Adult Stammering

Stammering in adults

New research based at Oxford University

Postgraduate researcher Birtan Demirel is receiving funding from the DBT to conduct several different research studies at Oxford University, beginning in Autumn 2021 and supervised by Professor Kate Watkins, Professor of Cognitive Neuroscience in the Department of Experimental Psychology.  Birtan plans to initially develop the following areas of reserach:-

  1. Collection of pilot data for his primary research proposal on brain stimulation to improve speech fluency.
  2. Investigation into lateralization of speech in the brain of people who stammer to establish if there is a difference compared with typically fluent speakers.
  3. Measurement of grey matter volumes in the brain of people who stammer to conclude if there is a difference compared with typically fluent speakers. 
  4. Examination of movement initiations of people who stammer.

Additionally, Birtan is becoming involved in communication campaigns to increase awareness of stammering and overcome negative stigmas in society.

Brain imaging research

Researcher Naheem Bashir, funded by UCL and the DBT is exploring the brain basis of stammering, and methods of reducing speech difficulty and enhancing therapy in people who stammer, using brain stimulation techniques. Over the course of his PhD, he has conducted brain stimulation studies with both fluent speakers and people who stammer and demonstrated that brain stimulation can be used to enhance speech production processes in both groups. He has also conducted brain imaging studies using Functional NearInfrared Spectroscopy (fNIRS) with people who stammer and also with fluent speakers, assessing brain activity within a face-to-face conversation style task. Having won the Rogue Resolutions Brainbox Initiative Research Challenge, Naheem was loaned fNIRS-EEG brain imaging equipment which he used to conduct new studies. In future, Naheem aims to use brain imaging to enhance understanding of the mechanisms behind stammering and find reliable targets for brain stimulation to reduce stammering. Commenting Naheem says: “Support from the DBT has been vital in allowing me to develop this research and it’s a relationship I hope will continue. I am now starting pilot work that will provide the foundation for a post doc application which will include a NIRS-EEG study and a NIRS-Virtual Reality experiment using the Brainbox equipment (pictured) with the aim of developing a closed-loop brain stimulation system.” In addition to his scientific research, Naheem raises awareness of speech impediments through UCL panel discussions, appearing in a ‘Stambassador video for Action for Stammering Children, speaking at diversity events and even educating audiences through stand-up comedy.

Stammering and attentional performance

Dr Silviya Doneva has been working with the DBT since 2015 as a research associate examining the relationship between stuttering and attentional ability. Together with Prof. Penny Cavenagh, University of Suffolk (UoS) and Dr Steve Davis, UCL, Silviya first conducted a primary research project which showed that people who stutter performed significantly worse on tasks tapping into visual selective and divided attentional resources. The results also revealed a negative association between stuttering severity and performance on two Test of Everyday Attention (TEA) subtests measuring visual selective attention. This study was published in the Journal of Clinical and Experimental Neuropsychology and presented at the 11th Oxford Dysfluency Conference.

The team, together with Sarah Costelloe had also conducted a very similar project which revealed an overall tendency for children who stutter (CWS) to score lower than children who do not stutter (CWDS) on all 13 TEA measures of the children’s version of the test (TEA-Ch). A second revision of the article has been accepted for publication by Applied Neuropsychology: Child for consideration. Building on the work to date, the trust is currently funding Silviya to conduct a meta-analytic review on adult stuttering and attentional ability. A thorough search of the literature has already been conducted amongst three of the most popular research engines: PubMed, Web of Science and Science Direct. Each of the chosen search terms: attention, vigilance, inhibitory, inhibition, interference, executive and processing, was cross-referenced with one of the following words at a time: stutter, stammer, speech disfluency and speech dysluency. A total of 22 articles met the criteria for inclusion in the review. After the meta-analysis is completed and the results are written up, the review will be submitted for publication to an academic journal.

Brain imaging research into stammering and speech mechanisms

Thanks to a very generous donation from the Mackie Foundation, the Trust is delighted to be co-financing a PhD with UCL which is investigating the Impact of Transcranial Direct Current Stimulation (tDCS) on Speech Fluency. Researcher Naheem Bashir, supervised by Professor Pete Howell, is investigating the effect of stimulating the brain with transcranial direct current stimulation (tDCS) in conjunction with the use of conventional treatment for stammering. He has so far shown that this combination does seem to work to improve speech in fluent speakers, so providing proof of the principle that tDCS can have a positive effect on speech mechanisms. There are several lines of research that Naheem is following. One study involves tDCS as an adjunct to conventional therapy. Another study currently being planned aims to assess if tDCS is more effective when delivered during or before an assessment. A further study will involve using a brain imaging system (NIRS) to look at assessing brain activity in real-time in social situations, as well as fluency enhancing situations, in people who stammer. Naheem hopes this will give an insight into the mechanisms of stuttering, as well as fluent speech production in people who stutter, and an insight into variations in speech fluency levels experienced by people who stutter in various different situations, for example high fluency when speaking alone as compared to low fluency when introducing oneself to a stranger. This could possibly provide new neural targets for treatment and have exciting implications for use in therapy.

Research on Attention and Stammering in Adults

Researcher Silviya Doneva has recently completed a year-long research project investigating the links between attention and stammering in adults, funded by the Trust and supervised by Professor Penny Cavenagh at University Campus Suffolk. This builds on earlier work undertaken at UCS, which found that children who stammer may also experience difficulties with sustaining attention. Silviya has been testing the hypothesis that stammering interferes with control of processing information and thereby affects the performance of everyday tasks. She has found a difference in attention between people who stammer and people who are fluent speakers and that people who stammer have more difficulty in sustaining attention when undertaking tasks. Although her research suggests a link between the severity of a stammer and difficulties with attention, it is not clear which is cause and which is effect. The project, which was carried out at both UCS and UCL, to ensure the population was fairly represented, was completed in May 2016 and submitted to a high-impact academic journal on fluency disorders. The findings have been presented at the 30th World Conference of the International Association of Logopedics and Phoniatrics (August 2016) and sparked local interest. The team expressed their thanks to City Lit’s Rachel Everard, BSA’s Norbert Lieckfeldt and Allan Tyrer – for raising awareness and aiding recruitment – and Professor Peter Howell for providing a testing venue in London; also to the Trust and all the participants.