The effects of acute aerobic exercise on executive function in individuals with type 2 diabetes

105 Pages·2014·1.27 MB·English

by  Corrie Vincent

The effects of acute aerobic exercise on executive function
in individuals with type 2 diabetes

by

Corita Vincent

A thesis
presented to the University of Waterloo
in fulfillment of the
thesis requirement for the degree of
Master of Science
in
Health Studies and Gerontology

Waterloo, Ontario, Canada, 2014

©Corita Vincent 2014
AUTHOR'S DECLARATION
I hereby declare that I am the sole author of this thesis. This is a true copy of the thesis, including any
required final revisions, as accepted by my examiners.
I understand that my thesis may be made electronically available to the public.

ii
Abstract
Prevention and treatment of type 2 diabetes mellitus (T2DM), relies heavily on self-care behaviours
such as dietary modification, physical activity, and medication adherence. Ability to perform these
self-care behaviours depends, at least in part, on executive function (EF). Recent evidence suggests a
correlation between T2DM and impaired cognitive function, including EF. Given the importance of
EF for regulation of behaviours, and the importance of self-care in diabetes management, attenuated
EF would represent a potential barrier to proper disease management. Thus the objective of Study 1
was to examine the association between T2DM and EF through meta-analytic techniques. Medline,
PsychoInfo, and Scopus, as well as article references, were used to identify studies comparing
individuals with T2DM to a control population. Effect size was calculated using cohen’s d and
random effects modeling, and the potential impact of moderators (age, sex, and T2DM duration) were
examined. Review of 60 studies (59 articles), revealed a significant, small-to-moderate effect size
(d=-0.249, p<0.001) such that those with T2DM have lower EF. This finding was consistent across all
aspects of EF examined (verbal fluency, mental flexibility, inhibition, working memory, and
attention), and the association was stronger for those with shorter disease duration. The findings of
study 1 illustrate that although individuals with T2DM have a great need for EF, as evidenced by the
reliance of self-care behaviours on EF, this population has lower EF upon which to draw to perform
these behaviours. Thus, strategies that improve EF, such as aerobic exercise, may be particularly
relevant to this population. Acute aerobic exercise has been shown to improve EF in young and older
adults; however this effect had not yet been examined in individuals with T2DM. Thus the objective
of Study 2 was to examine the effects of acute aerobic exercise on EF in adults with T2DM. A within-
subject design was used to compare the change in EF task performance following moderate and
minimal intensity aerobic exercise, using Stroop and GNG to measure EF. Analysis revealed a
significant effect of moderate exercise in women (but not men) and recently active (but not inactive)
individuals, such that moderate exercise mitigated the self-regulatory fatigue effect observed
following exercise. This study provides preliminary evidence of a significant beneficial effect of
moderate aerobic exercise on EF in female and recently active adults with T2DM.
iii
Acknowledgements
I would like to, first and foremost, thank my supervisor, Dr. Peter Hall, for his help and
guidance throughout the development, implementation, and interpretation of this research project, as
well as, for extensive feedback provided during the writing process. I also wish to thank Dr. George
Heckman and Dr. John Mielke, my committee members, for a number of helpful discussions
particularly with respect to the design and protocol of the thesis project. This thesis project would not
have been possible without the help and guidance of these individuals.
I also wish to acknowledge the many individuals who were involved in the recruitment and
data collection phases of this project. Specifically, I would like to thank Cassandra Lowe, Dimitar
Kolev, Kimmi Luu, and other members of the Social Neuroscience and Health Lab for their
assistance with data collection. As well, I would like to express my immense gratitude to Stephanie
Thayer, Caryl Russell, and other UW fitness instructors for overseeing the exercise component of the
study protocol, and for a number of helpful discussions. Thank you to all the health professionals, and
diabetes education classes who aided in the recruitment phases of this project, and particularly to Dr.
Nadira Husein for all of her help with recruitment.
Finally, I wish to thank my friends and family for all their support throughout this entire
degree. I truly would not be where I am today without your support and encouragement.
iv
Table of Contents
AUTHOR'S DECLARATION ............................................................................................................... ii

Abstract ................................................................................................................................................. iii

Acknowledgements ................................................................................................................................ iv

Table of Contents .................................................................................................................................... v

List of Figures ..................................................................................................................................... viii

List of Tables .......................................................................................................................................... ix

Chapter 1 Overview ................................................................................................................................ 1

Chapter 2 Executive Function and Type 2 Diabetes Mellitus ................................................................. 3

