Friday, May 15, 2009

Read the articles, Rex

I have to post on Rex's reply to me pointing out that everyone with a stuttering-is-learned-behaviour theory needs to tell me why genetics influences stuttering and why we have abnormal brains. I say it loud and clear. THE TIME IS OVER WHERE YOU COULD JUST WAFFLE ALONG WITH RANDOM LOGICAL THOUGHTS. YOU ACTUALLY NEED TO READ THE SCIENTIFIC LITERATURE BECAUSE GENE AND BRAIN EVIDENCE IS CONSTRAINING AND RULING OUT ALL KINDS OF THEORIES!

Here is Re's response highlighting my point exquisitely.

How come stuttering is strongly influenced by genes?

Is it? How has this been proven? Have they discovered the genes responsible? No they haven't. Have they done tests on twins *reared apart*? I don't know, but I doubt it. What is the contribution of genes and what is the contribution of environment? Lets face it - after all these years of research, nobody has a clue.

Yes, they have shown this. A quick 5 minute search would tell you. Go to PubMedline archive and search for "stuttering genetics". Or check out tese review articles: here, and here.

Here is the evidence:

a. There are whole families where nearly everyone stutters. They are in Cameroon, Kansas, and Pakistan. Read Drayna's review article or

See Drayna, D. "Newly discovered families give impetus to genetic research," Stuttering Foundation of America newsletter, Fall 2005, page 1. Viswanath, N., H.S. Lee, R. Chakraborty. "Evidence for a Major Gene Influence on Persistance Developmental Stuttering," Human Biology, June 2004, 76:3, 401-412.

b. One-egg twins are much more likely to both stutter at the same time than two-egg twins.

See Am J Speech Lang Pathol. 2007 May;16(2):169-78. Genetic etiology in cases of recovered and persistent stuttering in an unselected, longitudinal sample of young twins. Dworzynski K, Remington A, Rijsdijk F, Howell P, Plomin R.

c. Currently, studies are underway to locate the genes: see work by Drayna and by Ambrose.

And the same for brain imaging.
These structural differences: are they congenital, or are they caused by the fact that a stutterer has been stuttering all his/her life? Remember, years of stuttering behaviour can change the brain ... plasticity, and all that. Nobody can answer this with certainty.

No, they have now done studies on older kids which shows the similar kids, and you still have the genes which are the physical objects that build up the brain.

One thing about stuttering which has been largely been ignored by researchers and commentators is that there may well be more than one variant of it - even though they may manifest themselves as the same behaviours.

I agree with your statement, but that doesn't mean that anything that looks feasible as a cause is a cause.


BJ said...

The issue is the vague definition of a stutterer vs. non-stutterer.

Stuttering genes should not change with therapy or anything, it should always be there. Still don't quite understand the unequal female to male ratio??

Why hasn't Dennis Drayna published anything on genetics of stuttering since 2004?? Not sure if he has made any Real progress or still to the location of the genes, when do you think it will happen? (what year, maybe 2020)

Whole families of stutterers? Wow, how is stuttering defined, is a stutterer still a stutterer after successful treatment? If there are indeed whole families of stutterers, then it should be quite easy to find the stuttering gene, right?

Thought the correlation factor was 0.4 to 0.6, weak correlation...

Rex said...


This research into twins has been going on for decades. You said, "read the articles, Rex". Here are a couple of articles:

"Concordance for Stuttering in Monozygotic and Dizygotic Twin Pairs", Journal of Speech and Hearing Research, 24 (1981), pp.317-321

This paper (written in 1981!!!) showed that there is a 73% concordance for stuttering in identical twins and 32% in non-dentical twins.

Another paper from 1991:
"Genetic Factors in Stuttering Confirmed", Archives of General Psychiatry, 48, pp. 1034-1035

In identical twins, there was a 20% concordance, and in the non-identical twins it was 5%.

The figures suggest that genetics plays a role, but identical twins are (as the name suggests) identical, so their parents treat them in identical ways, and their environments are usually identical. However, the figures also indicate that environmental factors play a very significant role. If stuttering were purely genetic, there would be 100% concordance among identical twin stutterers ... but there isn't!

You call it "random logical thoughts", I call it "questioning the current paradigm of stuttering research". The scientific literature that you cite is just a rehash of what has been done for decades. Nothing new has been found. The same questions that were asked 30 years ago are still being asked today ... zero progress.

The same goes for brain imaging studies. No progress!

My understanding is that the stuttering researchers are of an embarrassingly poor standard ... and something tells me that you agree with me.

TJ said...

Tom, do you agree or Disagree? With Rex...Rex is making a good point. The lack of progress? Can't teach old dogs new tricks....Rex said he read the papers, now your turn to respond!

>My understanding is that the stuttering researchers are of an embarrassingly poor standard ... and something tells me that you agree with me.

Blanka Koffer said...

I agree with Rex. Brain research shows that experiences are highly responsible for not only psychological but also physical development - so changing the software does change the hardware, too.

Tom, your answer a: what does that prove? the reason can be social, too.

b: others have written on that twin-issue. here the reason can be social, like in a.

c: is not really a valid answer to the question posed.