The repeated Montreal Imaging Stress Test (rMIST): Testing habituation, sensitization, and anticipation effects to repeated stress induction

Background: A psychosocial task that can induce comparable levels of stress repeatedly is fundamental to effectively study changes in stress reactivity over time or as a result of an intervention. However, existing tasks have struggled to provide consistent stress responses across repeated trials. Aim: The goal was to assess the efficacy of two different designs of the repeated Montreal Imaging Stress Test (rMIST) in reproducing the same pattern of reactivity over two separate sessions. Methods: In two different studies, stress was induced using the rMIST on two separate sessions, one week apart. Each study used a different task design. In the first study (53 participants [45 women]; mean age=24.16 [SD=3.29]), the rMIST consisted of a single-longer stress exposure, while the second study (30 participants [27 women]; mean age=21.81 [SD=2.09]) consisted of several shorter stress exposures per session. Self-reported (i.e perceived stress [PS] and negative affect [NA]), physiological (i.e heart rate [HR], root mean square of successive differences [RMSSD]) and hormonal (i.e. salivary cortisol) measures of stress were used. Results: Stress reactivity was comparable across the two repeated stress sessions in both studies. However, baseline HR in the second session increased relative to the first session in the first study, and there was no cortisol response. Additionally, there was a decrease in HR and HRV reactivity within the session on the second study, suggesting a habituation effect not between but within the session itself. Conclusion: The rMIST overcomes some of the challenges associated with repeated stress induction. However, an anticipation effect and a lack of cortisol response indicate that further adjustments to the task are necessary. Finally, task design is important for repeated stress reactivity.

Automated summary

This study examined the efficacy of repeated Montreal Imaging Stress Test in reproducing stress reactivity patterns across two different designs. While stress reactivity was comparable between repeated sessions, differences in heart rate and cortisol response indicate that further adjustments to the task may be necessary for improved consistency. Task design was highlighted as an important factor in repeated stress reactivity.