Searching for a cause
Speechies, by nature, are a curious bunch. I think that a pre-requisite personality trait for this field is to be constantly asking “Why?”, and searching for answers to questions such as “What is causing this speech issue in my client?” The class of 2013 recently began our Fluency class to learn more about stuttering. We have had a couple of lectures, labs and guest talks so far, but as this is an area of interest of mine, I decided to set out to get more answers.
Here at the U of A, we are lucky enough to be located right across the street from ISTAR, the Institute for Stuttering Treatment and Research, a world renown stuttering institute. New executive director and associate professor at the U of A, Dr. Deryk Beal, recently presented a talk to our class about genetics, neuroimaging, and the neurobiology of stuttering. He agreed to sit down with me to discuss more about some of the underlying mechanisms of stuttering and his current research.
Adele: For many of the speech and language areas that SLP’s work in, we always want an answer to the question of “What is causing this?”. Is there an easy answer to this question when it comes to stuttering?
Dr. Beal: For a long time we’ve said that we don’t know what causes stuttering, and there is an element of truth to that statement, but I think that when we talk to families we do them a disservice when we leave the subject at that. I think what’s more appropriate moving forward is for us to say that we don’t know what causes stuttering but we strongly suspect that it’s a combination of inherited or genetic factors in interaction with non-genetic factors. It may sound strange to say “non genetic factors” rather than “environment”, but if you say environment to families then you run the risk of a concerned parent thinking they haven’t created a nurturing environment for their child and its not that at all, from a clinical point of view you don’t want to go down that road. When you say “nongenetic” you open it up to other variables, there has been some work done on temperament, there may be differences in temperament between children who stutter and those that don’t – so that’s a non genetic factor that’s not necessarily environmental.. Also, we do know that in some cases you are able to identify a genetic difference that can account for stuttering. It is likely that the implicated gene plays a role in brain development, which leads to a risk of stuttering and a potential difference in the way the brain is working for speech in people who stutter as compared to people who don’t. We can help families understand this on a simple level by explaining that the way stuttering runs in families is very different from the way that something simple like hair or skin or eye color is transmitted. In stuttering it appears that it is polygenetic, so it is likely possible that you can have very minor things wrong with any number of different genes that would all lead to something that looks like stuttering in the speech production network of the brain. Connecting all of the dots between genetics and brain development, be it structural or functional, is not something we are capable of doing right now, but we are getting there slowly.
Adele: So it’s a very complex picture to unravel all the strands of what goes into causing a speech issue such as stuttering, can you tell me more about some of the work you’ve been doing to unravel one of these pieces?
Dr. Beal: There are two streams of research—one is advancing the neuroimaging techniques that we use to understand how the brain works for speaking to include children and children who stutter or who have other speech disorders. Because stuttering has its onset between 2 and 6 years of age, and then you go on to recover or persist, and right now research is mostly focusing on adults, we are limiting our knowledge to people whose stuttering persists into adulthood. We are trying to understand the structure and function of the brain so far beyond when the stuttering first occurred, which is problematic when your greatest chance to achieve change in terms of leading a more fluent way of life is in the those preschool years. My research involves trying to use neuroimaging as close to the onset of stuttering as possible. The other piece is bringing the neural network modeling aspect to the table, so using computer engineering to make a model of how we think the network of areas in the brain communicate with each other for the purposes of speech communication. There are a number of models out there that can account for a number of typical speech phenomena. These can be used to think about how changes in the model can induce stuttering to occur and then using that model as a testing ground for hypotheses about how the brain is working for both fluent speech and stuttered speech. Not only does the model have behavioural outcomes, so it produces actual speech, but it also produces a pattern of brain activity it thinks is matching the type of speech that it is producing. You can look at a statistical parametric map of brain activity produced by the model, so that you can compare it side by side from real fMRI data from a human. If the data match then you know the story you are telling with the model is on par, but if they don’t, you can still learn how to tweak the model to make it match the results, and then learn more about how the brain is actually working.
The next thing I hope to do is to take stuttering research to the next level and move beyond neuroimaging and modeling alone in kids and adults, to bringing in the genetic components. The cost of extracting information from DNA is plummeting on a regular basis, so what used to cost tens of thousands of dollars is now a few thousand, so within the financial scope of a health operating research grant, you can now afford to analyze genetic data as a small part of a bigger data set. The place to start is to take genetic information and neuroimaging data from the same person and then look for relations between the two data sets.
Adele: So once we have the information from this research, or even based on what we know now about how the brain works during speech, how does all this information inform our practice, how does it translate into therapy or what clinicians are actually doing?
Dr. Beal: The most important piece of information for clinicians and families is that the disorder is not due to the ideas put forward by all of those old theories of stuttering, that it is due to psychological distress or something that your parents did to you. Educating families that we know stuttering is not due to these factors has a huge impact on how we provide our treatment. For the most part it puts people at ease, for some people it makes them feel that that there is less control over it or ability to change the stutter, but then if you teach a client about brain plasticity then you can quickly overcome what might be a misconception. I think there is this habit that we have to think that somehow the brain is magical in nature, I mean that when you talk about neuroplasticity, people think that it is some special thing that happens like bringing the monster in Frankenstein to life, when really, neuroplasticity is happening every second of every day, as we are having this conversation our brains are changing, neurons are interpreting the sounds that we are saying, extracting meaning and language and storing it in memory. Your brain is changing as a result of everything you do every day, the stimulation you take in; that’s neuroplasticity, or at least one broad definition of it. And that is what we do in speech pathology, we change the brain, if you teach someone to speak using an altered set of motor skills you’ve changed the way the brain is working, there is nothing “Frankenstein” like about it.
The research informs practice in terms of the education we can give our clients, and also in what we know about motor learning in terms of scheduling practicing, how often we have to do things in order to learn, which we can use to optimize our therapy, so how often we see our clients, how often we are working them. The research also teaches us how to change the brain, and that we can change the brain. In the long term you are looking at enhanced speech therapy, there has been lots of investigations on pharmaceutical interventions on stuttering, nothing has really been shown to be the magic bullet, but if we learn more about how the brain is working, perhaps we could combine behavioural therapy with a pharmaceutical intervention, or even combine it with a brain stimulation type of therapy using low level current or trans-cranial magnetic stimulation, guided by neural network modeling or brain imaging techniques. Additionally, the research will have an impact on understanding the genetic influences on the brain.
So as you can see, not even the experts in the field have an answer to the question of what causes stuttering. Asking the questions however, leads to the research being done that further expands our knowledge on the causes and mechanisms and brain areas involved, as well as the underlying genetic influences that may play a role. This in turn, helps to inform our practise, so we can continue to improve our therapies and treatment techniques to help our clients! Did reading the above interview with Dr. Beal spark any questions in your inner researcher? Leave a comment below!
- Adele Courchesne