Monday, May 30, 2005

Why do only the young go to therapy?

Today, I am trying something new, namely to publish a picture on my blog. It is a bit of tedious process and the quality is not great. The graph that I want to show you is the age profile of the people who attended the Kassel Stuttering Therapy (KST). The sample contains more than 300 patients. To get a better resolution, you can click on the picture.

AgeProfileKST Posted by Hello

The picture clearly shows that the majority of the patients are young, under 30. Now, it is interesting to speculate why only young people go to the therapy. Here are some reasons why they don't feel the need to go to therapy:

1. They don't need it, because the severity of their stuttering has decreased with age.

2. They don't need it, because they don't or suffer less despite them still having the same severity as always. For example, they got used to jokes or the inability/difficulty to speak out on an issue, which makes it less hurting.

3. They don't feel the pressure from society anymore, because they have settled down with a permanent job, a partner, children, etc.

4. They are fed up going to therapies, because they have done several ones without any apparent long-term success. So why try another therapy?

5. The therapy uses computer, and they are unsure that they can use them. Also, they need a computer to practise at home, and might not have a computer.

My opinion is: I don't believe in 1). 2) and 3) are relevant, but I still think that if I give them the choice between getting 100'000 dollars or having no speech impediment, they will choose no speech impediment. And the real reason is in my view 4). I am not sure about 5), but I dont think it is very important.

This graph really shows that older people with PDS have really given up on therapies, and that therapists are unable to get older people to take part, which in my view is a devastating verdict on therapy. And I suspect this is relevant for all types of therapy?

Friday, May 27, 2005

Another twist to the sex story

Roger Ingham has sent me an interesting article that adds another twist to the sex ratio story. A study by Drayna, Kilshaw and Kelly claims to have found a difference in the sex ratio between patients with a family history and patients without a family history. They say: "One possibility suggested by these data is that roughly half of all cases of stuttering is due to inherited causes, while the other half are due to poorly understood but nongenetic factors. This hypothesis is consistent with the view that persistent stuttering of nongenetic origin is largely a male disorder and may be related to a greater ability of females to overcome childhood stuttering (Ambrose et al. 1997). Genetic stuttering, in contrast, affects males and females more equally, which has important implications for genetic studies of this disorder that exclude young children. In particular, genetic-linkage studies will be much less obscured by the distortion in sex ratio, since this distortion is largely a phenomenon of sporadic stuttering." (Source: Am. J. Hum. Genet. 65:1473–1475, 1999)

This research is quite intriguing, and opens up a pandora box of questions. Here is what I fished out of the box: Does this mean that there are subtypes of PDS (e.g. genetic or non-genetic) or is it all the same just caused by different factors (e.g. I can break your arm with a metal bar or you fall)? Is there a stuttering gene? Or many genes in combination? What is recovery rates of genetic vs non-genetic? Is their research correct? How accurate are family histories? Why does the sex ratio differ between genetic and non-genetic?

For those who are not geneticists. Nor am I one! Here is how I visualise genes. I see the brain/body as a big city with factories, highways, buildings, people, etc. Many different objects are interacting to create an emergent structure. Genes are the blueprints of the objects that make up the city. A gene tells an object how to manufacture another object, e.g. how to manufacture cars, a building, a tool that lets two objects interact. Lets take PDS. Naively, I view it as a city WITHOUT an underground/metro in the speech and language areas. As a result, information travels slower and might get stuck in traffic jams, with secondary consequences on life in that area. Now, there are two ways how this could have happened. First, a gene or many genes are missing or not working, i.e. the blueprints for crucial objects like underground trains are missing. But sometimes even if a gene is missing, you can still build the underground but it might be harder. For example, if there are no genes/blue prints for escalators, less people can travel at peak hours. Or a gene might be missing, but its functionality can be easily replaced by another one. Second, all genes are there but something went wrong during the construction. Maybe there was an earthquake, an economic recession, a political intrigue, etc. And thus, they never build an underground system. Finally, it might well be that both effects interact...

OK this is just a picture but I think it pretty much gets the essence, no?

Tuesday, May 24, 2005

Does nature or nurture discriminate against men?

In my last posts, I have spoken about the sex ratio in PDS. About 80% are men and 66% 3-year old boys who stutter. Why??? What is the reason that the figure is not 50%-50%? Is it nature or nurture that discriminates against men/boys??

