clinical assessment of psychopharmacological treatment of preschoolers with adhd

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This article was downloaded by: [Washington State University Libraries ] On: 01 November 2014, At: 19:58 Publisher: Routledge Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK Journal of Clinical and Experimental Neuropsychology Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/ncen20 Clinical Assessment of Psychopharmacological Treatment of Preschoolers with ADHD Joseph M. Byrne , Harry N. Bawden , Nadine A. DeWolfe & Tricia L. Beattie Published online: 09 Aug 2010. To cite this article: Joseph M. Byrne , Harry N. Bawden , Nadine A. DeWolfe & Tricia L. Beattie (1998) Clinical Assessment of Psychopharmacological Treatment of Preschoolers with ADHD, Journal of Clinical and Experimental Neuropsychology, 20:5, 613-627, DOI: 10.1076/jcen.20.5.613.1121 To link to this article: http://dx.doi.org/10.1076/jcen.20.5.613.1121 PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions

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Page 1: Clinical Assessment of Psychopharmacological Treatment of Preschoolers with ADHD

This article was downloaded by: [Washington State University Libraries ]On: 01 November 2014, At: 19:58Publisher: RoutledgeInforma Ltd Registered in England and Wales Registered Number: 1072954 Registered office: MortimerHouse, 37-41 Mortimer Street, London W1T 3JH, UK

Journal of Clinical and ExperimentalNeuropsychologyPublication details, including instructions for authors and subscription information:http://www.tandfonline.com/loi/ncen20

Clinical Assessment of PsychopharmacologicalTreatment of Preschoolers with ADHDJoseph M. Byrne , Harry N. Bawden , Nadine A. DeWolfe & Tricia L. BeattiePublished online: 09 Aug 2010.

To cite this article: Joseph M. Byrne , Harry N. Bawden , Nadine A. DeWolfe & Tricia L. Beattie (1998) Clinical Assessmentof Psychopharmacological Treatment of Preschoolers with ADHD, Journal of Clinical and Experimental Neuropsychology,20:5, 613-627, DOI: 10.1076/jcen.20.5.613.1121

To link to this article: http://dx.doi.org/10.1076/jcen.20.5.613.1121

PLEASE SCROLL DOWN FOR ARTICLE

Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) containedin the publications on our platform. However, Taylor & Francis, our agents, and our licensors make norepresentations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose ofthe Content. Any opinions and views expressed in this publication are the opinions and views of the authors,and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be reliedupon and should be independently verified with primary sources of information. Taylor and Francis shallnot be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and otherliabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to orarising out of the use of the Content.

This article may be used for research, teaching, and private study purposes. Any substantial or systematicreproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in anyform to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://www.tandfonline.com/page/terms-and-conditions

Page 2: Clinical Assessment of Psychopharmacological Treatment of Preschoolers with ADHD

* Address correspondence to: J.M. Byrne, IWK-Grace Health Centre, 5850 University Ave., P.O. Box 3070,Halifax, N.S., B3J 3G9, Canada. E-mail: [email protected] for publication: April 23, 1998.

Journal of Clinical and Experimental Neuropsychology 1380-3395/98/2005-613$12.001998, Vol. 20, No. 5, pp. 613-627 © Swets & Zeitlinger

Clinical Assessment of Psychopharmacological Treatment ofPreschoolers with ADHD*

Joseph M. Byrne1,2, Harry N. Bawden1, Nadine A. DeWolfe3, and Tricia L. Beattie11IWK-Grace Health Centre, Halifax, Nova Scotia,2Dalhousie University School of Medicine,

and3Dalhousie University

ABSTRACT

Sixteen preschoolers, (8 with Attention-Deficit / Hyperactivity Disorder [ADHD], 8 matched controls)were assessed twice, 5 months apart. Preschoolers with ADHD were rated by their parents as significantlymore inattentive, exhibited more behavior problems, fewer age-appropriate social skills, made more errorsof omission on both the visual and auditory attention tests, and more errors of commission on both thevisual attention and the visual-search cancellation tests. Preschoolers with ADHD were then treated withstimulant medication and exhibited improved behavior as well as significantly reduced errors of omissionon visual and auditory preschool vigilance tests, and fewer errors of commission on the visual-searchpreschool cancellation test. Developmentally appropriate direct measures of attention, in conjunction withparental ratings of child behavior, can be used to assess the efficacy of pharmacological treatment of pre-schoolers with ADHD.

The diagnostic criteria for Attention-Deficit /Hyperactivity Disorder (ADHD) specify that thesymptomsmustbe present prior to 7 years ofage (DSM-III-R; DSM-IV; American Psychiat-ric Association, 1987, 1994). However, the vastmajority of research on ADHD has been con-ducted with school-age children (see Barkley,1990, 1997; Campbell, 1985, 1990, 1995 forreviews). There is a remarkably smaller numberof scientific studies dealing with the characteris-tics and correlates of preschoolers with ADHD,which has hindered progress on earlier assess-ment and treatment of this disorder.

One reason for the paucity of preschool stud-ies is the absence of appropriate measures todetermine developmentally inappropriate levelsof preschool defiance, activity level, temper tan-trums, and inattention (Barkley, 1991; Camp-bell, 1985; Campbell, Szumowski, Ewing,Gluck, & Breaux, 1982). The absence of devel-opmentally appropriate assessment protocols hascontributed to an understandable reluctance to

either diagnose ADHD in preschoolers, or torecommend for those diagnosed, a full treatmentregime which may include pharmacologicaltreatment.

As one of the most common behavioral disor-ders in North America for which health servicesare requested, unresolved issues surrounding thediagnosis and treatment of ADHD continue.This is due in part to the heterogeneous methodsemployed for diagnosing, treating, and monitor-ing treatment efficacy, and/or side effects.Nonetheless, the overwhelming evidence span-ning the past 30 years confirms the positive ther-apeutic effects of pharmacological treatment ofADHD, effects which may be enhanced withconcurrent behavioral and cognitive-behavioraltherapies,and psychotherapy (Shaywitz,Fletcher, & Shaywitz, 1997; Whalen & Henker,1991; Wilens & Biederman, 1992).

