Fluency changes in persons who stutter following a double blind trial of clomipramine and desipramine

The Pharmacologic Treatment of Stuttering and Its Neuropharmacologic Basis

Stuttering is a DSM V psychiatric condition for which there are no FDA-approved medications for treatment. A growing body of evidence suggests that dopamine antagonist medications are effective in reducing the severity of stuttering symptoms. Stuttering shares many similarities to Tourette's Syndrome in that both begin in childhood, follow a similar male to female ratio of 4:1, respond to dopamine antagonists, and symptomatically worsen with dopamine agonists. In recent years, advances in the neurophysiology of stuttering have helped further guide pharmacological treatment. A newer medication with a novel mechanism of action, selective D1 antagonism, is currently being investigated in FDA trials for the treatment of stuttering. D1 antagonists possess different side-effect profiles than D2 antagonist medications and may provide a unique option for those who stutter. In addition, VMAT-2 inhibitors alter dopamine transmission in a unique mechanism of action that offers a promising treatment avenue in stuttering. This review seeks to highlight the different treatment options to help guide the practicing clinician in the treatment of stuttering.

Stuttering inhibition via altered auditory feedback during scripted telephone conversations

BACKGROUND

Overt stuttering is inhibited by approximately 80% when people who stutter read aloud as they hear an altered form of their speech feedback to them. However, levels of stuttering inhibition vary from 60% to 100% depending on speaking situation and signal presentation. For example, binaural presentations of delayed auditory feedback (DAF) and frequency-altered feedback (FAF) have been shown to reduce stuttering by approximately 57% during scripted telephone conversations.

AIMS

To examine stuttering frequency under monaural auditory feedback with one combination of DAF with FAF (COMBO-2) and two combinations of DAF with FAF (COMBO-4) during scripted telephone conversations.

METHODS & PROCEDURES

Nine adult participants who stutter called 15 local businesses during scripted telephone conversations; each condition consisted of five randomized telephone calls. Conditions consisted of (1) baseline (i.e. non-altered feedback), (2) COMBO-2 (i.e. 50-ms delay with a half octave spectral shift up), and (3) COMBO-4 (i.e. 200-ms delay and a half octave spectral shift down in addition to the COMBO-2). Participants wore a supra-aural headset with a dynamic condenser microphone while holding a receiver to their contralateral ear when making telephone calls.

OUTCOMES & RESULTS

Stuttering was significantly reduced during both altered auditory feedback (AAF) conditions by approximately 65%. Furthermore, a greater reduction in stuttering was revealed during the COMBO with four effects (74%) as compared with the COMBO with two effects (63%).

CONCLUSIONS & IMPLICATIONS

Results from the current study support prior research reporting decreased stuttering under AAF during scripted telephone conversations. Findings that stuttering was significantly reduced to a greater extent under the COMBO with four effects condition suggest that second signals reduce stuttering along a continuum. Additionally, findings support prior research results of decreased stuttering frequency under AAF during hierarchically difficult speaking situations. Clinical application of these findings may be that people who stutter can use specific software or smartphone applications that produce second speech signals to inhibit stuttering frequency effectively during telephone conversations.

The influence of stuttering severity on acoustic startle responses

PURPOSE

This study examined the potential impact of stuttering severity, as measured by the Perceptions of Stuttering Inventory (Woolf, 1967) on acoustic startle responses.

METHOD

Three groups, consisting of 10 nonstuttering adults, 9 mild stutterering adults, and 11 moderate/severe stutterering adults, were presented with identical 95-dB acoustic stimuli to elicit acoustic startle responses across 10 trials. Electromyographic recordings of orbicularis occuli activity were used to measure individual acoustic startle responses.

RESULTS

Participant groups failed to exhibit statistically significant differences in initial acoustic startle response amplitude, mean acoustic startle response amplitude, habituation rates, and onset latency. Acoustic startle responses were characterized by high levels of variability across all participant groups but with highest levels of variability in the moderate/severe stuttering group.

CONCLUSIONS

The current results suggest that stuttering severity, as measured in this study, does not effectively predict acoustic startle responses in groups of adults who stutter.

