in the diagnosis and evaluation of stuttering. This study contributes further support to investigate the immune system as a target for future therapeutic development. LEVEL OF EVIDENCE: Level 4.