In the largest and most well-controlled randomized control trial of mindfulness-based interventions (MBIs) training in irritable bowel syndrome (IBS) to-date (N=360), the investigators will evaluate whether a smartphone MBI program (with attention monitoring and acceptance skills training; Monitor+Accept, MA-MBI) reduces daily life stress and IBS symptoms at post-treatment and two-month follow-up, relative to a matched MBI program with acceptance skills training removed (training in attention monitoring skills only; Monitor Only, MO-MBI) or to an active stress management training control group (Coping Control, CC). Participants will not only provide clinician and patient assessed measures of IBS symptoms at the three time points, but they will also provide sensitive experience sampling assessments (using Ecological Momentary Assessment) of their stress and symptoms in daily life at each time point. Finally, as an exploratory aim, participants will provide stool samples at baseline and post-intervention to provide the first ever test of whether MBIs can alter the gut microbiome in IBS. We will also conduct a sub-study that will include completion of a cold-water challenge performance task to test individuals' distress tolerance.

All assessments and patient interactions have been designed with COVID-19 uncertainties in mind: the investigators can maintain social distancing and use masks during the two in-person visits, and much of the study, including the follow-up session, is conducted remotely.

Baseline Screening and Assessment. Individuals interested in participating will complete a brief online screening survey, and final study determination will be made by the recruitment project manager. For special cases where eligibility is in doubt or uncertain, members of the investigative team will be contacted to make a final determination. Each eligible participant will come to the Health and Human Performance laboratory at CMU for a baseline assessment appointment. They will be apprised of the study aims and approach, and provide written informed consent. Eligible participants will complete a baseline survey assessment (including measures such as IBS illness severity, IBS quality of life, demographics and health measures) and learn how to complete the EMA assessments on data-enabled smartphones. The EMA smartphone assessments will consist of three types of momentary experience data over a period of seven consecutive days following the baseline appointment: (1) participants will be quasi-randomly sampled 3 times per day during waking hours to assess stress, IBS symptoms, affect, coping, and mindful acceptance; (2) participants will be asked to complete event-driven momentary assessments of distress and IBS symptoms after bowel movements; and (3) participants will be asked to complete a daily diary assessment to assess IBS symptoms, IBS distress, social interactions, and loneliness and mood throughout the day. The investigators will implement an easy-to-use smartphone-enabled EMA sampling program that is downloaded onto each of the phones provided to participants for the duration of the study. Participants will be instructed to complete each EMA assessment within the allotted 60 minute window for quasi-random daily surveys, and within the allotted 3 hour window for daily dairy assessments. Additionally, participants will be given instructions on how to provide a baseline stool sample for microbiome analysis.

Intervention. Participants will be randomized to either MA-MBI, MO-MBI, or Coping Control (CC) using a 2:2:1 randomization sequence (i.e., for every five individuals randomized, 1 will be assigned to CC). Participants will remain blind to the type of intervention program they are receiving until post-study debriefing, to minimize potential expectancies. The MA-MBI program is a Mindfulness-Based Intervention (MBI). The instructed meditation techniques enable participants to (a) monitor their present-moment body experience while (b) accepting each experience. The MO-MBI program is structurally matched to the MA-MBI program, with no instruction on acceptance. The program instructs participants to concentrate on and (a) monitor physical and emotional body experience during each meditation practice. The Coping Control (CC) program, also matched to the MBI programs, includes no monitoring or acceptance instruction and instead focuses on coping effectiveness strategies. Participants are instructed in 3 skills: (a) thoughtful reflection; (b) reappraisal and reframing past and anticipated stressful events; and (c) problem solving, such as analyzing and solving personal problems. Each intervention begins with the same 5-minute introductory video and involves the completion of one 20-minute audio-guided lesson plus daily life homework practice (3-10 minutes) each day for 14 days. Lessons train specific techniques through didactic explanation and guided practices. After each lesson, participants will complete event-based assessments of stress and IBS distress. On Days 3 and 9 of the intervention program, study staff will contact participants by phone to answer training-specific questions, address difficulties, and encourage program adherence.

Post-Treatment Assessment. Participants in all three conditions will be asked to complete a week of EMA sampling in the week following the completion of the intervention programs, identical in form to their baseline EMA week. They will then come back into the lab for a post-intervention assessment of the same measures used during the baseline assessment, as well as to provide a second stool sample.

2-Month Follow-Up Assessment. Two months after the intervention, participants will complete a final week of EMA sampling. They will then be scheduled to complete a final assessment remotely, where they will complete the same trial outcomes assessment battery as they did at baseline and post-intervention. Additionally, participants will be asked to complete a treatment program evaluation survey measure at this time. After completing the study measures at the 2-month follow-up assessment, participants will be debriefed on the study aims and thanked for their participation.

