Director, Editorial: Lane Akers Executive Assistant: Bonita D'Amil Cover Design: Kathryn Houghtaling Lacey Textbook Production Manager: Paul Smolenski Full-Service Compositor: TechBooks Text and Cover Printer: Hamilton Printing Company This book was typeset in 10/12 pt. ITC New Baskerville, Bold, and Italic. NOT FOR Copyright © 2005 by Lawrence Erlbaum Associates, Inc. All rights reserved. No part of this book may be reproduced in any form, by photostat, microform, retrieval system, or any other means, without prior written permission of the publisher. Lawrence Erlbaum Associates, DISTRIBUTIONInc., Publishers 10 Industrial Avenue Mahwah, New Jersey 07430 www.erlbaum.com Library of Congress Cataloging-in-Publication Data Autism spectrum disorders : identification, education, and treatment / edited by Dianne Zager.—3rd ed. p. cm. Rev. ed. of: Autism : identification, education, and treatment. 1999. Includes bibliographical references and index. ISBN 0-8058-4578-X (case : alk. paper)—ISBN 0-8058-4579-8 (pbk. : alk. paper) 1. Autism in children. 2. Autistic children—Education. 3. Autism—Treatment. I. Zager, Dianne, 1948- II. Autism. RJ506.A9A9223 2004 371.94—dc22 2004013164 Books published by Lawrence Erlbaum Associates are printed on acid-free paper, and their bindings are chosen for strength and durability. Printed in the United States of America 10 987654321 Chapter 1 Definitions and Characteristics of the Spectrum NOT Joel D. Bregman North Shore-Long Island Jewish Health System Yale Child Study Center FOR DISTRIBUTION OVERVIEW OF THE AUTISM SPECTRUM Conception of the Autism Spectrum Autism and the pervasive developmental disorders (PDDs) are highly com- plex and variable in their clinical presentation and manifestations. For ex- ample, symptoms and characteristics change with developmental maturity and vary with the degree of associated cognitive impairment (Filipek et al., 1999a). This evolving pattern of clinical features can make the differential diagnostic process very difficult in some cases. Nonetheless, the defining feature of autism is the presence of a distinctive impairment in the nature and quality of social and communicative development (influenced by the specific biological and environmental circumstances of the individual). It is this impairment that distinguishes autism from other neurodevelopmen- tal conditions (e.g., mental retardation, developmental language disorders, specific learning disabilities). For example, whereas mental retardation is characterized by a pervasive developmental delay, autism is characterized by a distinctive impairment in the nature of social-communicative devel- opment. The prognostic significance of this autistic social dysfunction is underscored by preliminary studies that report a negative correlation be- tween the severity of this social impairment and treatment responsiveness, 4 BREGMAN at least with regard to social and linguistic growth following intensive, behaviorally based early intervention (Ingersoll, Schreibman, & Stahmer, 2001). Additional complexity in the differential diagnosis of autism and related PDDs results from a wide range of accompanying abnormalities within cogni- tive, adaptive, affective, and behavioral domains of development, including mental retardation (Volkmar, Cook, Jr., Pomeroy, Realmuto, & Tanguay, Volkmar & Klin, 1999), deficits in executive functions (Liss, Fein, et al., 2001; Ozonoff, 1995, 1997; Pennington et al., 1997), limitations in adaptive skills (especially in socialization and functional communication; Liss, Harel, et al.NOT, 2001), learnin g disabilities (e.g., nonverbal learning disability; Rourke, 1995), mood instability (Di Martino & Tuchman, 2001; Hellings, 1999; Hol- lander, Dolgoff-Kaspar, Cartwright, Rawitt, & Novotny, 2001), stereotypic and self-injurious behaviors (King, 2000), anxiety disorders (Kim, Szatmari, Bryson, Streiner, &: Wilson, 2000), and aggression (Hollander et al.; King, 2000). FOR The Broader Autism SpectrumDISTRIBUTION During the past decade, the reported prevalence of autism-related condi- tions has risen markedly (Bryson, Clark, Sc Smith, 1988; Fombonne, Du Mazaubrun, Cans, & Grandjean, 1997; Fombonne, Simmons, Ford, Meltzer, & Goodman, 2001; Wing & Potter, 2002; Yeargin-Allsopp et al., 2003), in part as a result of a broadening of the diagnostic concept to include milder and more atypical variants. This has led to the increasingly frequent use of the term autism spectrum disorder (ASD) within clinical and educational settings (Filipek et al., 1999b), consistent with prior conceptions of autism, including the broader autistic spectrum (Wing & Gould, 1979) and ASD (Allen, 1988). Recent genetic studies lend support to this concept, because it appears that the heritable factor in autism is not the