A 2021 study published in Nature found that noninvasive vagus nerve stimulation (nVNS) may improve motor function in patients with Parkinson’s disease. Nerve stimulation, or neurostimulation, involves using a device to send electrical signals to certain nerves in the body. In VNS, the vagus nerve is targeted, a nerve that may play a role in Parkinson’s.
36 patients with Parkinson’s disease were included in the study. 17 received nVNS, while the remaining 19 received sham stimulation as a placebo. nVNS was used in conjunction with the patients’ standard-of-care treatments. To determine the effectiveness of the therapy, the researchers measured certain key biomarkers to gauge inflammation, oxidative stress and brain-derived neurotrophic factor (BDNF). BDNF is a protein involved in the maintenance and growth of neurons in the brain.
At the end of the study, the researchers found that walking speed increased by 16%, step length increased by 11%, and step time decreased by 16% in the participants undergoing nVNS. No significant changes were detected in the control group.
“Overall, our results provide the first evidence that nVNS downregulates major pro-inflammatory cytokines, upregulates BDNF and increases levels of the antioxidant (reduced glutathione) in [patients with Parkinson disease], and that nVNS might have disease-modifying effects in [Parkinson disease],” the researchers concluded.
“Moreover, BDNF, [tumor necrosis factor]-α and reduced glutathione might serve as biomarkers, alongside improvement in motor symptoms in patients with Parkinson disease.”
The study’s limitations
However, after adjusting for comparisons between the groups, the researchers were unable to find any significant improvements in patient falls, freezing of gait, cognitive function, or sleep in either group. Nonetheless, the improvements in walking speed and step time / length, as well as the biological changes measured, were promising.
Future uses of nVNS for Parkinson’s
The use of VNS has already been approved for diseases such as epilepsy and has shown potential in treating headaches, pain and depression. Furthermore, earlier studies on nVNS found the therapy to reduce gait impairment in Parkinson’s patients. Although future studies are still required to determine if nVNS could one day replace conventional treatment, the study’s researchers are optimistic.
“This study has provided preliminary evidence supporting the efficacy and safety of nVNS in treating motor and non-motor symptoms of Parkinson’s disease (PD)”, they wrote. “Larger, multi-centre trials of nVNS in PD are now warranted.”
Written by Natan Rosenfeld