Trial Outcomes & Findings for Impact of Transcutaneous Vagal Nerve Stimulation on Stress Response in Major Depression (NCT NCT04448327)

Impact of Transcutaneous Vagal Nerve Stimulation on Stress Response in Major Depression

A functional magnetic resonance imaging (fMRI) analysis was used to evaluate changes in brain activity \[blood oxygenation level-dependent (BOLD) signal\] in response to a visual stress challenge during transcutaneous vagus nerve stimulation. For this analysis a General Lineal Model analysis with the statistical parametrical software (SPM) was used to model the change in BOLD signals during exposure to negative vs neutral images of the stress task. A voxel-wise height threshold of p\<0.001, and a cluster correction with FWE p-value \<0.05 was used to identify brain areas with significant activation in response to the task. Mean beta weights within each significant cluster were extracted for each participant, and average beta weights were estimated for each group. A positive value indicates increased activation of a particular brain region in response to the stress task during the stimulation, whereas a negative value indicates a reduction in brain activity.

Cardiac pulsatility data were collected during baseline and exposure to a visual stress task. Interbeat intervals were estimated, and a point-process algorithm was then used to evaluate heart rate variability dynamics in the classic spectral components within the high-frequency (HF) and low-frequency (LF) ranges. Normalized HF \[HFn=(HF/(LF+HF))\] values were estimated during exposure to the stress task as a metric of parasympathetic regulation. The percent change in HFn (during the stress task vs baseline) was calculated for each intervention group. A positive percent change value indicates an increase in cardiovagal activity, whereas a negative change indicates a reduction in cardiovagal activity.

Changes in serum cortisol levels from baseline to post-stimulation will be assessed and compared between active and sham tVNS

Changes in serum levels of proinflammatory cytokines (IL1B, IL6, TNF alfa) from baseline to post-stimulation will be assessed and compared between active and sham tVNS

Changes from baseline to post-stimulation in the score of the Beck Depression Inventory will be compared between active and sham tVNS. (Beck depression inventory minimum score= 0, maximum score= 63; higher total scores indicate more severe depressive symptoms)