<p>Interesting question! </p>

<p>Assuming you are talking about stuttering, as occurs in about 1% of the population (<a href="http://www.keck.ucsf.edu/~houde/speech/stutter/MSommer03a.pdf" rel="nofollow">Sommer et al., 2003</a>), as opposed to non-pathological stammering during stressful situations that many more people experience, my answer is as follows:</p>

<p>Stress and speech disruption in stutterers are undoubtedly related (e.g., <a href="http://jshd.pubs.asha.org/article.aspx?articleid=1775558" rel="nofollow">Craig, 1999</a>). In fact, they may be causally related, as stress can provoke or aggravate stuttering, which in turn may cause more stress to the stutterer due to feelings of shame or loss of control. This in turn may induce more stuttering and may thus lead to a downward spiral, or vicious circle (<a href="http://copingwithstuttering.blogspot.com.au/2010/02/stuttering-child.html" rel="nofollow">Schwartz, The Stuttering Child</a>) that may grossly disrupt speech. </p>

<p>The underlying physiological basis of <strong><em>why</em></strong> stress provokes stuttering has been addressed by <a href="http://www.ncbi.nlm.nih.gov/pubmed/2273884" rel="nofollow">Weber &amp; Smith, (1990</a>). It shows that speaking increases autonomic activity (elevated blood flow, increased heart rate, sweating) and that this sympathetic arousal was correlated with increased stuttering behaviors in stutterers. Interestingly, the sympathetic arousal of stutterers was found not to be outside the range of controls. The authors bring up several hypotheses as to why sympathetic activity may deteriorate speech fluency in stutterers: </p>

<ul>
<li>Increased autonomic activity has been associated with <strong>irregular breathing</strong>, which may affect speaking;       </li>
<li>Release of the <strong>stress hormone adrenalin</strong> may induce <strong>muscle tremor</strong> and <strong>spasms</strong> that can affect speech production;</li>
<li>Sympathetic regulation of <strong>afferent control of the sensitivity of sensory receptors</strong> (muscle spindles and mechanoreceptors) in the <strong>oralmotor, laryngeal and respiratory system</strong> may affect speech motor processes;</li>
<li>The <strong>gain of reflex arches</strong> (feedback) involved in the <strong>musculature engaged in speech</strong> may be modulated such that speech fluency is negatively impacted. </li>
</ul>

<p>These processes may aggravate the underlying pathology of stutterers (<a href="http://www.plosbiology.org/article/info%3Adoi%2F10.1371%2Fjournal.pbio.0020046#pbio-0020046-g003" rel="nofollow">Büchel &amp; Sommer</a>) and hence lead to more pronounced stuttering under stress.  </p>

<p><sup><em>PS: Being a stutterer myself since early childhood, I support the behavioral consequences of stress mentioned in above studies by anecdotal experience :)</em></sup></p>

<p><strong>References</strong><br>
- <a href="http://www.plosbiology.org/article/info%3Adoi%2F10.1371%2Fjournal.pbio.0020046#pbio-0020046-g003" rel="nofollow">Buchel &amp; Sommer, <em>PLoS Biol</em> 2004; <strong>2</strong>(2): e46</a><br>
- <a href="http://jshd.pubs.asha.org/article.aspx?articleid=1775558" rel="nofollow">Craig, <em>J Speech Hear Disorders</em> 1990; <strong>55</strong>: 290-4</a><br>
- <a href="http://copingwithstuttering.blogspot.com.au/2010/02/stuttering-child.html" rel="nofollow">Schwartz, The Stuttering Child, Coping With Stuttering</a><br>
- <a href="http://www.keck.ucsf.edu/~houde/speech/stutter/MSommer03a.pdf" rel="nofollow">Sommer et al., <em>Movement Disorders</em> 2003; <strong>18</strong>(7): 826*30</a><br>
- <a href="http://www.ncbi.nlm.nih.gov/pubmed/2273884" rel="nofollow">Weber &amp; Smith, <em>J Speech Hear Res</em> 1990;<strong>33</strong>(4): 690-706</a></p>

CC BY-SA 3.0
2014-12-29T01:09:16.460Z
Why have I developed stuttering over the years I grown up? Remember I didn't have any problem speaking even when nervous, as a kid.
user11355
CC BY-SA 3.0
2014-12-29T01:39:23.727Z
Also is stuttering dyslexia ?
user11355
CC BY-SA 3.0
2014-12-29T11:09:26.063Z
user11355: As to your first comment: good question. I am not a speech therapist and this is something to ask to an expert. And even if I had known the answer, I couldn't have answered it, as it is (1) a self-help question (please see @JeromyAnglim 's comment above) and (2) comments should not be used to ask new questions (please visit the help-center)  .
AliceD
CC BY-SA 3.0
2014-12-29T11:11:04.737Z
@user11355 - To your second question: as said, comments should not be used to ask new ones, and hence I will suffice by saying - no, dyslexia is not a synonym for stuttering.
AliceD
CC BY-SA 3.0
2014-12-29T13:41:49.367Z
Where is self help center? You mean on this site?
user11355
CC BY-SA 3.0
2014-12-29T13:43:24.527Z
no the help center :) upper-right corner of your screen
AliceD
CC BY-SA 3.0
2014-12-29T13:48:48.757Z
Yeh, I probably need to visit my psychologist, instead of asking all the questions here.
user11355
CC BY-SA 3.0
2014-12-24T13:55:42.507Z
2015-04-24T11:05:10.097Z
2015-04-24T11:05:10.097Z
AliceD
<p><strong>Background:</strong> I don't stutter at least not always. For example, if I be reading out a article to myself, It is sure that I will not stutter even that I am reading it out loud.
The times when I do stutter is say when I am doing a presentation in class! or just saying something to my mother.The time always came up without warning. I will not know If I am gonna be stuttering reading a certain word until I actually reach it. It really creates a problem for me, and I can't find the reason for it..</p>

<p><strong>Question:</strong></p>

<ul>
<li>Why do people stutter when they are nervous?</li>
</ul>

CC BY-SA 3.0
2014-12-22T03:17:56.357Z
Welcome to the site. In order to make this not a "self-help" question, I've tried to reframe it around the more general research question.
Jeromy Anglim
<neuroscience><abnormal-psychology>
Why do some people stutter only when they are nervous?
user11355
# Why do some people stutter only when they are nervous?