2.1 Type 2 Diabetes Mellitus .............................................................................................................. 3

2.2 Executive Function ........................................................................................................................ 3

2.3 EF & Diabetes Self-Care ............................................................................................................... 4

2.3.1 Glycaemic Control ................................................................................................................. 5

2.3.2 Self Management Behaviours ................................................................................................ 5

2.4 EF & T2DM .................................................................................................................................. 8

Chapter 3 Study 1: Meta-analysis of the association between T2DM & EF ........................................ 10

3.1 Methods ....................................................................................................................................... 11

3.1.1 Inclusion/Exclusion .............................................................................................................. 11

3.1.2 Coding Procedure ................................................................................................................. 12

3.1.3 Moderator Analysis .............................................................................................................. 12

3.1.4 Statistics ............................................................................................................................... 13

3.2 Results ......................................................................................................................................... 14

3.2.1 Overall Executive Function .................................................................................................. 14

3.2.2 Moderator Analysis .............................................................................................................. 16

3.2.3 Verbal Fluency ..................................................................................................................... 16

3.2.4 Mental Flexibility ................................................................................................................. 17

3.2.5 Inhibition .............................................................................................................................. 17

3.2.6 Working Memory ................................................................................................................. 18

3.2.7 Attention ............................................................................................................................... 18

3.3 Discussion ................................................................................................................................... 18

3.3.1 Moderator Analysis .............................................................................................................. 19

3.3.2 Relevance for Clinical Practice and Self-Management ........................................................ 21

v
3.3.3 Summary .............................................................................................................................. 22

3.3.4 Implications of Study 1 ........................................................................................................ 22

Chapter 4 Aerobic Exercise and Executive Function ........................................................................... 23

4.1 Chronic/ Long-term Effects ........................................................................................................ 23

4.1.1 Chronic Aerobic Exercise and Brain Changes .................................................................... 23

4.2 Acute Effects .............................................................................................................................. 24

4.2.1 Acute Aerobic Exercise and Brain Changes ........................................................................ 24

4.2.2 Acute Aerobic Exercise and Executive Function ................................................................ 25

Chapter 5 Study 2: The effects of acute aerobic exercise on EF in individuals with T2DM ............... 29

5.1 Methods ...................................................................................................................................... 30

5.1.1 Participants .......................................................................................................................... 30

5.1.2 Design .................................................................................................................................. 31

5.1.3 Executive Function Measures .............................................................................................. 31

5.1.4 Exercise Protocol ................................................................................................................. 32

5.1.5 Exercise Measures ............................................................................................................... 33

5.1.6 Moderators ........................................................................................................................... 33

5.1.7 Statistics ............................................................................................................................... 33

5.2 Results ......................................................................................................................................... 34

5.2.1 Preliminary Analyses ........................................................................................................... 34

5.2.2 Stroop Effects ...................................................................................................................... 35

5.2.3 GNG Effects ........................................................................................................................ 37

5.3 Discussion ................................................................................................................................... 38

5.3.1 Strengths and Limitations .................................................................................................... 41

5.3.2 Conclusion ........................................................................................................................... 41

Chapter 6 Conclusions and Future Directions ...................................................................................... 43

Appendix A Meta-Analysis Article Inclusion Flow Chart ................................................................... 45

Appendix B Meta-Analysis Article Included Studies Characteristics .................................................. 46

Appendix C Funnel Plot for Overall Effect Size of T2DM-EF Association ........................................ 48

Appendix D Meta-Analysis Forest Plot of Effect Size by EF Category .............................................. 49

Appendix E PAR-Q .............................................................................................................................. 50

Appendix F Acute Aerobic Exercise and EF in T2DM Project Overview ........................................... 51

Appendix G Consent Form ................................................................................................................... 52

vi
Appendix H Demographic and Health Behaviour Questionnaires ....................................................... 57

References ............................................................................................................................................. 72

vii
List of Figures
Figure 1: Stroop interference change by condition and sex .................................................................. 36
Figure 2: Stroop interference change by condition and activity status ................................................. 37
viii
List of Tables
Table 1: Weighted mean effect size analysis ........................................................................................ 15
Table 2: Moderator analysis – Meta-regression .................................................................................... 16
Table 3: Acute effects of aerobic exercise on cognitive performance after exercise in older adults .... 28
Table 4: Population Characteristics ....................................................................................................... 31
Table 5: Stroop interference and GNG RT by condition and time ....................................................... 34

ix