The Science, The Treatments, and The Controversies of Stuttering
Tom, is there audio of your talk?
Hi Tom,I agree that we need a theoretical framework regarding stuttering “from genes to social environment”, but I do not believe three things:(1) I do not believe that stuttering results from a breakdown of speech motor control. In my view, the core symptoms of stuttering are too specific for being the result of a simple breakdown. Why don't we slur or cry or confound speech sounds at these moments? You know my theory: I believe that, at the moment of stuttering, the speech motor control network exactly does it's job and interrupts speech flow because it hasn't got the sufficient feedback input. Observable stuttering symptoms occur because we spontaneously and automatically try to continue talking.(2) I do not believe that stuttering is a capacity issue. The weakness of fibers mainly regards the connection between the speech motor and premotor areas on the frontal lobe and the speech comprehension areas on the temporal lobe – simply said, the connection between speaking and hearing one's own speech. It is well known for a long time that hearing one's own speech strongly influences stuttering. In fluency-enhancing conditions like chorus reading, paced speech (with metronome), or shadowing, the speaker not only has to listen to the external acoustic stimuli, but also has to listen to his own speech in order to monitor whether he is synchronously speaking resp. exactly shadowing. Interestingly, we are able to do this without problem (the connection between speech comprehension and speech production obviously works well; auditory feedback can be integrated in speech motor control), and we usually do not stutter under these conditions. Moreover, simultaneous interpretation, which can considered “shadowing in another language”, is also a fluency-enhancing condition. I know two persons who stutter who can simultaneously interpret and who, meanwhile, speak fluently; one of them is a professional interpreter. You will not say that simultaneously interpreting is a speech situation of low demand.Therefore, I think that fibers are able to work well, and not their weakness is the cause of stuttering, but their disuse. The weakness of the fibers is assumed to be indicative of a lower myelination. There is evidence that myelination in the brain is depending on the activity of the fibers . If fibers have been less activated over years, myelination may be lower. In a study , it was demonstrated that fractional anisotropy, which is assumed to be a measure of myelination, was significantly enhanced after a juggling training over six weeks (the examined fiber tract, in this case, connected the cortical areas of visual processing and hand movement).Thus I (3) do not believe that the lower density of some fiber tracts in our brains is caused by genes. I think, it is caused by longstanding lower activation of these fibers. Other factors contributing to a predisposition for stuttering may, however, caused by genes, for example, a bias for inattention or hyperactivity/impulsivity . Wake, H., Lee, P. R., & Fields, R. D. (2011). Control of local protein synthesis and initial events in myelination by action potentials. Science, 333, 1647–1651.  Scholz, J., Klein, M. C., Behrens, T. E. J., & Johansen-Berg, H. (2009). Training induces changes in white matter architecture. Nature Neuroscience, 12, 1370–1371.  Alm, P. A. (2014). Stuttering in relation to anxiety, temperament, and personality: Review and analysis with focus on causality. Journal of Fluency Disorders, 40, 5–21.
Stuttering is a genetic disorder:It runs in families.It persists more in boys compare to girls.This two simple observations shall be enough to prove that it is a genetic disorder.
@ Anonymous.I wouldn’t refer stuttering as to a genetic disorder. There may be many people who have the same mutations as found in some ²stuttering families”, but who do not stutter. And why should the fact that stuttering persists more in boys than in girls be a reason to believe that it is genetically caused? Males and females are different in many regards including speech processing in the brain, and these differences may be genetically caused. But that more girls than boys recover from stuttering may simply be caused by these sexual differences in cerebral speech processing – and additionally perhaps in part by differences between the sexes in behavioral routines in general and in social cognition.
I would challenge your point of view:The fact that some that have the stuttering gene do not stutter is not proving your point. It is very typical that one caries the disorder gene and the disorder is not dominant. What causes the fact that it is active or not ( or how much one can influence this ) is another discussion topic."The question": Is it possible to develop stuttering if one does not carry the stuttering gene? Is this really million dollar question? I think the answer is in front of our eyes.Growing out of stuttering favoring one sex over the other. This is the X-linked recessive inheritance pattern. X-linked disorders affects males more severely than they do females. Another analogy: ( hardware/software) If one illness is running in the families,in all cultures, in all regions: it proves that it is due to the hardware. Social roles of people changed a lot in the last 2000 years, stuttering did not change. The sexual behavior routines changed a lot; stuttering is still the same.