The nature/nurture discussion has always been a very heated one, especially as scientific evidence regularly clashes with cherished political positions and public attitudes (from the left and right political spectrum!) e.g. on gender/race differences, or causes of criminality/murder/rape. When reading some of the PDS literature, I have the feeling that often science comes second to sticking to cherished views. Anyone interested in these debates, I recommend reading Steven Pinker's book "The Blank Slate". But also his earlier books "How the Mind Works", and "The Language Instinct". His books are just absolutely outstanding in quality and clarity. In "How The Mind Works", he gives an update on what science has found out about human nature, and weaves it into a cohesive picture of human nature. I have found it a very useful mental tool to get a grip on the nature of PDS on the various level and put it into a cohesive picture.

On the sex ratio, here are some arguments to consider:

1) By asking "Is it nature or nurture?" I have committed on purpose a logical fallacy for the sake of attention seeking. Rarely is a human phenomenon only nature or nurture. Some phenomena are clearly nurture like which language you speak or which religion you practice. Others are nature like hereditary disorders. But mostly it is a mixture of both, of the genes and the environment.

2) The gap between the genders is increasing with time from about 2:1 for 3 year olds to about 4:1 for adults. But quickly stabilize lets say after age 7.

3) This sex ratio discrepancy is across virtually all developmental disorders like autism, learning difficulties, speech and language disorder in general, and more. As Patricia Sims has pointed out in her recent comment . I don't know of any article that discusses this. But ultimately, a theory must come up with an explanation of why these ratios exist and why they are different across disorders.

Recent research has shown further difference between women and men on the genetic level in addition to sex hormone differences: Apart from men having a Y chromosome, women (who have two X chromosomes with one being active) are able to activate the inactive one to some degree. The authors speculate that "these differences should be recognized as potential factors for explaining normal differences between the sexes but also gender differences in how certain diseases are manifested, progress and respond to treatment." In general, the female brain is also more plastic (e.g. men recover less well after strokes) and greater interaction between left/right brain (have a thicker corpus callosum, evidence from brain imaging during mental tasks), and also develops faster (eg girls start speaking earlier). All this would fit well the evolutionary arguments that it is far more important for the survival of a tribe that nature ensures stable and quick development of fertile women than of men as women have limited reproductivity and men no limits.

4) The difference between genders is not just a few percent, but four times are as many men. This is a very clear difference.

5) A recent brain imaging studies by Ingham et al. has shown some gender differences in brain activation.

My view on the origin is very similar to the one given by Buechler and Sommer: "Given that boys are about four times less likely to recover from stuttering than girls, it is tempting to speculate that all stutterers have a slight abnormality, but only those that can use the right hemisphere for language can develop into fluent speakers. Language lateralization is less pronounced in women (McGlone 1980) and might therefore be related to the fact that women show an overall lower incidence in PDS." Girls probably have a higher recovery rate or may have better compensation techniques. So I would say that nature has done the discrimination to a very large degree. The environment might only be relevant in DECIDING WHO of the disfluent kids might recover and who doesnt. In a sense Nature says to Environment: Take care of these kids, girls will recover more often. I dont care who you choose. Environment it is up to you to decide but keep the sex ratio.


Myth propagation

On Sunday, I surfed the net to find out what the sex ratio is resp. what others say it is. I came across a lot of inaccurate data. It is just shocking how the facts are wrong or people have just cut and paste "facts" from other websites without checking them for accuracy. You might find me pedantic, but there is nothing more harmful to proper thinking that working with facts that are not obviously wrong but also not quite right. I often found that good researchers are not necessarily more intelligent, but their facts undergo a security check before entering their thinking! Little inaccuracies are like little holes in ship, and will ultimately and silently sink it. No wonder understanding PDS can be confusing. Here are some examples.

Source: "Of two- and three-year-olds, equal numbers of boys and girls stutter. The sex ratio becomes 3:1 by the first grade and 5:1 by the fifth grade, the same ratio as adults. 80% of adult stutterers are men."

This is interesting since the text says that 5:1 in adults and 80% of adult stutterers are men. But 80%:20% leads to a ratio of 4:1 and not 5:1!!!

Source: "80% of adult stutterers are men. Of two- and three-year-olds, equal numbers of boys and girls stutter. The sex ratio becomes 3:1 by the first grade and 5:1 by the fifth grade, the same ratio as adults."

Note the similarity of the texts. One is clearly the copy of the other one. And the worst thing is that the mistake of 5:1 instead of 4:1 is still in there. So the person who copied it did not really read the text in depth.

Source: "At two and three years of age, equal numbers of boys and girls stutter. The sex ratio becomes three males for every female by the age of five and four to one by the age of 10, the same ratio as adults. Of adult stutterers, 80% are men."

