SPECIAL SECTION

Issues in the Diagnosis and Phenomenology of the PervasiveDevelopmental Disorders

Introduction

Issues in the Classification of Pervasive Developmental Disorders:History and Current Status of Nosology

DONALD J. COHEN, M.D., FRED R. VOLKMAR, M.D., AND RHEA PAUL, PH.D.

The current Diagnostic and Statistical Manual of the American Psychiatric Associationpresents a comprehensive diagnostic system for what it terms "pervasive developmentaldisorders." This paper presents a critical review of this system. Advantages of the systeminclude the use of explicit diagnostic criteria and a multiaxial approach. Disadvantagesinclude the applicability of criteria to disordered children and adults and the rationale forincluding certain disorders. Available information suggests the need for revision of diagnos­tic categories and criteria for research and clinical purposes.

Journal of the American Academy of Child Psychiatry, 25, 2:158-161, 1986.

Over the past century great attention has been paidto the diagnosis and classification of adult psychiatricdisorders. Such a taxonomic history has not existedin child psychiatry because of the difficulties in devel­opmental diagnosis, developmental changes in theexpression of the disorders, the lack of overarchingtheoretical perspectives, concerns about diagnostic la­beling (Hobbs, 1975; Rutter, 1978), and limited childpsychiatric research in diagnosis and epidemiology.The failure to place syndromic concepts within adevelopmental context has led to disagreement aboutthe validity of proposed syndromes and impeded re­search efforts. During the past decade, a consensusabout the validity and nosology of various psychiatricdisorders of childhood onset has begun to emerge as aresult of greater diagnostic precision (Spitzer et aI.,1978), the use of multiaxial classification schemes

l Ir. Donald Cohen and Dr. Fred Volkmar are the Guest Editorsof this special section. Dr. Cohen is Director, Yale University ChildStudy Center, and Professor of Pediatrics. Psychiatry. and Psychol­o#y. Yale University School of Medicine. Dr. Volkmar~, AssistantProfessor of Psychiatry, Pediatrics. and Psychology.

An earlier ['ersion of this paper wa., discussed at the NINCDSuiorkshup on research duumostic criteria for aut~,m, Wa.,hington.D.C. /91'1.'1. This research wa., supported by NIMH grant MH30929and NIH grants HD0300H and RROO/2.5. the John Merck Fund, andMr. Leonard Berger. Drs. Bennett A. Shayuntz, James F. Lechman,Sally Shavuntz, Kirsten Dahl, and Sally Provence provided helpfulconsultation. Address correspondence to Donald J. Cohen, M.D..Child Study Center. 1'.0.8. 3333, New Haven. CT 06.5/0.

0002-71 :IR/RG/2f,02-0IGR $02.00/0 (c, 19R6 by the American Acad­emy of Child Psychiatry.

(Cohen, 1976; Rutter et aI., 1975), and the availabilityof longitudinal data. DSM-III represents the mostrecent comprehensive diagnostic scheme for childhooddisorders though issues regarding its use for suchdisorders were immediately apparent (Rutter andShaffer, 1980). In this introductory paper we presenta critical review of the DSM-III classification systemfor infantile autism and other pervasive developmen­tal disorders and outline an alternative phenomeno­logical, system for conceptualizing such disorders.

Historical Background

Historically, interest in the "psychoses" of child­hood dates to the latter half of the 19th century.Kraeplin's description of dementia praecox was ex­tended to children by DeSanctis (dementia praecoc­cisima) in 1906. Potter (1933) proposed criteria forchildhood schizophrenia though this term became syn­onymous with childhood "psychosis." Kanner, in 1943,published his report of early infantile autism whichhe believed to be distinct from childhood schizophre­nia and known medical conditions and which he be­lieved to be characterized by early onset disturbancesin social relatedness and an insistence of sameness inthe context of apparently good intellectual potential.Subsequently a variety of other diagnostic categories,atypical personality developmental (Rank, 1949), au­tistic psychopathy (Asperger, 1944), and symbioticpsychosis (Mahler, 1952), were proposed. However,

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CLASSIFICATION OF PERVASIVE DEVELOPMENTAL DISORDERS 11)9

the confusion over possible continuities with adultpsychoses, especially schizophrenia, the role of asso­ciated medical conditions, mental retardation, andpsychodynamic factors impeded efforts at more pre­cise syndrome delineation (see Fish and Ritvo (1979)and Rutter and Garmezy (198~) for reviews). In thefirst and second editions of the Diagnostic and Statis­tical Manual only the term childhood schizophreniawas available to describe children with early onset"psychosis." This scheme presumed continuity ofchildhood "psychosis" with adult schizophrenialargely on the basis of severity and ignored the diffi­culties in assessing thought disturbance in childhood.Subsequent data clarified important features of theautistic syndrome such as its association with varyingdegrees of mental retardation, neurological abnormal­ities, its distinctive characteristics, and its lack ofassociation with other disorders such as schizophrenia(Kelvin, 1971; Rutter, 1972). Over the past decademany investigators have come to share the view thatthe final behavioral expression of the autistic syn­drome is potentially the result of multiple factors.

