► Onset of stuttering. ► Incidence and prevalence. ► Developmental paths. ► Genetic of stuttering. ► Subtypes of stuttering. Epidemiological advances in stuttering during the current century are reviewed within the perspectives of past knowledge. The review is organized in six sections: (a) onset, (b) incidence, (c) prevalence, (d) developmental paths, (e) genetics and (f) subtypes. It is concluded that: (1) most of the risk for stuttering onset is over by age 5, earlier than has been previously thought, with a male-to-female ratio near onset smaller than what has been thought, (2) there are indications that the lifespan incidence in the general population may be higher than the 5% commonly cited in past work, (3) the average prevalence over the lifespan may be lower than the commonly held 1%, (4) the effects of race, ethnicity, culture, bilingualism, and socioeconomic status on the incidence/prevalence of stuttering remain uncertain, (5) longitudinal, as well as incidence and prevalence studies support high levels of natural recovery from stuttering, (6) advances in biological genetic research have brought within reach the identification of candidate genes that contribute to stuttering in the population at large, (7) subtype-differentiation has attracted growing interest, with most of the accumulated evidence supporting a distinction between persistent and recovered subtypes. Readers will be exposed to a summary presentation of the most recent data concerning basic epidemiological factors in stuttering. Most of these factors also pertain to children's risks for experiencing stuttering onset, as well as risks for persistency. The article also aims to increase awareness of the implications of the information to research, and professional preparation that meets the epidemiology of the disorder.
Anxiety is one of the most widely observed and extensively studied psychological concomitants of stuttering. Research conducted prior to the turn of the century produced evidence of heightened anxiety in people who stutter, yet findings were inconsistent and ambiguous. Failure to detect a clear and systematic relationship between anxiety and stuttering was attributed to methodological flaws, including use of small sample sizes and unidimensional measures of anxiety. More recent research, however, has generated far less equivocal findings when using social anxiety questionnaires and psychiatric diagnostic assessments in larger samples of people who stutter. In particular, a growing body of research has demonstrated an alarmingly high rate of social anxiety disorder among adults who stutter. Social anxiety disorder is a prevalent and chronic anxiety disorder characterised by significant fear of humiliation, embarrassment, and negative evaluation in social or performance-based situations. In light of the debilitating nature of social anxiety disorder, and the impact of stuttering on quality of life and personal functioning, collaboration between speech pathologists and psychologists is required to develop and implement comprehensive assessment and treatment programmes for social anxiety among people who stutter. This comprehensive approach has the potential to improve quality of life and engagement in everyday activities for people who stutter. Determining the prevalence of social anxiety disorder among children and adolescents who stutter is a critical line of future research. Further studies are also required to confirm the efficacy of Cognitive Behaviour Therapy in treating social anxiety disorder in stuttering. : The reader will be able to: (a) describe the nature and course of social anxiety disorder; (b) outline previous research regarding anxiety and stuttering, including features of social anxiety disorder; (c) summarise research findings regarding the diagnostic assessment of social anxiety disorder among people who stutter; (d) describe approaches for the assessment and treatment of social anxiety in stuttering, including the efficacy of Cognitive Behaviour Therapy; and (e) outline clinical implications and future directions associated with heightened social anxiety in stuttering.
Stuttering is an involuntary fluency disorder that is not uncommon in society. However, the impact of stuttering on a composite measure such as quality of life has rarely been estimated. Quality of life (QOL) assesses the well-being of a person from a multidimensional perspective, and valid and reliable general QOL measures are available that can be used to estimate the impact of stuttering on QOL. This study involved the use of a general measure of QOL called the Medical Outcomes Study Short Form-36 (SF-36) in order to assess the impact of stuttering in 200 adults who stutter (AWS). Comparisons to 200 adults of similar age and sex ratio who do not stutter were made so that the unique contribution of stuttering on QOL could be estimated. Findings indicated that stuttering does negatively impact QOL in the vitality, social functioning, emotional functioning and mental health status domains. Results also tentatively suggest that people who stutter with increased levels of severity may have a higher risk of poor emotional functioning. These findings have implications for treatment such as the necessity to address the emotional and psychological aspects of QOL in AWS and the need for additional clinical resources to be invested in stuttering treatment. : The reader will be able to: (a) summarize the method used in quality of life assessment using the SF-36; (b) describe the impact of stuttering on the quality of life of adults who stutter; (c) compare the impact of stuttering to the quality of life of adults who do not stutter; (d) describe the relationship between frequency of stuttering and quality of life.
