Dissociations among linguistic, cognitive, and auditory-motor neuroanatomical domains in children who stutter

Exploring the Activation of Target Words in Picture Naming in Children Who Stutter: Evidence From Event-Related Potentials

PURPOSE

Target word activation in picture naming was explored in children who stutter (CWS) and typically fluent children (TFC) using event-related potentials (ERPs).

METHOD

A total of 18 CWS and 16 TFC completed a task combining picture naming and probe word identification. On each trial, a picture-to-be-named was followed by an auditory probe word-to-be-identified; the probe was identical (Identity condition) or Unrelated to the picture name. ERPs were recorded from probe onset. Attenuation of the N400 ERP component was predicted to Identity versus Unrelated trials (N400 priming). Between-groups differences in amplitude, timing, and topography of N400 priming were explored.

RESULTS

Naming was more accurate on Identity versus Unrelated trials. Probe word identification accuracy was not affected by Condition. N400 priming was detected, indicating that self-generated picture names facilitated semantic processing of identical probes. This effect was larger in amplitude in CWS versus TFC. Unexpectedly, an N400-preceding, frontally maximal, positive-going ERP component-associated with expectancy processing-was larger in amplitude to Unrelated versus Identity trials. This effect was smaller in CWS versus TFC.

CONCLUSIONS

A larger N400 priming effect in CWS versus TFC reflects a tendency toward more extensive semantic processing in picture naming in CWS. A smaller Condition effect on frontally maximal, positive-going, N400-preceding ERP activity in CWS versus TFC indicates a reduced ability to form expectancies about the lexical and/or phonological identity of probe words in CWS. Both effects may point to inefficient activation of target words in picture naming in CWS.

Erasmus clinical model of the onset and development of stuttering 2.0

A clinical, evidence-based model to inform clients and their parents about the nature of stuttering is indispensable for the field. In this paper, we propose the Erasmus Clinical Model of Stuttering 2.0 for children who stutter and their parents, and adult clients. It provides an up-to-date, clinical model summary of current insights into the genetic, neurological, motoric, linguistic, sensory, temperamental, psychological and social factors (be it causal, eliciting, or maintaining) related to stuttering. First a review is presented of current insights in these factors, and of six scientific theories or models that have inspired the development of our current clinical model. Following this, we will propose the model, which has proven to be useful in clinical practice. The proposed Erasmus Clinical Model of Stuttering visualizes the onset and course of stuttering, and includes scales for stuttering severity and impact, to be completed by the (parent of) the person who stutters. The pathway of the model towards stuttering onset is based on predisposing and mediating factors. In most children with an onset of stuttering, stuttering is transient, but if stuttering continues, its severity and impact vary widely. The model includes the circle of Engel (1977), which visualizes unique interactions of relevant biological, psychological, and social factors that determine the speaker's experience of stuttering severity and its impact. Discussing these factors and their interaction with an individual client can feed into therapeutic targets. The model is supplemented by a lifeline casus.

Evidence for planning and motor subtypes of stuttering based on resting state functional connectivity

We tested the hypothesis, generated from the Gradient Order Directions Into Velocities of Articulators (GODIVA) model, that adults who stutter (AWS) may comprise subtypes based on differing connectivity within the cortico-basal ganglia planning or motor loop. Resting state functional connectivity from 91 AWS and 79 controls was measured for all GODIVA model connections. Based on a principal components analysis, two connections accounted for most of the connectivity variability in AWS: left thalamus - left posterior inferior frontal sulcus (planning loop component) and left supplementary motor area - left ventral premotor cortex (motor loop component). A k-means clustering algorithm using the two connections revealed three clusters of AWS. Cluster 1 was significantly different from controls in both connections; Cluster 2 was significantly different in only the planning loop; and Cluster 3 was significantly different in only the motor loop. These findings suggest the presence of planning and motor subtypes of stuttering.

Multiple-Community-Based Epidemiological Study of Stuttering among 3-Year-Old Children in Japan

INTRODUCTION

Many epidemiological studies of the disorder of stuttering have been conducted during the 20th century, continuing during the current one. Unfortunately, only a few were carried out in Japan. This study aimed at assessing (1) the incidence and prevalence of stuttering in 3-year-old children in multiple Japanese communities and (2) factors associated with the onset of stuttering among these children.

