Transcutaneous vagus nerve stimulation (t-VNS): A novel effective treatment for temper outbursts in adults with Prader-Willi Syndrome indicated by results from a non-blind study.

Author: Manning KE1,2,3, Beresford-Webb JA1, Aman LCS1, Ring HA1, Watson PC4, Porges SW5, Oliver C6, Jennings SR1, Holland AJ1
1Department of Psychiatry, University of Cambridge, Cambridge, Cambridgeshire, United Kingdom.
2School of Health and Social Care, University of Essex, Colchester, Essex, United Kingdom.
3Essex Partnership University NHS Foundation Trust, Wickford, Essex, United Kingdom.
4MRC Cognition and Brain Sciences Unit, University of Cambridge, Cambridge, Cambridgeshire, United Kingdom.
5Department of Psychiatry, University of North Carolina, Chapel Hill, North Carolina, United States of America.
6School of Psychology, University of Birmingham, Birmingham, West Midlands, United Kingdom.
Conference/Journal: PLoS One.
Date published: 2019 Dec 3
Other: Volume ID: 14 , Issue ID: 12 , Pages: e0223750 , Special Notes: doi: 10.1371/journal.pone.0223750. eCollection 2019. , Word Count: 288

Temper outbursts are a severe problem for people with Prader-Willi Syndrome (PWS). Previous reports indicate that vagus nerve stimulation (VNS) may reduce maladaptive behaviour in neurodevelopmental disorders, including PWS. We systematically investigated the effectiveness of transcutaneous VNS (t-VNS) in PWS. Using a non-blind single case repeat measures modified ABA design, with participants as their own controls, t-VNS was evaluated in five individuals with PWS [three males; age 22-41 (M = 26.8)]. After a baseline phase, participants received four-hours of t-VNS daily for 12 months, followed by one month of daily t-VNS for two-hours. The primary outcome measure was the mean number of behavioural outbursts per day. Secondary outcomes included findings from behavioural questionnaires and both qualitative and goal attainment interviews. Four of the five participants who completed the study exhibited a statistically significant reduction in number and severity of temper outbursts after approximately nine months of daily four-hour t-VNS. Subsequent two-hour daily t-VNS was associated with increased outbursts for all participants, two reaching significance. Questionnaire and interview data supported these findings, the latter indicating potential mechanisms of action. No serious safety issues were reported. t-VNS is an effective, novel and safe intervention for chronic temper outbursts in PWS. We propose these changes are mediated through vagal projections and their effects both centrally and on the functioning of the parasympathetic nervous system. These findings challenge our present biopsychosocial understanding of such behaviours suggesting that there is a single major mechanism that is modifiable using t-VNS. This intervention is potentially generalizable across other clinical groups. Future research should address the lack of a sham condition in this study along with the prevalence of high drop out rates, and the potential effects of different stimulation intensities, frequencies and pulse widths.

PMID: 31794560 DOI: 10.1371/journal.pone.0223750