Toward a Theory of Stuttering

Stuttering as a spectrum disorder: A hypothesis

Childhood-onset fluency disorder, commonly referred to as stuttering, affects over 70 million adults worldwide. While stuttering predominantly initiates during childhood and is more prevalent in males, it presents consistent symptoms during conversational speech. Despite these common clinical manifestations, evidence suggests that stuttering, may arise from different etiologies, emphasizing the need for personalized therapy approaches. Current research models often regard the stuttering population as a singular, homogenous group, potentially overlooking the inherent heterogeneity. This perspective consolidates both historical and recent observations to emphasize that stuttering is a heterogeneous condition with diverse causes. As such, it is crucial that both therapeutic research and clinical practices consider the potential for varied etiologies leading to stuttering. Recognizing stuttering as a spectrum disorder embraces its inherent variability, allowing for a more nuanced categorization of individuals based on the underlying causes. This perspective aligns with the principles of precision medicine, advocating for tailored treatments for distinct subgroups of people who stutter, ultimately leading to personalized therapeutic approaches.

Assessing the psychosocial impact of stammering on work

BACKGROUND

Stammering (stuttering) is a speech condition with high heterogeneity, affecting approximately 1% of adults. Research shows it can limit career progression, impact job performance and quality of life.

AIMS

To assess the psychosocial impact of stammering among healthcare workers and to develop a new workplace support intervention.

METHODS

A cross-sectional questionnaire of healthcare workers who stammer with qualitative work and a survey of occupational health (OH) usual care to assess the need for a workplace intervention.

RESULTS

Data from 470 staff questionnaires and 32 OH clinicians were analysed. Eighty-four per cent rated their stammering severity as mild-to-moderate, with the majority reporting adverse impact on job performance and career progression. Most experienced a high degree of anxiety and embarrassment at work, with avoidance behaviours commonplace. Four per cent of respondents sought OH advice for work difficulties. Qualitative data highlighted practical challenges staff experience in the workplace. Sixty-five per cent supported the proposal for a new workplace intervention. We found workplace stress and anxiety were the most common reasons for OH referrals, and we found wide variation in the scope of OH assessments and work adjustments recommended. Most OH respondents reported insufficient clinical knowledge of speech disorders and their impact on work.

CONCLUSIONS

Stammering can have a negative impact of workers' job performance and job satisfaction. This can precipitate feelings of stress and anxiety, and can affect self-identity at work. We found wide variation in the provision of OH usual care. The results informed the development of a new workplace intervention.

Dopamine, vocalization, and astrocytes

Dopamine, the main catecholamine neurotransmitter in the brain, is predominately produced in the basal ganglia and released to various brain regions including the frontal cortex, midbrain and brainstem. Dopamine's effects are widespread and include modulation of a number of voluntary and innate behaviors. Vigilant regulation and modulation of dopamine levels throughout the brain is imperative for proper execution of motor behaviors, in particular speech and other types of vocalizations. While dopamine's role in motor circuitry is widely accepted, its unique function in normal and abnormal speech production is not fully understood. In this perspective, we first review the role of dopaminergic circuits in vocal production. We then discuss and propose the conceivable involvement of astrocytes, the numerous star-shaped glia cells of the brain, in the dopaminergic network modulating normal and abnormal vocal productions.

Evaluating parents' reactions to Children's stuttering using a Persian version of reaction to Speech Disfluency Scale

OBJECTIVES

Stuttering is one of the most common speech disorders with many negative effects on children and their parents. The parents play a very important role in the treatment and management of children's stuttering. The parents' reactions to children's stuttering are pivotal in the exacerbation or improvement of stuttering. The present study aimed to investigate the parents' reactions to their children's stuttering using the Persian version of Reaction to Speech Disfluency Scale (RSDS).

METHODS

The present study was conducted in two stages; phase 1: translation and cultural adaptation of RSDS into Persian and phase 2: investigation of the reaction of parents to children's stuttering using the RSDS. The first phase of the study included the following steps, forward translation, backward translation, content validity, face validity, and reliability of the scale using internal consistency and test-retest reliability. The second phase of the study was to examine the reactions of 110 parents of 3-6-year-old children who stutter by using the RSDS. Data were analyzed using SPSS software.

RESULTS

The results of translation and cultural adaptation of the RSDS showed that the Persian version of RSDS has suitable validity. The internal consistency (Cronbach's alpha = 0.94) and the test-retest reliability (ICC = 0.98) were also appropriate for this scale. The most reactions of parents to children's stuttering were cognitive, emotional, and behavioral, respectively. The results of evaluating the maternal and paternal reactions separately indicated that the highest value of paternal reaction score was cognitive, behavioral and emotional reactions, respectively, while the highest value of maternal reaction score was cognitive, emotional and behavioral reactions, respectively. Differences between fathers and mothers were statistically significant only in emotional reaction subscale (P < 0.001). The mean overall score of the RSDS for all parents was 29, as well as 27.72 and 30.27 in fathers and mothers groups, respectively, but this differences between groups not statistically significant (P = 0.12). Comparing the scores between parents of boys and girls who stutter showed that the mean overall scores of cognitive, emotional, and behavioral subscales, and overall scores in the parents of girls who stutter was higher than in the parents of boys who stutter, and this difference was statistically significant in the emotional subscale and the overall score between the two groups (P < 0.05).

CONCLUSION

The parental cognitive and behavioral reactions to children's stuttering had the maximum and minimum frequency, respectively. The paternal reactions to their children's stuttering were different from maternal reactions. The parents of girls who stutter in all subscales had a greater reaction compared to the parents of boys who stutter. Given the importance of the reactions of parents to their children's stuttering, the results of the present study can help to complete the information of therapists and researchers in this field.

An evaluation of oxidative and nitrosative stress in children-who-stutter and its relationship to severity

OBJECTIVES

Although there has been much research into the cause of stuttering, it has not yet been fully clarified. There is known to be a close relationship between stress severity and stuttering. The aim of this study was to evaluate the levels of oxidative and nitrosative stress by comparing a stuttering group and a control group. It was also aimed to evaluate the relationship between the oxidative and nitrosative stress levels and the severity of the stutter.

METHODS

The study included a total of 80 individuals, comprising a study group of 40 and a control group of 40. The severity of the stutter in the patient group was evaluated with the Stuttering Severity Instrument 3 (SSI). Blood samples were taken from both the patient and control groups and malondialdehyde (MDA), 3 nitrotyrosine (3-NT), nitric oxide (NO), catalase (CAT), and superoxide dismutase (SOD) concentrations were examined.

RESULTS

In the stuttering patients, MDA, 3-NT, NO, CAT, and SOD activity were determined to be statistically significantly higher than those of the control group (all p:0.001). In the ROC analysis, there was good diagnostic value for NO, with the area under the curve as 1.0. A direct, positive, statistically significant correlation was determined between SSI points and MDA values (r = 0.317, p = 0.046).

CONCLUSION

The results of the study showed that the oxidative and nitrosative stress levels of the stuttering patients were higher than those of the control group. With 100% sensitivity and specificity, it is thought that NO in particular could be important for the diagnosis and treatment of these patients. As the severity of the stutter increased, so there was an increase in MDA, suggesting that MDA is important in stuttering.