Hey, this looks again very much like a copy due to the same sentence construction. BUT this time it's four to one and not 5:1!!! But now I have the suspicion that the person, who copied it, spotted the mistake, BUT did not bother to tell the other people of their mistake!! In my eyes, this is an even greater sin. I hate nothing more than people not telling me of my mistakes...

But unfortunately there is still a mistake in there, namely that they say that equal numbers of boys and girls stutter. And it is written in all three texts!! The sex ratio is roughly 2:1 or 3:1 far from 1:1. See the longitudinal studies by Ambrose, Cox and Yairi and by Rommel et al. I actually have Rommel's paper in front of me. He gave it to me at the IFA congress 2003 in Montreal. We did some sightseeing together and went to a Radiohead concert, which was cool. Since then, he has wisely given up on research, and earns far more money as a psychologist in private practise!

Next time I will talk about the possible origins of the sex ratio difference. If you want more myths, look here. It is just amazing how creative our mind can be.

Sunday, May 22, 2005

PDS discriminates against men!

One of the few things that everyone can agree on for PDS is the sex ratio. The general consensus (dangerous term to use!) is that many more men than women have PDS. Figures from reliable sources (dangerous term to use!) are between 3:1 to 5:1.

I also looked at the sex ratio during my statistical analysis of the Kassel Stuttering Therapy (KST) sample. It is always a good idea to make up your mind on your expectations BEFORE looking at the actual data. The human mind is such a skillfull master in twisting your interpretation of the data to make it fit its preceived worldview. So what should I expect? Well, the KST sample is a subset of the PDS population (i.e. all members in the KST sample are members of the PDS population). So it is interesting to see whether the sample is a representative snapshot, i.e. similar to the PDS population, or whether the KST fluency shaping therapy only attracts a certain type e.g. attracts more men than women.

The KST sample could be biased, because 1) women are more likely to seek therapy than men, or the opposite. 2) women are turned off by fluency shaping therapies as they mostly involve speech exercises, or the use of a computer, but have limited focus on pyschological/social issues. OR, the two effects could also balance out, i.e. the women might be more eager to attend therapy in general but less likely to go to fluency shaping therapies.

Intuitively (dangerous term to use!), the two effects are probably not very significant. For effect 1), women might be more likely to seek help in general, but I think, due to the clear and apparent handicap of stuttering, men will also seek help or might be pushed by others to do so. For effect 2), most people with PDS are rarely well-informed on different choices or able to make different choices of equal costs to them. Often, they/we are "desperate" for help and would to do pretty much everything.

The KST sample contains 385 patients. And the split is 305 men and 78 women. Two of them had no sex (entry in the database). This gives a ratio of 1:3.9, so roughly one man to four women. Thus this is pretty much in line with the general consensus. Unfortunately, it does not allow me to exclude effect 1) or 2). I could exclude effect 2) if I could compare the sex ratio to other therapy forms. I could exclude effect 1) if I had very reliable data on sex ratio, something like large scale studies with a number like 1:3.34 plus error estimates. Unfortunately, I dont have free access to academic literature to dig out numbers. And secondly, I guess that the numbers are not very reliable anyway, so it's not worth the effort. (Is this an example of my mind twisting my thinking to accommodate my laziness?? :-) So for the time being, I will conclude that there is no clear difference in gender between people attending the KST fluency shaping therapy and the general population.

A side issue is whether the sex ratio is constant across culture. To my knowledge, there is no difference at all. But, I found this citation: "In Canada, the United States, most European countries, and Japan, people who stutter make up about 1% of the population. In the West Indies, 3-4% of the population stutters. African countries seem to have the highest prevalence of stuttering with about 8-9% of the population stuttering." ( Source ) I refuse to believe this. My guess is that the difference comes from different definitions, and bad statistics. Unless it is a genetic effect. You are welcome to disprove me. Also, if it were true, then you would expect differences in sex ratio, as gender effects differ across different cultures, or not?

I did even more Internet searches on sex ratio, which has inspired my next post's title "How myths are propagated".

Saturday, May 21, 2005

A big big sample

I began to look through my results of the statistical study of the Kassel Stuttering Therapy (KST). I need to submit the article at the beginning of June for the Oxford Dysfluency Conference . The paradoxical thing about conference submissions is that the researcher FIRST has to submit an abstract, which most often leads to them writing the abstract (i.e. the summary) before writing the article!

The KST sample is very good. All patients fill out questionnaires just before the therapy, just after the intensive 3-week phase, one year later, and three years later. In addition they have to do speech samples in four different speaking situations, reading, phone call, speaking to therapist, and interviewing a by-passer on the public's attitude on stuttering (!).