METHODS

A questionnaire aimed at screening for the presence of stuttering was employed for 2,055 children aged 3 years, who underwent a standard nationwide health checkup. Positive responses were confirmed in several ways: (1) direct interviews and assessment of the child's speech, (2) confirmatory questionnaire, or (3) telephone interviews by licensed Speech Language Hearing Therapists.

RESULTS

Approximately 6.5% of the children were found to exhibit stuttering at the time of their health checkup. This figure rose to 8.9% after including individuals who previously, but not currently, were reported to have exhibited stuttering. Among the putative risk factors, higher stuttering odds (odds ratio, OR = 3.27) were detected in those with a family history of stuttering, those whose guardians had concerns about their child's development (OR = 1.75), and those with diagnosed diseases or disabilities (OR = 2.13).

DISCUSSION/CONCLUSIONS

It was concluded that, in Japan, both the risk of stuttering incidence (8.9%) in children up to, and including, the age of 3 years, as well as its prevalence (6.5%) in this population, was similar to those reported by recent studies in other countries. Additionally, our findings also confirmed that an increased risk for stuttering at age 3 is associated with a family history of stuttering.

Hand Preference in Stuttering: Meta-Analyses

Reduced hemispheric asymmetries, as well as their behavioral manifestation in the form of atypical handedness (i.e., non-right, left-, or mixed-handedness), are linked to neurodevelopmental disorders, such as autism spectrum disorder, and several psychiatric disorders, such as schizophrenia. One neurodevelopmental disorder that is associated with reduced hemispheric asymmetries, but for which findings on behavioral laterality are conflicting, is stuttering. Here, we report a series of meta-analyses of studies that report handedness (assessed as hand preference) levels in individuals who stutter (otherwise healthy) compared to controls. For this purpose, articles were identified via a search in PubMed, Scopus, and PsycInfo (13 June 2023). On the basis of k = 52 identified studies totaling n = 2590 individuals who stutter and n = 17,148 controls, five random effects meta-analyses were conducted: four using the odds ratio [left-handers (forced choice); left-handers (extreme); mixed-handers; non-right-handers vs. total)] and one using the standardized difference in means as the effect size. We did not find evidence of a left (extreme)- or mixed-handedness difference or a difference in mean handedness scores, but evidence did emerge, when it came to left-handedness (forced-choice) and (inconclusively for) non-right-handedness. Risk-of-bias analysis was not deemed necessary in the context of these meta-analyses. Differences in hand skill or strength of handedness could not be assessed as no pertinent studies were located. Severity of stuttering could not be used s a moderator, as too few studies broke down their data according to severity. Our findings do not allow for firm conclusions to be drawn on whether stuttering is associated with reduced hemispheric asymmetries, at least when it comes to their behavioral manifestation.

Rate of Stuttering and Factors Associated With Speech Fluency Characteristics in Adult Struggling Readers

Stuttering is a disorder that affects about 1% of the population and manifests as speech disfluencies. Reading difficulties and disabilities are commonly found in this population. Nonetheless, speech disfluencies have not been explored in adult struggling readers (ASRs). In the current study, we examined the rate of stuttering in ASRs as well as the relationships between their speech fluency and reading skills. A total of 120 participants were interviewed about their experiences with reading and administered standardized reading and reading-related assessments. Speech fluency and the criterion for stuttering were based on the interview. About 18.3% of the sample met the criterion for stuttering. ASRs who stutter (ASRs-S) and ASRs who do not stutter (ASRs-NS) did not differ in their reading and reading-related skills. ASRs-S had higher rates of negative correlations between reading and reading-related skills compared with ASRs-NS. Correlation patterns between performance on standardized assessments point to higher rates of uneven skills or dissociations in ASRs-S. These findings may have implications for the assessment and instruction for ASRs.

Novel word recognition in childhood stuttering

Language skills have long been posited to be a factor contributing to developmental stuttering. The current study aimed to evaluate whether novel word recognition, a critical skill for language development, differentiated children who stutter from children who do not stutter. Twenty children who stutter and 18 children who do not stutter, aged 3–8 years, completed a novel word recognition task. Real-time eye gaze was used to evaluate online learning. Retention was measured immediately and after a 1-hr delay. Children who stutter and children who do not stutter exhibited similar patterns of online novel word recognition. Both groups also had comparable retention accuracy. Together, these results revealed that novel word recognition and retention were similar in children who stutter and children who do not stutter. These patterns suggest that differences observed in previous studies of language in stuttering may not be driven by novel word recognition abilities in children who stutter.