The relationship between chronic stuttering and anxiety has been a matter of some debate over the past two decades, with a major emphasis of research focused on examining whether people who stutter have abnormally elevated levels of trait or social anxiety. The major goal of this paper was to perform a systematic literature review and perform meta-analyses on research that has assessed (i) trait anxiety and (ii) social anxiety, in adults who stutter. Only studies that met strict inclusion criteria were selected for the meta-analyses. Two meta-analyses were conducted, the first for trait anxiety, and the second for social anxiety. Meta-analysis combines statistically the results of selected studies that meet strict design criteria, thereby clarifying the size of differences in trait and social anxiety between adults who stutter and adults who do not stutter. Meta-analytic results confirmed that adults with chronic stuttering do have substantially elevated trait and social anxiety. The overall effect size for trait and social anxiety was calculated to be .57 and .82, respectively. Trait and social anxiety are definite problems for many adults who stutter. Clinical implications of these findings for the diagnosis and treatment of adult who stutter are discussed. : The reader will be able to: (a) describe the process of conducting a systematic review and meta-analysis; (b) describe the possible impact of publication bias on meta-analysis results; (c) explain the impact of a chronic disorder like stuttering on levels of trait anxiety; (d) explain the impact of stuttering on levels of social anxiety; (e) interpret the results of meta-analysis when applied to differences in anxiety between adult people who stutter and those who do not stutter; and (f) describe implications for fluency enhancing treatments.
Anxiety and emotional reactions have a central role in many theories of stuttering, for example that persons who stutter would tend to have an emotionally sensitive temperament. The possible relation between stuttering and certain traits of temperament or personality were reviewed and analyzed, with focus on temporal relations (i.e., what comes first). It was consistently found that preschool children who stutter (as a group) do not show any tendencies toward elevated temperamental traits of shyness or social anxiety compared with children who do not stutter. Significant group differences were, however, repeatedly reported for traits associated with inattention and hyperactivity/impulsivity, which is likely to reflect a subgroup of children who stutter. Available data is not consistent with the proposal that the risk for persistent stuttering is increased by an emotionally reactive temperament in children who stutter. Speech-related social anxiety develops in many cases of stuttering, before adulthood. Reduction of social anxiety in adults who stutter does not in itself appear to result in significant improvement of speech fluency. Studies have not revealed any relation between the severity of the motor symptoms of stuttering and temperamental traits. It is proposed that situational variability of stuttering, related to social complexity, is an effect of interference from social cognition and not directly from the emotions of social anxiety. In summary, the studies in this review provide strong evidence that persons who stutter are not characterized by constitutional traits of anxiety or similar constructs. : This paper provides a review and analysis of studies of anxiety, temperament, and personality, organized with the objective to clarify cause and effect relations. Readers will be able to (a) understand the importance of effect size and distribution of data for interpretation of group differences; (b) understand the role of temporal relations for interpretation of cause and effect; (c) discuss the results of studies of anxiety, temperament and personality in relation to stuttering; and (d) discuss situational variations of stuttering and the possible role of social cognition.
Stuttering is a disorder that affects millions of people all over the world. Over the past two decades, there has been a great deal of interest in investigating the neural basis of the disorder. This systematic literature review is intended to provide a comprehensive summary of the neuroimaging literature on developmental stuttering. It is a resource for researchers to quickly and easily identify relevant studies for their areas of interest and enable them to determine the most appropriate methodology to utilize in their work. The review also highlights gaps in the literature in terms of methodology and areas of research. We conducted a systematic literature review on neuroimaging studies on developmental stuttering according to the PRISMA guidelines. We searched for articles in the pubmed database containing “stuttering” OR “stammering” AND either “MRI”, “PET”, “EEG”, “MEG”, “TMS”or “brain” that were published between 1995/01/01 and 2016/01/01. The search returned a total of 359 items with an additional 26 identified from a manual search. Of these, there were a total of 111 full text articles that met criteria for inclusion in the systematic literature review. We also discuss neuroimaging studies on developmental stuttering published throughout 2016. The discussion of the results is organized first by methodology and second by population (i.e., adults or children) and includes tables that contain all items returned by the search. There are widespread abnormalities in the structural architecture and functional organization of the brains of adults and children who stutter. These are evident not only in speech tasks, but also non-speech tasks. Future research should make greater use of functional neuroimaging and noninvasive brain stimulation, and employ structural methodologies that have greater sensitivity. Newly planned studies should also investigate sex differences, focus on augmenting treatment, examine moments of dysfluency and longitudinally or cross-sectionally investigate developmental trajectories in stuttering.