Signs of developmental stuttering up to age eight and at 12 plus

Clinicians who are familiar with the general DSM-IV-TR scheme may want to know how to identify whether a child does, or (equally importantly) does not, stutter and what differences there are in the presenting signs for children of different ages. This article reviews and discusses topics in the research literature that have a bearing on these questions. The review compared language, social-environmental and host factors of children who stutter across two age groups (up to age eight and 12 plus). Dysfluency types mainly involved repetition of one or more whole function words up to age eight whereas at age 12 plus, dysfluency on parts of content words often occurred. Twin studies showed that environmental and host factors were split roughly 30/70 for both ages. Though the disorder is genetically transmitted, the mode of transmission is not known at present. At the earlier age, there were few clearcut socio-environmental influences. There were, however, some suggestions of sensory (high incidence of otitis media with effusion) and motor differences (high proportion of left-handed individuals in the stuttering group relative to norms) compared to control speakers. At age 12 plus, socio-environmental influences (like state anxiety) occurred in the children who persist, but were not evident in the children who recover from the disorder. Brain scans at the older age show some replicable abnormality in the areas connecting motor and sensory areas in speakers who stutter. The topics considered in the discussion return to the question of how to identify whether a child does or does not stutter. The review identifies extra details that might be considered to improve the classification of stuttering (e.g. sensory and motor assessments). Also, some age-dependent factors and processes are identified (such as change in dysfluency type with age). Knowing the distinguishing features of the disorder allows it to be contrasted with other disorders which show superficially similar features. Two or more disorders can co-occur for two reasons: comorbidity, where the child has two identifiable disorders (e.g. a child with Down Syndrome whose speech has been properly assessed and classed as stuttering). Ambiguous classifications, where an individual suffering from one disorder meets the criteria for one or more other disorders. One way DSM-IV-TR deals with the latter is by giving certain classification axes priority over others. The grounds for such superordinacy seem circular as the main role for allowing this appears to be to avoid such ambiguities.

Stuttering treatment research 1970-2005: II. Systematic review incorporating trial quality assessment of pharmacological approaches

PURPOSE

To complete a systematic review, incorporating trial quality assessment, of published research about pharmacological treatments for stuttering. Goals included the identification of treatment recommendations and research needs based on the available high-quality evidence.

METHOD

Multiple readers reviewed 31 articles published between 1970 and 2005, using a written data extraction instrument developed as a synthesis of existing standards and recommendations. Articles were then assessed using 5 methodological criteria and 4 outcomes criteria, also developed from previously published recommendations.

RESULTS

None of the 31 articles met more than 3 of the 5 methodological criteria (M = 1.74). Four articles provided data to support a claim of short-term improvement in social, emotional, or cognitive variables. One article provided data to show that stuttering frequency was reduced to less than 5%, and 4 additional articles provided data to show that stuttering may have been reduced by at least half. Among the articles that met the trial quality inclusion criterion for the second stage of this review, none provided uncomplicated positive reports.

CONCLUSIONS

None of the pharmacological agents tested for stuttering have been shown in methodologically sound reports to improve stuttering frequency to below 5%, to reduce stuttering by at least half, or to improve relevant social, emotional, or cognitive variables. These findings raise questions about the logic supporting the continued use of current pharmacological agents for stuttering.

Treatment with medications affecting dopaminergic and serotonergic mechanisms: effects on fluency and anxiety in persons who stutter

Medications with dopamine antagonist properties, such as haloperidol, and those with serotonin reuptake inhibitor properties, such as clomipramine, have been shown to improve fluency. To examine the degree to which each of these two pharmacological mechanisms might independently affect fluency, a selective serotonin reuptake inhibitor, paroxetine, and a selective dopamine (D-2) antagonist, pimozide, were evaluated. Both types of medications also affect mood and anxiety, factors that could influence fluency levels. Therefore, we also evaluated the medications' effects on generalized and speech-related anxiety and the relationships between changes in anxiety and changes in fluency in 11 subjects with a history of developmental stuttering. The randomized, double blind, placebo-controlled crossover study that was designed had to be terminated prior to completion due to severe side effects following withdrawal from paroxetine. Even with a reduced sample size (n=6), significant improvement in percent fluent speaking time (p=0.02) was found using a telephone task between baseline and pimozide (n=6), with average duration of dysfluencies significantly shorter (p=0.04) but no significant difference in the estimated number of dysfluencies per minute. This significant improvement was associated with non-significant increases in generalized anxiety, but non-significant decreases in speech-related anxiety. No significant differences were found in fluency between baseline and paroxetine (n=5). These preliminary results suggest that fluency improvement is more likely to be mediated by dopaminergic rather than serotonergic mechanisms. Due to its side effects, however, pimozide may be considered a risk for treatment of stuttering.

