INVESTIGATING THE ANXIOLYTIC EFFECTS OF AEROBIC EXERCISE FOR THE TREATMENT ...

210 Pages·2013·0.88 MB·English

INVESTIGATING THE ANXIOLYTIC EFFECTS OF AEROBIC EXERCISE FOR
THE TREATMENT OF POSTTRAUMATIC STRESS DISORDER

A Thesis
Submitted to the Faculty of Graduate Studies and Research
In Partial Fulfillment of the Requirements
For the Degree of
Doctor Philosophy
In
Clinical Psychology
University of Regina

by
Mathew Greg Fetzner
Regina, Saskatchewan
November 2013

Copyright 2013: M. G. Fetzner
UNIVERSITY OF REGINA

FACULTY OF GRADUATE STUDIES AND RESEARCH

SUPERVISORY AND EXAMINING COMMITTEE

Mathew Greg Fetzner, candidate for the degree of Doctor of Philosophy in Clinical
Psychology, has presented a thesis titled, Investigating the Anxiolytic Effects of Aerobic
Exercise for the Treatment of Posttraumatic Stress Disorder, in an oral examination held
on October 29, 2013. 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. Jon D. Elhai, University of Toledo

Supervisor: Dr. Gordon Asmundson, Department of Psychology

Committee Member: Dr. Heather Hadjistavropoulos, Department of Psychology

Committee Member: **Dr. Kristi Wright, Department of Psychology

Committee Member: Dr. Darren Candow, Faculty of Kinesiology & Health Studies

Chair of Defense: Dr. Dongyan Blachford,
Faculty of Graduate Studies & Research

*via teleconference
**Not present at defense
Abstract
Preliminary evidence has demonstrated the anxiolytic capabilities of aerobic exercise;
however, the treatment potential for posttraumatic stress disorder (PTSD) has received
comparably less attention. Aerobic exercise may work similar to interoceptive exposure
therapy–an empirically supported treatment for PTSD–but this hypothesis has received
scarce empirical attention. The current study investigated the therapeutic potential (i.e.,
whether or not PTSD symptoms, anxiety sensitivity [AS], and depressive symptoms
would decline) and mechanisms (i.e., whether or not therapeutic benefit is changed by
increasing or decreasing interoceptive awareness) of a brief aerobic exercise program for
individuals with PTSD. Thirty-three participants (M =36.9 years; 76% female; 18%
age
drop-out rate) with PTSD were recruited from the surrounding community and completed
two weeks of aerobic exercise (six sessions) on a stationary bike. Participants were
randomized into three groups to direct their cognitive focus during exercise, thereby
testing hypothesized therapeutic agents; group one (cognitive distraction) watched a
nature documentary, group two (exercise only) exercised in silence with no distractions,
and group three (interoceptive exposure) received interoceptive prompts. Data was
collected at pre-treatment, after each exercise session, and one week and one month after
treatment ended. Hierarchal linear modeling indicated that each variable decreased
significantly in a quadratic fashion; specifically, scores tended to reduce steadily from
baseline to their lowest point after the last exercise session and steadily rose during the
follow-up period. The effect of group membership was largely not statistically
significant, whereas the interaction between time and group membership was significant
among hyperarousal symptoms, fear of physical sensations, and fear of socially
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observable symptoms. In cases where interactions were present, between group
comparisons suggested that the interoceptive prompts group consistently reported less
change on primary outcome variables than the remaining groups. Given that the decline
in outcome variables was present in each of the three study groups, results suggest that
aerobic exercise is effective regardless of cognitive focus during exercise.
Notwithstanding, given the subjacent impact of the intervention among interoceptive
exposure group participants, anxiolytic properties of aerobic exercise may be accented in
the short term by employing strategies to detract from the discomfort of the exercise
protocol.