These findings, however, have been basedalmost exclusively on school-age and adolescentpopulations. Although pharmacological treat-

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Page 3: Clinical Assessment of Psychopharmacological Treatment of Preschoolers with ADHD

614 JOSEPH M. BYRNE ET AL.

ment is used with young preschoolers, it is oftensuggested that it be considered after demon-strated ineffectiveness of non-pharmacologicaltreatments (e.g., behavior management, psycho-therapy), and confined only to preschoolers pre-senting with moderate to severe clinical presen-tation (see Barkley, 1990, and Wilens & Bieder-man, 1992 for discussion).

There are very few empirical studies, espe-cially peer-reviewed journal studies, in whichthe efficacy of pharmacological treatment hasbeen empirically evaluated with preschoolerswith ADHD. Some studies have included chil-dren within the preschool range, but preschool-ers have typically represented less than 10 to20% of the study sample, (i.e., school-age oradolescent patients) (e.g., Fischer, Newby, &Gordon, 1995; Mayes, Crites, Bixler, Hum-phrey, & Mattison, 1994). For the few studiesthat have specifically studied preschoolers, theresults have been encouraging but mixed.Schliefer et al. (1975) found that the mothers of3-to-5-year-old preschoolers with ADHDreported that their children were more focussedwhile on medication. However, the preschoolersdid not exhibit notable change in their behaviorwithin an unstructured play setting. Significantside effects (impaired socialization, mood insta-bility) were also reported. Conners (1975) foundthat 3-to-6-year-old preschoolers did not exhibitsignificant side effects. Although a general posi-tive clinical response (group) was evident, theresponse was found to be highly variable acrossindividuals. Barkley, Karlsson, Strzelecki, andMurphy (1984) also did not find significant sideeffects in 4-to-6-year-old preschoolers. Theyfound that both low (0.3 mg/kg) and high (1.0mg/kg) doses of methylphenidate resulted inincreased child compliance with decreasedchild-directed maternal behavior (negativity).However, Barkley (1988) found that within aplay observation setting there were limited ef-fects of a low dose (0.15 mg/kg b.i.d.) of meth-ylphenidate on the preschoolers’ play behavior.However, at the higher dosage (0.50 mg/kgb.i.d.) off-task and noncompliant child behav-iors were significantly reduced.

Alessandri and Schramm (1991) reported asingle case in which a 4-year-old preschooler

with ADHD exhibited a positive response todextroamphetamine, manifested in more sus-tained attention during play and structured groupactivity. The generalizations from these findingsare obviously limited given that only one pre-schooler was assessed. Mayes, Crites, Bixler,Humphreys, and Mattison (1994) reported find-ings from a sample of 69 participants from 22months to 13 years of age. Of the small sub-sample of 14 preschoolers in their study, adultquestionnaire ratings revealed a positive re-sponse to methylphenidate in 71% of the pre-schoolers. However, this study included a re-markably heterogeneous sample. The sampleincluded patients with ADHD only and ADHDwith neurodevelopmental disorders, and it wascharacterized by a wide range of IQ (mentallychallenged to superior). Furthermore, some pa-tients were assessed as outpatients, others wereassessed as inpatients, and the Conners’ 10-itemrating scale was the only instrument used to de-termine treatment effects.

Few pharmacological studies of preschoolershave employed parental ratings, direct behav-ioral observation, as well as direct tests of atten-tion. Cohen, Sullivan, Minde, Novak, andHelwig (1981) evaluated the relative efficacy ofa ‘‘3-month treatment’’ of methylphenidateand/or cognitive-behavior therapies in 5-year-old kindergarten children. A one-year follow-upwas conducted (end of grade one). They foundfewer impulsive errors on a cognitive and on avisual-motor task, and a general reduction ofADHD symptomatology regardless of treatmentprotocol. Solitary classroom play was noted tobe increased, yet, there was no change in disrup-tive play or social ignoring exhibited by the kin-dergarten children with hyperactivity. For sev-eral measures, data were available for only 15 ofthe 24 kindergarten children with hyperactivity.It is noteworthy that the sample of this studywas relatively small when one considers the sub-ject distribution over one of three treatment pro-tocols, as well as identification of ‘‘subtypes’’of ADHD by the authors. Despite the compari-son of all protocols, the cognitive-behavioraltherapy, unlike the methylphenidate therapy,was provided for only 3 months. The children inthe methylphenidate therapy group or methyl-

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phenidate plus cognitive-behavior therapy groupwere on medication before and at the time of thefollow-up, thereby compromising comparativeanalyses. The measures of attention used in theCohen et al. (1981) study have weak psychomet-ric properties for assessing attentional impair-ment and are infrequently used in current ADHDresearch (Barkley, 1990).

Musten and colleagues (Musten et al., 1994)studied sixteen 4-to-6-year-old preschoolers andfound, consistent with the previous studies ofschool-age and preschool-age children, that pa-rental ratings were improved during the periodwhen the preschooler was medicated; there wasa significant reduction of parental rating of hy-peractivity related to either low (0.3 mg/kg) orhigh (0.5 mg/kg) dose of methylphenidate. How-ever, no significant medication-related changewas found for direct-coded observation of pre-schooler compliancewithinchild-parent interac-tion, in contrast to the findings of Barkley(1988). In regard to performance on a vigilancetest (Gordon Diagnostic System [GDS]; Gordon,1983), only the low dose resulted in signifi-cantly reduced errors of commission (impulsi-vity), and only the high dosage was sufficient toyield reduced errors of omission (inattention). Inaddition, irrespective of dosage, no medicationeffect was found on a second measure of sus-tained attention (pencil-paper: connect dotstask). These results are therefore encouraging,but the positive medication effects appeared tovary depending on dosage and type of measureemployed.