Performance of Bimanual Finger Coordination Tasks in Speakers Who Stutter

Stuttering is a neurodevelopmental speech disorder characterized by the symptoms of speech repetition, prolongation, and blocking. Stuttering-related dysfluency can be transiently alleviated by providing an external timing signal such as a metronome or the voice of another person. Therefore, the existence of a core motor timing deficit in stuttering has been speculated. If this is the case, then motoric behaviors other than speech should be disrupted in stuttering. This study examined motoric performance on four complex bimanual tasks in 37 adults who stutter and 31 fluent controls. Two tasks utilized bimanual rotation to examine motor dexterity, and two tasks used the bimanual mirror and parallel tapping movements to examine timing control ability. Video-based analyses were conducted to determine performance accuracy and speed. The results showed that individuals who stutter performed worse than fluent speakers on tapping tasks but not on bimanual rotation tasks. These results suggest stuttering is associated with timing control for general motor behavior.

Speech Fluency Improvement in Developmental Stuttering Using Non-invasive Brain Stimulation: Insights From Available Evidence

Developmental stuttering (DS) is a disturbance of the normal rhythm of speech that may be interpreted as very debilitating in the most affected cases. Interventions for DS are historically based on the behavioral modifications of speech patterns (e.g., through speech therapy), which are useful to regain a better speech fluency. However, a great variability in intervention outcomes is normally observed, and no definitive evidence is currently available to resolve stuttering, especially in the case of its persistence in adulthood. In the last few decades, DS has been increasingly considered as a functional disturbance, affecting the correct programming of complex motor sequences such as speech. Compatibly, understanding of the neurophysiological bases of DS has dramatically improved, thanks to neuroimaging, and techniques able to interact with neural tissue functioning [e.g., non-invasive brain stimulation (NIBS)]. In this context, the dysfunctional activity of the cortico-basal-thalamo-cortical networks, as well as the defective patterns of connectivity, seems to play a key role, especially in sensorimotor networks. As a consequence, a direct action on the functionality of "defective" or "impaired" brain circuits may help people who stutter to manage dysfluencies in a better way. This may also "potentiate" available interventions, thus favoring more stable outcomes of speech fluency. Attempts aiming at modulating (and improving) brain functioning of people who stutter, realized by using NIBS, are quickly increasing. Here, we will review these recent advancements being applied to the treatment of DS. Insights will be useful not only to assess whether the speech fluency of people who stutter may be ameliorated by acting directly on brain functioning but also will provide further suggestions about the complex and dynamic pathophysiology of DS, where causal effects and "adaptive''/''maladaptive" compensation mechanisms may be strongly overlapped. In conclusion, this review focuses future research toward more specific, targeted, and effective interventions for DS, based on neuromodulation of brain functioning.

Associations between stuttering, comorbid conditions and executive function in children: a population-based study

Background

The aim of this study was to investigate the relationship between executive function (EF), stuttering, and comorbidity by examining children who stutter (CWS) and children who do not stutter (CWNS) with and without comorbid conditions. Data from the National Health Interview Survey were used to examine behavioral manifestations of EF, such as inattention and self-regulation, in CWS and CWNS.

Methods

The sample included 2258 CWS (girls = 638, boys = 1620), and 117,725 CWNS (girls = 57,512; boys = 60,213). EF, and the presence of stuttering and comorbid conditions were based on parent report. Descriptive statistics were used to describe the distribution of stuttering and comorbidity across group and sex. Regression analyses were to determine the effects of stuttering and comorbidity on EF, and the relationship between EF and socioemotional competence.

Results

Results point to weaker EF in CWS compared to CWNS. Also, having comorbid conditions was also associated with weaker EF. CWS with comorbidity showed the weakest EF compared to CWNS with and without comorbidity, and CWS without comorbidity. Children with stronger EF showed higher socioemotional competence. A majority (60.32%) of CWS had at least one other comorbid condition in addition to stuttering. Boys who stutter were more likely to have comorbid conditions compared to girls who stutter.

Conclusion

Present findings suggest that comorbidity is a common feature in CWS. Stuttering and comorbid conditions negatively impact EF.

