Our research on Developmental Stuttering (Stammering)
BRAIN STRUCTURE AND FUNCTION IN STUTTERING
Recently, using MRI scans we found increased concentration of iron in the brains of people who stutter in the parts of the brain involved in movement initiation and control. These new findings might relate to some of the genetic findings that are thought to cause stuttering in about 10% of people who stutter. We don't yet know if stuttering causes the increased iron in the brain or whether stuttering is caused by increased iron. More studies following people who stutter longitudinally from early in development are needed.
Brain stimulation to enhance fluency
In a randomised controlled trial, we used transcranial direct current stimulation coupled with choral reading and metronome-timed speech to enhance fluency in people who stutter. A very weak electrical current was applied over the scalp for 20 minutes a day while people used these fluency enhancers for five consecutive days. This reduced speech disfluency measured a week later and was still reduced six weeks later. A group who had the fluency enhancers but coupled with "sham" stimulation (the stimulator was turned on briefly and off again so people could not tell if they had real or sham stimulation) showed no change in their fluency. We are currently analysing the data from a follow-up study. Listen to Jen Chesters talk about these results.
MRI Scans of the vocal tract during speaking
Recently we used vocal tract MRI to visualise movements during fluent and disfluent speech in people who stutter. We found that speech movements are more variable in people who stutter even when speech is perceptibly fluent.
Cler GJ, Krishnan S, Papp D, Wiltshire CEE, Chesters J, Watkins KE. Elevated iron concentration in putamen and cortical speech motor network in developmental stuttering. Brain. 2021 Nov 29;144(10):2979-2984. doi: 10.1093/brain/awab283.
Wiltshire CEE, Chiew M, Chesters J, Healy MP, Watkins KE. Speech Movement Variability in People Who Stutter: A Vocal Tract Magnetic Resonance Imaging Study. J Speech Lang Hear Res. 2021 Jul 16;64(7):2438-2452. doi: 10.1044/2021_JSLHR-20-00507.
Chesters J, Möttönen R, Watkins KE. Transcranial direct current stimulation over left inferior frontal cortex improves speech fluency in adults who stutter. Brain. 2018 Apr 1;141(4):1161-1171. doi: 10.1093/brain/awy011.
Watkins KE, Smith SM, Davis S & Howell P (2008) Structural and functional abnormalities of the motor system in developmental stuttering. Brain, 131(Pt 1):50-59.