In summary, very few studies have directlyexamined the efficacy of pharmacological treat-ment of ADHD in preschoolers, despite the factthat: (a) 35% of pediatricians and 15% of familyphysicians prescribe medication for such veryyoung children (Musten et al., 1994); (b) physi-cians treating ADHD substantially more oftenprescribe pharmacological therapies, especiallystimulant medication, than behavioral treatmentor psychotherapy (Wolraich et al., 1990); and(c) pharmacological treatment is still thesinglemost effective treatment for ADHD in school-age children (Barkley, 1990; Wilens &Biederman, 1992). Although few in number, thefindings of several sudies of preschool children

are encouraging. However, given the paucity ofdirect clinic-based measures of attention in pre-school-age children further study is needed todevelop protocols to directly assess treatmenteffects of pharmacological agents in preschool-ers. In particular, further study is needed usingdirect, developmentally appropriate measures toassess treatment efficacy, particularly if thetreatment effects could be monitored across age(i.e., shared psychometric/conceptual features).

In this regard, we recently demonstrated thatnormally developing preschoolers aged 3 to 5years could understand and successfully com-plete two tests of vigilance specifically designedto be developmentally appropriate for pre-schoolers, which maintain the core features ofsimilar tests used with older children and ado-lescents (i.e., visual continuous performancetest; visual-search [cancellation] test: Corkum,Byrne, & Ellsworth, 1995). The study supportedthe construct validity of these developmentallyappropriate measures of attention with pre-schoolers, and confirmed the expected develop-mental change in performance as a function ofchronological age. In a subsequent study, wefound that compared with school-age children,preschoolers with ADHD committed signifi-cantly more errors of commission on a visual-search (cancellation) test. We also found thatpreschoolers with ADHD were rated by theirparents as significantly more challenging tomanage, resulting in increased maternal stress(Byrne, DeWolfe, & Bawden, 1998).

The purpose of the present study was not toadvocate the use of pharmacological treatmentas either the preferred or first method of treat-ment for preschoolers with ADHD. The purposeof the study was to test the clinical validity ofseveral new clinic-based, developmentally ap-propriate measures in detecting response topharmacological treatment of preschoolers withADHD. These preschoolers were prescribed sti-mulant medication by their physician, indepen-dent of this follow-up study.

Using the findings of these previous studiesas a point of reference, the present study wasdesigned to assess the clinical validity of similardevelopmental measures to monitor the efficacyof pharmacological treatment of ADHD in pre-

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Page 5: Clinical Assessment of Psychopharmacological Treatment of Preschoolers with ADHD

616 JOSEPH M. BYRNE ET AL.

Table 1. Type and Dosage of Stimulant Medication for Preschoolers with Attention-Deficit/Hyperactivity Disor-der (ADHD).

StimulantMedication

ADHDPreschooler

Total DailyDosage

Individual Daily Dosage

D-Amphetamine(Dexedrine®)Methylphenidate(Ritalin®)

12345678

17.5 mg15.0 mg15.0 mg15.0 mg15.0 mg15.0 mg20.0 mg20.0 mg

17.5 mg × 1 (morning)15.0 mg × 1 (morning) SR15.0 mg × 3 (morning, afternoon, evening)15.0 mg × 3 (morning, afternoon, evening)17.5 mg × 2 (morning, afternoon)17.5 mg × 2 (morning, afternoon)10.0 mg × 2 (morning, afternoon)10.0 mg × 2 (morning, afternoon)

Note. SR = Slow Release.

schoolers. The preschoolers were: (1) indepen-dently diagnosed as ADHD or Non-ADHD (con-trol) by an experienced doctoral-level clinicalchild psychologist; (2) without comorbid diag-noses (e.g., Oppositional Defiant Disorder[ODD], developmental delay or deficit); (3) di-rectly assessed on three measures of attention(multi-modal: auditory, visual, visual-motor);(4) indirectly assessed on three rating measures(parental ratings) for attention, problem behav-iors, social skills, and hyperactivity; (5) matched(SES, age, gender: clinic / control); and (6) ex-hibited normal language (directly assessed).

The issue of language status is important as itrelates to assessing ADHD, particularly in as-sessing ADHD in preschoolers, whose languageis still in a rapidly changing period of develop-ment. The comorbidity of language delay/deficithas been demonstrated to have significant diag-nostic and prognostic implications for currentand subsequent psychological / psychiatrichealth status (Baker & Cantwell, 1987; Beitch-man, Hood, & Inglis, 1990; Cantwell & Baker,1991; Richman, Stevenson, & Graham, 1982).In many studies of children with ADHD, it hasbeen common to only report a standard score ona single-word receptive vocabulary test as partof the inclusion criteria. The score is used toimply global language status (receptive and ex-pressive language domains). However, pre-schoolers and school-age children can possessnormal single-word receptive vocabulary, yetpresent with an underlying language disorder(Johnston, 1994; Rice, 1994; Watkins, 1994).

In the present study, it was hypothesized thatcompared to their matched controls, preschool-ers with ADHD would commit more errors ofomission and commission on each of the threeattention measures, and that these differenceswould be significantly reduced at follow-up, dueto the positive therapeutic response to the phar-macological treatment (preschoolers withADHD). The same pattern was predicted on indi-rect (parental ratings) measures of attention, be-havior problems, social skills and hyperactivity.

METHOD

ParticipantsA total of 20 preschoolers were initially includedin the study and tested at Assessment 1. However,2 of the 10 matched-control preschoolers were un-able to be tested at Assessment 2 (1 had schedulingconflict; 1 had moved). To ensure a conservative,more powerful matched-control design, the 16 pre-schoolers (4 to 5 years) who completed both As-sessments 1 and 2 were included in the final sam-ple. Eight were diagnosed with ADHD and 8 wereidentified as matched controls (gender, age, andSES [Hollingshead, 1975]). After the first assess-ment, the 8 preschoolers with ADHD were pre-scribed stimulant medication (6 Ritalin; 2Dexedrine) by their physician, and were seen ap-proximately 5 months after medication was initi-ated. The preschoolers were on a dose clinicallydetermined by their physician to be therapeutic(see Table 1). Their matched controls were thenasked to be seen again for comparative purposes.The final sample of 16 preschoolers were partici-pants in a previous study (N = 50) on the diagnos-

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ADHD IN PRESCHOOLERS 617

tic validity of a multi-dimensional assessment pro-tocol for preschoolers with ADHD (DeWolfe,Byrne, & Bawden, 1998).

