Russell A. Barkley - Executive Functions: What They Are, How They Work, and Why They Evolved

For more information, visit the authors website: www.russellbarkley.org

FOR PROFESSIONALS

ADHD in Adults: What the Science Says

Russell A. Barkley, Kevin R. Murphy, and Mariellen Fischer

FOR GENERAL READERS

Taking Charge of ADHD , Revised Edition:

The Complete, Authoritative Guide for Parents

Russell A. Barkley

Your Defiant Child: Eight Steps to Better Behavior

Russell A. Barkley

Your Defiant Teen: 10 Steps to Resolve Conflict
and Rebuild Your Relationship

Russell A. Barkley and Arthur L. Robin with Christine M. Benton

ADULT ASSESSMENT SCALES

Barkley Adult ADHD Rating ScaleIV (BAARS-IV)

Russell A. Barkley

Barkley Deficits in Executive Functioning Scale (BDEFS for Adults)

Russell A. Barkley

Barkley Functional Impairment Scale (BFIS for Adults)

Russell A. Barkley

CHILD ASSESSMENT SCALES

Barkley Deficits in Executive Functioning Scale

Children and Adolescents (BDEFS-CA)

Russell A. Barkley

Barkley Functional Impairment Scale

Children and Adolescents (BFIS-CA)

Russell A. Barkley

EXECUTIVE
FUNCTIONS

What They Are, How They Work,
and Why They Evolved

RUSSELL A. BARKLEY

THE GUILFORD PRESS

New York London

Epub Edition ISBN: 9781462505371; Kindle Edition ISBN: 9781462505388

2012 The Guilford Press

A Division of Guilford Publications, Inc.

72 Spring Street, New York, NY 10012

www.guilford.com

All rights reserved

No part of this book may be reproduced, translated, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, microfilming, recording, or otherwise, without written permission from the publisher.

Last digit is print number: 9 8 7 6 5 4 3 2 1

Library of Congress Cataloging-in-Publication Data

Barkley, Russell A., 1949
Executive functions : what they are, how they work, and why they evolved /
Russell A. Barkley.
p. cm.
Includes bibliographical references and index.
ISBN 978-1-4625-0535-7 (hardcover : alk. paper)
1. Neuropsychological tests. I. Title.
RC386.6.N48B376 2012
616.80475dc23

2012005366

For Pat, Steve, Ken, Laura, and Liam

R ussell A. Barkley, PhD, ABPP , is Clinical Professor of Psychiatry and Pediatrics at the Medical University of South Carolina. Dr. Barkley has published numerous books and five assessment scales, plus more than 260 scientific articles and book chapters on ADHD, executive functioning, and childhood defiance. He is also the editor of the newsletter The ADHD Report . A frequent conference presenter and speaker who is widely cited in the national media, he is past president of the Section on Clinical Child Psychology (the former Division 12) of the American Psychological Association, and of the International Society for Research in Child and Adolescent Psychopathology.

I wish to thank several of my colleagues for their comments on and review of some of the content of this work and my presentations about it. These include Jeanette Wasserstein, PhD, and Rosemary Tannock, PhD, for their constructive reviews of previous versions of the manuscript, and John Schureman, PhD, who shared with me but a small portion of his vast knowledge of neuroscience and philosophy as it may pertain to this model. I am especially indebted to Barbara Watkins of The Guilford Press for her close editing of the manuscript and exceptionally constructive recommendations for revisions so as to more clearly express the model and related ideas presented here. I am also grateful for the production editing by Bianca Cavanaugh, and once more express my deep appreciation to Kitty Moore, Seymour Weingarten, and Robert Matloff for their acceptance and support of the publication of this book. Finally, I thank my wife of more than 40 years, Patricia Gann Barkley, for her support throughout the research behind this book and its writing.

Contents

2.The Extended Phenotype: A Foundation
for Modeling Executive Functioning

9.Implications for Understanding Executive
Functioning and Its Disorders

10.Implications for the Assessment and Clinical
Management of Deficits in Executive Functioning

Problems with the Concept
of Executive Functioning

T he basis for the concept of executive functioning (EF) arose in the 1840s in the initial efforts by scientists to understand the functions of the frontal lobes generally and the prefrontal cortex (PFC) specifically (Harlow, 1848, 1868; Luria, 1966). Indeed, the concept predates the term EF by more than 120 years. The concept of EF was at first defined by default as what the prefrontal lobes do (Pribram, 1973, 1976); they are, as Pribram said, the executive brain. The term EF came out of these earlier efforts to understand the neuropsychological functions mediated by the prefrontal or premotor regions of the brain. This history has led to a conflating of the term EF with the functions of the PFC and vice versa.

Over time, this conflation has led to a circularity of reasoning in that the functions of the PFC are said to be EF while EF is then defined back to the functions of the PFC. It has also led to a slippage in the discourse on EF between two separate levels of analysis (Denckla, 1996). One is the neuropsychological level involving thought (cognition), emotion, and verbal or motor action (behavior); the other is the neuroanatomical level involving the localization of those neuropsychological functions to specific regions of the brain and their physiological activity. But EF is not exclusively a function of the PFC given that the PFC has various networks of connections to other cortical and subcortical regions as well as to the basal ganglia, amygdala and limbic system, and cerebellum (Denckla, 1996; Fuster, 1989, 1997; Luria, 1966; Nigg & Casey, 2005; Stuss & Benson, 1986). The PFC may well engage in certain neuropsychological functions that would not be considered to fall under the umbrella of EF, such as simple or automatic sensorymotor activities, speech, and olfactory identification, to name just a few.

Thus, despite an extensive history concerning the nature of EF and of the functions of the PFC, several significant problems continue to exist in the definition of the term EF, its conceptualization, and its measurement. EF is a term describing psychological functions and is therefore a construct at the psychological level of analysis. If our understanding of EF is to advance, the concept of EF and its nature must be defined separately and specifically at the psychological level without reference to the neurological level being an essential part of that definition. Such a cross-referencing of levels is of interest to neuropsychology in determining what specific brain regions engage in what specific functions. But this activity requires that we have such functions properly defined at the psychological level first before we can determine what brain networks give rise to that psychological function. If EF and its larger purposes in human life are not well defined and developed, only confusion can reign at the neurological level as one searches for the neural networks that supposedly underlie a vaguely defined and poorly crafted psychological construct, perhaps in vain.