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Acknowledgments
Thanks to the following funding agencies and groups for providing valuable
financial support for this project: Canadian Insitutues of Health Research – Vanier
Canada Graduate Scholarship; George William Brown Scholarship; and Faculty of
Graduate Studies Travel Awards and Research Grants.
I would also like to acknowledge a number of individuals who were instrumental
in the formulation, execution, and dissemination of this project. First, special thanks to
my supervisor Dr. Gordon Asmundson for his guidance and mentorship throughout this
project and my entire graduate school experience. I appreciate the support and
encouragement.
Second, I would like to acknowledge the efforts of my dissertation committee Dr.
Heather Hadjistavropolous, Dr. Kristi Wright, and Dr. Darren Candow. Each of you has
brought much appreciated expertise to this project that I could not have done without.
Third, this project would not have been possible without the amazing dedication
and time put forth by my four research assistants Samantha Levin, Mike Barber, Sarah
Johannsmeyer, and Marcus Brahms, and the Anxiety and Illness Behaviors Laboratory
research coordinator Michelle Sapach (Teale). My colleagues in the Anxiety and Illness
Behaviors Laboratory deserve equal mention for assisting in coordinating and supervising
participants throughout the data collection portion of the study.
Fourth, I would like to thank Jay Branch for assisting in publicizing the study
which proved instrumental in recruiting participants.
Fifth, I would like to thank Dr. David Rosenfeild of Southern Methodist
University for his knowledge and patience with assisting me in the statistical analyses
conducted in the current dissertation.
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Finally, I would like to thank the University of Regina Psychology department
and departmental secretaries Brenda Yung and Catherine Hologroski for their continued
dedication to each student in the department.
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Dedication
For Team Fetzner: My beautiful and supportive wife (KDF) and my crazy but
lovable kids (LKF, NXF, and TBD). You’ve made this all worthwhile.
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Table of Contents
Abstract………….…………………………………………………………………………i
Acknowledgments...………………………………………………………………………ii
Dedication...........................................................................................................................iv
Table of Contents...............................................................................................................vi
List of Appendices..............................................................................................................x
1.0 Literature review...........................................................................................................1
1.1 Posttraumatic Stress Disorder...........................................................................3
1.1.1 DSM–IV–TR diagnostic criteria........................................................4
1.1.2 DSM–5 changes to diagnostic criteria................................................6
1.1.3 Etiological models..............................................................................7
1.1.3.1 The conditioning model of PTSD........................................7
1.1.3.2 The emotional processing model of PTSD..........................8
1.1.3.3 The cognitive model of PTSD.............................................8
1.1.4 Prevalence...........................................................................................9
1.1.5 Prevalence among at–risk populations..............................................10
1.1.6 Adherence and drop–out in traditional evidence–based
treatments for PTSD.................................................................................12
1.2 Physiological Consequences of PTSD……………………………………….13
1.3 Physical Exercise: Prevalence, Explanations, and Mental Health
Correlates...............................................................................................................15
1.4 Anxiety Disorders and Physical Exercise........................................................17
1.4.1 PTSD and aerobic exercise………………………………………...18
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1.5 Potential Mechanisms Responsible for the Anxiolytic Effects of
Aerobic Exercise....................................................................................................20
1.5.1 Improved physical fitness.................................................................20
1.5.2 Neuroendocrine and thermoregulatory adaptations..........................22
1.5.3 Distraction.........................................................................................23
1.5.4 Reductions in AS and exposure to feared bodily
sensations (interoceptive exposure).......................................................... 24
2.0 Current Study…….......................................................................................................28
2.1 Purposes……………………………………………………………………...28
2.2 Hypotheses…………………………………………………………………...29
2.3 Participants…………………………………………………………………...30
2.3.1 Eligibility criteria…………………………………………………..31
2.4 Psychological and Lifestyle Measures……………………………………….31
2.4.1 Traumatic Life Events Checklist…………………………………..32
2.4.2 Posttraumatic Stress Disorder Checklist – Civilian Version …..….32
2.4.3 Anxiety Sensitivity Index – 3………………………………….…..34
2.4.4 Center for Epidemiological Studies – Depression Scale……….….34
2.4.5 Fantastic Lifestyle Questionnaire …………………………………35
2.4.6 Stages of Changes Questionnaire …………………………………35
2.4.7 Healthy Physical Activity Participation Questionnaire……………35
2.4.8 Physical Activity Readiness Questionnaire ………………….……36
2.5 Exercise Session Response Questions………………………………….……36
2.6 Phone Screen Measures……………………………………………………...37
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2.6.1 Structured Clinical Interview for DSM–IV Axis I Disorders……37
2.6.2 MINI International Neuropsychiatric
Interview Screener Modified………………………………………38
2.6.3 Beck Suicide Severity Inventory…………………………………..38
2.7 Physical Testing Procedures…………………………………………………39
2.8 Equipment…………………………………………………….……………...41
2.9 Trial Design, Setting, and Target Population Availability…………………..41
2.10 Procedure…………………………………………………………………...42
2.10.1 Intervention groups……………………………………………….44
2.10.1.1 Similarities between intervention groups…………….…45
2.10.1.2 Differences between intervention groups………………46
2.10.2 Randomization sequence, generation,
type, and implementation...............................................................48
2.10.3 Blinding…………………………………………………………..48
2.11 Analytic Procedure……………………………………………………….…49
2.11.1 Participant flow and sample size…………………………….……50
2.11.2 Descriptive statistics……………………………………………..50
2.11.3 Preliminary analyses……………………………………………...50
2.11.4 Primary statistical analyses……………………………………….52
2.11.4.1 Missing data imputation………………………………...53
2.11.5 Secondary statistical analyses…………………………………….55
2.11.6 Assessing for clinically significant change……………………….55
3.0 Results………………………………………………………………………………..56
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