Description

After consenting to participate in the study, participants will complete a baseline survey battery online via REDCap while with the Research Coordinator/Research Assistant (RC/RA) in the consent/screening call. During this call, the RC/RA will also schedule the participant's two in-person lab visits. The first lab visit will be scheduled for approximately one week from the consent call, but no more than two weeks from the consent call and baseline survey battery. The second lab visit will take place 1 week after the first lab visit +/- 3 business days if the participant or study team need to reschedule for any reason. Participants will attend a final virtual visit on Zoom or Google Meets 1 week (+/- 3 business days) after the second lab visit to complete follow-up surveys via REDCap.

A trained RC/RA will run participants through lab visits 1 and 2, and at least one senior study team member will be present in the Center for Mindfunless and Compassion (CMC) office space during the visit so that they are available to help troubleshoot if issues arise with the RAVANS stimulation set-up.

During lab visit 1, participants will: complete a 30-minute survey battery via REDCap on a study computer, engage in four 5-minute resting periods for heart rate variability measurements spaced throughout the session, complete a fit test to set up the RAVANS device and ear electrode, and engage in a drinking-related stimuli exposure task including visual cues. After visual cues participants will have initial 10 minute exposure to either active or inactive RAVANS stimulation based on randomization. Additionally, participants will complete a short set of surveys at the end of the visit.

During lab visit 2, participants will: complete a 30-minute survey battery via REDCap on a study computer, engage in four 5-minute resting periods for heart rate variability measurements spaced throughout the session, complete a 30-minute session with active or inactive RAVANS while listening to a mindful breathing audio recording. Participants will be exposed to visual drinking related cues twice: once without the RAVANS device and once with the RAVANS device (active or inactive depending on randomization status). Additionally, participants will complete a short set of surveys at the end of the visit.

Survey Battery:

Participants will fill out a series of self-report assessments in REDCap (see Data/Specimen Collection Procedures for list of assessments). They will complete these assessments at each lab visit and during a follow-up virtual visit approximately 1-week after lab visit 2.

HRV Set-Up and 5-minute Rest Periods:

After completing the questionnaires, each participant will be guided through putting on a Movesense MD device. This device is a wearable ECG sensor that is worn over the heart area using one of three chest straps (small, medium, or large) designed for use with the device. The Movesense MD will use a Bluetooth transmitter to deliver heart rate data to a device with Kubios Heart Rate Variability (HRV) Scientific software installed for data handling. Once a participant has put on the Movesense MD device and a member of the research team has confirmed that the device is functioning properly, the participant will be asked to find a comfortable position in their seat and try to sit still without thinking about anything in particular while their resting heart rate variability is measured for 5 minutes. Participants will complete similar 5-minute rest period throughout the lab visit protocol.

Drinking-Related Stimuli Exposure:

Participants will complete an alcohol-related cue reactivity task designed to assess the effects of alcohol-related visual stimuli on autonomic nervous system function, as measured by heart rate variability (HRV). The task will be administered on a study computer using the PsychoPy stimulus presentation toolbox for the Python programming language. The task includes both still images and video clips, some depicting alcohol-related content (e.g., alcoholic beverages, people drinking, alcohol branding), and others depicting neutral content unrelated to alcohol. Visual stimuli are categorized into four types:

Alcohol-related still images Neutral still images Alcohol-related video clips (e.g., alcohol commercials) Neutral video clips (e.g., product commercials unrelated to alcohol) Stimuli will be presented in blocks. Each block of still images will include four images of the same category (alcohol or neutral), each displayed for 5 seconds, for a total of 20 seconds per image block. Video blocks will consist of a single 20-second clip. Blocks will be pseudorandomized to avoid sequential repetition of the same stimulus type and to ensure balanced exposure across conditions. Between blocks, a fixation cross will be presented for a variable inter-block interval (e.g., 10-20 seconds) to allow HRV to return toward baseline.

Electrocardiogram (ECG) data will be recorded continuously throughout the task to assess HRV responses to alcohol versus neutral cues. No alcohol will be physically present during the study session.

RAVANS and Mindful Breathing:

RAVANS transcutaneous vagal nerve stimulation (tVNS) will be performed with a reusable electrode attached to the surface of the cymba and cavum concha of the auricle. A fit test will be conducted to ensure that the participant is using the proper electrode for their ear shape and size. A small current will be delivered with a constant current stimulator. For active tVNS, current amplitude will be set between the sensitivity threshold and the pain threshold for each subject. The output current will be increased gradually to a maximum of 5 milliamperes (mA) in 0.25-mA increments to allow accommodation to the stimulation until a comfortable tolerance level is reached. For inactive stimulation, electrodes will be placed in the same location of active tVNS but no electrical pulses will be administered. Both the active and inactive RAVANS tVNS groups will be told that they may or may not be able to feel the stimulation that the device is delivering. Respiratory gating for stimulation will require real-time evaluation of the respiratory cycle. A pneumatic belt will be placed around the subject's lower thorax. Low-compliance tubing will connect this belt to a pressure transducer (Omegadyne, Inc., Sunbury, Ohio), thereby producing voltage data that corresponds to changes in respiratory volume. The voltage signal from the transducer will be acquired by a laptop-controlled device. An adaptive threshold detection method will be employed to detect end-inspiration and end-expiration in real-time and send a Transistor-Transistor Logic (TTL) signal to a miniature high-frequency relay (Omron Electronics Components, Shaumburg, IL), controlling the timing of the stimulation. Correct respiratory-gated stimulation will be confirmed by the experimenter via running chart of the respiration signal and stimulus pulse. After the RAVANS device has been set up and calibrated, the participant will be guided through using the device during a mindful breathing practice for 30 minutes.

Intervention Week:

Participants will be provided a 10-minute audio meditation. They will be encouraged to listen to it daily during 6 out of the 7 days between lab visit one and lab visit two.

1-Week Follow-Up procedures: The study team will schedule a virtual visit with participants for 1-week after their 2nd lab visit. This visit will take place via Zoom or Google Meets. Participants will complete the final survey battery via REDCap on the call with a study team member to ensure robust data collection for this final timepoint. This visit will take 30-45 minutes. At the end of this visit, participants will be informed that study activities are complete and that their participation in the study has ended.