"The question": Is it possible to develop stuttering if one does not carry the stuttering gene? May be, it is impossible. I think that genes contribute to a predisposition for stuttering, and it might be very improbable or even impossible to develop stuttering without having a predisposition.Nevertheless, I would not say that stuttering is a genetic disorder. Speech is not innate, but must be learned. Before they begin to stutter, little children are able to produce sounds, syllables, and even single words without difficulty. Stuttering usually not occurs before children start forming simple sentences of three words. Sentence production is a new challenge for them: syntactical and grammatical rules must be respected. I think that stuttering is a developmental disorder in the process of speech acquisition – for most of the affected children a temporary imbalance between language ability (e.g. vocabulary) and the ability to produce connected speech. Some children are unable to overcome the imbalance; they develop several kinds of secondary behaviors which contributes to the disorder becoming persistent.“The question”, in my view, is: What is the crucial link in the causal chain from genes (or predisposition) to stuttering? Where can the causal chain be interrupted?
It would be a long conversation to discuss everything here. I will just underline a few points:I am a person who stutters. I read a lot about stuttering and follow the research papers. I believe: I will not able to see any break through in my life time. Therefore, I will not able to point you the crucial link in the causal chain from genes to stuttering. However this shall not shadow the fact that stuttering runs in the families and it is inherited. Speech is not innate. Walking is not innate too. If one has a walking related genetic disorder, would you call the disorder as developmental disorder? In addition, speech is much more complex than walking. The secondary behaviors are not the reason that makes the stuttering persistent. However the secondaries magnifies the stuttering. If one would have stutter only once in 300 word if he would not have the secondaries; he stutters once-twice in every word with the all the secondary avoidance behaviors.
Anonymous wrote:“If one has a walking related genetic disorder, would you call the disorder as developmental disorder?” Do you know a genetic disorder which is only walking related?In addition: Stuttering concerns speaking, but not singing. Do you know a genetic disorder which is only walking-, but not dancing-related?I follow the research papers about stuttering too, and I am optimistic. However, I think, it is not only a matter of empirical research. There are a lot of data about stuttering and about people who stutter. What we need is a comprehensive theoretical approach – and a broad theoretical debate.
Parkinson's is a genetic disorder and it effects walking.Parkinson's patients experience difficulty to initiate voluntary movements. ( including walking )After someone helps with the first steps, they are able to continue walking.*If* stuttering is due to timing/pre-processing/synching/etc; it is expected not to stutter if an outside rhythm is provided. When I read the research papers from 1950's and compare them today's papers; the progress is not giving me much hope. Unfortunately, many researchers are unable to differentiate the cause from the consequence of the stuttering. The neuro-physiology based research looks promising, however the progress is very slow.
Anonymous wrote: “Parkinson's is a genetic disorder and it effects walking...”Yes – but not only walking. Parkinson's affects all voluntary movement, and it mostly affects old people. Stuttering, in contrast, affects only speech, and in most cases, its onset seems to be linked to a particular phase in speech development: Children usually begin to stutter around the time they start forming simple sentences. There are many empirical data indicating that early childhood stuttering is related to sentence planning.Therefore, I refer stuttering as to a developmental disorder, though I think that only children are affected who have a genetic predisposition – not for stuttering per se, but for (mostly subtle) abnormalities in attention control, motor control, central auditory processing, or other abilities influencing speech acquisition. There is much empirical evidence of such abnormalities among children and adults who stutter.Anonymous wrote: “*If* stuttering is due to timing/pre-processing/synching/etc; it is expected not to stutter if an outside rhythm is provided.”I think, the provided rhythm is not crucial for that stuttering disappears. When you want to speak synchronously to the rhythm of a metronome, you cannot wait for the beat and, after you heard it and after a reaction time, speak your syllable. In order to keep in step with the rhythm, you must capture the rhythm and produce it in yourself.Similarly, in chorus reading, you cannot wait until you hear the co-readers speak a syllable because you will be too late then. Instead you must capture the tempo and have attention to keep in step. In chorus reading, stuttering disappears, though no uniform rhythm is provided.Finally, also shadowing is a condition in which stuttering usually disappears, but in shadowing, no rhythm is provided, and the “shadower” does not speak simultaneously to the “leader”.What is the similarity, the common feature of speaking synchronously with a metronome, chorus reading and shadowing? During speech, you must listen to an external acoustic signal, you must include this information in your speech planning and -control, and you must also listen to your own speech (to auditory feedback) in order to monitor whether you are in step with the metronome or the co-readers resp. whether you are correctly and completely repeating the “leader's” speech.Thus I think, stuttering disappears because the processing of auditory feedback and its involvement in speech control is improved in all these “fluency-enhancing conditions”.
