Abstract
FMRI Montreal Imaging Stress Tasks (MIST) have been shown to activate endocrine and autonomic stress responses that are mediated by a prefrontal cortex (PFC)-hippocampus-amygdala circuit. However, the stability of the neurobehavioral responses over time and the ability to monitor response to clinical interventions has yet to be validated. The objective of this study was to compare the fMRI and physiologic responses to acute psychosocial stress in healthy volunteers during initial and follow-up visits approximately 13 weeks later, simulating a typical duration of clinical intervention. We hypothesized that responses to stress would remain highly conserved across the 2 visits in the absence of an intervention. 15 healthy volunteers completed a variant of control math task (CMT) and stress math task (SMT) conditions based on MIST. Neural responses were modeled using an event-related design with estimates for math performance and auditory feedback for each task condition. For each visit, measures of stress reactivity included differential fMRI and heart rate (SMT-CMT), as well as salivary alpha-amylase before and after scanning sessions. The results revealed that differential fMRI, as well as increased heart rate and salivary alpha-amylase from before and after scanning remained similar between visits. Intraclass correlation coefficient (ICC) values revealed areas of reliable task-dependent BOLD fMRI signal response across visits for peaks of clusters for the main effect of condition (SMT vs CMT) within dorsal anterior cingulate cortex (ACC), insula, and hippocampus regions during math performance and within subgenual ACC, posterior cingulate cortex, dorsolateral PFC regions during auditory feedback. Given that the neurobehavioral response to acute stress remained highly conserved across visits in the absence of an intervention, this study confirms the utility for MIST for assessing longitudinal changes in controlled trials that can identify underlying neurobiological mechanisms involved in mediating the efficacy of stress-reduction interventions.
Highlights
The endocrine and autonomic responses to acute stress are part of the allostatic process that serves to maintain homeostasis in response to a threat (Ulrich-Lai and Herman, 2009; Karatsoreos and McEwen, 2011)
The results indicated that responses to acute psychosocial stress during Montreal Imaging Stress Tasks (MIST) remained largely consistent between Visit 1 (V1) and Visit 2 (V2)
Given that participants improved in response time during the control math task (CMT) and providing correct answers during the stress math task (SMT) condition after the initial visit, these results suggests that improvements in reaction time accuracy may reflect repeated testing effects and may not serve as a valid assessment of improvements to stress management
Summary
The endocrine and autonomic responses to acute stress are part of the allostatic process that serves to maintain homeostasis in response to a threat (Ulrich-Lai and Herman, 2009; Karatsoreos and McEwen, 2011). Prior studies utilizing MIST have demonstrated that a prefrontal cortex (PFC)-hippocampus-amygdala circuit mediates endocrine and autonomic stress responses (i.e., Pruessner et al, 2008; Dedovic et al, 2009a; Khalili-Mahani et al, 2010; Allendorfer et al, 2014; Wheelock et al, 2016, 2018; Goodman et al, 2019) Despite these contributions to our understanding of the neurobiology of stress, the utility of MIST for assessing longitudinal within-subject changes in reactivity to a common stressor has yet to be validated. Demonstrating the validity of MIST to examine the neurobiological benefits of clinical stress-reduction techniques first requires an assessment of the neurobehavioral stress response for potential sensitization (increased) or habituation (decreased) effects that may result from repeated exposure to the task. This new knowledge of the test-retest reliability of MIST will provide valuable insight into the utility of this task for assessing the neurobiological mechanisms underlying stress-reduction techniques
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