We combined a large longitudinal neuroimaging dataset that includes children who do and do not stutter and a whole-brain network analysis in order to examine the intra- and inter-network connectivity changes associated with stuttering. Additionally, we asked whether whole brain connectivity patterns observed at the initial year of scanning could predict persistent stuttering in later years. A total of 224 high-quality resting state fMRI scans collected from 84 children (42 stuttering, 42 controls) were entered into an independent component analysis (ICA), yielding a number of distinct network connectivity maps (“components”) as well as expression scores for each component that quantified the degree to which it is expressed for each child. These expression scores were compared between stuttering and control groups’ first scans. In a second analysis, we examined whether the components that were most predictive of stuttering status also predicted persistence in stuttering. Stuttering status, as well as stuttering persistence, were associated with aberrant network connectivity involving the default mode network and its connectivity with attention, somatomotor, and frontoparietal networks. The results suggest developmental alterations in the balance of integration and segregation of large-scale neural networks that support proficient task performance including fluent speech motor control. This study supports the view that stuttering is a complex neurodevelopmental disorder and provides comprehensive brain network maps that substantiate past theories emphasizing the importance of considering situational, emotional, attentional and linguistic factors in explaining the basis for stuttering onset, persistence, and recovery.
Stuttering during adulthood is associated with a heightened rate of anxiety disorders, especially social anxiety disorder. Given the early onset of both anxiety and stuttering, this comorbidity could be present among stuttering children. Participants were 75 stuttering children 7–12 years and 150 matched non-stuttering control children. Multinomial and binary logistic regression models were used to estimate odds ratios for anxiety disorders, and two-sample -tests compared scores on measures of anxiety and psycho-social difficulties. Compared to non-stuttering controls, the stuttering group had six-fold increased odds for social anxiety disorder, seven-fold increased odds for subclinical generalized anxiety disorder, and four-fold increased odds for any anxiety disorder. These results show that, as is the case during adulthood, stuttering during childhood is associated with a significantly heightened rate of anxiety disorders. Future research is needed to determine the impact of those disorders on speech treatment outcomes.
This paper investigates the hypothesis that stuttering may result in part from impaired readout of feedforward control of speech, which forces persons who stutter (PWS) to produce speech with a motor strategy that is weighted too much toward auditory feedback control. Over-reliance on feedback control leads to production errors which if they grow large enough, can cause the motor system to “reset” and repeat the current syllable. This hypothesis is investigated using computer simulations of a “neurally impaired” version of the DIVA model, a neural network model of speech acquisition and production. The model's outputs are compared to published acoustic data from PWS’ fluent speech, and to combined acoustic and articulatory movement data collected from the dysfluent speech of one PWS. The simulations mimic the errors observed in the PWS subject's speech, as well as the repairs of these errors. Additional simulations were able to account for enhancements of fluency gained by slowed/prolonged speech and masking noise. Together these results support the hypothesis that many dysfluencies in stuttering are due to a bias away from feedforward control and toward feedback control. : The reader will be able to (a) describe the contribution of auditory feedback control and feedforward control to normal and stuttered speech production, (b) summarize the neural modeling approach to speech production and its application to stuttering, and (c) explain how the DIVA model accounts for enhancements of fluency gained by slowed/prolonged speech and masking noise.
Stuttering Support Organizations (SSOs) are places where people who stutter can share their experiences with stuttering and lend support to each other. There is evidence that SSO participation may be helpful in reducing the negative impact of stuttering and promoting positive cognitive and affective changes in adults who stutter. The benefits of participating in SSO organizations for young people, however, are currently unknown. This study investigated the relationship between attending a multi-day SSO convention and cognitive and affective changes among young people who stutter (YPWS). Twenty-two YPWS (ages 10 to 18) were recruited from the 2016 FRIENDS annual convention to participate in this study. FRIENDS is the National Association of Young People Who Stutter. A mixed methods approach was used to collect and analyze quantitative and qualitative data. The Overall Assessment of the Speaker’s Experience with Stuttering (OASES) was administered at three times points: pre-convention, post-convention, and three months following the convention. Semi-structured interviews were conducted with seven participants to further explain the quantitative results. Analysis of OASES scores across the three time points indicated that there were significant decreases in the negative impact of stuttering between pre-convention and post-convention measures. Qualitative analysis of semi-structured interview transcripts revealed five themes related to community building, collaborative learning, cognitive and communicative changes, self-acceptance, and normalizing stuttering. SSOs may be beneficial in reducing the negative impact of stuttering and should be considered a potentially valuable addition to traditional therapy for stuttering.