The genetic disability can surface itself at age 3 as well as at age 73. Hesse said:>>The empirical data that is early childhood stuttering is related to sentence planning.The above statement is not correct.There are many cases where children have started stuttering after he was able to tell short stories, even after he learned writing and reading. The child is able write/type what he wants to say; however he stutters when he tries to say. Hesse said:>> – not for stuttering per se, but for (mostly subtle) abnormalities in attention control, motor control, central auditory processing, or other abilities influencing speech acquisition. There is much empirical evidence of such abnormalities among children and adults who stutter.Above states that PWS also has attention problem/etc. As if one could figured out the stuttering; now defining the correlations ? Let's first define the components of stuttering and then skip to the correlations.There are enough *confused* researches that claim PWS has higher level of anxiety. Good advice: Always look for the evidence. What kind of studies had done, how many people participated, how these people were selected, how long the study took place, what was the reasons for the discontinue, etc. You would be very surprised with what you will find out. Do you know that:There are cases, where Parkinson's patients childhood stuttering re emergenced. There are also cases, where Parkinson's patients, adulthood stuttering got better or got worse after the Parkinson's treatment.In addition:Lets review the rhythm definition. Any external help around the timing is rhythm. ie: In chorus reading at any point one enters the reading, there is an external rhythm ( otherwise chorus reading would be impossible).
Anonymous wrote:“ There are many cases where children have started stuttering after he was able to tell short stories, even after he learned writing and reading.”That's right, of course. What I wanted to say is that stuttering does not occur before children start forming simple sentences. In the Australian “Early Language in Victoria Study”, in 133 of 137 confirmed cases of stuttering, parents reported that they ﬁrst noticed stuttering when the child was stringing 3 or more words together.There are cases of later stuttering onset, even in adulthood, and these cases have probably nothing to do with speech development. Some cases reported in the literature (e.g. by Van Riper) are clearly related to psychologically traumatic experiences.Anonymous wrote:“Let's first define the components of stuttering and then skip to the correlations.”In my view, deficits of attention control / attention allocation during speech are a crucial component of stuttering. That's a theoretical position; I can't prove it, but it allows to explain the occurrence and many features of stuttering. In addition, it's my own experience: I'm a stutterer, but I do not stutter, and I'm sure that I will not stutter as long as I listen to my voice and my words during speech.Anonymous wrote:“There are enough *confused* researches that claim PWS has higher level of anxiety.”Recently, a special issue of the Journal of Fluency Disorders on this subject was published. There is strong evidence that children who begin to stutter, as a group, have no higher level of shyness or anxiety. But there is much evidence of abnormalities in attention control, motor control, and central auditory processing in PWS. Anonymous wrote:“There are cases, where Parkinson's patients childhood stuttering re emergenced. There are also cases, where Parkinson's patients, adulthood stuttering got better or got worse after the Parkinson's treatment.”Parkinson's is a relatively simple disorder: basal ganglia function is impaired. Stuttering, in contrast, seem to be a very complicated disorder. Basal ganglia are involved, but also SMA, cerebellum, cingular cortex, Broca's and Wernicke's area and their homologues on the other hemisphere, and other parts of the brain. The neural “network of stuttering” seem to be, at least, as large as the network controlling fluent speech.Because basal ganglia are involved in stuttering, it is not surprising that Parkinson's and the Parkinson's treatment influence stuttering.Last year, in Germany, a woman who stuttered underwent surgery because of a brain tumor close to the cerebellum. After that, her cerebellum was damaged (I don't know whether by the tumor or due to the operation), and she has been hampered since then and uses a rollator-walker – but her stuttering was completely disappeared when she woke up from anesthesia.Finally, concerning rhythm and stuttering:I'm a stutterer, and I'm a musician, and I'm sure that I can generate correct rhythm in myself without external pacing. In addition, already as a child, I could recite long poems from memory in front of a crowd without any stuttering. Thus I think, I am able to produce a correct speech rhythm, although I'm a stutterer.
Hi Tom, I have followed you quite some time now. I am currently a doctoral student who stutters, living in Seattle, WA. I am a published author, writing research articles to scholarly journals mostly. My next research article is on stuttering, past and present theologies and schools of thought, and treatment methods, past and present. I don't have an actual abstract or framework yet for this research, just the idea for the moment. However, I am currently conducting a literature review, and I would like to add you as a reference/source. Your lecture material from the Antwerp Stuttering Conference seems intriguing, and I would definitely like to mention it in my article. Is it currently published? To be able to use it as a primary source, I will need to obtain it from the publisher. My email is firstname.lastname@example.org, please contact me. Thanks,
Post a Comment