(Asked by: username_0 on 2014-12-22)

**Background:** I don't stutter at least not always. For example, if I be reading out a article to myself, It is sure that I will not stutter even that I am reading it out loud.
The times when I do stutter is say when I am doing a presentation in class! or just saying something to my mother.The time always came up without warning. I will not know If I am gonna be stuttering reading a certain word until I actually reach it. It really creates a problem for me, and I can't find the reason for it..

**Question:**

* Why do people stutter when they are nervous?

**Tags:** neuroscience, abnormal-psychology

> **Comments:**
> **username_1**: Welcome to the site. In order to make this not a "self-help" question, I've tried to reframe it around the more general research question.  

---

## 1 answers

### Answer by username_2 on 2014-12-24. Score: 4 | Accepted answer

Interesting question!

Assuming you are talking about stuttering, as occurs in about 1% of the population ([Sommer et al., 2003](http://www.keck.ucsf.edu/~houde/speech/stutter/MSommer03a.pdf)), as opposed to non-pathological stammering during stressful situations that many more people experience, my answer is as follows:

Stress and speech disruption in stutterers are undoubtedly related (e.g., [Craig, 1999](http://jshd.pubs.asha.org/article.aspx?articleid=1775558)). In fact, they may be causally related, as stress can provoke or aggravate stuttering, which in turn may cause more stress to the stutterer due to feelings of shame or loss of control. This in turn may induce more stuttering and may thus lead to a downward spiral, or vicious circle ([Schwartz, The Stuttering Child](http://copingwithstuttering.blogspot.com.au/2010/02/stuttering-child.html)) that may grossly disrupt speech.

The underlying physiological basis of ***why*** stress provokes stuttering has been addressed by [Weber & Smith, (1990](http://www.ncbi.nlm.nih.gov/pubmed/2273884)). It shows that speaking increases autonomic activity (elevated blood flow, increased heart rate, sweating) and that this sympathetic arousal was correlated with increased stuttering behaviors in stutterers. Interestingly, the sympathetic arousal of stutterers was found not to be outside the range of controls. The authors bring up several hypotheses as to why sympathetic activity may deteriorate speech fluency in stutterers:

* Increased autonomic activity has been associated with **irregular breathing**, which may affect speaking;
* Release of the **stress hormone adrenalin** may induce **muscle tremor** and **spasms** that can affect speech production;
* Sympathetic regulation of **afferent control of the sensitivity of sensory receptors** (muscle spindles and mechanoreceptors) in the **oralmotor, laryngeal and respiratory system** may affect speech motor processes;
* The **gain of reflex arches** (feedback) involved in the **musculature engaged in speech** may be modulated such that speech fluency is negatively impacted.

These processes may aggravate the underlying pathology of stutterers ([Büchel & Sommer](http://www.plosbiology.org/article/info%3Adoi%2F10.1371%2Fjournal.pbio.0020046#pbio-0020046-g003)) and hence lead to more pronounced stuttering under stress.

*PS: Being a stutterer myself since early childhood, I support the behavioral consequences of stress mentioned in above studies by anecdotal experience :)*

**References**  
- [Buchel & Sommer, *PLoS Biol* 2004; **2**(2): e46](http://www.plosbiology.org/article/info%3Adoi%2F10.1371%2Fjournal.pbio.0020046#pbio-0020046-g003)  
- [Craig, *J Speech Hear Disorders* 1990; **55**: 290-4](http://jshd.pubs.asha.org/article.aspx?articleid=1775558)  
- [Schwartz, The Stuttering Child, Coping With Stuttering](http://copingwithstuttering.blogspot.com.au/2010/02/stuttering-child.html)  
- [Sommer et al., *Movement Disorders* 2003; **18**(7): 826\*30](http://www.keck.ucsf.edu/~houde/speech/stutter/MSommer03a.pdf)  
- [Weber & Smith, *J Speech Hear Res* 1990;**33**(4): 690-706](http://www.ncbi.nlm.nih.gov/pubmed/2273884)

> **Comments:**
> **username_0**: Why have I developed stuttering over the years I grown up? Remember I didn't have any problem speaking even when nervous, as a kid.  
> **username_0**: Also is stuttering dyslexia ?  
> **username_2**: username_0: As to your first comment: good question. I am not a speech therapist and this is something to ask to an expert. And even if I had known the answer, I couldn't have answered it, as it is (1) a self-help question (please see @JeromyAnglim 's comment above) and (2) comments should not be used to ask new questions (please visit the help-center)  .  
> **username_2**: @username_0 - To your second question: as said, comments should not be used to ask new ones, and hence I will suffice by saying - no, dyslexia is not a synonym for stuttering.  
> **username_0**: Where is self help center? You mean on this site?  
> **username_2**: no the help center :) upper-right corner of your screen  
> **username_0**: Yeh, I probably need to visit my psychologist, instead of asking all the questions here.  

---

