Physiological, cognitive, and expectancy effects of aromatherapy following acute stress

217 Pages·2015·1.64 MB·English

Oregon Health & Science University
OHSU Digital Commons
Scholar Archive
January 2013
Physiological, cognitive, and expectancy effects of
aromatherapy following acute stress
Irina Fonareva
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Fonareva, Irina, "Physiological, cognitive, and expectancy effects of aromatherapy following acute stress" (2013).Scholar Archive. 904.
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PHYSIOLOGICAL, COGNITIVE, AND EXPECTANCY EFFECTS OF
AROMATHERAPY FOLLOWING ACUTE STRESS

By
Irina Fonareva

A DISSERTATION
Presented to the Department of Behavioral Neuroscience
and the Oregon Health & Science University in partial fulfillment
of the requirements for the degree of

Doctor of Philosophy
January 2013
School of Medicine

Oregon Health & Science University

CERTIFICATE OF APPROVAL

This is to certify that the PhD dissertation of

Irina Fonareva

has been approved

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Mentor/Advisor

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Member

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TABLE OF CONTENTS
Acknowledgements…………………………………………………………………… iv
Abstract………………………………………………………………………………… vi
Chapter 1: General Introduction……………………………………………….……. 1
Effects of stress exposure on brain, body, and health………………..………. 1
Complementary and alternative medicine (CAM) for well-being…………….. 4
Aromatherapy: an overview of a popular CAM approach ……………………. 6
Lavender aromatherapy: therapeutic effects and mechanisms…………....... 8
Major limitations in previous research: lessons learned for future studies…. 17
Hypotheses of aromatherapy mechanism……………………………………… 20
Goals of this work and general study approach……………………………….. 24
Chapter 2: General Approach……………………………………………………….. 25
RCT overview and specific aims…………………………………………………. 25
Methods and procedures…………………………………………………………. 27
Participants……………………………………………………………………. 27
Telephone screening for eligibility…………………………………………... 29
Study groups, randomization process, and blinding……………………… 29
Laboratory visit: procedures………………………………………………… 35
Statistical analyses…………………………………………………………… 38
Participant baseline characteristics……………………………………………… 40
Stress battery effectiveness check………………………………………………. 43
Aroma hedonic qualities for different aromas…………………………………… 43
Chapter 3: Effects of aromatherapy on physiological stress markers following
acute stress: the role of expectancy in aromatherapy actions ……...
49
Introduction……………………………………………………………………....... 50
Methods…………………………………………………………………………….. 54
Participants…………………………………………………………………….. 54
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Study groups, randomization process, and blinding……………………… 54
Laboratory visit………………………………………………………………… 54
Statistical analyses……………………………………………………………. 61
Results…………………………………………………………………………….. 65
Stress battery effectiveness check…………………………………………. 65
Group effects on stress-related self-reported measures…………………. 65
Primary analyses: aromatherapy effects on physiologic function……… 66
Primary analyses: aromatherapy effects on salivary measures………... 68
Secondary analyses…………………………………………………………. 72
Discussion…………………………………………………………………………… 74

Chapter 4: Potential mechanisms of aromatherapy effects on cognitive function
following acute stress: contribution of aroma hedonic qualities and
expectancy effects………………………………………………………... 83
Introduction………………………………………………………………………...... 84
Methods……………………………………………………………………………… 86
Participants…………………………………………………………………….. 86
Study groups, randomization process, and blinding…………………….. 86
Laboratory visit……………………………………………………………….. 87
Statistical analyses………………………………………………………….. 90
Results……………………………………………………………………………… 92

Primary analyses: aromatherapy and expectancy effects on cognitive
performance…………………………………………………………………. 94
Secondary analyses: exploring the role of other factors………………… 101
Discussion…………………………………………………………………………… 111

Evidence for pharmacological mechanism involved in lavender effect
on cognitive performance………………………………………………….. 111
Evidence for hedonically-driven mechanism…………………………….. 112
Evidence for psychological mechanism: role of expectancy…………… 114
Evidence for contextual/associative mechanism of action……………... 115

Chapter 5: Effects of stress-reducing aromatherapy on go-nogo task following
iii

acute stress: an evoked related potentials (ERP) study……………..
118
Introduction ………………………………………………………………………….. 119
Methods……………………………………………………………………………… 123
Participants…………………………………………………………………… 123
Study groups, randomization process, and blinding……………………… 123
EEG/ERP measurement…………………………………………………….. 123
Laboratory visit ……………………………………………………………….. 124
Statistical analyses……………………………………………………………. 127
Results……………………………………………………………………………... 129
Primary analyses: Behavioral results………………………………………. 132
Primary analyses: ERP results……………………………………………… 136

Relationships among GNG behavior, ERP measures, and aroma-
related measures……………………………………………………………… 142
Discussion…………………………………………………………………………. 145
Behavioral results……………………………………………………………... 145
ERP results……………………………………………………………………. 145
Chapter 6: General Discussion……………………………………………………… 152
Overview of the results………………………………………………………...... 152
Is there evidence for lavender-specific stress-reducing effects?……………. 154
The role of expectancy in aromatherapy actions…………………………….... 160
Expectancy, placebo effects, search for mechanisms………………………... 164
Limitations of the current work………………………………………….............. 166
Future direction……………………………………………………………………. 169
Overall conclusions……………………………………………………………..... 170
Appendices………………………………………………………………………… 173
References…………………………………………………………………………….. 184
iv