Recruitment and screeningParticipants in the ADHD group were referred tothe Preschool Attention-Deficit/Hyperactivity Dis-order Clinic, Department of Psychology, IWK-Grace Health Centre, a tertiary-care, universityteaching hospital. Participants in the normal con-trol group were recruited from preschools in a met-ropolitan-county area (ca. 300,000).

Parents of all preschoolers were asked to com-plete two well-known clinically valid standardizedquestionnaires (i.e., Child Development Inventory[CDI], Ireton, 1992; Conners Parent Rating Scale[CPRS], Goyette, Conners, & Ulrich, 1978) priorto scheduling a clinic appointment, to screen fordevelopmental status (CDI), and the presence ofhyperactivity/externalizing behavior problems(CPRS: Hyperactivity Index subscale). The IWK-Grace Developmental Assessment Form also wascompleted from which familial SES was calcu-lated, and from which information regarding basichealth and developmental history was assessed(Byrne et al., 1998).

Initial group assignmentPreschoolers with aT score of 70 on the Hyper-activity Index of the CPRS-48 were assigned to theADHD group; those scoring < 70 were assigned tothe normal control group. All children had to scorewithin normal limits on the General Development(GD) scale of the CDI (i.e., age-equivalent < 2 SDbelow chronological age). None of the preschool-ers had other health conditions (e.g., cerebraltrauma, seizures, genetic anomalies, sensory im-pairments, developmental delay/deficit). In addi-tion, none of the preschoolers with ADHD exhib-ited a comorbid disorder (e.g., ODD).

DiagnosisChild and family histories, and profiles gleanedfrom parent-completed screening questionnaires(CDI, CPRS-48, IWK-Grace Developmental His-tory Form) were reviewed within the context of anin-depth psychological parent interview of all par-ticipants. Diagnosis (ADHD, Normal Control) wasindependently made by one of two experiencedclinical child psychologists, with reference to theDSM-IV (1994). There was no significant differ-ence in age (months) between participants withADHD and controls at Assessment 1 or Assess-ment 2 (Assessment 1: 62.13 vs. 63.25,t(16) =–1.76, p > .05; Assessment 2: 67.25 vs. 71.50,t(16) = –2.10,p > .05). Participants were matched

on gender, chronological age (± 4 months), andSES (±1 classification Rank [1-5]; Hollingshead,1975). The sample distribution across each socialstratum was as follows: High: 25%, High Average:44%, Average: 19%, Low Average: 6%, Low: 6%.All participants were male. All preschoolers werefree from neurological or neurodevelopmental dis-orders, and exhibited language abilities (expressiveand receptive) directly assessed to be within nor-mal limits (Reynell Developmental LanguageScale Revised [RDLS-R]; Reynell & Huntly,1985). Parents were offered reimbursement forparking costs incurred during the assessment.Three of the 8 preschoolers with ADHD had beenprescribed stimulant medication less than 2 monthsbefore the first clinic assessment (Assessment 1).They were off medication 24 to 48 hours beforeAssessment 1. All preschoolers with ADHD wereon medication at Assessment 2. None of the con-trol preschoolers were on medication.

Materials and Procedure

Assessment 1 ProtocolAfter informed parent-signed consent was granted(preschoolers gave verbal assent to participate),the preschooler was assessed by a trained testerblind to the diagnoses at Assessment 1 while theparent was separately interviewed by the psycholo-gist. The psychologist also was blind to the pre-schooler’s specific test performance at Assessment1. That is, diagnoses were made independent of thepreschooler’s specific test performance. At Assess-ment 1, each preschooler was first assessed usingthe RDLS-R to ensure that they presented withexpressive and receptive language skills withinnormal limits. The Continuous Performance Testfor Preschoolers-Visual (CPTP-V; Corkum et al.,1995), the Picture Deletion Test for Preschoolers-Revised (PDTP-R) (Corkum et al., 1995; Byrne etal., 1998), and the Continuous Performance Test-Auditory (CPT-A;‘‘Zoo Runner’’; Prather, Sara-mento, & Alexander, 1995) were subsequently ad-ministered. For administration of the RDLS-R,PDTP-R, and CPT-A, the preschooler and the ex-aminer were seated at a preschool-size table andchair. For the CPTP-V, the examiner was situatedoutside the room, observing the preschooler on aclosed-circuit monitor. The assessment protocolwas divided into two components: (a) Indirect as-sessment: Parent ratings, and (b) Direct assess-ment: Clinic testing.

Indirect assessment: Parental ratingsAt each appointment, the parent was given theCPRS-48 (Barkley, 1990; Conners, 1990; Goyette

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618 JOSEPH M. BYRNE ET AL.

et al., 1978), the Child Behavior Checklist (CBCL;Achenbach, 1991), and the Social Skills RatingSystem (SSRS; Gresham & Elliott, 1990). The par-ents completed the questionnaires while their pre-schooler was being assessed. A postage-paid, self-addressed envelope was provided to the parent ifinsufficient time resulted in an uncompleted ques-tionnaire. The CBCL is a widely used, standard-ized and norm-referenced questionnaire whichyields three global scales (Total Problems, Inter-nalizing, and Externalizing) and six narrow-bandscales (Anxious/Depressed, Withdrawn, SleepProblems, Somatic Problems, Aggressive Behav-ior, and Destructive Behavior). The 4-to-16-year-old version results in three global scales (TotalProblems, Internalizing, and Externalizing) andeight behavior problem scales (Withdrawn, So-matic Complaints, Anxious/Depressed, SocialProblems, Thought Problems, Attention Problems,Delinquent Behavior, and Aggressive Behavior),as well as four other Competence scales for chil-dren aged 6 to 16 years. AT score of 70 or above(equivalent to a 98th centile cutoff) is consideredto be within the clinical range.