DSM-IIIDSM-III includes criteria for three disorders under

the rubric of "pervasive developmental disorder";these three disorders, infantile autism OA), childhoodonset pervasive developmental disorder (COPDD),and atypical pervasive developmental disorder(APDD), are all characterized by distortions of mul­tiple psychological functions involving social and lin­guistic development. The description of IA in DSM­III rests on Kanner's (194:~) original report as modifiedby subsequent research (see Rutter and Garmezy(198:H for a review). The COPDD cateogory is pro­posed for children who develop an "autistic-like" syn­drome after ~o months of age while the atypical cate­gory is reserved for those children whose disorderappears to lie within the PDD class but who fail tomeet criteria for either IA or COPDD. It should beemphasized that the "atypical" term in DSM-IIImeans "otherwise unclassified" rather than "atypical"in the sense suggested by Rank (1949), though thereappears to be substantial overlap between these twogroups. Advantages of the DSM-III scheme for autismare readily apparent. DSM-III recognizes the validityof this diagnostic class, proposes explicit diagnosticcriteria, and emphasizes the need for multiaxial as­sessment. However, in the years since its publication,various problems with this scheme have become ap­parent.

Relationship to Childhood Schizophrenia. Childhoodschizophrenia is no longer included as a separatediagnostic category in DSM-III (Cantor et aI., 1982)though a diagnosis of schizophrenia can be made in

childhood if criteria for the adult disorder are satisfied.The presence of hallucinations and delusions excludesa child from the diagnosis of PDD.

Although the distinction between PDD and schizo­phrenia rests on a substantial body of research (Rut­ter, 1972) it is problematic in two ways. First, manyverbal autistic children would satisfy at least somecriteria for schizophrenia on the basis of their mark­edly illogical thinking, incoherence, poverty or speechand inappropriate or blunted affect, and virtually allautistic individuals would satisfy the prodromal orresidual schizophrenic criteria such as social isolation,inappropriate affect, etc. Second, some autistic chil­dren hold strange beliefs bordering on delusions(Volkmar et al., 1986).

Interpretation of Diagnostic Criteria. The nature ofthe criteria proposed for the PDDs are also problem­atic in several ways. They are difficult to quantify oroperationalize and may be somewhat misleading(Volkmar et al., 1986). For example, a "pervasive lackof responsiveness to other people" is included as acriterion for infantile autism and many investigators(e.g., Fein et al. (1986) in this issue) would agree thatthe social disturbance in autistic individuals is animportant defining feature of the syndrome. However,autistic individuals often form real, although deviant,social relationships by the time they reach school age(Rutter, 1970; Volkmar and Cohen, 1985; Wing andGould, 1979). If this criterion is strictly applied it isdifficult to confer a diagnosis of IA on many autisticchildren, particularly the brighter autistic individualswho show some degree of social relatedness. Paradox­ically, the criteria for social deviance in the COPDDcategory are less stringent and might be more appro­priately applied to autistic individuals.

Criteria for language deviance present a similarproblem in DSM III. For lA, DSM III specifies "grossdeficits in language development" and "peculiarspeech patterns, if speech is present" while forCOPDD the criteria include "abnormalities ofspeech." Studies of autistic children's language andcommunication skills suggest that these criteria maybe too general and incorrectly focused (Paul, 1986;Tager-Flushberg, 1981) since many autistic individu­als never speak (Fay and Schuler, 1980) and muteindividuals show deficits in nonverbal communicationskills (Curcio, 1976; Wetherby and Prutting, 1984).Thus DSM-III overemphasizes speech per se and failsto address in sufficient detail communication deficitsseen in autistic individuals.

COPDD and Age of Onset. The COPDD diagnosticcategory in DSM-III represents a new diagnostic con­cept. COPDD is grouped with IA in the PDD classi­fication scheme. Children with COPDD, as defined in

IGO COHEN ET AL.

DSM-III, would appear to differ from autistic childrenin two important ways : age of onset and severity ofdisturbance. CaPDD develops, according to DSM-III,after :m months and before age 12. The rationale forincluding this new diagnostic concept appears to reston the work of Kolvin (1971) which suggested a bi­modal age of onset of "psychosis" in childhood. InKelvin 's data a very small number of children ex­hibited an onset of their disorder after age :5 and beforeage!) and it appears that DSM-III attempts to encom­pass such children in the CaPDD concept. However,age limits suggested for CaPDD do not agree withthose used by Kolvin (1971) and the utility of age ofonset as a diagnostic criterion is somewhat suspectsince the age of onset depends, in most cases, onparent reports which may be affected by parentalsophistication and denial (Robbins, 1963) . Most in­vestigators would agree that the PDDs have an onsetearly in life and retrospective deviations in develop­ment are almost always identified (Ornitz et al., 1978) .While the select ion of any cutting point must bearbit rary, if it is to be used at all, practically fewchildren who exhibit CaPDD are identified and manydevelop the disorder in association with some CNSinsult (Kolvin, 1971; Volkmar et al., 1985).