Migration is a contemporary, global matter. With the number of international migrants doubling over the past four decades, speech-language pathologists will likely work with migrants who have childhood-onset stuttering. However, combined migration and stuttering experiences have never been investigated specifically. This study is the first to investigate the experiences of migrants to Australia who stutter. Three women and six men, aged 23 to 66 years old, participated. Data from individual interviews were analysed using Interpretative Phenomenological Analysis to examine the ‘lived experience’ of participants, as well as with NVivo 12 software for the management of coding. Participants also completed The Overall Assessment of the Speaker’s Experience of Stuttering (OASES™). The stress experienced from migration interacted and compounded the existing stress of stuttering. Central themes emerged pertaining to the impact of increased stress on self-identity, the interactions of the stresses, as well as the coping strategies/facilitators. Stuttering and other personal factors, such as language(s) spoken and accent, had a negative impact on communication skills. Migration cannot be experienced independently of a stutter, as both are intrinsically linked to self-identity. The combined stress of migration with stuttering amplified the perception of feeling abnormal and resulted in difficulties with establishing a stable self-identity and a sense of belonging in the new context. Participants found strength in the company of others and considered Australia to be accepting of stuttering.
Multifactorial explanations of developmental stuttering suggest that difficulties in self-regulation and weak attentional flexibility contribute to persisting stuttering. We tested this prediction by examining whether preschool-age children who stutter (CWS) shift their attention less flexibly than children who do not stutter (CWNS) during a modified version of the Dimension Card Change Sort (DCCS), a reliable measure of attention switching for young children. Sixteen CWS (12 males) and 30 children CWNS (11 males) participated in the study. Groups were matched on age (CWS: = 49.63, = 10.34, = 38–80 months; CWNS: = 50.63, = 9.82, = 37–74 months), cognitive ability, and language skills. All children completed a computer-based variation of the DCCS, in which they matched on-screen bivalent stimuli to response buttons based on rules that switched mid-task. Results showed increased slowing for CWS compared to controls during the postswitch phase, as well as contrasting patterns of speed-accuracy tradeoff for CWS and CWNS as they moved from the preswitch to postswitch phase of the task. Group differences in performance suggest that early stuttering may be associated with difficulty shifting attention efficiently and greater concern about errors. Findings are consistent with a growing literature indicating links between weak attentional control and persisting developmental stuttering.
The aim of this study was to identify potential relationships between self-stigma (stigma awareness and stigma application) and stress, physical health, and health care satisfaction among a large sample of adults who stutter. It was hypothesized that both stigma awareness and stigma application would be inversely related to measures of physical health and health care satisfaction, and positively related to stress. Furthermore, it was anticipated that stress mediated the relationship between self-stigma and physical health. A sample of adults who stutter in the United States ( = 397) completed a web survey that assessed levels of stigma awareness and stigma application, stress, physical health, and health care satisfaction. Correlational analyses were conducted to determine the relationships between these variables. Higher levels of stigma awareness and stigma application were associated with increased stress, decreased overall physical health, and decreased health care satisfaction (i.e., discomfort obtaining health care due to stuttering, and adverse health care outcomes due to stuttering), and these relationships were statistically significant. Stress was identified as a mediator between stigma application and physical health. Because adults who stutter with higher levels of self-stigma are at risk for decreased physical health through increased stress, and lower satisfaction with their health care experiences as a result of stuttering, it is important for professionals to assess and manage self-stigma in clients who stutter. Self-stigma has implications for not only psychological well-being, but stress, physical health, and health care satisfaction as well.
To compare two experimental Westmead Program treatments with a control Lidcombe Program treatment for early stuttering. The design was a three-arm randomized controlled trial with blinded outcome assessments 9 months post-randomization. Participants were 91 pre-school children. There was no evidence of difference in percentage syllables stuttered at 9 months among groups. Dropout rates were substantive and may have been connected with novel aspects of the trial design: the use of community clinicians, no exclusion criteria, and randomization of children younger than 3 years of age. The substantive dropout rate for all three arms in this trial means that any conclusions about the 9-month stuttering outcomes must be regarded as tentative. However, continued development of the Westmead Program is warranted, and we are currently constructing an internet version.
