Intention Motor Inhibition in Adults with ADHD

276 Pages·2012·1.59 MB·English

by  Erin B. Gorman

Intentional Motor Inhibition in Adults with Attention-Deficit/Hyperactivity Disorder:
An Evaluation of Performance and Lateralized Readiness Potentials
During a Go/No-Go Discrimination Task

By

Erin Brooke Gorman Bozorgpour

Submitted in Partial Fulfillment
of the
Requirements for the Degree
Doctor of Philosophy

Supervised by
Rafael Klorman, Ph.D.

Department of Clinical and Social Sciences in Psychology
Arts, Sciences and Engineering
School of Arts and Sciences

University of Rochester
Rochester, New York

2012
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CURRICULUM VITAE
Erin Brooke Gorman Bozorgpour was born in Glendale, California on
September 25, 1978. She completed her high school degree at Flintridge Sacred
Heart Academy in La Canada Flintridge, California in 1996. She attended Pitzer
College, A Member of the Claremont Colleges and graduated summa cum laude in
2000 with a Bachelor of Arts degree in Psychology. During her undergraduate
studies and one year post-graduation, Erin was involved with several NIMH funded
longitudinal studies examining cognitive functioning and memory processing in older
adults under the guidance of Leah Light, Ph.D. In 2001, Erin was awarded a year-
long post-baccalaureate urban fellowship at the Claremont Colleges, Center for
California Cultural and Social Issues where she collaborated with a multidisciplinary
team of faculty members and served as a liaison to bridge connections between the
academic institution and community partners to create community based educational
opportunities for students at the Claremont Colleges.
In 2002, Erin began her graduate studies in clinical psychology at the
University of Rochester, New York. She completed her Master’s thesis under the
direction of Rafael Klorman, Ph.D., on the effects of methylphenidate on children
with the Combined and Inattentive subtypes of Attention-Deficit/Hyperactivity
Disorder and received her Master’s degree in 2006. In 2006, she published the
findings in the Journal of the American Academy of Child and Adolescent
Psychiatry. As a graduate student, Erin collaborated with Drs. Klorman and Gift on
an NIMH funded study examining executive functioning and the nature of inhibition
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deficits in adults with ADHD utilizing brain event-related potentials (ERP) and eye
tracking methodologies. From 2003-2009, under the mentorship of Rafael Klorman,
Ph.D., Erin administered psychoeducational assessments to adults with ADHD and
control participants and collected data as part of the research protocol evaluating
executive dysfunction and inhibition deficits in adults with ADHD. As a doctoral
candidate she continued her research, in the area of ADHD with a specific focus on
examining reaction time and its variability and motor preparatory and processing
states (e.g., intentional motor inhibition) in adults with ADHD measured by the
Lateralized Readiness Potential (an ERP) during a choice reaction time Go/ No-Go
task, again under the mentorship of Rafael Klorman, Ph.D. As part of this research
investigating adults with ADHD, in 2009, Drs. Klorman and Gift and Erin published
an article in the ADHD report on assessing attention-deficit/hyperactivity disorder in
a college-level sample.
During her graduate school years, Erin completed several clinical externships
at the University of Rochester and the University of Rochester Medical Center. From
2003-2004, Erin completed a practicum at the Counseling and Mental Health Services
at the University of Rochester under the supervision of Richard Ryan, Ph.D., and Lisa
Willis, Ph.D., and subsequently, she continued as a post-practicum trainee from 2004-
2006 under the supervision of Lisa Willis, Ph.D., and other pre- and post- psychology
doctoral candidates and licensed clinical psychologists. Erin completed a pediatric
neuropsychology practicum from 2004-2005 in the Department of Pediatrics,
Division of Pediatric Hematology-Oncology and Child Neurology at the University of
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Rochester Medical under the supervision of Heather Adams, Ph.D. From 2005-2009,
Erin conducted neuropsychological assessments as part of a longitudinal study of
children to assess the neurocognitive effects of hypertension, under the supervision of
Heather Adams and Marc Lande, M.D, in the Department of Pediatrics, Division of
Pediatric Nephrology at the University of Rochester Medical Center. From 2005-
2006, Erin served as a psychology trainee fellow, as part of the Leadership Education
in Neurodevelopmental Disabilities and Related Disorders Program (LEND) of the
Strong Center for Developmental Disabilities, Division of Neurodevelopmental and
Behavioral Pediatrics, University of Rochester Medical Center under the supervision
of Daniel Mruzek, Ph.D., and Steven Sulkes, M.D. From 2006-2007, Erin served as
an extern in the Child and Adolescent Psychiatric Outpatient Services in the
Department of Psychiatry of the University of Rochester Medical Center under the
supervision of Drs. Linda Alpert-Gillis and Pamela Schippell. From 2008-2009, Erin
served as a psychology extern at the Mount Hope Family Center Clinical Training
