Reduction in left frontal alpha oscillations by transcranial alternating current stimulation in major depressive disorder is context-dependent in a randomized-clinical trial

Abstract

Background: Left frontal alpha oscillations are associated with decreased approach motivation and have been proposed as a target for non-invasive brain stimulation for the treatment of depression and anhedonia. Indeed, transcranial alternating current stimulation (tACS) at the alpha frequency reduced left frontal alpha power and was associated with a higher response rate than placebo stimulation in patients with major depressive disorder (MDD) in a recent double-blind placebo controlled clinical trial. Methods: In this current study, we aimed to replicate such successful target engagement by delineating the effects of a single session of bifrontal tACS at the individualized alpha frequency (IAF-tACS) on alpha oscillations in patients with MDD. Electrical brain activity was recorded during rest and while viewing emotionally-salient images before and after stimulation to investigate if the modulation of alpha oscillation by tACS exhibited specificity with regards to valence. Results: In agreement with the previous study of tACS in MDD, we found that a single session of bifrontal IAF-tACS reduced left frontal alpha power during the resting state when compared to placebo. Furthermore, the reduction of left frontal alpha oscillation by tACS was specific for stimuli with positive valence. In contrast, these effects on left frontal alpha power were not found in healthy control participants. Conclusion: Together these results support an important role of tACS in reducing left frontal alpha oscillations as a future treatment for MDD. National Clinical Trial: NCT03449979, Single Session of tACS in a Depressive Episode (SSDE) https://www.clinicaltrials.gov/ct2/show/NCT03449979 .

Effect of tACS on prefrontal neural activity is menstrual phase dependent in patients with premenstrual dysphoric disorder

“…Critically, the analysis of brain activity as a function of menstrual phase prior to stimulation provides an understanding of the neural activity that was impacted by stimulation. In our previous study on major depressive disorder, we found that patients within a major depressive episode showed elevated left frontal alpha oscillations while processing positive valence images and that this pathologically elevated left frontal alpha activity was reduced by alpha-tACS (Riddle et al, 2022). By contrast, in this case series, patients with PMDD showed decreased alpha activity over the frontal-midline during the late luteal phase and this activity was increased by alpha-tACS.…”

Network Action of Subcallosal Cingulate White Matter Deep Brain Stimulation

“…Marginalized across channel, the α and β * oscillatory powers demonstrate significant, consistent deviations from zero (Figure 3c) indicating that different patterns of EEG changes are evoked across the scalp. While DBS has historically focused on β oscillations[10, 35, 36], including in our own group’s intraoperative observations [13, 37], α has been shown to be modulated by neuromodulation [8, 38] and to be linked to depressed mood [39, 40, 41, 42, 43].…”

Neurostimulation as a treatment for mood disorders in patients: recent findings

“…The left dlPFC plays a key role in positive emotions and it is sometimes affected by disorders that lead to increased alpha oscillations in EEG. According to the study, increased left frontal alpha oscillations are associated with MDD, tACS can reduce these oscillations [24].…”