Linking Lysosomal Enzyme Targeting Genes and Energy Metabolism with Altered Gray Matter Volume in Children with Persistent Stuttering

Developmental stuttering is a childhood onset neurodevelopmental disorder with an unclear etiology. Subtle changes in brain structure and function are present in both children and adults who stutter. It is a highly heritable disorder, and 12-20% of stuttering cases may carry a mutation in one of four genes involved in intracellular trafficking. To better understand the relationship between genetics and neuroanatomical changes, we used gene expression data from the Allen Institute for Brain Science and voxel-based morphometry to investigate the spatial correspondence between gene expression patterns and differences in gray matter volume between children with persistent stuttering (n = 26, and 87 scans) and their fluent peers (n = 44, and 139 scans). We found that the expression patterns of two stuttering-related genes (GNPTG and NAGPA) from the Allen Institute data exhibited a strong positive spatial correlation with the magnitude of between-group gray matter volume differences. Additional gene set enrichment analyses revealed that genes whose expression was highly correlated with the gray matter volume differences were enriched for glycolysis and oxidative metabolism in mitochondria. Because our current study did not examine the participants' genomes, these results cannot establish the direct association between genetic mutations and gray matter volume differences in stuttering. However, our results support further study of the involvement of lysosomal enzyme targeting genes, as well as energy metabolism in stuttering. Future studies assessing variations of these genes in the participants' genomes may lead to increased understanding of the biological mechanisms of the observed spatial relationship between gene expression and gray matter volume.

Long-latency auditory evoked potential in children with stuttering

Objective

To analyze the latency and the amplitude values of Mismatch Negativity and P300 cognitive potential in children with stuttering, with no auditory complaints, with auditory thresholds within the normality range, comparing them to the findings of a Control Group.

Methods

A cross-sectional study involving 50 children of both sexes, 15 with stuttering and 35 without stuttering, aged 6 to 11 years, with no diagnosis of ear pathology or other diseases. All children were submitted to peripheral audiological evaluation (meatoscopy, pure tone testing, speech audiometry, and acoustic immittance measures) and a central audiological evaluation (investigation of the Mismatch Negativity and P300 cognitive potential). For the evaluation of fluency, all children with stuttering had a specific history taken and were video recorded in a spontaneous speech. Afterwards, the transcription was done, followed by speech analysis to classify children according the severity of stuttering.

Results

There was a significant difference in the latencies of Mismatch Negativity and P300 cognitive potential, as well as in the amplitude of Mismatch Negativity.

Conclusion

There was a significant delay in the latencies of Mismatch Negativity and P300 cognitive potential, as well as increase in the amplitude of the Mismatch Negativity in children with stuttering when compared to children in the Control Group. Changes in the morphology of the waves were found in the Stuttering Group.

Developmental stuttering and the role of the supplementary motor cortex

Developmental stuttering is a frequent neurodevelopmental disorder with a complex neurobiological basis. Robust neural markers of stuttering include imbalanced activity of speech and motor related brain regions, and their impaired structural connectivity. The dynamic interaction of cortical regions is regulated by the cortico-basal ganglia-thalamo-cortical system with the supplementary motor area constituting a crucial cortical site. The SMA integrates information from different neural circuits, and manages information about motor programs such as self-initiated movements, motor sequences, and motor learning. Abnormal functioning of SMA is increasingly reported in stuttering, and has been recently indicated as an additional "neural marker" of DS: anatomical and functional data have documented abnormal structure and activity of the SMA, especially in motor and speech networks. Its connectivity is often impaired, especially when considering networks of the left hemisphere. Compatibly, recent data suggest that, in DS, SMA is part of a poorly synchronized neural network, thus resulting in a likely substrate for the appearance of DS symptoms. However, as evident when considering neural models of stuttering, the role of SMA has not been fully clarified. Herein, the available evidence is reviewed, which highlights the role of the SMA in DS as a neural "hub", receiving and conveying altered information, thus "gating" the release of correct or abnormal motor plans.

Lexical diversity and lexical skills in children who stutter

PURPOSE

Numerous "small N" studies of language ability in children who stutter have produced differing conclusions. We combined test and spontaneous language data from a large cohort of children who stutter (CWS) and typically fluent peers, gathered from independent laboratories across the US, to appraise a variety of lexical measures.

METHOD

Standardized receptive and expressive vocabulary test data and spontaneous language samples from 99 pairs of CWS (ages 25-100 months), and age-, gender-, and SES-matched children who do not stutter (CWNS) were compared. Language sample transcripts were analyzed with four measures of lexical diversity. Correlations between lexical diversity measures and expressive vocabulary scores were also calculated.