The SSRS is a standardized, norm-referencedrating system used to document the perceived fre-quency of behaviors associated with a child’s so-cial competence and adaptive functioning. TheSSRS assists in screening and classifying childrensuspected of having significant social behaviorproblems. Two versions of the parent rating formwere used, determined by the age of the pre-schooler (ages 3 to 5 years vs. grades K to 6). TheSocial Skills factor provides an assessment of So-cial Skills (positive) organized into four to fivedomains (age dependent) (Cooperation, Assertion,Self-control, Responsibility, and Empathy). Scoresfalling below a standard score of 85 (<16th centileor <1 SD below mean) are considered clinicallysignificant low scores (fewer social skills than av-erage). The Problem Behavior factor provides anassessment of problem behaviors (negative) orga-nized into two to three domains (age dependent)(Externalizing, Internalizing, Hyperactivity).Scores falling above a standard score of 115(>84th centile or >1 SD above mean) are consid-ered clinically significant high scores (more prob-lem behaviors than average).

The CPRS-48 is a widely used, parent-rated be-havior questionnaire (Barkley, 1990; Conners,1990) which assists in the identification of behav-ioral and attentional problems for children aged 3to 17 years. Scoring of these symptoms yields fivefactors (Conduct Problems, Learning Problems,Psychosomatic, Impulsive-Hyperactive, and Anxi-ety) and the Hyperactivity Index. AT score of 70

is recommended as a clinical cutoff for purposes ofscreening (Conners, 1990). The Hyperactivity In-dex has been found to be a reliable screen forADHD (Conners, 1990).

Direct assessment: Clinic testingContinuous Performance Test for Preschoolers –Visual (CPTP-V).The CPTP-V (Corkum et al.,1995) provided a measure of the preschooler’s sus-tained visual attention. The CPTP-V was specifi-cally designed for use with preschoolers by mak-ing age-appropriate modifications to ContinuousPerformance Tests traditionally used with olderchildren and adults. The CPTP-V was tested witha sample of 60 (3-, 4-, and 5-year-olds) typicallydeveloping preschoolers (i.e., free from develop-mental and behavioral problems). The Corkum etal. (1995) findings strongly supported the con-struct validity of the CPTP-V as a measure of sus-tained visual attention in preschoolers. As ex-pected, response latency, omission errors, andcommission errors systematically changed withage.

In the present study, the CPTP-V was adminis-tered on an ARS 386 microcomputer connected toa 47.5 cm NEC color monitor. Each child sat on apreschool-size chair in front of the monitor (60cm), which was positioned at eye level. During thetraining phase of the assessment (i.e., instructionsand practice), the examiner was seated next to thepreschooler inside a sound-attenuated testingchamber. During the test phase, the examiner wasseated outside the chamber, and viewed the pre-schooler on the closed-circuit monitor. The pre-schooler used an 11-cm × 8-cm Neuroscan™ re-sponse pad (single-finger button) to respond to thepictures on the screen. A tripod-supported videocamera was located in the corner of the room to thepreschooler’s right, allowing a display of the pre-schooler’s image and recording of the pre-schooler’s behavior during the test.

The CPTP-V lasted 13½ min (familiarizationand practice: 5 min; test phase: 8½ min). Six indi-vidual, white-on-black line drawings were pre-sented in the test phase (target: pig’s face;distracters: girl’s face, sun, ice-cream cone, lolli-pop, flower; see Corkum et al., 1995). There werea total of 240 stimulus presentations (40 target, 20distracters). All of the pictures shared a commonshape (85%) (i.e., a circle), individually distin-guished by defining properties. The line drawingswere electronically scanned using the CompleteHalf-Page Scanner™ and the SmartScan Soft-ware™. The average visual angle was 12°. The sixpictures were presented individually in a random-ized sequence for a duration of 750 ms each, with

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ADHD IN PRESCHOOLERS 619

a fixed interstimulus interval (ISI) of 1350 ms. Thestimuli were essentially randomly presented withthe one constraint that the target and each of thedistracters occurred once every six trials. Stimuluspresentation and response were controlled and re-corded using a customized program within theNeuroscan Gentask Program™. The preschooler’stask was to depress the response pad key when thetarget stimulus (pig’s face) appeared. Any re-sponse (i.e., button depression) occurring withinstimulus presentation or subsequent ISI was re-corded for latency and accuracy.

During the familiarization trials, the six picturessequentially appeared on the computer screen;each picture remained on the screen until it wascorrectly named by the preschooler. In the practicetrials, randomized sequences of the six pictureswere presented until the preschooler had correctlyidentified the target on two successive occasionsand committed no errors of commission. CPTP-Vperformance was calculated by the number of er-rors of omission and the number of errors of com-mission.

Picture Deletion Test for Preschoolers – Re-vised (PDTP-R).The PDTP-R, represented a re-vised form of the original PDTP (Corkum et al.,1995), specifically designed to assess attention(visual search) in preschoolers; it is conceptuallysimilar to cancellation tests used with older chil-dren (e.g., Underlining Test; Rourke & Orr, 1977).The PDTP-R provided improvements in terms ofstructure, content, and scoring. As with its prede-cessor, the PDTP-R provided the opportunity tomeasure the preschooler’s sustained attention us-ing a paper-and-pencil test. The PDTP-R retainedthe stimuli and training phase of the previous formof the PDTP (Corkum et al., 1995), and incorpo-rated several modifications. First, the pages uponwhich the stimuli were printed were presented asconsecutive pages in a booklet. This change facili-tated the preschooler’s manipulation of the testbooklet, thereby allowing more independent workthroughout the test. Second, the cat task was in-creased from two to eight arrays (pages) of pic-tures to improve testing of the limits of sustainedattention. Third, the fish task used by Corkum etal. (1995) was deleted because previous findingsshowed there to be a significantly large number oferrors of omission across all ages (3 to 5 years),and a significantly large number of errors of com-mission for the 4-year-olds. These findings suggestpossible underlying difficulties in stimulus differ-entiation within a timed test, thereby reducing itsvalue in inferring a preschooler’s level of sus-tained attention.

