Stress-Mediated Widespread Hypersensitivity in People with Irritable Bowel Syndrome

MATERIALS: Both groups will be screened for the minimum eligibility criteria over the phone in the recruitment phase using the “Medical Checklist”. The Medical checklist was composed for this study to rule out any physical or psychiatric variables that may put the participant at risk during the experiment or may confound the results. The remaining questionnaires will be completed before the participant begins the experiment session. Demographic Demographic variables will be assessed in “Generic Demographic Questionnaire”. Questions include: age, gender, ethnicity, height, weight (used to calculate BMI), smoking status. Depression, anxiety and stress DASS21 The DASS21 (Lovibond & Lovibond, 1995) is a shortened version of the original 42 item self-report measure of depression, anxiety and stress that has demonstrated adequate reliability and validity in normative (Crawford & Henry, 2003; Henry & Crawford, 2005) and clinical samples (Antony, Bieling, Cox, Enns, & Swinson, 1998; Brown, Chorpita, Korotitsch, & Barlow, 1997). It is opted for in place of the Beck Depression Inventory used in (Piche et al., 2010; Piche et al., 2011) to get baseline measures of trait stress and anxiety which is relevant to the proposed study. Those participants who meet caseness on the DASS21 for depression or anxiety will be included in the study and their scores controlled for in the data analysis. They will also be notified of their scores for the purposes of enabling them to seek medical attention if they wish. The Pain Catastrophizing Scale (PCS) The PCS (Sullivan, Bishop, & Pivik, 1995) is a 13 item scale that asks respondents to reflect on a painful experience and the frequency they were thinking or feeling each item in relation to that experience. It has three subscales: rumination, magnification and helplessness. The PCS has been found to significantly independently predict conditioned pain modulation in IBS participants (Piche et al., 2011) Pain unpleasantness and intensity Pain unpleasantness and intensity will be measured on two separate numeric rating scales. Each 11-point (0-10) scale will be anchored at three points: no pain/unpleasantness (0), moderate pain/unpleasantness (5), extreme pain/unpleasantness (10). Unpleasantness will include both unpleasantness related to pain and non-painful discomfort produced by the stimulus (Piche et al., 2010). Stress Stress will be measured on a 11 point (0-10) numeric rating scale anchored at three points: no stress (0), moderate stress (5) and extreme stress (10). Triers Social Stress Test (TSST) The TSST (Kirschbaum, Pirke, & Hellhammer, 1993) is commonly used test to experimentally induce a stress response from which physiological measures can be taken as a proxy for how stressed the individual is. The aim of the TSST in this study is elevate levels of stress for which perceived and actual stress levels can be measured. The public speaking component of the TSST will be utilised (see procedure) and participants will be given a sheet with a list of five topic pointers: What is your dream job? Why do you want this job? Why do you think you deserve this job? What personal attributes do you bring to the position? What are some of your personal strengths and weaknesses? Physiological measures Heart rate (HR) and heart rate variability (HRV) will be monitored using a RS800 Polar HRV wristwatch and chest band which is non-invasive (Darragh, Vanderboor, Booth, Sollers, & Consedine, 2015). HR and HRV will be used as objective measures of stress and worn by the participants for the duration of the experiment where HR is used as an index of physiological arousal and HRV measures the variance between adjacent beats (Sztajzel, 2004). Cold packs A pack of five reusable Green Cross hot/cold packs will be ordered from Industrial First Aid Supplies Limited. Uni-Grip elastic tubular support bandages will be placed around the cold pack over the arm to hold the cold pack in place. Kleenex antibacterial wipes will be used to clean the ice pack and the bandages will be washed between participants. Participant information sheet and consent forms: Both IBS patients and controls will receive PIS-CF so read and sign before attending the lab session. The document is 6 pages long and includes information about the study, what their participation would involve, safety measures, ethical statements that require consent and contact information. PROCEDURE: The procedure for this study is in two general stages. The first stage is the recruitment and screening stage and the second stage is the experiment session. IBS patients and healthy controls will undergo the same procedure with minor differences in the recruitment and screening stage. IBS patients will be identified from patient records through the Department of Gastroenterology and Hepatology and contacted by telephone to invite them to participate in the study. If they are interested they will be screened for the minimum inclusion and exclusion criteria. If they meet the inclusion criteria, they will be sent a participant information sheet and consent form. They will be followed up a few days later when their consent form has been received to ensure that they are still interested in the study and if they have any questions. Next they will be booked into an experiment session at the University of Auckland Clinical Research Centre. Healthy controls will be recruited by flyers placed in various public spaces and posts on relevant Facebook pages. They will be given a number that they can contact me on where the procedure from this point will then be the same as for the IBS participants. The second stage is the