RESULTS

On standardized tests of both receptive and expressive vocabulary, there were significant differences between CWS and CWNS. In contrast, on spontaneous language measures of lexical diversity, CWS did not differ in their lexical diversity, across analyses, compared to CWNS. Three of the four lexical diversity analyses, MATTR, VocD, and NDW, were significantly correlated with each other.

CONCLUSIONS

We were able to confirm prior findings of relative disadvantage on standardized vocabulary tests for a very large sample of well-matched CWS. However, spontaneous language measures of lexical diversity did not distinguish the groups. This relative weakness in CWS may emerge from task differences: CWS are free to encode their own spontaneous utterances but must comply with explicit lexical prompts in standardized testing situations.

Attention, Speech-Language Dissociations, and Stuttering Chronicity

The purpose of this study was to investigate the singular and joint contributions of speech-language dissociations and attention (i.e., distractibility and attention span) to stuttering chronicity. Method Participants, aged 3;0-4;11 (years;months) at an initial visit, were classified as persisting (n = 10; 9 boys), recovered (n = 32; 23 boys), and nonstuttering (n = 28; 19 boys) based on multiple speech and language evaluations spread across 2 years. The evaluations included assessments of articulation, receptive and expressive vocabulary, and omnibus receptive and expressive language. These measures were used to identify speech-language dissociations using a correlation-based statistical approach. Attentional characteristics, which included measures of distractibility and attention span, were based on parent report. Analyses investigated between-group differences related to dissociations and attentional characteristics as well as the relation between these indices. Results There were no significant between-group differences for the persisting and recovered groups on measures of speech-language dissociations; however, the recovered group was found to exhibit less optimal attention span than the persisting group. In addition, children with dissociations exhibited less optimal distractibility and attention spans at the final time point than children without dissociations. Conclusions Present results indicate that attention is related to both stuttering chronicity and the presence of speech-language dissociations; however, they do not support the notion that dissociations are associated with stuttering persistence. These results provide novel insights into the complex nature of the association between developmental stuttering, speech-language dissociations, and attention.

The Application of EEG Mu Rhythm Measures to Neurophysiological Research in Stuttering

Deficits in basal ganglia-based inhibitory and timing circuits along with sensorimotor internal modeling mechanisms are thought to underlie stuttering. However, much remains to be learned regarding the precise manner how these deficits contribute to disrupting both speech and cognitive functions in those who stutter. Herein, we examine the suitability of electroencephalographic (EEG) mu rhythms for addressing these deficits. We review some previous findings of mu rhythm activity differentiating stuttering from non-stuttering individuals and present some new preliminary findings capturing stuttering-related deficits in working memory. Mu rhythms are characterized by spectral peaks in alpha (8-13 Hz) and beta (14-25 Hz) frequency bands (mu-alpha and mu-beta). They emanate from premotor/motor regions and are influenced by basal ganglia and sensorimotor function. More specifically, alpha peaks (mu-alpha) are sensitive to basal ganglia-based inhibitory signals and sensory-to-motor feedback. Beta peaks (mu-beta) are sensitive to changes in timing and capture motor-to-sensory (i.e., forward model) projections. Observing simultaneous changes in mu-alpha and mu-beta across the time-course of specific events provides a rich window for observing neurophysiological deficits associated with stuttering in both speech and cognitive tasks and can provide a better understanding of the functional relationship between these stuttering symptoms. We review how independent component analysis (ICA) can extract mu rhythms from raw EEG signals in speech production tasks, such that changes in alpha and beta power are mapped to myogenic activity from articulators. We review findings from speech production and auditory discrimination tasks demonstrating that mu-alpha and mu-beta are highly sensitive to capturing sensorimotor and basal ganglia deficits associated with stuttering with high temporal precision. Novel findings from a non-word repetition (working memory) task are also included. They show reduced mu-alpha suppression in a stuttering group compared to a typically fluent group. Finally, we review current limitations and directions for future research.

Bimanual task performance: Adults who do and do not stutter

Research has demonstrated children who stutter score significantly lower than children who do not stutter on the Purdue Pegboard Test. Past data also suggest performance on this task may be associated with stuttering frequency (Choo et al., 2016; Mohammadi et al., 2016). The purpose of this study was to explore whether these performance differences and the relationship to stuttering frequency are present in adults who stutter (AWS). Forty-eight participants (AWS = 24, and AWNS = 24) matched for age, gender, education, and handedness completed all four tasks of the Purdue Pegboard Test. There were no significant between group differences and stuttering frequency did not predict performance. These findings suggest previous differences may only be applicable to subgroups and/or that, with development, the manual tasks unique to the Purdue Pegboard Test may not be sensitive enough to reveal differences.