There have been 383 patients recorded over 7 years, I think, as of June 2003. This is a very large sample, and it's complete as all patients are in it. This dedication in time and effort (--> MONEY) on the part of the KST (led by Alex von Gudenberg , by the way the picture is an older and thinner one.. :-) is mostly to provide the German health insurers with evidence that the therapy is indeed beneficial, but also a genuine interest in going beyond the practice-based therapy.

In my article, I will only focus on the profile of the KST patients. Who are they? How much do they stutter? In which speaking situations do they stutter most? I have also looked at the outcome of the therapy, but this will be presented by Prof Euler at ODC.

Before discussing some results, I want to say a few words on therapy research. I have seen many studies, also at ODC 2001, on therapy outcome, and I think many are of little value. There are often serious issues, in my view: 1) the sample is often much too small (less than 30) 2) the sample is biased in some way e.g. only patients who have finished the therapy phase are included, 3) no long-term data, and 4) they look at statistical significance even though the important measure to look out for is effect size. Having said this, there are also researchers who do it well. But generally, they have a science background, and not a therapy background. Dont get me wrong I think therapists have an important contribution to make, but I, as a hard-core quantitative person, would prefer to see more first/second person experiences like case studies and discussion of them. Quantitative analysis is only useful for big and unbiased samples, and useless to get across complex issues/situations.

In my next post, I will talk about the sex ratio in the KST sample, and discuss why it's not balanced in PDS.

Wednesday, May 18, 2005

Interesting Comments by Prof Ingham

Prof Ingham (UC at Santa Barbara) has posted a note of support and interesting comments on some of my statements from the blog. Thanks! Here are two of them:

"You suggested that perhaps “one way of dealing with effect/cause is to knock out a region with TMS. But I am not sure whether this can be done precisely enough.” In reply I pointed out that is the main focus of our work in San Antonio at the moment. We have invested a huge amount of time and money into refining the TMS aiming system. And by the end of the summer I think we'll be in good shape to start exploring some of the options. We are currently running some preliminary experiments on ourselves. So far, so good."

This is indeed an interesting development. Let's wait and see. But the breaking news is going to be "on this channel"! :-)

"You indicated that "there has been no constructive approach to developing better therapies." I would have to disagree. There has been a very constructive approach adopted by some of us in this domain. The work behind the development of therapy for children and our own work on refining the parameters of prolonged speech and then converting them to therapy has certainly not been a hit and miss affair."

Good. I was not aware of such approaches. My intention was to point out that improvement of therapies are mostly due to analysing old therapies rather than built on the understanding of the disorder. Roger has sent me an article on this topic. I will discuss it on this blog after I finished my article for ODC.



Fluency shaping therapies involve a lot of speech practise for example gentle onset or connecting-the-syllables. There are several softwares available to aid the patient to practise efficiently. I know of three: Speak Gentle , Dr Fluency , Flunatic .

In my view, the advantages of CAF is: 1) the patient receives an accurate freedback of his/her performance 2) can easily see how much he has practised and set clear daily targets

The "disadvantages" are: 1) it is not a real speaking situation (so it can only be part of the therapy, transfer is therefore crucial) 2) some might find it boring to sit in front a computer for a long time.

Which software is the best? Hard to say as I have only practised with Speak Gentle, and I think it is a very good and stable software and the design is very efficient/elegant. I dont know much about Dr Fluency, just that it is the best known and most distributed one. Here is a case study. Looking at their website, they are certainly aggressively pushing their product commercially and know how to. It is my understanding that they have even pursued their interest in court. Finally, Flunatics is a newly developed software for the Kassel Stuttering Therapy that replaces SpeakGentle.

And here is my disclaimer, the past paragraph does only represent my understanding, and is not necessarily a reflection of the reality. For more and reliable information, please contact the companies themselves!!!!

Even if it does not make you fluent. It's a great way to practise your singing as you can see your voice curve. I has certainly improved my volume and gentle onset. Next time you see me, ask me to show you! But unfortunately it does not train you getting the right pitch, so I am still a long way from becoming a rock star! :-)


Sunday, May 15, 2005

I'll pay Dave Rowley a drink at ODC!

Thx Dave for writing the first comment on my blog!!! Despite me misspelling his name, linking him to his official rather than personal website, and the Comment section at being a bit cumbersome. I will be forever grateful! ;-)

The way that the blog site handles comments is indeed a bit cumbersome. You can get to the COMMENTS page by clicking on the x Comments at the end of my posts. Each post has a comments page to it. On this page, you can read the comments or write one yourself, or reply to another comments.