EDUCATIONAL OBJECTIVES

As a result of reading this paper the reader will describe and explain: (1) how medications may affect fluency and the rationale for selecting medications for treatment trials; (2) the interrelationship between fluency and anxiety; and (3) factors important in developing clinical trials using medications.

Developmental stuttering: manifestations, treatment and dental implications

Developmental stuttering (DS) is a disturbance in the normal fluency and time patterning of speech resulting in involuntary repetition, prolongation, or cessation of sound. The scientific literature has implicated the lack of strong left cerebral dominance and abnormal levels of the neurotransmitters dopamine and possibly serotonin in regions of the brain controlling the coordination of language processing and motor activity of the vocal apparatus as possible causative factors in DS. Speech-language therapy is the most common form of treatment, but antipsychotic, antidepressant, and anxiolytic medications may be prescribed for some children and adults with persistent stuttering. These medications may cause xerostomia and adversely interact with certain antibiotics, analgesics, and sedatives routinely used in dentistry. Some people who stutter have sensory-motor and tactile-proprioceptive deficits that impede accurate and timely movements of the mandible, lips, and tongue, necessitating protection of the airway by staff during dental care.

Reboxetine promotes social bonding in healthy volunteers

Reboxetine is a novel antidepressant with a selective action on noradrenaline. In addition to its efficacy in depression, it has been found to improve social adaptation. The objective of this study was to assess the specific social behavioural effects of reboxetine which might be associated with social adaptation. Ten pairs of healthy volunteers took part in a randomized double-blind, crossover study of 2 weeks treatment with reboxetine (4 mg b.d.) and placebo with a 2-week washout period. In each pair, one person (subject) took the tablets and the other (flatmate) received no treatment. On the last day of each treatment period, the subjects socially interacted with a stranger (a confederate behaving as a responsive person) in a stranger-dyadic social interaction paradigm. After the interaction, subjects played the Mixed-Motive game, which measures cooperative behaviour and communication, with the confederate. Subjects read a short story before and after the social interaction. The flatmates evaluated the social behaviour of the subjects before and at the end of the two treatment periods. On reboxetine, the subjects were rated to be significantly more agreeable and cooperative (passive participant) and less submissive by their flatmates. They showed significantly less eye contact with the confederate in the social interaction paradigm and gave significantly fewer helplessness messages during the game. They spoke faster on the reading task after the social interaction. This study provides evidence that reboxetine increases cooperative social behaviour and increases social drive, which might be important for social adaptation.

Assessing Efficacy of Stuttering Treatments

Efficacy has been defined as the extent to which a specific intervention, procedure, regimen or service produces a beneficial result under ideally controlled conditions when administered or monitored by experts. Studies on efficacy can be divided into those that study methods of conducting treatment (treatment process research) and those that are concerned with the effects of treatments (treatment outcome research). This reviews both of these areas, emphasizes the former and considers such key determinants of efficacy as measurement, treatment integrity and design issues. A set of criteria is given and a meta-analysis of whether studies published since 1993 meet these criteria is reported (incorporating some pragmatic and ethical considerations). The review ends by considering future directions that warrant further investigation.

Drug-induced stuttering: a review of the literature

The author critically reviews the world literature on drug-induced stuttering. The literature on stuttering as a side effect of pharmacologic agents was identified by means of a computer-assisted search. A diversity of drugs has been reported to induce stuttering in susceptible persons, including some agents that improve the speech of some known stutterers. In all instances, normal speech returned shortly after the offending drug was discontinued. Multiple, interacting neurotransmitter systems seem to be involved. Drug-induced imbalances in these systems may account for the speech disturbances.