As defined in DSM-III, IA and CaPDD also appearto differ with regard to the severity of the syndrome.Criteria for lA are monothetic (i.e., a child must meetevery crit erion) while t hose for the presumably muchrarer COI'DD are polythetic (so that a child can meetsome criteria and still receive the CaPDD diagnosis) .Practically, the criteria for COPDD, with the excep­t ion of age of onset, are in many ways more appropri­ately applied to autistic individuals (Volkmar et al.,(1986), in t his issue); since the phenomenological de­scriptions of the two disorders are generally similar,there seems little need to add a distinct category forchildren who develop a disorder similar to autism after:1O mont hs of age. Rather, it would appear more rea­sonable to include age of onset as an associated featureof t he aut ist.ic syndrome and not as an exclusionarydiagnost ic criterion.

Alypicnl J)[)1J. In each DSM-III diagnostic class an"atypical" diagnostic category is available to describeconditions which seem to be phenomenologically sim­ilar to disorders in t he class but which fail to meetdiagnostic criteria for a specific disorder. In this sense"atypical PDD" in DSM-III refers to those childrenwho share many, though not all, the features of IAand COPDD. In the case of atypical PDD DSM-IIIhas appropriated a previously existing term "atypicalpersonalit y development" which has been used(Brown, 19GO; Rank, 1949) to describe children withmajor disturbances in social, affective, and communi-

cative development. This latter term, while clinicallyuseful, has lacked diagnostic precision. The DSM-IIIterm, while also imprecise, is readily confused withthe earlier term. Several papers in this special section(Dahl et al.; Rescorla; Sparrow et al.) are relevant tothis issue . The elaboration of diagnostic criteria forsuch children remains an important topic for futureresearch.

Residual Autism. DSM-III includes a category forthose individuals who once met criteria for IA but nolonger do so, though signs of the illness such as "odd­ities of communication" and social awkwardness per­sist. This diagnostic category suggests that some au­tistic children "grow out" of autism; in fact, a fewautistic children, 1-2% of samples in follow-up stud­ies, will have a very good outcome and function rela­tively well (DeMeyer et al., 1981). Most autistic chil­dren, however, grow up to be autistic adults. DSM­Ill's scheme does not direct sufficient attention to theexpression of the disorder during development (Rut­ter, 1970) i.e. it focuses on the infantile aspect of IA.

New Diagnostic Directions

In research and clinical work with autistic andsimilar children, professionals have had to confrontthe dilemmas posed by the DSM-III system. Often, inboth clinical and research settings, children are diag­nosed as autistic or CaPDD, with an explicit state­ment "according to DSM-III criteria" though patientsfail to meet the specified criteria. It might be arguedthat the intent of the DSM-III scheme is fundamen­tally sound, suggesting that a more appropriate diag­nostic statement would be "according to the intent ofDSM-III criteria." This solution has the advantage ofhonesty but the disadvantages introduced by incon­sistent and idiosyncratic diagnostic approaches.

At the same time several factors would suggestreasonable conservatism in modifying the diagnosticscheme. DSM-III is still quite new and, in general, itseems to be doing a reasonable job in facilitatingresearch and the provision of clinical services. Empir­ical studies of proposed diagnostic criteria are justbeginning to appear. Diagnostic concepts, such asautism, also function outside the domain of researchand clinical service. "Autism" is included as a term infederal legislation, legal decisions, and third-party (in­surance) guidelines, and introducing changes in no­menclature prematurely may have important impli­cations for disordered children. Terms such as PDDand CaPDD were introduced as a creation of com­mittee. The PDD term, in particular, has achievedwidespread utility as a designation for a large groupof children since it is acceptable in multidisciplinarysettings and is theoretically unencumbered. Theseterms have also begun to appear with regularity in

CLASSIFICATION OF PERVASIVE DEVELOPMENTAL DISORDERS 161

research studies and changes in the definition or in­clusion of diagnostic categories should be made onlyon the basis of solid empirical data. Thus, changes inthe DSM-III scheme for these disorders should con­form, to the extent possible, to conventions already inuse; he based on replicated data; be conservative inintroducing diagnostic innovations; and be applicahleboth in clinical work and in research.

The research presented in this Special Section ad­dresses empirically some of these issues. While argu­ing for conservatism and agaisnt precipitous changesin terminology and nosolocial systems, some modifi­cations of current criteria for the PODs warrant con­sideration. Suggestions for these modifications will bepresented at the conclusion of this section in the hopeof stimulating discussion and moving toward a betterdiagnostic system in DSM-IV.

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