Phonological working memory in developmental stuttering: Potential insights from the neurobiology of language and cognition

The current review examines how neurobiological models of language and cognition could shed light on the role of phonological working memory (PWM) in developmental stuttering (DS). Toward that aim, we review Baddeley's influential multicomponent model of PWM and evidence for load-dependent differences between children and adults who stutter and typically fluent speakers in nonword repetition and dual-task paradigms. We suggest that, while nonword repetition and dual-task findings implicate processes related to PWM, it is unclear from behavioral studies alone what mechanisms are involved. To address how PWM could be related to speech output in DS, a third section reviews neurobiological models of language proposing that PWM is an emergent property of cyclic sensory and motor buffers in the dorsal stream critical for speech production. We propose that anomalous sensorimotor timing could potentially interrupt both fluent speech in DS and the emergent properties of PWM. To further address the role of attention and executive function in PWM and DS, we also review neurobiological models proposing that prefrontal cortex (PFC) and basal ganglia (BG) function to facilitate working memory under distracting conditions and neuroimaging evidence implicating the PFC and BG in stuttering. Finally, we argue that cognitive-behavioral differences in nonword repetition and dual-tasks are consistent with the involvement of neurocognitive networks related to executive function and sensorimotor integration in PWM. We suggest progress in understanding the relationship between stuttering and PWM may be accomplished using high-temporal resolution electromagnetic experimental approaches.

A systematic literature review of neuroimaging research on developmental stuttering between 1995 and 2016

PURPOSE

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Neural Indices of Semantic Processing in Early Childhood Distinguish Eventual Stuttering Persistence and Recovery

Purpose

Maturation of neural processes for language may lag in some children who stutter (CWS), and event-related potentials (ERPs) distinguish CWS who have recovered from those who have persisted. The current study explores whether ERPs indexing semantic processing may distinguish children who will eventually persist in stuttering (CWS-ePersisted) from those who will recover from stuttering (CWS-eRecovered).

Method

Fifty-six 5-year-old children with normal receptive language listened to naturally spoken sentences in a story context. ERP components elicited for semantic processing (N400, late positive component [LPC]) were compared for CWS-ePersisted, CWS-eRecovered, and children who do not stutter (CWNS).

Results

The N400 elicited by semantic violations had a more focal scalp distribution (left lateralized and less anterior) in the CWS-eRecovered compared with CWS-ePersisted. Although the LPC elicited in CWS-eRecovered and CWNS did not differ, the LPC elicited in the CWS-ePersisted was smaller in amplitude compared with that in CWNS.

Conclusions

ERPs elicited in 5-year-old CWS-eRecovered compared with CWS-ePersisted suggest that future recovery from stuttering may be associated with earlier maturation of semantic processes in the preschool years. Subtle differences in ERP indices offer a window into neural maturation processes for language and may help distinguish the course of stuttering development.

A pilot study into a possible relationship between diet and stuttering

PURPOSE

There are theoretical and empirical reasons to consider a potential role for copper metabolism in the brain in how it could influence stuttering. However, a link between stuttering and dietary intake has never been researched in a systematic way. This pilot study therefore aimed to explore a possible association between ingested amounts of copper and thiamine (vitamin B1) with stuttering frequency using a double blind cross-over longitudinal paradigm.

METHODS

19 adults who stutter between 20 and 51 years old filled out an online survey for 9 consecutive weeks. The survey consisted of self-assessed fluency and mood state scales, as well as food journals. After 4 weeks, the participants consumed either copper or thiamine supplements for 2 weeks, followed by a 1-week washout period, and another period of two weeks taking the other supplement. Formal speech assessments were done pre/post baseline and at the end of each supplement intake. Participants were not informed about the nature of the supplements during the experiment and the investigators were blinded to the order of the supplements.

RESULTS

The results demonstrated that copper and thiamine had no measurable effect on the amount of stuttering (self and formal assessments) but there was a moderate, significant correlation between mood state and fluency.

CONCLUSION

The findings do not support notions of dietary influences of ingested copper or thiamine on stuttering but do provide modest support for a relationship between variations in stuttering and self-perceived anxiety.