DOES EXERCISE PREVENT EXACERBATION OF ANXIETY-RELATED VULNERABILITY FACTORS FOLLOWING AN ANALOGUE STRESSOR: A RANDOMIZED CONTROLLED TRIAL A Thesis Submitted to The Faculty of Graduate Studies and Research In Partial Fulfillment of the Requirements for the Degree of Master of Arts in Clinical Psychology University of Regina By Rachel Lauren Krakauer Regina, Saskatchewan December 2019 © Copyright 2019: R. Krakauer UNIVERSITY OF REGINA FACULTY OF GRADUATE STUDIES AND RESEARCH SUPERVISORY AND EXAMINING COMMITTEE Rachel Lauren Krakauer, candidate for the degree of Master of Arts in Clinical Psychology, has presented a thesis titled, Does Exercise Prevent Exacerbation of Anxiety-Related Vulnerability Factors Following An Analogue Stressor: A Randomized Controlled Trial, in an oral examination held on November 28, 2019. The following committee members have found the thesis acceptable in form and content, and that the candidate demonstrated satisfactory knowledge of the subject material. External Examiner: *Dr.
Francis Xavier University Co-Supervisor: Dr. Gordon Asmundson, Department of Psychology Co-Supervisor: Dr. Nicholas Carleton, Department of Psychology Committee Member: Dr. Shadi Beshai, Department of Psychology Chair of Defense: Dr.
Jason Demers, Department of English *via ZOOM Conferencing Abstract The most common mental disorders are anxiety-related disorders (Andlin-Sobocki & Wittchen, 2005). The diathesis-stress model of psychopathology explains that stressors interact with vulnerability factors to influence the development of anxiety-related disorders (Monroe & Simmons, 1991); therefore, modifying vulnerability factors before a stressor occurs may reduce or prevent anxiety. Researchers have observed significant reductions in anxiety-related vulnerability factors following as little as a single session of exercise (Asmundson et al., 2013), suggesting exercise effectively targets vulnerability factors. Research is needed to investigate whether exercise interventions implemented prior to a stressful event can target anxiety-related vulnerability factors, thereby protecting against future anxiety or distress.
The current randomized controlled trial assessed whether exercise could prevent elevations in measures of anxiety-related vulnerability factors following a stressful exposure. A nonclinical sample of community adults was randomly assigned to complete a 30-minute exercise protocol on a stationary bike (experimental condition) or lightly stretch for 30 minutes (placebo control condition). All participants subsequently watched a traumatic film clip used as an analogue stressor. Participants completed measures of anxiety-related vulnerability factors—state and trait anxiety, anxiety sensitivity (AS), distress tolerance (DT), and intolerance of uncertainty (IU)—at baseline, after exercise, after the analogue stressor, and at 3-day and 7-day follow-ups.
Participants in the experimental group did not report statistically significantly lower scores on measures of vulnerability factors compared to the placebo control group. Overall, vulnerability factor scores were relatively stable across time. Effects of time were observed, demonstrating anxiolytic effects of physical i activity that protected both groups against elevations in putative anxiety-related vulnerability factors. The results offer initial support for the efficacy of both exercise and stretching control to prevent elevations in AS, IU, state anxiety, trait anxiety, and reductions in DT, although analyses may have been underpowered.
The current trial offers practical implications for individuals who regularly experience potentially traumatic events, as well as community adults who deal with minor daily stressors. ii Acknowledgements Many people contributed to the success of this thesis. Gordon Asmundson and Dr. Nicholas Carleton deserve more acknowledgement for their mentorship than I can offer in this paragraph.
Thank you to my co-supervisors for being my dream team and making sure all the stars aligned for this project. To my committee member, Dr. Shadi Beshai, thank you for your supportive feedback and fostering learning opportunities. I would also like to acknowledge my research assistants for dedicating their time to this project.
This trial was financially supported by Drs. Asmundson and Carleton, without whom I could not have afforded to hire a qualified personal trainer or buy six kinds of nut butter. I also acknowledge the University of Regina Faculty of Graduate Studies and Research and the Department of Psychology for their financial support. I would like to share my deep appreciation for my AIBL lab mates; thank you for your endless words of encouragement, valuable feedback, reminders to stand, and mostly, your friendship.
Thank you to my incredibly supportive cohort; I am lucky to have you. To my friends and family, thank you for understanding when I disappeared to Canada and managing to send endless support across the border. Finally, I have immense gratitude for all of the individuals who participated in this trial and became my personal heroes. iii Dedication To the woman who inspires me, motivates me, and whole-heartedly believes in me.
