by Justin Jackson , Medical Xpress

Credit: Unsplash/CC0 Public Domain

China Academy of Chinese Medical Sciences (CACMS) researchers at the Acupuncture and Moxibustion Hospital have conducted a study showing that transcutaneous auricular vagus nerve stimulation improves sleep quality in patients with chronic insomnia.

Insomnia is a prevalent global health issue, impacting approximately one-third of adults, with associated symptoms including excessive sleepiness, fatigue, mood disturbances and reduced cognitive ability.

Transcutaneous auricular vagus nerve stimulation (taVNS) is a non-invasive method of electrically stimulating the vagus nerve by small electrodes placed on the outer ear at locations innervated by the auricular branch of the vagus nerve.

According to the study, taVNS has previously shown promise in addressing conditions like depression, epilepsy, and migraine with emerging research suggesting it may alleviate insomnia symptoms, but evidence from rigorous trials has been limited.

In a study titled “Transcutaneous Auricular Vagus Nerve Stimulation for Chronic Insomnia Disorder: A Randomized Clinical Trial,” published in JAMA Network Open, the researchers evaluated the efficacy and safety of taVNS for insomnia compared with sham taVNS.

Researchers evaluated 72 adults with chronic insomnia disorder who had Pittsburgh Sleep Quality Index (PSQI) scores of at least 8. Participants were randomly assigned to either receive active taVNS or a sham version.

Both groups underwent 30-minute self-administered stimulation sessions twice daily, 5 days a week for 8 weeks, with a 12-week follow-up. Blinding was confirmed for participants and outcome assessors.

The primary endpoint measured the mean change in PSQI scores from baseline to week 8. Minimal clinically important difference was set at 2.5 points. Secondary outcomes included measures of insomnia severity, mental health, fatigue, and sleepiness. Adverse events were recorded for safety assessment.

Participants in the taVNS group showed a statistically significant and clinically meaningful improvement in sleep quality. Improvements in PSQI were sustained throughout the 20-week study period.

Secondary outcomes reinforced the primary findings. The Insomnia Severity Index (ISI) scores decreased more significantly in the taVNS group, with a mean difference of −4.7 points at week 8. Reductions were also observed in the Hamilton Anxiety Scale, Hamilton Depression Scale, and Flinders Fatigue Scale scores. No significant difference in daytime sleepiness, measured by the Epworth Sleepiness Scale, was observed between the groups.

Adverse events occurred in 13.9% of taVNS participants and 11.1% of sham participants. Most adverse events were minor, such as slight ear discomfort during stimulation, which resolved quickly. One participant in the taVNS group reported bleeding gums, while dizziness was reported in one participant in the sham group.

Results support taVNS as a safe and effective intervention for chronic insomnia, with sustained improvements in sleep quality, mental health, and fatigue that could serve as a promising nonpharmacological treatment alternative.

Is this a legitimate registered trial?

The stated objective of the trial, as listed in the Chinese Clinical Trial Registry, was to observe the brain mechanisms, structure and function of taVNS in patients with insomnia disorder based on multimodal magnetic resonance imaging (MRI), an intriguing mechanistic inquiry into the relationship.

In the study presented, no MRI data was provided and it is unclear whether any MRIs were performed, as the published study makes no mention of them. Cohort inclusion and exclusion conditions regarding MRI in the registration are not mentioned in the paper, and a non-treatment, non-sham, healthy group—part of the trial registration—was not included in the published study.

There can be very legitimate reasons for alterations to a planned study, such as a loss of funding, loss of data or a problem with a proposed method, but these should then be adequately explained. Without such transparency, it is difficult for outside observers to contextualize the findings or trust that the study adhered to any pre-specified design.

As the stated goal in the registry was to explore taVNS brain mechanisms using multimodal MRI, and the actual trial omitted any MRI data, this could be considered a significant deviation from the registered protocol.

With one of the primary indicators and main investigative tool of the registered trial entirely absent, along with cohort and study group changes, it is unclear why it was accepted for publication as a registered clinical trial.

More information: Shuai Zhang et al, Transcutaneous Auricular Vagus Nerve Stimulation for Chronic Insomnia Disorder, JAMA Network Open (2024). DOI: 10.1001/jamanetworkopen.2024.51217

Journal information:JAMA Network Open

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