experiment session which will be the same for both groups with the only difference being that IBS patients will have additional questionnaires to complete. The experiment will take place in a closed body room where the power is not connected the the mains. When the participants arrive for the experiment session, they will be asked to complete a series of questionnaires. IBS participants will complete an IBS information checklist, a demographic questionnaire, and the short version of the Depression, Anxiety and Stress Scale (DASS21), the Pain Catastrophizing Scale as well as completing a hard copy of the inclusion and exclusion criteria that they were screened for on the phone (Medical Checklist –IBS). Healthy controls will complete all of these questionnaires except the IBS information checklist. The experiment will involve taking objective and subjective measures of pain and stress. The general procedure is in three stages: 1. establish baseline pain and stress measures during a counter-irritation paradigm, 2. complete a stress task, 3. repeat the counter-irritation paradigm. The pain stimulus will be electrocutaneous delivered by an electrode to the forearm and the counter-irritation paradigm will be based on methods of Piche et al. (2010). The equipment is expected to be a PowerLab and Digitizer/Stimulator made by ADInstruments. The counter-irritation paradigm will be modified version based on the methods used by Piche et al. (2011) and (Piche et al., 2010). Electrical stimulation will begin with a stabilization period which aims to control habituation that can occur during this kind of stimulation. Shocks will be delivered approximately every 12 seconds. Then a baseline period will begin where 10 stimuli are delivered every 12 seconds followed by the induction of the counter-irritation stimulus where a cold pack at -12C will be wrapped around the contralateral forearm for two minutes while another 10 electrical stimuli are delivered every 12 seconds. The cold pack will be held in place using a bandage sleeve. After two minutes the cold pack will be removed and another 10 stimuli ever 12 seconds will be delivered which constitutes the recovery period. Ratings of pain intensity, pain unpleasantness and stress will be made on numeric rating scales before stabilisation, before the application of the cold pack and after the removal of the cold pack. Pain unpleasantness, pain intensity and stress ratings in response to counterirritation stimulus (cold pack) will be made at the end of the recovery period. Numeric rating scales will be printed off as slips for the participants to complete. This is to avoid experimenter effects and impression management bias which can result from from participants scoring out loud. The PCS will also be completed at the end of the recovery period The level of electrical stimulation delivered will be based on a modified version of the staircase method established in earlier studies such as Gracely, Lota, Walter, and Dubner (1988) and (Willer, 1977). This method has been modified in two recent studies; (Piche et al., 2010; Piche et al., 2011) in which the method of this study will aim to partially replicate. Participants will be subject to an increasing level of stimulation until pain tolerance is reached, 80% of that stimulation will be used to deliver the electrical stimulation at for each participant. This will be established using a pain intensity numeric rating scale where 80% of tolerance will be inferred at when a score of 8 is given. After the counter-irritation paradigm, participants will then engage in a 10 minute resting period (Kirschbaum et al., 1993) before beginning the TSST. The stress task will be a modified TSST which will involve the participant preparing a five-minute speech to present to A ‘selection committee’ about why they should receive their dream job. They will have 10 minutes to prepare this speech using topic pointers but they cannot use this during the delivery of their speech. They will also be informed that their speech will be recorded to perform a voice analysis on later. This will involve one of the committee members holding up their phone and pointing it at the participant claiming to be filming them. In reality, the participant is not being filmed and this deception is used to help elevate stress levels. When they have completed the stress task, they will have a five-minute rest period. Finally, they will engage in the counterirritation-paradigm described above to test for the effects of stress on the pain responding. For the entire duration of the experiment, participants will be wearing a polar watch which will be recording their heart rate and heart rate variability which will be used and an objective measures of stress. At the end of the experiment participants will be debriefed about not being filmed while delivering their speech and will be invited to ask any questions or raise any concerns. WHO: I, Katrina Simpson, will be conducting the experiment. I am second yer Master in Health Psychology student. I have worked for the non-emergency triage service for the NHS while living in the UK. MODE: The experiment involve initially screening participants over the phone then will be run face-to-face and will involve myself and one participant at a time. DURATION: The experiment will be a one-off, one hour laboratory session. Please see "procedure" above for information about the delivery of the conditioned pain modulation paradigm. LOCATION: The experiment will be held in the Department of Physiology labs, in the University of Auckland Medical school. PERSONALISATION: Each participant will have their pain tolerance established to which shocks will be delivered at 80% (see PROCEDURE above).