Neurofeedback-Assisted Mindfulness Techniques to Reduce Symptoms of Mental Distress

The present study is a single-blind, randomized-controlled clinical trial involving 80 healthy, meditation-naïve adults. All participants will be randomly assigned to either take part in experimental neurofeedback training or control (sham) neurofeedback training. Each training consists of 10 training sessions, with a frequency of 2 sessions per week (i.e., 5 weeks total training duration).

During each neurofeedback training session, participants will sit in front of a computer screen in a dimly lit room. Each training session will start and finish with a self-report mood assessment (POMS) and a 2-minute neural resting-state recording. In-between, participants will take part in 10 consecutive 2-minute neurofeedback trials. During these trials, participants are instructed to close their eyes and focus their attention on a specific point of their body (i.e., an anchor point). Simultaneously, neural recordings will be made, and reinforcing auditory cues will be presented upon the measurement of non-harmonic ratios between alpha and theta rhythms at the Pz channel. Participants are informed that the feedback sounds serve as positive feedback for their ability to engage in a neurophysiological state associated with meditative practice for stress regulation, and that this sound will assist their body in self-regulating to sustain this desired state. The sham training will be indistinguishable from the experimental biofeedback training for the participants involved. However, during the sham training, auditory cues will be unrelated to the participant's underlying brain activity, presented at random timepoints and therefore, no specific training can occur. After every two training trials, participants will be asked to indicate their levels of focus, sleepiness, and relaxation.

The investigators will measure psychological, neurophysiological, and biological mental health outcomes before the start of the training (T0), following the end of the training (T1), and again at the 5-week follow-up (T2).

During these three assessment points, participants will complete self-report questionnaires on emotional distress (DASS), mindfulness skills (CHIME), perceived stress (PSS), repetitive negative thinking (PTQ), and sleep quality (PSQI). Next, neurophysiological measurements will be made during a 5-minute eyes-closed resting state recording, during a 10-minute eyes-closed focused attention meditation, and during eyes-closed stress induction (3 min) and recovery (17 out of 57 min). Stress will be induced by utilizing the cold pressor task procedure which involves the participant submerging their hand into cold water (0-2°C) for a duration of three minutes while being perceived to be recorded by a video camera. Cortisol samples will be obtained right before the stress induction (T0), during the expected cortisol peak (T0 + 20 minutes) and after a recovery period (T0 + 60 minutes).

In addition, the day following each assessment session, participants will be asked to apply mobile health patches for ambulant recording of their cardiac activity for a duration of 24 hours. At the same time, stress reactivity in daily life will be assessed using the experience sampling method. To this end, participants will be prompted on their smartphones at semi-random moments during the daytime to indicate how they are feeling for 4 consecutive days (10 prompts per day). Finally, in the morning of each assessment day, participants will collect salivary samples for the assessment of cortisol and oxytocin levels.