Program of the University of Rochester under the supervision of Drs. Sheree Toth,
Jody Todd Manly, and Alisa Hathaway.
Erin completed an APA-approved child clinical and pediatric psychology
internship in 2009-2010 at the Children’s Hospital Colorado in Aurora, Colorado. In
September 2012, Erin will begin a psychology postdoctoral fellowship in pediatric
developmental disabilities in the Child Development Unit of the Neurodevelopment
and Behavioral Pediatrics at the Children’s Hospital Colorado and the University of
Colorado Denver School of Medicine.
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ACKNOWLEDGMENTS
This dissertation manuscript symbolizes far more than the culmination of
many years of study. For its very manifestation was made possible through the
support and guidance of many generous and inspiring mentors, who have supervised
my research and clinical endeavors over the course of my many years as a graduate
student. Their support, guidance, patience, knowledge and commitment to teaching
and supervision have been instrumental in shaping my growth and development
throughout graduate school and while on internship. It is to them, as well as to my
friends and family, that I owe my deepest respect and gratitude.
First and foremost, I extend my sincere appreciation and gratitude to my
academic advisor, Rafael Klorman, Ph.D. for his continued support and mentorship
during my graduate school years and for his kindness and patience. Thank you for
persevering with me as my advisor throughout the time it has taken me to complete
this research and write this dissertation. You have devoted countless hours
supporting me throughout all phases of my dissertation research. I will forever
appreciate your help with participant recruitment, diagnostic interviewing and testing,
assistance with data collection and scoring programs, teaching me
electrophysiological and statistical concepts, discussing my research and findings,
and for reviewing and providing feedback as I prepared this thesis. As my academic
advisor, you have taught me more than you know and have deeply enriched my life in
your support of my professional growth over our years working together. You are a
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living example of a person with great integrity and I can only strive to have the kind
of character that you put forth in all that you do.
I am especially thankful and grateful to my committee members, Loisa
Bennetto, Ph.D. and Lisa Willis, Ph.D. for the time and energy they have personally
invested in reviewing my dissertation work and supporting me with this final step in
my graduate school career. I am deeply appreciative to Loisa Bennetto, Ph.D. for
helping me to acquire a foundation of clinical assessment skills, and for guiding me in
areas of teaching and professional development. Loisa has been there for me at times
when I had lost faith in myself and has helped me to get unstuck and refocus on the
bright future ahead and all the reasons I was drawn to this field of study. Thanks to
Loisa’s support, I now am about to start a post-doctoral fellowship that matches my
interests perfectly and that will serve as a platform to continue to develop my career
in Denver. I would also like to extend my sincerest thanks to Lisa Willis, Ph.D. for
supporting my growth and development as a psychology practicum and post-
practicum trainee at the University Counseling Center and also for supporting my
interest in working with transgendered persons. Your supervision and teachings
helped me acquire a foundation of clinical skills that has later served me in other
clinical settings beyond measure. In addition, I am deeply thankful for the support of
the amazingly dedicated administrative staff in the Department of Clinical and Social
Sciences in Psychology who have supported me throughout all my years of graduate
school. I am especially thankful to Maryann Gilbert for her abundant administrative
and emotional support. I’d also like to thank Loretta Pratt, April Engram, and Chris
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Schulz for helping me reach milestones throughout the years. Arthur Loveland also
provided invaluable technical support and I deeply appreciate his assistance and
willingness to help me.
I extend a special thank-you to colleagues who were instrumental in their
involvement in this dissertation research. I was fortunate to adapt the computerized
Go/No-Go discrimination task that was originally created by Nora Ilniczky, Ph.D. for
use in her dissertation research, which also afforded me to the opportunity to replicate
and extend her findings with a clinical population. I will forever appreciate the
overlapping time we had together as graduate students and confidants. It has been my
pleasure to collaborate with Tom Gift, M.D. over the years we collected data, and I
offer my sincere thanks to him and Rafael Klorman, Ph.D. for administering clinical
interviews to participants and informant(s) that were evaluated for this study and for
their careful precision to determining diagnostic statuses of the sample. I’d also like
to thank my fellow graduate students Melissa Dakis, Anna Gekker, and Kelly
Wheaton for their role in conducting psychoeducational assessments for participants
included in this study. I’d also like to thank all the people who participated in this