Acknowledgements

This work is the result of a collaborative effort of impressive number of
people, but the most critical person who made it all possible is my mentor, Dr.
Barry Oken. Throughout the years he has provided me with many amazing
opportunities to learn and conduct research that I am passionate about and has
been and continues to be the greatest source of brilliant ideas and advice as well
as financial and moral support for me and my research endeavors. Thank you so
much Barry.
I am very grateful to the members of my dissertation and oral exam
committees who helped shaping up my dissertation project and provided
insightful feedback for my project, data analyses, and this document. Thank you
so much, Drs. Suzanne Mitchell, Matt Lattal, Alexander Stevens, Helane’
Wahbeh, and Chris Cunningham, for your support.
All members of Oken Cognitive Neuroscience and Neurophysiology
Laboratory deserve a huge thank you for their help with blinding, randomization,
and data processing. Special thanks to Roger Ellingson, a talented engineer, for
finding creative and working solutions for many technical issues that are way
beyond my understanding. Thank you, Elena Goodrich and Meghan Miller, for
dealing with all non-blinded procedures. Many thanks to Andy Fish who makes
the onerous tasks of grant management and taking care of diverse aspects of lab
management look easy. Additionally I would like to thank Michael Demidenko for
volunteering his time to help with data processing.
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I would also like to acknowledge the always-present support of wonderful
Behavioral Neuroscience Department faculty members and administrative staff. I
also appreciate the camaraderie of my fellow students.
It is very important to acknowledge the funding that allowed this project to
happen. NIH grants U19AT002656, T32AT002688, K24AT005121, and
F31AT006647 provided me with funds to conduct this study. Parts of this
research were also supported by the APA Dissertation Research Award. I would
like to thank the Oregon Clinical Translational Research Institute Core Laboratory
and its Director, Dr. Clive Woffendin, for analyzing salivary measures used in the
study. I am also thankful to Dr. Jens Pruessner for sharing his MIST software that
helped to stress the study participants.
Lastly I want to thank my family, the most precious people in my life, who
infuse my life with happiness and joy every day.
vi

Abstract

Objective. Aromatherapy is commonly used for stress relief, yet the evidence for
its effectiveness is weak due to the poor quality of previous studies and lack of
understanding for the aromatherapy mechanism. The main goal of this work was
to use a rigorous randomized control trial (RCT) design to assess effects of a
popular stress-reducing aromatherapy on subjective, physiologic, and cognitive
measures sensitive to stress. Additionally, the study evaluated the role of a
psychological mechanism (expectancy) in aromatherapy actions.
Methods. Ninety-two healthy adults were randomized to 3 groups based on
aroma type (experimental lavender aroma, detectable coconut placebo aroma,
and undetectable water placebo aroma) to evaluate efficacy of lavender
aromatherapy compared to the placebo groups. Detectable placebo aroma was
utilized to test the role of aroma-mediated expectancy in aromatherapy actions.
Additionally, participants in each group were randomized to one of two
subgroups: either receiving a suggestion that the assigned aroma is a powerful
stress-reducing agent (prime) or receiving a neutral statement about the aroma
qualities (no prime). This manipulation was used to assess the role of verbally-
mediated expectancy in aromatherapy actions. To reach the study goals,
participants underwent a stress battery and completed baseline and post-stress
assessments during which participants’ physiological, endocrine, and cognitive
function were assessed with objective stress markers. Subjects’ perceived
stress, affect, anxiety, and expectancy of improvement were also evaluated.
vii

Results. Beneficial effects of lavender aromatherapy during stress exposure
were shown for cognitive function (performance on working memory task) as well
as physiological (respiration rate) outcome measures. Next, the results
suggested that both aroma- and verbally-mediated expectancies contribute to
aromatherapy actions. Aroma-mediated expectancy associated with the
presence of a detectable aroma affected EEG frontal asymmetry and
chromogranin A after stress induction. Hedonic qualities of aroma, including
aroma intensity and pleasantness, were linked to aroma-mediated expectancy
and were likely critical for producing such effects.
The role of verbally-mediated expectancy, enhanced by the suggestion of
stress-reducing properties of the assigned aroma, was also supported for
aromatherapy effects on cognitive performance and function. Specifically,
priming aromatherapy recipients on expected stress-reducing aromatherapy
effects produced beneficial effects on cognitive function evident in ERP changes
and behavioral performance on cognitive tests of processing speed and
executive functioning. Curiously, the changes in objective measures were not
paralleled by changes in subjective stress, anxiety, or affect.
Conclusions. In addition to showing specific effects of lavender aromatherapy
on physiologic and cognitive measures, current findings indicated that
expectancy effects play a major role in aromatherapy actions. Overall, the results
indicate that objectively measured aromatherapy effects are produced by a
combination of pharmacological and psychological mechanisms that are probably
independent.