: Motor theories indicate that focusing attention on well-practiced movements interferes with skilled performance; however, specific forms of attention (alerting vs. orienting vs. executive control) associated with this effect are not well understood. The present study explored this question in relation to stuttering, and examined whether dual task conditions that engaged sustained attention or working memory (WM) affected speech fluency in different ways. We also considered whether fluency changes were associated with changes in speech rate and language. : Nineteen adults who stutter (AWS) and 20 controls produced spontaneous speech under a baseline condition and two dual task conditions: one involving a sustained attention task, the other involving WM demands. : Both groups produced fewer stutter-like disfluencies under dual task relative to baseline conditions and this reduction did not differ between the two dual tasks (attention vs. WM). Speech rate and language variables, which were potentially influenced by attention conditions, were not affected by dual tasks in the same way as disfluencies, and appeared to be unassociated with fluency results. : Findings indicate that atypical disfluencies decrease when attention is divided, even when secondary task demands are minimal, as they were in the sustained attention task. For simple secondary tasks, fluency changes do not appear to be a byproduct of slowed rate and are not accompanied by observable changes in language. These results demonstrate that simple manipulations of attention can induce measurable effects on aspects of speech production, and may be a useful tool for facilitating fluency in clinical intervention.
Individuals who covertly stutter have a unique experience of stuttering that involves concealing the core behaviors of stuttering (e.g., repetitions, prolongations, and blocks). From the listener’s perspective, covert stuttering results in minimum typical, overt stuttering behaviors. However, from the speaker’s perspective, covert stuttering often increases the cognitive and emotional impact of stuttering. This study explores the speech-language therapy experiences of individuals who covertly stutter in order to improve treatment recommendations and best practice. This investigation is a qualitative analysis of individuals’ speech-language therapy experiences as persons who covertly stutter. Real-time video interviews were conducted with the use of open-ended phenomenological interview questions. Interviews were transcribed and thematic analysis of interview transcripts was conducted to investigate the speech-language therapy experiences of the participants. The participants indicated that stuttering therapy was most impactful when it included explicit goals and activities, personalized selection of therapy techniques or strategies beyond fluency techniques, encouraged self-education, and educated those in the person’s environment. The evidence suggests individualized therapy based on each client’s unique manifestation of covert stuttering is beneficial; while, fluency-focused stuttering therapy is often incongruent with the needs of persons who covertly stutter. Therapeutic implications and recommendations for speech-language pathologists are discussed.
The purpose of this study was to examine how the therapeutic alliances (TA) of graduate student clinicians and adult clients who stutter relate to perceived treatment outcomes. Student clinicians (N = 42) and adult clients who stutter (N = 22) completed a survey assessing their TA strength and perception of treatment outcomes. Responses were analyzed to determine similarities and differences in how clinicians and clients relate the TA to perceptions of treatment effectiveness, progress, and outcome satisfaction. Results suggest that clinicians and clients who stutter both relate the TA to treatment outcome, but in different ways. While clinicians associate the TA most with treatment effectiveness and client progress, clients relate the TA most to outcome satisfaction. Clinicians should be aware that for adult clients who stutter, outcome satisfaction is related to the degree of shared understanding, agreement on daily tasks, and bond they experience with their clinician. To ensure a strong TA and client satisfaction, clinicians should actively seek their clients’ perspective regarding TA status.
Empirical investigations have revealed a strong association between linguistic factors and stuttering, specifically phonological and morphological factors. However, the effect of these factors is suggested to vary across languages owing to the differences in their linguistic structure. Further, the trend is found to vary between AWS and CWS. Literature in this regard is scarce in the Kannada language, particularly in children. Hence, the study was driven by the need to understand the effect of phonological and morphological factors on stuttering in Kannada speaking CWS. Spontaneous speech samples were obtained from twenty Kannada speaking preschool CWS with a confirmed diagnosis of stuttering by an experienced speech-language pathologist. The recorded samples were transcribed, and disfluencies were marked. Further, the stuttered words were analysed for phonological and morphological features. The phonological factors included were phoneme position in a word, phoneme type and word length. Morphological factors consisted of word class and word end inflectional morphology. The percentage of stuttering was calculated with respect to each of the factors mentioned above. Phoneme in the initial position of a word and words beginning with consonants had a higher rate of stuttering. Word length, word class and word end inflections were found to have no significant effect on the rate of stuttering in CWS. Overall, current findings revealed that stuttering might manifest differently across languages varying in their linguistic structures.