study and their informant(s) who gave of their time to participant in this investigation.
I would like to thank the adults with ADHD for helping to advance the field and I
truly hope we provided you with helpful feedback and answers. It is through the
combined efforts of all these individuals through which my data came to be.
I also extend my gratitude to all of my clinical supervisors that I have been
blessed to work with in a variety of treatment settings. Each of you has uniquely
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contributed to my development as a clinician and helped shape my understanding and
practice of evidence based treatments. You have all nurtured my life’s work and
professionalism and allowed me to be part of meaningful work. I appreciate and
thank all of you for your time, dedication, wisdom and commitment to supervising
my clinical work: Casey Moser, Ph.D., Daniel Mruzek, Ph.D., Heather Adams, Ph.D.,
Pamela Schippell, Ph.D., Linda Alpert-Gillis., Jody Todd-Manly, Ph.D., Sheree Toth,
Ph.D., Alisa Hathaway, Ph.D., Rebecca Wilson, Psy.D., Robin Gabriels, Psy.D.,
Alyssa Oland, Ph.D., Tami Roblek, Ph.D., and Lina Patel, Psy.D.
To my invaluable network of supportive, forgiving, generous and loving
friends and extended family, I extend to you all my gratitude and affection. I will
always be mindful of the ways each of you have thoughtfully supported and
encouraged me through these years of graduate school toward this final project.
To my grandparents, Arthur and Barbara Schunck and to my aunt, Pamela
Schunck: in ways too numerous to count, your love, caring, patience and support of
me along this very long and colorful journey will forever be tucked away in my heart.
With deep appreciation, I give thanks to you all for always being there to listen to me
and support me, for your love has kept me grounded.
To my brother Eric: you have been my partner, confidant and dear friend as
we have walked through life together. All those years ago, I shared with you my goal
of one day earning a graduate degree in clinical psychology and you have stood by
me every step along the journey with all its twists and turns. I am forever grateful for
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your love, support, and that sense of humor of yours that always keeps me laughing.
You are my inspiration and I am deeply proud to be your sister.
To my parents, Hugh and Susan Gorman: this completed dissertation is a
milestone long coming, not only of mine, but yours too. You two have been my
foundation, my rocks; there are no words adequate enough to express my eternal
gratitude and appreciation for the unconditional love, guidance, nurturing and
opportunities that have been given to me by you both throughout my life. You both
have stood by me every day of my existence with unwavering support and
commitment and have lifted me up during my lows and made all things possible. We
did it!
To my husband, Dariush Bozorgpour: having you to love and walk through
life with is my life’s biggest gift and miracle to treasure. I thank you with all of my
being for giving me the freedom to pursue my dreams and for encouraging me above
all to do whatever it is that makes me happy. I am forever grateful for the sacrifices
you have made to support me in the completion of my dissertation and for putting my
needs above your own. Your unwavering love and commitment to me has helped me
immensely in reaching my goal of completing graduate school. You have taught me
that by working together, anything is possible and I extend my eternal thanks for all
the choices you have made in your life that allows us to live a beautiful one together.
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ABSTRACT
The aims of the present work were to evaluate whether adults with Attention-
Deficit Hyperactivity Disorder (ADHD) exhibit attentional dysfunction and deficits in
intentional motor inhibition found in children with ADHD and to compare findings
among well delineated adult subtypes of ADHD. A Go/No-Go discrimination task
was administered to 38 healthy and 40 unmedicated participants with ADHD (18
ADHD/Inattentive and 22 ADHD/Combined).
The Go/No-Go discrimination task required right/left responses based on
target position and responding/inhibiting responses (Go/No-Go, p = .50) based on
stimulus characteristics (letter/numbers). Stimuli varied along two levels of
discriminability (easy, 2/V; hard, 1/l). On the Go/No-Go discrimination task, the
ADHD sample had reduced accuracy and slower and more variable reaction time.
The ADHD/Combined sample displayed worse performance compared to controls
whereas the ADHD/Inattentive sample performed intermediate to both other samples
on most measures of task performance. The following exceptions were that the
ADHD/Inattentive sample had slower reaction time compared to controls, slower
EMG onset latency compared to both other samples, and made marginally fewer false
alarms and had better d’ than ADHD/Combined participants.
As expected, participants developed Lateralized Readiness Potentials (LRPs)
to both No-Go and Go stimuli, thereby providing evidence of partial preparation of
responses based on stimulus position. The ADHD sample had smaller stimulus-
synchronized LRP amplitude, especially for No-Go stimuli; this finding points to