Self-Regulation Processes of Depressive Symptoms and Participation in Persons with Stroke Using Heart Rate Variability as a Real-Time Biomarker

Depressive symptoms are a key risk factor for restrictions in participation in daily activities in persons with stroke. Thus, many researchers have attempted to develop interventions for relieving depressive symptoms after stroke, however, post-stroke depressive symptoms are still undertreated. To develop evidence-based approaches for reducing depressive symptoms, and thereby ultimately enhancing participation in daily activities, it is important to understand what moderates the associations between depressive symptoms and participation in daily activities in persons with stroke to employ the moderator as an intervention target. One possible mechanism to moderate such associations is self-regulation – cognitive, behavioral, and emotion regulation. Self-regulation appears to be positively related to participation in daily activities. Moreover, self-regulation failures seem to be associated with depressive symptoms. However, despite these relationships, evidence is needed to understand whether self-regulation moderates the associations between depressive symptoms and participation in daily activities in persons with stroke. In addition, given that vagally mediated heart rate variability (vmHRV) has been conceived as a biomarker of emotion regulation, it is crucial to investigate whether vmHRV can be a useful biomarker of emotion regulation to understand physiological indicators of emotional states and emotion regulation in persons with stroke. Therefore, the overall objective of this dissertation was to uncover the interplay among self-regulation, depressive symptoms, and participation post-stroke, and investigate the use of vmHRV as a biomarker of emotion regulation in persons with stroke. To address the objective of this dissertation, I employed smartphone-based ecological momentary assessment (EMA) to explore the real-time associations among self-regulation including cognitive, behavioral, and emotion regulation, depressive symptoms, and participation (i.e., performance and satisfaction) in persons with stroke. In addition, I applied a wearable smart watch to obtain real-time vmHRV data to investigate its real-time associations with emotion regulation measured using EMA self-reports in persons with stroke. The self-regulation process model of participation was developed in chapter 2 to provide a theoretical rationale of the relationship between self-regulation and participation in meaningful activities. This model hypothesized that self-regulation failures momentarily generate negative emotions including depressive symptoms, which may momentarily impede participation in meaningful activities. Chapter 3 partially confirmed this hypothesis by demonstrating the synergistic momentary effects of difficulties in self-regulation, in particular emotion regulation, with depressive symptoms on satisfaction in persons with stroke. Moreover, in chapter 4, the findings of the study demonstrated that vmHRV can be a useful real-time biomarker of emotion regulation in persons with stroke. The findings of this dissertation provide evidence for using self-regulation and emotion regulation strategies as a just-in-time intervention to reduce the momentary, adverse impacts of depressive symptoms on satisfaction with performance of daily activities in persons with stroke. Moreover, this dissertation suggests vmHRV may be a useful real-time biomarker to monitor emotion regulation in real-world environments in persons with stroke