The PDTP-R used pictures rather than lettersand a self-inking stamper rather than a pencil (is-sue of preschool skill proficiency; see Corkum etal., 1995) in contrast to similar cancellation teststraditionally used with older children. Thesechanges reflect the need to make such a test devel-opmentally appropriate for preschoolers for whompencil control and letter recognition are not oftenfully established (O’Doughtery, Nuechterlein, &Drew, 1984). The results from a study of 60 (3-,4-, and 5-year-olds) typically developing children(i.e., free from developmental and behavioral prob-lems), supported the validity of the PDTP as anage-appropriate measure of attention in preschool-ers, reflecting as well, expected systematic devel-opmental changes in performance with increasedchronological age (Corkum et al., 1995).

The preschooler’s task during the PDTP-R wasto visually search an array of pictures, in whichboth targets and nontargets were presented, and toidentify each target. The test consisted of a train-ing phase (3 min) and a test phase (average: 16min). The test was presented in a booklet formatsuch that the preschooler could turn pages and in-dependently proceed. Right- and left-handed ver-sions of the test were available. In the trainingphase the preschooler was taught to identify thetarget pictures and to use a washable, self-inkingbingo stamper to mark each target (e.g., ina 2 × 6array). The discrimination and practice arrays werepresented until the preschooler accurately identi-fied the target(s) and made no errors of commis-sion. The training phase consisted of two pagesupon which the target([30]: triangle) and distracter([90]: circle, square, diamond, and octagon) werearranged in 10 × 6 array. After successful comple-tion of the training phase, the test phase was be-gun. The test phase consisted of eight pages; eachpage consisted of a 10 × 6 array of target ([120]:cat) and distracter ([360]: four identical cats vary-ing in position only). The arrays were presented inthe test booklet, each on a legal-size page with thetarget picture located at the top-centre of the page.The pictures were arranged in a randomized fash-ion, with the only constraint that there were 15 tar-gets and 45 distracters within each array.

The preschooler was asked to mark each targetpicture with the self-inking bingo stamper asquickly as possible. The preschooler also was toldto turn the page as soon as each page was com-pleted to continue working on subsequent pages. Ifthe preschooler demonstrated six consecutive er-rors on the first page of either the shape or cat task,the page was discontinued and the preschooler wasreturned to the discrimination page. Upon accurate

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620 JOSEPH M. BYRNE ET AL.

identification of the target and a second review ofthe task, the preschooler was re-administered thefirst page. The preschooler’s performance duringthe shape and cat task was measured both in termsof number of errors of omission and number oferrors of commission.

Continuous Performance Test – Auditory (CPT-A). The CPT-A was the ‘‘Zoo Runner’’ designedby Prather et al. (1995) as a measure of sustainedauditory attention. This test consisted of a trainingphase and a test phase. During the training phase,preschoolers were told that an audio tape containeda list of different animal names presented througha tape recorder. The preschooler was requested tocarefully listen for a particular animal name (‘‘ti-ger’’) and to touch a blue target circle (diameter:10.5 cm ; positioned directly in front of the pre-schooler on a desk) each time that animal name(target) was heard. The training phase continuedwith practice trials which included feedback to thepreschoolers regarding their performance. In orderto proceed with the test phase, the preschooler hadto accurately inform the examiner of the test in-structions, thus ensuring that the test was under-stood. The total time for the test phase of the testwas approximately 6½ min.

The test phase consisted of 200 presentations(animal names) of which there were target ([32]:tiger), and distracter stimuli ([168]: camel, rabbit,cat, cow, lion, dog, horse, fish, elephant, monkey,bear). Each word was presented in random se-quence, with an average duration per word of 1 s,separated by a 2000-ms ISI. The animal nameswere recorded with a monotone female voice withno inflection on any target or distracter name. Theexaminer provided feedback to the preschoolerregarding test accuracy until the first five targetswere heard; no feedback was given beyond thispoint. The preschooler’s performance was mea-sured by the number of errors of omission and thenumber of errors of commission.

Assessment 2 ProtocolThe 16 preschoolers returned to the hospital for the5-month follow-up assessment. There was not asignificant difference between the participantswith ADHD and matched controls with regard tointerval between Assessment 1 and Assessment 2,t(7) = -1.67,p>.05. All participants were tested atapproximately the same time of day (i.e., ± 2 hr)relative to their individual evaluation at Assess-ment 1. ADHD participants took their dose ofstimulant medication approximately 1 to 1.5 hrprior to testing. The assessment protocol includedthe re-administration of all the previously listedmeasures for Assessment 1, with the exception of

the RDLS-R, which was used as an inclusion crite-rion to establish normal language status.

RESULTS

Tests of homogeneity of variance and skewnesswere conducted and the nonparametric Mann-Whitney U-Test was chosen as the most appro-priate statistical procedure to compare groupperformance (ADHD vs. Matched-Control). TheWilcoxon Matched-Pairs Signed-Ranks Testwas chosen as the most appropriate statisticalprocedure to evaluate possible change in indi-vidual performance between Assessment 1 and2. Based on our previous studies ( Byrne et al.,1998; Corkum et al., 1995) a priori predictionswere made. There would be significantly poorerparental ratings and test performance for pre-schoolers with ADHD versus their matched-con-trol peers at Assessment 1. There would be asignificant change (improvement) in ratings andtest performance (difference scores: Assessment2 – Assessment 1) at Assessment 2 for the pre-schoolers with ADHD only as a result of stimu-lant treatment. Means and standard deviationsare presented in tabular form (Table 2).