Without you, none of this would be possible. iv Table of Contents Abstract. iv Table of Contents. v List of Tables .viii List of Figures.
ix List of Appendices.2 Anxiety-Related Vulnerability Factors .3 Anxiety-Related Interventions.1 Potential protective mechanisms.2 Exercise and vulnerability factors .3 Exercise intervention paradigms .5 The Trauma Film Paradigm .6 The Current Trial .1 Sample characterization and screening measures.2 In-person session .1 Exercise and Primary Anxiety-Related Vulnerability Factors .3 Strengths and Limitations. 92 vii List of Tables Table 1. Participant Demographics………………………………………………………52 Table 2. Descriptive Statistics for Outcome Measures at each Timepoint………………56 Table 3.
Mean Outcome Scores……………………………………………………. Post-Analogue Stressor Scores for Film………………………………………. MLM for Primary Outcomes at Baseline, Post-Activity, and Post-Stressor. MLM for Exercise Group Scores at Baseline and Post-Stressor……………….
MLM for Placebo Control Group Scores at Baseline and Post-Stressor………. MLM for Primary Outcomes at Follow-Ups Compared to Post-Stressor. MLM for STAI-T Total for Baseline, Post-Activity, and Post-Stressor………. MLM for STAI-T Total at Follow-Ups Compared to Post-Stressor………….71 viii List of Figures Figure 1.
ASI-3 Total Scores……………………………………………………………. STAI-S Total Scores…………………………………………………………. IUS-12 Total Scores…………………………………………………………. DTS Total Scores…………………………………………………………….
STAI-T Total Scores………………………………………………………….72 ix List of Appendices Appendix A. Physical Activity Readiness Questionnaire for Everyone………………. Physician Physical Activity Readiness Clearance………………………. Life Events Checklist-5………………………………………………….
Posttraumatic Stress Disorder Checklist for DSM-5……………………. Healthy Physical Activity Participation Questionnaire………………. The Center for Epidemiological Studies of Depression Scale Revised…. Anxiety Sensitivity Index-3……………………………………………….
Distress Tolerance Scale…………………………………………………. Intolerance of Uncertainty, Short Form………………………………. Research Ethics Board Certificate of Approval…………………………. Description of Irréversible Scene……………………………………….
Post-In-Person Session Questionnaire…………………………………. Questionnaire for Intrusive Memories……………………………….1 Overview Anxiety-related disorders are the most common mental disorders (Andlin-Sobocki & Wittchen, 2005). Even at sub-clinical levels, individuals suffering from anxiety may experience significant impairment, such as lost work days, disability, and reduced social functioning (Zatzick et al. Preventing anxiety-related impairments would reduce individual and societal costs of anxiety.
Scientific evidence often motivates individuals to take preventive action to reduce their risk to diseases; for example, people wear sunscreen to protect their skin following recommendations to reduce the risk of skin cancer (Berwick, Fine, & Bolognia, 1992). The diathesis-stress model of mental disorders postulates that stressors interact with vulnerabilities to transform predisposition into pathological states (Beard, 1881; Monroe & Simmons, 1991). Higher levels of psychological vulnerability factors indicate higher risk for anxiety-related disorders (Elwood, Mott, Williams, Lohr, & Schroeder, 2009) and can become maintenance factors contributing to and perpetuating anxiety-related disorders (Stice, 2002). Modifying predispositional traits such as cognitive vulnerability factors could be effective for prevention and treatment of anxiety.
Preventive interventions designed to target a collection of putative vulnerability factors have not been tested (Schmidt, Allan, Knapp, & Capron, 2019). Exercise is currently recommended to reduce the risk of physiological diseases (e., Orozco et al., 2008) and may also protect against psychological disorders. Exercise interventions are efficacious for reducing anxiety-related vulnerability factors and are easily implemented, cost-effective, and do not require immediate access to a mental 1 health professional (Stonerock, Hoffman, Smith, & Blumenthal, 2015). Accordingly, exercise may be an efficacious preventive tool for protecting mental health.
The current trial assessed whether exercise protects against elevations in measures of anxiety-related vulnerability factors following an analogue stressor. The introduction first examines empirically-supported anxiety-related vulnerability factors, including state anxiety, trait anxiety, anxiety sensitivity (AS), distress tolerance (DT), and intolerance of uncertainty (IU). Second, support for interventions that reduce anxiety and related vulnerability factors are reviewed, with a specific focus on exercise. Potential protective mechanisms supporting the anxiolytic effects of exercise are also discussed.