I'll see if I can make the layout more intuitive by using another template or edit the code myself. I just need to take some time to understand the HTML add-ons that they use.

Concerning Dave's question "Do you think there are any brain changes before and after!?". My answer is: It depends on what you mean by "brain changes". I can think of three meanings: 1) an un-detectable change in the brain (like new memories, learned behaviour) 2) a detectable functional change in the brain (like a region is now under or overactivated in comparison with the activation for the same task before), or 3) a detectable structural change in the brain (like the auditory processing region in a blind person becomes larger).

It is clear that the/any therapy leads to type-1 changes, as most patients are noticeably more fluent just after intensive fluency shaping therapy , for example. There must be something different to their brains. On the other hand, relapse is the norm, and thus this change is not very long-lasting.

Concerning type-2, I know of two brain imaging studies by Neumann et al. and by de Nil et al. that see that the typically PDS right-brain activation disappears about treatment (therapy), and more. So, the answer is yes there are detectable differences in the brain, assuming their results are OK. But I think the point might be that the activation has changed because the brain calls up a different software, but the old one leading to stuttering is still there waiting...

Concerning type-3, there is not evidence. I guess this is possible, but only over the long time. To which degree is not clear to me?

More research is needed.

Interesting questions from the top of my head: Does this change also happen for post-block modification or drugs? What is the role of the PDS severity? How much can the brain really change? Can you do brain scans and predict whether a person is more likely to get better? Can you distinguish in brain scans between neurological cause and the habits/learned behaviour? I.e. two people might stutter equally strong, but one has 10% neurological 90% habits and the other 90% neurological and 10% habits? Making therapy more individual might decrease relapse?

In my next post, I will talk about computers/software in therapy.


Friday, May 13, 2005

The Kassel Stuttering Therapy

Last March, I was in Kassel and did an independent study of the KST data with respect to outcome but also on the profile of the KST patients. The outcome measure project is directed by Prof. Harald Euler of the University of Kassel. I stayed at his home, and I must say that he is very good cook! :-) At ODC 2005, I will not talk about the outcome study which Harald will present, but on the profile of the patients themselves.

Here is a description of the Kassel Stuttering Therapy (KST):

"The Kassel Stuttering Therapy is a fluency shaping approach which consists of a 3-week in-patient intensive treatment and a 1-year relapse prevention programme. Treatment is composed of speech modification (mainly prolongation), intensification with desensitization, and application (transfer). A computer programme guides through lessons of increasing demand. The client speaks into a microphone, watches the voice curve and evaluates the utterance, followed by an evaluation by the computer which considers gentle onset, syllable prolongation, and smooth intonation. The visual feedback enables the clients to correct the utterance immediately. After the treatment phase of extreme prolongation to 2 sec per syllable the speech rate is gradually increased to one-half second per syllable. The intensive solitary speech training is embedded in non-avoidance treatment principles, common therapeutic practices and training in relaxation, proper breathing, and speech proprioception, mostly in group situations. During the application phase, after a further increase in speech rate, the newly acquired speech pattern is practiced in a variety of speech situations with increasing communicative demands. Relapse prevention includes daily home practice at the computer in decreasing amounts of time until the end of the first year, and two 3-day refresher courses. The daily home practice sessions are recorded on disk, mailed in, and inspected by the therapist." (Author: Prof. Harald Euler)

The current findings suggest that the therapy is relatively successful in DECREASING stuttering severity in patients over the long-term. Of course, measuring sucess is a bit of a pandora box. I'll keep it closed for the time being. OK?

Actually, I could be a bit cheeky and note that the secret of the long-term success is not included in the description above. Namely, the patients only get the therapy paid by their health service IF AND ONLY IF they can show that they practise x amount with the software over a period of one year!!!!!! So there is a real incentive to practise, which is good. But I guess such tactics can only exist in Germany... but I support this practise!

But this had led to some strange avoidance pattern. I was told that one patient recruited his 90 year-old grand-mum to do the daily practise for him!!!! :-D

Tomorrow, I will talk about the software.


Wednesday, May 11, 2005

With trial and error to fluency

I am currently working on a paper for ODC 2005, and it's about analysing patient and outcome data of a fluency shaping therapy, the Kassel Stuttering Therapy (KST)

Historically, there has been no constructive approach to developing better therapies. No-one is really to blame, as no-one really knows what causes people to stutter. The constructive way is: 1) understand PDS completely 2) devise new treatment or improve therapies based on 1)

But unfortunatly, we are stuck at 1). But hopefully new understanding of PDS will help.

