An Ecological Momentary Intervention for the Reduction of Impairment in Somatic Symptom Disorder

Somatic symptoms, particularly when medically unexplained, are common stress‐relatedhealth issues that significantly affect the daily lives of those experiencing them,especially in the more severe form known as Somatic Symptom Disorder (SSD). Specificnegative psychological factors (NPFs), such as catastrophizing, negative affectivity, andrumination about somatic symptoms, may contribute to the intensity of and impairmentcaused by somatic symptoms (Mewes et al., 2022). The intensity and impairment associatedwith somatic symptoms are crucial outcome variables for both clinicians and thoseaffected, and should therefore be considered in intervention studies (Rief et al., 2017).The best psychological treatment for somatic symptoms is cognitive behavioral therapywith low to moderate effect sizes (van Dessel et al., 2014). Considering the long waitingtime for a therapy appointment and the small effect size, other interventions should beconsidered. Ecological Momentary Interventions (EMIs; Heron & Smyth, 2010; Mewes, 2022)provide a promising approach for delivering interventions in real time, directly inpeople's daily lives and their natural environment. By collecting real‐time data, EMIscan provide insights into the dynamic relationship between NPFs and somatic symptoms thatwould otherwise go unnoticed. Because they can address specific events as they occur,EMIs also enable just‐in‐time interventions in daily life. In addition, real‐timeassessment of treatment outcomes can contribute to the evaluation of effectiveinterventions. Music listening could be such an intervention. Music listening plays animportant role in pain management (Frei & Szucs, 2025) as listening to music inaccordance with the individual music preference has an analgesic effect on pain (Van derValk Bouman et al., 2024). Music that is perceived as happy predicts the reduction ofintensity and impairment caused by somatic symptoms in people with SSD (Feneberg et al.,2021). Thus, music listening seems to be a promising low‐threshold intervention in dailylife. Another promising approach to reduce somatic symptoms is cognitive reappraisal,since people with SSD show significantly less use of cognitive reappraisal than healthyindividuals (Schnabel et al., 2022). When cognitive reappraisal is used as a standaloneintervention, it reduces symptom annoyance in individuals with medically unexplainedsomatic symptoms (Kleinstäuber et al., 2019). Furthermore, when combined with otherCognitive Behavioral Therapy interventions such as stress management, it leads to animprovement in the impairment caused by somatic symptoms (Allen et al., 2006; Visser &Bouman, 2001). The present study will examine the effects of an EMI in individuals withSSD, employing an intraindividual randomized controlled design with repeated measures.The investigators hypothesize that, from baseline (week 1) to post‐intervention (week 6),participants will show a reduction in the weekly average intensity of somatic symptoms, areduction in impairment due to somatic symptoms, and a reduction in the strength ofnegative psychological factors (intermediate effect). Furthermore, the investigatorshypothesize that, following an acute event, impairment due to somatic symptoms, theintensity of somatic symptoms, and the severity of negative psychological factors willdecrease more during an intervention event than during a control event (immediateeffects). In addition, the investigators expect a decrease in somatic symptom severity asmeasured by the Patient Health Questionnaire‐15, a decrease in symptom‐related distressas measured by the Somatic Symptom Disorder ‐ B Criteria Scale, and a change in perceivedstress as measured by the Perceived Stress Scale ‐10 from pre‐intervention (before week1) to post‐intervention (after week 6). Finally, the investigators hypothesize thathigher expectations regarding future somatic symptom intensity will be associated withhigher somatic symptom intensity at the subsequent assessment, and that higherexpectations regarding future somatic symptom impairment will be associated with highersomatic symptom intensity at the subsequent assessment (fixed measurement pointsthroughout the day). Potential participants will be recruited through flyers, onlineannouncements, and potentially newspaper advertisements. The participants will beGerman‐speaking individuals with SSD. Participants will be screened for SSD using asemi‐structured interview based on the DSM‐5, an operationalization used in a previousstudy (Mewes et al., 2022). The sample size was calculated using G*Power (Faul et al.,2007) for an F‐test in a repeated‐measures ANOVA with the within factors. The mainoutcome is a change in somatic symptoms, with an estimated effect size of f = 0.35 basedon Kleinstäuber (2011), and an assumed correlation among repeated measures of 0.3. With adesired power of 0.90, an alpha error of 0.05, one group, two measurement points (averageimpairment levels baseline vs. post‐intervention), and a nonsphericity correction of 1,the required total sample size was 33 participants. To ensure robustness and improvegeneralizability, and considering a dropout rate of 20%, the aim is to include 40participants. Potential study participants will either undergo an initial onlinescreening, during which they will be informed about the study and then contacted by usvia phone, or proceed directly to a phone screening. During this call, information aboutthe study will be provided, and a semi‐structured interview to check for SSD will beconducted (Mewes et al., 2022). Upon receiving verbal consent to participate in thestudy, an appointment for the distribution of study materials will be arranged. Ifparticipants give their verbal consent during the phone screening, they can completequestionnaires, including potential control variables, before the distributionappointment. A link to the pre‐questionnaire on SoSci Survey (Leiner, 2024) will be sentvia email. If consent is not given during the phone screening, these questionnaires willbe completed at the distribution appointment after consent is obtained. At thedistribution appointment, the study information will first be discussed with theparticipants, and written consent to participate in the study will be obtained.Additionally, study materials (either a study smartphone or the installation of an app onthe participants' smartphones) and a study manual will be distributed. The EMI begins oneday after material distribution. After the post phase of the EMI, participants will againcomplete questionnaires on SoSci Survey (Leiner, 2024) regarding somatic symptoms. Areturn date for the materials will be scheduled via email. At the return appointmentafter the study period, all study materials will be collected. To achieve the researchobjective, an intraindividual randomized controlled trial will be conducted. An EMI willbe conducted, which will be administered using the software MovisensXS. The studyconsists of three phases spanning a total of 42 days: The baseline phase (7 days), theintervention phase (28 days), and the post phase (7 days). During all three phases, datawill be collected three times a day (11 am, 4 pm, and a self‐initiated eveningassessment). Additionally, in the intervention phase, an additional measurement pointoccurs 20 minutes after the evening assessment. During all three phases, participantsreceive prompts through the app at 11 am and 4 pm. The evening assessment can beinitiated before going to bed by pressing a button in the app; participants will alsoreceive a reminder at 9 pm. Additionally, participants will be asked to makeself‐initiated event‐based inputs by pressing a button in the app whenever they feelacute somatic symptoms. They will then receive event‐related questions immediately and 20minutes later via a prompt. During the intervention phase, participants will be randomlyassigned each day to either an intervention event or a control event. The interventiontakes place in the evening and after self‐initiated measurements, which are carried outdue to impairment caused by somatic symptoms. On any given day, participants will have a50% chance of receiving no intervention, and a 25% chance of receiving either musiclistening (Intervention 1) or cognitive reappraisal (Intervention 2). On days allocatedto the intervention event, after the evening measurement, participants will engage in afixed exercise session and receive another prompt 20 minutes after. In the control event,there will be no exercise between the measurement time points. In addition, at theevent‐based measurements, participants will again be randomly assigned in a 50:25:25ratio to either continue with their current activity (control condition), engage in musiclistening (Intervention 1), or perform a cognitive reappraisal task of their somaticsymptoms (Intervention 2).