Third, a description of the trauma film paradigm is presented and evidence for the analogue stressor is examined. Finally, an overview of the current trial is provided, results are presented, and the findings are discussed.2 Anxiety-Related Vulnerability Factors The Diagnostic and Statistical Manual of Mental Disorders fifth-edition (DSM-5) follows the categorical model of mental disorders, contending that classes or disorders are independent and distinct from one another (American Psychiatric Association, 2013). When classifying disorders, the philosophy of the DSM-5 appears to follow a “splitting” rather than “lumping” method (Mayr, 1982). The number of disorders in the current edition has increased almost three-fold compared to the first edition of the DSM (Norton & Paulus, 2016); however, research suggests there are similar features among some mental disorders (e., depressive and anxiety disorders), such as distress, fear, or difficulties with emotion regulation (Krueger & Eaton, 2015; Norton & Paulus, 2016).
Commonalities among mental disorders explain the high prevalence of comorbidities 2 observed with anxiety and depressive disorders and why treating a single anxiety disorder improves other comorbid anxiety or depressive disorders that were not specifically targeted within that treatment (Barlow, Allen, & Choate, 2004). Negative affectivity is a shared feature observed in anxiety and depressive disorders, supporting the existence of factors that are not diagnosis-specific (Barlow et al. Similarly, many mental disorder symptoms include maladaptive behaviors intended to avoid or escape uncomfortable emotions, thoughts, or memories (Hayes, Wilson, Gifford, Follette, & Strosahl, 1996). A non-exhaustive list of other shared processes supporting a transdiagnostic model of mental disorders includes perceived control (Gallagher, Bentley, & Barlow, 2014), sleep disturbance (Cox & Olatunji, 2016), attention biases (Mogg & Bradley, 2016), and anxiety sensitivity (Olatunji & Wolitzky-Taylor, 2009).
Research from genetic (Kendler, Neale, Kessler, Heath, & Eaves, 1992), neurobiological (Etkin & Wager, 2007), developmental (Kessler, Chiu, Demler, & Walters, 2005), behavioral (Helbig-Lang & Petermann, 2010), cognitive (Cisler & Koster, 2010), and treatment (Barlow et al., 2017) perspectives support transdiagnostic processes. Variables that are related to and precede undesirable outcomes are considered vulnerability factors across various areas of study (Kraemer et al. Measurable vulnerability factors can be used to characterize a sample of interest along a spectrum of risk (Mrazek & Haggerty, 1994), which includes vulnerability factors on one end of the spectrum and protective factors on the opposite end (Rutter, 1987). High levels of vulnerability factors indicate high-risk and low levels of vulnerability factors indicate low-risk.
For example, individuals living in an urban city belong to the high-risk group for anxiety disorders and more rural inhabitants are low-risk individuals, or are 3 “protected”, based on location (Judd et al. Dwelling location is a fairly stable vulnerability factor, and is not readily modifiable. Vulnerability factors that can be changed within an individual (e., through psychological intervention) and affect the outcome risk (e., anxiety disorder symptoms) when manipulated are labeled causal vulnerability factors (Kraemer et al. Lowering the level of a causal vulnerability factor may reduce the risk of developing anxiety-related disorders.
Reduced vulnerability is especially important during periods of high stress wherein individuals may be more susceptible to environmental influences. For example, in a trauma-exposed sample, high AS predicted posttraumatic stress symptoms only in the presence of highly negative life events (Elwood et al. Targeted vulnerability reduction may be critical to protect mental health given that individuals are more susceptible to anxiety-related symptoms when stress is high or a when a major life stressor occurs (Pedersen & Larson, 2016; Schmidt et al. The current trial focused on empirically-supported anxiety-related vulnerability factors amenable to change—state anxiety, trait anxiety, AS, DT, and IU.
State anxiety refers to the “emotional reaction or pattern of response that occurs in an individual who perceives a particular situation as personally dangerous or threatening, irrespective of the presence or absence of objective danger” (Spielberger, 2013b, p. State anxiety represents the tangible anxiety experienced in a given moment in response to threat; as such, fluctuations in state anxiety are observed in different situations depending on individual differences (Spielberger, 2013a). Research evidence supports the postulate that state anxiety fluctuates in the face of threatening or frightening stimuli.