Indirect Assessment: Parental RatingsAt Assessment 1 the preschoolers with ADHD(untreated) were rated by their parents as signifi-cantly more inattentive (CBCL: Attention), U =.0,p <.0005, exhibiting significantly more prob-lem behaviors (SSRS: Problem Behaviors), U =2.5,p <.005, and exhibiting significantly fewerage-appropriate social skills, U = 4.0,p <.01,compared to their matched-control peers (seeFig. 1).

At Assessment 2, however, there was no lon-ger a significant group difference between rat-ings of the preschoolers with ADHD (treated)and their matched-control peers. The preschool-ers with ADHD (treated) were no longer rated asmore inattentive (CBCL: Attention), U = 13.50,p > .05, nor were they rated as exhibiting moreproblem behaviors (SSRS: Problem Behaviors),U = 12.0,p > .05, or fewer age-appropriate so-cial skills (SSRS: Social Skills), U = 16.5,p >.05 (see Fig. 1).

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ADHD IN PRESCHOOLERS 621

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622 JOSEPH M. BYRNE ET AL.

Fig. 1. MeanT score on the (Top) Child Behavior Checklist: Attention Problems factor; (Middle) mean stan-dard scores on the Social Skills Rating System: Social Skills and Problem Behaviors; and (Bottom)Conners Parent Rating Scale-48: Hyperactivity Index scales at Assessment 1 and 2 for preschoolers withAttention-Deficit / Hyperactivity Disorder and their matched-control peers.

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ADHD IN PRESCHOOLERS 623

To determine the source of this between-group change at Assessment 2, the WilcoxonMatched Pairs Signed-Rank Test (Assessment 2– Assessment 1) was conducted separately forthe matched-control preschoolers and for thepreschoolers with ADHD (treated). The resultsshowed that the parental ratings of the matched-control peers did not significantly change be-tween Assessment 1 and 2 in regard to inatten-tion (CBCL: Attention),z = –0.45,p > .05,problem behaviors (SSRS: Problem Behaviors),z = –0.74,p > .05, or social skills (SSRS: So-cial Skills), z = –0.94,p > .05. Analysis wasalso conducted using the CPRS-48: Hyperactiv-ity Index. As previously noted, it was used as ascreening measure for initial group assignment.As such, it was not included in the Assessment 1or 2 group analyses. However, given the wide-spread use of this or different forms of this mea-sure to monitor effectiveness of treatment re-gimes, it was determined that this measureshould be evaluated for possible change betweenAssessment 1 and 2. For the matched-controlpreschoolers there also was no change in paren-tal ratings on the CPRS-48 Hyperactivity Index,z = –1.12,p > .05.

With regard to the preschoolers with ADHD(treated), parental ratings significantly changed(improved) at Assessment 2. The preschoolerswith ADHD (treated) were rated as exhibitingfewer symptoms of inattention (CBCL: Atten-tion), z = –2.52,p < .025, problem behaviors(SSRS: Problem Behaviors),z = –2.37,p <.025, and impaired social skills (SSRS: SocialSkills), z = –2.03,p < .05. They were also ratedsignificantly lower on the CPRS-48: Hyperactiv-ity Index,z = –2.52,p < .025, at Assessment 2(see Fig. 1).

Direct Assessment: Clinic TestingAt Assessment 1 the preschoolers with ADHD(untreated) exhibited significantly more Errorsof Omission on the Auditory CPT, U = 12.5,p< .05, and Visual CPTP, U = 12.5,p < .05 tests,but not on the PDTP-R, U = 22.0,p > .05. Theyalso exhibited more Errors of Commission onthe Visual CPTP, U = 12.5,p < .05, and thePDTP-R, U = 5.5,p < .01, but not on the Audi-tory CPT, U = 22.0,p > .05 (see Fig. 2 ).

At Assessment 2 the preschoolers withADHD (treated) no longer exhibited signifi-cantly more Errors of Omission on any of theattention measures (Auditory CPT, U = 20.5,p> .05, Visual CPTP, U = 20.5,p > .05, PDTP-R, U = 20.0,p > .05), nor did they exhibit sig-nificantly more Errors of Commission on any ofthe tests (Auditory CPT, U = 14.5,p > .05, Vi-sual CPTP, U = 19.0,p > .05, PDTP-R, U =27.5,p > .05) (see Fig. 2).

The Wilcoxon Matched-Pairs Signed-RanksTest (Assessment 2 – Assessment 1) was subse-quently conducted. The matched-control peersdid not significantly change their performanceon any of the attention tests in terms of Errors ofOmission (Auditory CPT,z = –0.17,p > .05,Visual CPTP,z = 0.0, p > .05, PDTP-R,z =–1.68,p > .05), nor did they exhibit a significantchange in regard to Errors of Commission (Au-ditory CPT,z = –1.97,p = .05, Visual CPTP,z = –0.68,p > .05, PDTP-R,z = –0.60,p >.05) (see Fig. 2).

In contrast, the preschoolers with ADHD(treated) exhibited significant change from As-sessment 1 to 2. They exhibited significantlyfewer Errors of Omission on each attention test(Auditory CPT, z = –2.52,p < .025, VisualCPTP,z = –2.24,p < .05, PDTP-R,z = –2.52,p < .025). They also exhibited significantlyfewer Errors of Commission on the VisualCPTP,z = –2.03,p < .05, and the PDTP-R,z =–2.39,p < .025, but not on the Auditory CPTtest,z = –1.47,p > .05 (see Fig. 2).

DISCUSSION

The results of the present study demonstrate thatfor preschoolers diagnosed with ADHD andtreated with stimulant medication, the efficacyof pharmacological treatment can be empiricallymeasured not only by developmentally appropri-ate parental ratings, but by developmentally ap-propriate clinic-based tests of attention. Specifi-cally, while treated with stimulant medicationpreschoolers with ADHD were rated by theirparents as exhibiting significantly fewer epi-sodes of inattention, problem behaviors, andhyperactivity. These findings confirm those of

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624 JOSEPH M. BYRNE ET AL.