Over the centuries, everyone had his own theory, and there were many innovative therapies: cutting a part of the tongue out, putting pebbles in your mouth, wearing a special braces, solving childhood traumas, swinging your right hand, and probably the most radical and effective one: not speaking for 3 weeks!!

Why did they never do these things for a broken bone?? Well, because everyone understands what has happened, a fatal blow to human creativity.

The therapy approaches we have now have mostly emerged from trial and error. Two stand out: fluency shaping and post-block modification. Fluency shaping is about modifying your speech like gentle onset or slower. Post-block modification is about learning to deal with blocks when they occur, using techniques like mental focus, repeating a stuttered word until fluent and relaxed, and dissensitisation. There is of course more to it, but just so you get the idea.

I could go on for hours... Isnt therapy not more about unlearning bad habits? How about dealing with the social and psychological effects? Why do so many relapse? What is the best outcome measure? How about drugs? Gene therapy? Why are you not fluent Tom? Were all the speakers who claim to have been cured only very mildly stuttering????

I'll come back to these issues at a later time. I have a deadline for the paper for beginning of June, so I better talk about these issues...

Oxford Dysfluency Conference 2005

The Oxford Dysfluency Conference is one of the few PDS conferences worldwide. Others are the IFA and ISA congresses, and ASHA which is not PDS specific. IFA is the International Fluency Association (mostly practionners, researchers, but also others), ISA is the International Stuttering Association (the umbrella association of all national associations), and ASHA is the American Speech and Hearing Association.

There is a conference this year from July 29th to June 2nd. It is organised by the Michael Palin Centre. The conference organisors are Frances Cook and Dave Rowley . The Michael Palin Centre has been at the forefront in the UK in offering specialist therapy from dysfluent children and also adolescents. They are mostly funded by the Association of Research into Stammering in Childhood . But that's really a misnomer, as I havent seen much, if any, research coming out of the centre. Their focus and expertise is really on therapy. But they deserve credit for organising the ODC in the UK which in terms of quantity and quality of research (in comparison to US and Germany) is rather in the Middle Ages.

The conference atmosphere is a bit strange in the sense that it's not really a scientific/research conference (the majority are practionners) and not really a therapist gathering (as there are scientists attending). So it's interesting to see this culture clash between consensus-building communication style by therapists and the confrontational-truth-seeking style by researchers/scientists. The point really is that in therapy patients are entitled to their opinion, in science if your opinion is wrong, it's wrong and everyone tells you. So what's best? Depends on the situation. In therapy, and especially group therapy, you need to accept other people's opinions to work with them even if you think it's wrong, but most of the time there is no absolute truth like do you like green or blue, what is the best political party. But in science there is often one truth, and there is nothing more corrosive for scientific debate than having to be afraid that someone is personally offended if you point out that his/her opinion is wrong due to a logical fallacy or convincing arguments.

I will also talk at ODC. The topic is my analysis of patient data (300!) of a fluency shaping therapy in Germany called KST . They are really big in Germany, and have collected a massive amount of data over several years with German zeal, I might add. :-)

Tuesday, May 10, 2005

What's cause and effect?

Last time I described that Brown, Ingham, Ingham, Laird and Fox proposed a theory based on the efference copy concept to explain the differences in brain activation for PDS. Here are a few quick&dirty comments:

1) The explanation of overactivation in the cerebellar vermis and the lack of activation in auditory regions using the concept of efference copy seems reasonable and makes sense to me. I am not really an expert, so I cannot say more about it.

2) They provide testable predictions, which is always good.

3) The theory only focusses on explaining the observed difference in brain activation. So it's not really a theory of PDS, and leaves many questions open like genetics, gender difference, why fluency-inducing work, and much more. So it's just the beginning...

3) They assume that the problem really starts in unsucessful initiation of speech motor plans. So paradoxically that could lead me to conclude that all the observed functional activation differences in the PDS brain in fMRI and PET is not really about PDS (as I have been preaching to everyone for years), but only effect or symptons of the disorder like disfluent speech.

4) In this respect, I found their explanation of motor region overactivation quite vague, and I am not sure that they are all consequences of unsucessful initiation or low skilled regions that need to activate more to achieve the same than normally functioning regions. Also the atypical right hemispheric regions with reference to the abnormalities found by Sommer et al. and Foundas et al. Maybe it's the cause of unsucessful initiation?? Thus, unlike the cerebellar vermis and auditory regions, I am less convinced that it's only effect.

