Non-invasive vagus nerve stimulation normalizes food liking and improves liking ratings in depression

Abstract

Introduction: The vagus nerve plays a prominent role in the regulation of food reward and energy metabolism. However, previous studies using vagus nerve stimulation yielded conflicting results regarding changes in food reward in healthy participants and participants with major depressive disorder (MDD), for which vagal nerve stimulation is an effective treatment. Methods: We investigated the acute effects of right transcutaneous auricular vagus nerve stimulation (taVNS) on ratings of liking and wanting of food and non-food items in 63 participants, including 31 patients with MDD. To test for taVNS-induced changes and interactions with between-subject variables group (MDD vs. healthy controls) and questionnaire scores as well as within-subject variables, we performed linear mixed-effects analysis. In addition, we assessed whether individual taVNS-induced changes in food reward ratings were dependent on average ratings.Results: taVNS increased liking of food cues in participants with MDD (p= 0.023), but not in healthy participants (p= 0.657). Specifically, taVNS induced larger improvements in liking ratings with increasing scores of anhedonia (p= 0.029). Notably, across all participants, taVNS reduced the variance of food liking compared to sham, suggesting that taVNS normalizes extreme liking ratings towards moderate levels (p = 0.039).Discussion: Our results show that taVNS acutely ameliorates hedonic responses in MDD suggesting that it could provide an effective treatment of anhedonia. Since anhedonia is difficult to treat with conventional therapies, taVNS may provide a powerful adjuvant to rapidly improve motivational deficiencies.

Non-invasive vagus nerve stimulation in a hungry state decreases heart rate variability and wanting of a palatable drink

“…This is in agreement with the observation that nVNS increases drive to obtain less-wanted prospective food rewards [22] and increases liking of less-liked low-fat puddings [21]. Other studies have not shown effects of increases in liking or wanting of food (images) in healthy controls [42,43]. Perhaps effects of nVNS vary as a function of food stimulus saliency, which is presumably higher when it is sufficiently proximal (in the mouth) [21] or the object of a goal-directed task…”

Non-invasive vagus nerve stimulation conditions increased invigoration and wanting in depression

“…In contrast, HCPs had no history of depression. We only included participants without other mental comorbidities apart from anxiety disorders (in HCP only specific phobias) and tobacco use disorder 56 . Participants provided written informed consent at the beginning of Session 1 and received either monetary compensation (32€ fixed amount) or course credit for their participation after completing the second session.…”

“…After a food-cue reactivity task (∼20 min; 56, 60 ), participants completed the EAT (∼40 min). The EAT 16 , was adapted from 62 and assesses reward-related processes by the willingness to exert physical effort to gain food or money rewards depending on the difficulty and reward magnitude.…”