Fig. 2. Mean errors of omission and commission at Assessment 1 and 2 on the (Top) Auditory ContinuousPerformance Test; (Middle) Visual Continuous Performance Test, and the (Bottom) Picture DeletionTest for Preschoolers-Revised for preschoolers with Attention-Deficit / Hyperactivity Disorder andmatched-control peers (–––– = omissions; ---- = commissions).

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ADHD IN PRESCHOOLERS 625

previous preschool studies (e.g., Barkley, 1988;Conners, 1975; Musten et al., 1994). In an ex-tension of previous research, parental rating oftheir child’s social skills, an often neglected do-main in diagnosis and treatment, was also foundto change. Preschoolers with ADHD, treatedwith stimulant medication over a 5-month pe-riod, were rated by their parents as exhibitingmore age-appropriate social skills when on med-ication.

These positive treatment effects were notconfined to parental ratings. Using developmen-tally appropriate, clinic-based tests of attentionsimilar to those used with school-age children,preschoolers with ADHD (treated) exhibitedsignificantly improved attention. Compared to 5months earlier, they exhibited significantlyfewer errors of omission on Auditory and VisualContinuous Performance Tests, and a visual-search cancellation test (PDTP-R), as well assignificantly fewer errors of commission on theVisual CPTP and visual-search cancellation test(PDTP-R), although not on the Auditory CPT.Furthermore, in contrast to the majority ofADHD studies, including those with school-agechildren, the present study: (a) tested more thanone sensory modality (visual most often tested);and (b) found significant treatment effects inmore than one modality (see Corkum & Siegel,1993 for discussion).

Musten et al. (1994) did not test within theauditory sensory modality. In regard to the vi-sual modality, they found that on the Gordonvisual CPT (GDS), preschoolers committedfewer errors of omission while on stimulantmedication. Musten et al. also tested pre-schooler’s attention using a pencil-paper test(connect dots), but they did not find a therapeu-tic effect of the stimulant medication at eitherthe low or high dosage. In contrast, the findingsof the present study showed significantly im-proved performance on our preschool pencil-paper test (PDTP-R), for both errors of omissionand errors of commission. This difference maybe attributable to the differences in the testsused in the two studies. Our test is conceptuallyand procedurally similar to the cancellation testsused with school-age children and adolescents(Byrne et al., 1998; Corkum et al., 1995).

In combination, these results demonstrate thefollowing: (1) stimulant medication can yieldpositive therapeutic effects in preschoolers withADHD, effects repeatedly demonstrated withschool-age children with ADHD; (2) preschool-ers’ therapeutic response (general behavior andsocial skills) to stimulant medication can be reli-ably measured using parental ratings on stan-dardized questionnaires; and (3) preschoolers’therapeutic response to stimulant medication canbe reliably measured using developmentally ap-propriate clinic tests of attention. Given the un-derstandable reluctance to prescribe stimulantmedication for preschoolers with ADHD, andgiven the recommended use of multiple mea-sures (convergent profile) for diagnostic andtreatment purposes (Barkley, 1990), these find-ings are particularly valuable. The resulting con-vergent profile (clinic-based, parental ratings)may provide the clinician with additional valuedinformation to assess treatment efficacy. In ad-dition, the conceptual and procedural similaritybetween these preschool clinic tests and parentalrating questionnaires, and those used withschool-age children should be helpful in exam-ining the stability of diagnosis or treatment effi-cacy across important developmental stages(e.g., preschool, school-age, adolescent).

As with any complex disorder spanning sev-eral neurodevelopmental phases, additionalstudy is needed. First, it would be informative todetermine whether the therapeutic effects in thepresent study vary with dosage, and/or type ofmedication, duration of treatment, and withcomorbid diagnostic profiles (e.g., ADHD vs.ADHD + ODD). Second, it would be informa-tive to determine whether similar positive thera-peutic effects would be evident when evaluatingpreschoolers with ADHD for whom only behav-ioral therapy was provided or for whom a com-bined therapy (medication + behavior therapy)was provided (Cohen et al., 1981). Third, theremay be value in studying a larger sample of pre-schoolers with ADHD using a placebo con-trolled, double-blind experimental design. None-theless, the predicted effects were found. Fur-thermore, in contrast to many previous ADHDstudies, even those with a comparably largersample, the design of the present study incorpo-

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626 JOSEPH M. BYRNE ET AL.

rated a matched-control comparison, a formalcomprehensive language assessment to ensurelanguage functioning could not be a covaryinginfluence on the preschoolers’ behavioral orattentional profiles (Baker & Cantwell, 1987;Beitchman et al., 1990; Cantwell & Baker, 1991;Richman et al., 1982), and incorporated a formalindependent diagnosis conducted by a doctoral-level experienced clinical child psychologist(e.g., versus rating scale cut-off score or re-search assistant checklist interview). Fourth, itwould be of interest to explore further why thestimulant medication did not reduce errors ofcommission on the Auditory CPT test in contrastto results on the Visual CPTP and PDTP-R. Theissue of whether ADHD symptomatology is mo-dality specific continues to be debated, with lit-tle comparative study even in school-age chil-dren, and especially in preschoolers (Ballard,1996; Barkley, 1991; Corkum & Seigel, 1993).

In summary, this is the first matched-controlstudy of preschoolers with ADHD for whomstimulant medication was found to be effectivein significantly reducing ADHD symptomatol-ogy across sensory modality (omission) andacross different tests (auditory CPT, visualCPTP, PDTP-R), concurrently corroborated byparent report. The findings of the present studyshould not be used to support the position thatstimulant medication should be the first or pre-ferred treatment of ADHD in preschoolers. Thefindings simply indicate that if a preschooler isdiagnosed with ADHD and a decision is madebetween the physician and the preschooler’s par-ents to initiate stimulant medication therapy,there is a methodology available to evaluate thetreatment efficacy, similar to that used withschool-age children with ADHD.

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