To finish off, a provacative thought: Is this the end of functional brain research on PDS using fMRI or PET? If all they say is true, it's unsucessful initiation that needs to be studied. This can only be done either by looking at structural difference or with a high temporal resolution (like MEEG, see for example Samelin et al. and Walls et al. )

In my next blog, I'll leave brain research behind and talk about the Oxford Disfluency Conference coming up in July.


Saturday, May 07, 2005

How tickling yourself helps to understand PDS

In the last part of their paper, Brown, Ingham, Ingham, Laird and Fox give a possible explanation of their meta-analysis' findings ( i.e motor overactivity and atypical right-hemispheric activation, auditory underactivity, and cerebellar overactivity) using a theory at least partially based on the concept of efference copy. Here is how I understand it. I hope I dont mess it up!!

They suggest that the "abnormality is... not likely a defect of motor programming per...nor an incorrect mental model of the desired movement... nor an abnormality of the motor execution system...The problem is limited to successful initiation of the motor program."

Then they go about explaining the differences in activation. To this aim, they introduce the concept of efference copy. Roughly, the theory goes that every motor plan (ie. the plan on how to move the muscles) is copied and sent to a predictor system that predicts the expected sensory feedback from the motor action. This copy is called the efference copy, and allows the brain to do self-monitoring by comparing the expected and the actual sensory feedback.

One application of efference copy concept is in the context of Why-Cant-You-Tickle-Yourself?? !!! :-) Answer: Because the efference copy is used to generate an expected sensory feedback that attenuates the tickling sensation.

Concerning lack of auditory activation, they speculate that every unsuccessful initiation of the motor plan sends an efference copy to auditory regions which attentuate their activity due to the expected sensory feedback. As there are many initiations, many efference copies are sent and the regions are constantly attentuated.

Concerning the cerebellar overactivation, the cerebellum is expected to be involved in the comparison of the expected and the actual sensory feedback. So each time an efference copy is created the cerebellum might prepare or perform this comparison task.

Concerning the overactivation in motor region and atypical hemispheric activation, they propose two effects. First, unsucessful initiation of a motor plan likely results in overactivation in motor regions that prepare or perform necessary tasks. Second, the lower skilled the brain is on a specific type of motor plan, the more active the regions involved are. This comes in handy, as they refer to Sommer et al. and Foundas et al. who found left-hemispheric structural defficiences, which suggest lower skills/ability of this region. (Actually there is now a THIRD article out by Jancke et al. ) This would also explain why there is some atypical right-hemispheric activation. The right brain might help out but is lowly skilled in the tasks.

That's roughly their theory, as I understand it. In my next post, I will comment on it...


Thursday, May 05, 2005

Shift of focus in brain research?

The Brown, Ingham, Ingham, Laird and Fox article is a good example of how this research area is slowly shifting focus. Over the last decade, brain research was rather "trivial": 1) find some people with PDS 2) put them in a brain scanner 3) look at the pretty pictures and use some basic statistical tests 4) write an article on what you find.

Their meta-analysis effectively summaries this empirical evidence from the last decade, in a sense drawing a line behind past imaging studies. But why is there overaction in motor areas plus one cerebellum area, atypical right hemispheric activation, and underactivation in auditory region?? Why does it lead to stuttering? And that's where the story becomes infinitely more complex: theory building.

Science really comes in two parts: collecting empirical evidence and constructing a theory that describes the patterns of the evidence and that predicts new empirical evidence which can be used to test the theory. There have been many theories on PDS around over the last century, but none made a decisive impact. Not surprisingly, some theories were not testable due to lack of empirical evidence e.g. it was not possible to look into the living brain 10-20 years ago. And most theories were pseudo-theories and not testable as they were only conceptual or made vague predictions like you are too nervous/have a conflict within you/had a bad experience. Thus many people were collecting experimental findings, and very few tried (or were unable either due to skill or lack of good evidence) to categorise them into a theory.

In 1999, at the IFA congress in Danemark, Prof. Conture , currently editor of The Journal of Fluency Disorders, complained in his keynote address that many researchers sofar gathered facts "like squirrels might gather nuts" rather than "develop and test theorectical explanations for facts and findings". But I have to slightly disagree. It is unfair as even the best scientists could in my opinion not have come up with a productive theory as no-one had access to the living brain 10 years ago. Or maybe 10-20 years ago, some good scientists left or never entered the field of PDS in the sense of "PDS must be in the brain, I cannot study the brain, so let's do research in another area"???