specifically defined disorder it- self, but rather, subtle weaknesses in social interaction and interpersonal dis- course (Bailey, Palferman, Heavey, & Le Couteur, 1998; Le Couteur, Bailey, Goode, Pickles, et al., 1996). The literature suggests that the genetic lia- bility for autism may be associated with limited interest in social interac- tion, few close confiding friendships, impaired socioemotional responsivity (a less robust finding), language delays, conversational impairments, prob- lems in communication planning, and possibly anxiety and rigidity (Bailey et al., 1998). The boundaries of the behavioral phenotype for autism has been examined in same-sex twin pairs (28 monozygotic [MZ] and 20 dizy- gotic [DZ]), one of whom had autism (Le Couteur et al., 1996). Among the discordant co-twins (those without autism), findings included language 1. DEFINITIONS AND CHARACTERISTICS 5 impairments in childhood and social deficits persisting into adulthood. This broader phenotype was much more common among MZ pairs than DZ pairs, indicating a strong genetic influence. Behavioral and cognitive character- istics of autism appear to be less genetically based because no differences were found within and between MZ twin pairs. Family and case control studies of community-ascertained probands with autism support the broader autism phenotype (BAP) concept (Folstein et al., 1999). These investigators identified a subset of autism family mem- bers manifesting a language component of the BAP (separate from the social component). This is consistent with the hypothesis that several inde- pendentlNOTy segregatin g genes (i.e., those that have distinguishable manifesta- tions) interact to cause autism (Folstein et al., 1999). Dawson and colleagues propose that the identification of autism susceptibility genes will be strongly influenced by success in characterizing dimensional attributes of broader phenotype autism traits (Dawson et al., 2002). These investigators have hypothesized thaFORt six traits characterize this broader phenotype, namely, (a) face processing, (b) social affiliation or responsiveness to social rein- forcement, (c) motor imitation, (d) memory for social-emotional stimuli, (e) executive functioning (e.g., planning and flexibility), and (f) language ability (e.g., phonology). DISTRIBUTION However, in considering the BAP, it is important to keep in mind that this is not synonymous with the diagnostic entity of autism or ASD, itself. Rather, it represents a genetically determined set of personal characteristics that increases the susceptibility of offspring to the development of the clinical syndrome. This is similar to a large number of clinical conditions that are influenced by susceptibility genes, such as certain types of malignancies, cardiovascular disease, and so forth. The presence of these susceptibility genes does not automatically result in the actual disorder; rather, it increases the likelihood that future generations will develop the clinical condition. Therefore, a "carrier" of these susceptibility genes should not be diagnosed as manifesting autism or ASD. Several methodological issues are present both within and across studies of the BAP that complicate the interpretation of reported findings (Bailey et al., 1998). For example, there is a good deal of heterogeneity among probands with regard to PDD subtype (e.g., autistic disorder vs. Asperger syndrome [AS] vs. PDD not otherwise specified [NOS]), diagnostic criteria (e.g., edition of DSMor /CD used), and the presence of known medical and co-morbid neuropsychiatric conditions. In addition, there are differences across studies with regard to the subject ascertainment procedures employed (e.g., epidemiological or consecutive case); the nature of control subjects, if any (e.g., other genetic conditions or developmental disabilities); and the relatives that were studied (e.g., siblings, parents, and cousins) (Bailey et al., 1998). 6 BREGMAN HISTORICAL PERSPECTIVE Current conceptions of the clinical syndrome of autism are direct extensions of the work of Leo Kanner, Hans Asperger, and Michael Rutter. Classic autism (or Kanner syndrome) is the pro to typical ASD, representing the FDD subtype that involves the most severe social-communicative impairments and the greatest number and range of clinical characteristics. The essential features of Kanner syndrome are most closely captured by the DSM-TVand ICD-10PDD subtypes of autistic disorder and childhood autism, respectively. In his seminal paper published in 1943, Leo Kanner carefully described a uniquNOTe neurodevelopmenta l condition (which he termed early infantile autism) that appeared to result from a congenital inability to form close af- fective ties with others and to tolerate minor changes in the