Effects of Transcutaneous Vagus Nerve Stimulation, Neurofeedback, and their Combination on Cortisol, Anxiety, and Depression Subtypes in Non-Clinical Adults.
Seyedeh Zeinab Molaeizadeh, Aitor Aritzeta Galan, Zahra Zolghadr
Applied psychophysiology and biofeedback · Dec 1, 2026
Non-invasive neuromodulation techniques such as neurofeedback (NF) and transcutaneous vagus nerve stimulation (tVNS) are attracting growing interest for their potential to influence brain activity and emotional regulation. This pilot study investigated the individual and combined effects of these methods on psychological measures, electrophysiological markers, and salivary cortisol. Twenty healthy young adults (19 females, 1 male, aged 18–24) participated, with outcomes including psychological measures (anxiety and depression), EEG Alpha / Theta ratio, and salivary cortisol. NF was associated with significant reductions in anxiety and depressive symptoms. Notably, despite the NF protocol directly targeting Alpha / Theta oscillations, a significant increase in the Alpha / Theta ratio was observed only in the tVNS group, indicating a distinct bottom-up influence on neural dynamics. The combined intervention did not yield additional benefits, and cortisol levels remained unchanged. These preliminary findings suggest that NF and tVNS may operate through distinct pathways—NF influencing psychological outcomes via top-down regulation and tVNS modulating electrophysiological activity via bottom-up pathways. The absence of sham control conditions limits causal attribution of effects. Given the small sample size (n = 5 per group) and exploratory nature of this study, these results should be interpreted as hypothesis-generating and require replication in larger, adequately powered trials. The online version contains supplementary material available at https://doi.org/10.1007/s10484-025-09764-4.
AnxietyDepressionPsychiatryPsychology
Learning in Neurofeedback is Heterogenous and Does Not Guarantee ADHD Symptom Improvement.
Elizaveta Kuznetsova, Roger de Beus, L Eugene Arnold, Evgenii Rudakov, Benjamin Ultan Cowley
Applied psychophysiology and biofeedback · Dec 1, 2026
Neurofeedback (NFB) is a non-invasive intervention for ADHD that aims to train self-regulation of brain activity. Despite decades of clinical application, evidence for its efficacy remains mixed, and the mechanisms-particularly the role of NFB learning in ADHD symptom reduction-are still not well understood. This study advances the NFB field by introducing both theoretically grounded and data-driven frameworks that conceptualize learning as a dynamic, individualized process. Data were drawn from a 25-month longitudinal randomized controlled trial of theta/beta ratio (TBR) NFB treatment in children with ADHD (N = 100; ages 7-10). Moving beyond prior work that characterized learning through binary classifications and group-level averages, we captured within- and between-session training dynamics and applied clustering methods to define distinct learner profiles, highlighting the heterogeneous nature of NFB responses. Our results demonstrate that while most participants learned to regulate TBR effectively, individual learning did not reliably predict symptom improvement. Instead, linear mixed-effects model results indicated that non-specific factors such as participant engagement and training context were more predictive of clinical outcomes. Moreover, variability in learning curve shapes-typically overlooked in standard NFB studies-suggests that NFB learning does not follow a uniform pattern, with individuals engaging through distinct mechanisms aligned with either operant-conditioning or skill-acquisition models. These insights advance theoretical understanding of NFB mechanisms and call for individualized, mechanism-informed approaches to optimize treatment outcomes and deepen clinical interpretation.
ADHDPsychiatryPediatrics