The meta-analysis puts some constraints on any theory of PDS:
1) The deficit happens INSIDE the brain, or up-stream from overt speech production.
2) Any complete theory on PDS MUST take into account the clear empirical evidence of differences in activation level in the PDS brain, or prove that the evidence of more than 10 brain studies is wrong.

Tomorrow more on why theory building is tricky and a discussion on the theory based on efference copy put forward by Ingham et al.


The latest on the brain imaging front.

From time to time, I do a keyword search on "stuttering" in PubMedline , which is an archive that contains abstracts of all published articles. It is a really useful way to stay updated with the latest research on PDS. Of course, most research is a year old or so when it appears, as the authors have to go through the tedious review process, but nevertheless. I also face the problem that I can only look at the abstracts as I dont have access to the fee-based journals. So I always need to plea with the authors to send me the pdf file of their paper!

I always look for the most recent articles, and on Monday came across an article by Brown, Ingham, Ingham, Laird and Fox. The group around Prof Ingham (UC at Santa Barbara) is one of the most active research groups in the field of brain imaging, actually probably the leading one because they have both expertise in brain imaging studies (together with Prof Fox's group at San Antonio, Texas, who had the first PET study out on the PDS brain) and on PDS itself. Many groups are either very good at brain imaging or understand PDS very well.

So what's in the article? Well, they do a meta-analysis of previous brain imaging studies using a statistical method called ALE. I dont know this method or how it works (as always there are probably some assumptions made...), but let's take it as God given. They have included brain scans from the research groups Fox/Ingham, de Nil from Toronto , and Neumann/Preibisch from Frankfurt. These groups have been quite active over the last years. Especially, the Frankfurt group around Neumann which is currently scanning people, especially those that have stuttered as kids but not adults, see their call for volunteers (in German).

Back to the article, first, Braun, InghamS, et al find that disfluent speech is different in brain activation level in three areas:
1) overactive motor regions and cerebellar vermis
2) atypical right-brain activiation (typically speech is processed in the left brain)
3) underactivation in auditory regions.

Second, they propose a (testable) theory of stuttering, which I will discuss tomorrow plus the general difficulties to construct a theory of stuttering.


Tuesday, May 03, 2005

Why Persistent Developmental Stuttering (PDS) instead of stuttering?

I am playing a bit with the fire here by starting my blog on boring terminology discussion! But I think it's very important for a constructive discussion to be clear on terminology.

I dont want to use the word "stuttering" or "stammering" to describe the disorder, because

a) stuttering is used both to label the symptom of the disorder and the disorder itself.

b) not all people who stutter have PDS. In fact, everyone has probably stuttered at some point in his/her life!

c) There are at least two classes of disorders that have stuttering as symptom, but it is not PDS. In the first disorder, people (typically over 60) might suddenly start stuttering due to brain damage to specific brain areas e.g. from a stroke. It's called neurogenic stuttering (I think). And the other class is childhood stuttering, where children start stuttering but most of them (more than 60%, probably 80%) recover.

d) There are even some who have PDS who dont stutter!!! Often called covert stuttering, they stutter very rarely, also by substituting difficult words and avoiding many speaking situations, but might still be severely impaired in social interactions.

d) I dont get confused anymore on whether I should write stuttering (US) or stammering (UK), as I am mainly in contact with British people due to my involvement with the British Stammering Association (BSA), and its research committee. :-)

Finally, using Persistent Development Stuttering (PDS) sends a clear signal that the disorder is NOT just about speech, it happens inside the brain. Speech disfluency is only the main symptom of the disorder.


Monday, May 02, 2005

Why this blog?

I think we are going through a revolutionary phase where new tools like brain imaging or genetics transform our understanding of Persistent Developmental Stuttering (PDS).

I would like to share my thoughts on the developments with you.

Scientists are often reluctant to disclose their current thinking or research projects, and they have a natural tendency to only talk about their own theory or research. Moreover, many articles and associated jargon is not easily accessible to non-scientists and practitioners.

In my blog, I attempt to be neutral, and present the current research issues and latest findings on PDS. I try to explain them in conceptual and non-technical terms, and analyse the impact on other areas of PDS. I also hope to discuss your feedback.

My perspective on PDS, and hence this choice for blog title, is the stuttering brain. I want to emphasise that something inside of the brain is going wrong, be it on the neurological, psychological, motor control, social, genetics level, and others, or a combination of many. The brain is us, it sends instructions to the speech muscles, creates fear, suggests avoidance, encodes language into instructions, and so on.

Finally, my blog is not just on understanding PDS, it's also on treatment like therapy efficacy or drugs, and the structures (like funding or national associations) necessary to achieve these aims.