The effect of different emotional imagery scripts on end-tidal CO2, psychological affect, and physical complaints in healthy individuals

Background\nEmotions evoke alterations in an individual’s physiological and psychological state. In order to obtain insights into the interaction between emotions, psychological state, and physical complaints, we analysed the effects of different emotional imagery scripts on end-tidal CO2 (PetCO2), psychological affect and physical complaints in healthy individuals.\n\nMethods\nThe protocol was registered at clinicaltrial.gov (NCT04074798). Healthy individuals (n= 16) were randomly exposed to three different emotional imagery scripts (i.e., hostile-resistance, relaxation, and acceptance) while standing on an unstable support surface with closed eyes. End-tidal CO2 (PetCO2) values were measured during the emotional imagery trials. After each script, participants filled out questionnaires about their affect and their physical complaints by means of the Positive and Negative Affect Scale (PANAS) and the Dagelijkse Leven Klachten Lijst (DLKL), respectively. The effect of the script’s content on PetCO2, psychological affect and physical complaints was calculated with a repeated measures full factorial model. \n\nResults\nIntermediate analyses revealed a significant effect of script on affect (positive affect: p= 0.008, negative affect: p< 0.001 – See Fig. 1.3), but not on PetCO2 (p= 0.51 – See Fig. 1.1) and physical complaints (p= 0.053 – See Fig. 1.2). Post-hoc analyses demonstrated that individual’s positive affect was higher during the relaxation script compared to the hostile-resistance script (mean difference (MD)= -8.78). Negative affect was higher during the hostile-resistance script compared to both the acceptance (MD= -2.94) and relaxation (MD= -4.78) script. By March 2024, the sample size will be enlarged to 30 participants. \n\nConclusion\nIn line with our hypothesis and earlier research, inducing negative emotions evoked stronger negative affect compared to inducing positive emotions, and vice versa. However, no effects of emotions on physical complaints nor on PetCO2 were present. Future research should investigate these effects in clinical populations, such as individuals with low back pain.