CGI Assessment. A subset of participants (n=15) will be randomly selected to complete the Clinical Global Impressions Improvement Scale (CGI-I) at three time points - shortly after baseline, post-treatment, and at a 2-month follow-up. This assessment will be conducted by our Co-Investigator, Dr. David Levinthal. The CGI-I will incorporate baseline severity of IBS symptoms and the degree of clinical change relative to that baseline. Dr. Levinthal will provide these ratings of the patient's change in IBS symptoms (1=substantially improved to 7=substantially worse) at post-treatment and 2-month follow-up compared to baseline. These assessments will consist of open-ended questions related to the participant's IBS symptoms and the assessment will be based on a scale similar to Table 2 of the CGI article uploaded under Supporting Documents. The assessments will occur over Zoom or over the phone, and no recordings, neither audio nor visual, will be made. Dr. Levinthal will also be blind to the patient's treatment condition. Data collected from these clinical interviews will only be linked to the participant through study ID number, and Dr. Levinthal will complete the assessments over a secure web-based platform such as Qualtrics. The study team will provide Dr. Levinthal the contact information of the randomly chosen participant so that he can reach out to the participant to schedule these assessments. The team will then provide him the study ID number separately, ensuring that the contact information and study ID number are never linked together.

Cold Challenge Sub-Study. For participants who indicated that they would be willing to participate in the cold-challenge sub-study, they will be shown an instructional video outlining the cold-pressor task (as specified below). Once the participant submerges their left hand in the water, the experimenter will start a stopwatch and will ask the participant to rate their sensation intensity and distress verbally by showing them the visual chart. This will occur every 30 seconds up to 5 minutes, which at that point the participant will be asked to remove their hand. Once the participant's hand is on the towel, the experimenter will ask them to rate their sensation intensity and distress immediately and then again, every 30 seconds up to 2 minutes. They will then be allowed to move and dry their hand. To help the participant warm their hand up, the experimenter will recommend them to use a few strategies. These strategies include hand exercises (e.g., moving the hand in circles, clenching and releasing the hand), massaging the hand, and placing the hand under an armpit or a warm area of the body.

During the trial, the dataset will be locked and maintained by the independent unblinded study statistician and the unblinded project manager(s). The statistician will remain unblind to participant study condition during data collection and analysis (the unblinded statistician and unblinded project manager(s) will maintain an electronic file on a secure online database that links the study statistician randomization codes (1,2,3) to condition codes (A,B,C) that reference study conditions).

Inclusion Criteria:

• Rome IV IBS diagnosis
• Indicate moderate to high levels of psychological distress over the past two weeks (composite score >=4 on the Patient Health Questionnaire-4)
• Willingness to provide assessments of bowel symptoms and complete study measures (including smartphone assessments)
• Willingness/availability to be randomized and participate in all study activities

Exclusion Criteria:

• Non-English speaking
• Report a new diagnosis of a (non-acute) medical or psychiatric condition requiring treatment within the last 3 months
• Have a history of diagnosed IBD or gastrointestinal malignancies.
• Begun any new treatments for IBS in the four weeks prior to baseline
• Currently pregnant
• Had a colonoscopy within 2 weeks of enrolling in the study or within the first 4 weeks of study procedures
• CGI Interview Only: Is a patient of Dr. David Levinthal

Cold Challenge Sub-study. Exclusion criteria: an existing pain condition, Reynaud's disease, history of heart/cardiovascular disease, high blood pressure, recent injuries, circulatory disorders, current or past frostbite, open cuts, or sores in both hands, a history of seizures, asthma, sickle cell disease or trait, cerebrovascular disease, a recent stroke or heart attack, or anxiolytic medication (e.g., Ativan, Xanax) or pain medication (e.g., aspirin) taken in the 2 hours prior to the study, pregnant or might be pregnant, and/or have a tendency/history of fainting after vaccines, shots, and/or blood draws. Participants will be excluded if they have taken anxiolytic medication (e.g., Ativan, Xanax) or pain medication (e.g., aspirin) taken in the 2 hours prior to the lab session. Participants who report viral illness (e.g., cold) and/or negative physical health symptoms (e.g., stomachache, nausea, fever, dehydration, hunger, sleep deprivation) before the start of the session will also be excluded.

As they will be visiting our laboratory on campus, participants will now be required to show proof of COVID-19 vaccination to participate in the study. Participants must also show proof of a booster shot, if they do not have one, they will be asked to wear a mask at in-person sessions to participate. Moving forward, we will continue to follow CMU COVID protocols.

The research team will share data associated with self-reports (e.g. demographics, stress levels) and adherence by depositing the data at the Inter-University Consortium for Political and Social Research (ICPSR), which is an NIH-funded repository. All data and documentation will be de-identified and will be consistent with applicable laws and regulations. Submitted data will confirm with relevant data and terminology standards.

This data will be shared with investigators working under an institution with a Federal Wide Assurance (FWA) and could be used for secondary study purposes. The study team agrees that the names and Institutions of persons either given or denied access to the data, and the bases for such decisions, will be summarized in the annual progress report.

The study team agrees to deposit and maintain the phenotypic data and secondary analysis of data (if any) at ICPSR. The repository has data access policies and procedures consistent with NIH data sharing policies.

The study team agrees to deposit outcome data into the ICPSR repository three years after the end of the grant period.

The study team agrees that they will identify where the data will be available and how to access the data in any publications and presentations that they author or co-author, as well as acknowledge the repository and funding source in any publications and presentations. The study team will be using the ICPSR, an NIH-funded repository with policies and procedures in place to provide data access to qualified researchers, fully consistent with NIH data sharing policies, applicable laws, and regulations.

All study investigators and the participant (excluding the independent unblinded statistician and unblinded project manager(s)), will be blinded to condition assignment.