diferenças entre ADD hiper com add sem hiper

8/2/2019 diferenas entre ADD hiper com add sem hiper

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Arcbfhives of CIinicat ffeurffpsycb~io~, Vol. 5, pp. 119-I 35, 1990 0887.6177190 $3.00 + .wPrinted in the USA. Ail rights reserved. Copyright 0 1990 National Academy of Neuropsychoiagisls

Do Neurocognitive Measures DifferentiateAttention Deficit Disorder (ADD) With

and Without flyperactivity?A&on R. Lorys

University of GeorgiaGeorge W. Hynd

University of Georgia and Medical College of GeorgiaBenjamin B. lahey

University of Georgia

Recent behav~oru~and n~ropharmaco~o~~ca~evidence suggests that the differ-entiation of children with Attention Deftcit Disorder with (ADD/H) and with-out hyperactivity (ADD/WOj may reflect an appropriate nosoiogical dis-tinction. There is also evidence that attention-regulatory mechanisms possiblyassociated with anterior-posterior processes may be independently implicatedin these children. To test this hypothesis, I00 clinic-referred children were reliablydiagnosed as ADD/H (n =48), ADD/W0 (n =26) and as having an internalizingdisorder (n=26) for inclusion as a clinic-control (CC} group. An analysis ofcovariance using Full-Scale IQ, chronological age, and the number of conduct-disorder symptoms provided liftle support for such a behavioral distinction usingselected WISC-R, Luria-Nebraska-Childrens Revision, and reaction-time varia-bies. Alternative conceptualizations, possibly reflecting deficient right-hemis-pheric processes in ADD/H, may provide more productive avenues for researchin d~tinguishing de~cien~ neu~cognitive processes in subtypes of ADD.

Attention Deficit Disorder (ADD) (DSM-III, 1980) is one of the most fre-quent of childhood disorders, diagnosed behaviorally by the presence ofdevelopmentally inappropriate inattention and impulsivity (Barkley, 1982).This report was completed while the senior author was on a FuIbright Fellowship at theDepartment of Psychology, University of Jyvaskyla, Finland.

Requests for reprints should be sent to Alison R. Lorys, Chitd Study Center, University ofOklahoma Health Sciences Center, 1100 N.E. 13th Street, Oklahoma City, OK 73117.

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120 A. R . Lorys , G. K Hynd, and B. B. LuheyExcess motor activity, commonly referred to as hyperactivity, often occursconcurrently with inattention and impulsivity, although motor activity is nota necessary component for the diagnosis of the disorder. Using DSM-IIIcriteria, children can be diagnosed as exhibiting ADD with Hyperactivity(ADD/H) or ADD without Hyperactivity (ADD/WO). An experimental lit-erature comparing these two behaviorally differentiated subtypes indicatesthey differ in significant ways (Lahey, Schaughency, Hynd, Carlson, &Nieves, 1987).

Generally, children with ADD/H exhibit significantly more aggressionand conduct problems (King & Young, 1982; Lahey, Schaughency, Strauss,& Frame, 1984; Lahey, Schaughency, Hynd, Carlson, & Nieves, 1987), aremore impulsive and distractible (Lahey, Schaughency, Frame, & Strauss,1985; Lahey, Schaughency, Hynd, Carlson, & Nieves, 1987), and appear tobe more socially rejected (King & Young, 1982; Lahey, Schaughency,Strauss, & Frame, 1984) than ADD/W0 children. Furthermore, it seemsthat ADD/W0 children exhibit a more sluggish cognitive tempo (Lahey,Schaughency, Frame, & Strauss, 1985; Lahey, Schaughency, Hynd, Carlson,& Nieves, 1987), are rated as more shy and anxious (Lahey, Schaughency,Strauss, & Frame, 1984; Lahey, Schaughency, Hynd, Carlson, & Nieves,1987) and experience a greater incidence of academic difficulties(Edelbrock, Costello, & Kessler, 1984; Lahey, Schaughency, Strauss, SCFrame, 1984) than ADD/H children.

An estimate of the incidence rate of ADD notes 3-5% of school-aged children are affected by this disorder, with 30-40% of the total refer-rals to child guidance clinics resulting from concerns regarding inattention,impulsivity, and excess motor behaviors (Barkley, 1982). These estimatessuggest that ADD is a disorder affecting many children and adolescents andunderscore the need to further investigate the validity of distinct subtypes ofADD.

At present, the body of literature attempting to differentiate ADD/Hfrom ADD/W0 consists of 13 behavioral studies. In the majority of thosestudies, empirically based psychometric data generally comprised of IQscores and academic achievement scores were reported. Behavioral measuressuch as parent and teacher checklists, rating scales, and sociometric mea-sures were also collected in the majority of these studies. However, in someof the studies, only behavioral data were collected and reported, while nopsychometric data were included. The results of the 13 studies suggest ADD/H can be consistently differentiated from ADD/W0 on behavioral mea-sures. However, the paucity of significant concurrently collected psychomet-ric or neurocognitive data reported in studies comparing ADD//H andADD/W0 does not allow the same to be said for those psychometric orneurocognitive measures believed to tap various constructs of attentionwhich presumably comprise the basis for the differential diagnosis of ADD.


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Neurocognitiv e Measures and ADD 121

For the purposes of this study, neurocognitive measures were defined asmeasures of cognitive ability that are presumed to have neurological correla-tion. A neuropsychological hypothesis regarding differentiating ADD/Hand ADD/W0 on attentional neurocognitive measures provided the impetusfor the present study.

As Schaughency and Hynd (1989) conclude after a comprehensive reviewof results from neuroanatomical, biochemical, and hemispheric specializa-tion studies related to attention and impulsivity as well as clinical studies ofchildren with ADD/H, it may be that children with ADD/H have disturb-ances in the activation or motor-readiness system of attentional control asdelineated by Tucker and Williamson (1984). Evidence cited earlier charac-terizing children with ADD/H as being more impulsive than those withADD/W0 (Lahey, Schaughency, Frame, & Strauss, 1985; Lahey, Schaugh-ency, Strauss, & Frame, 1984) would support this hypothesis. In contrast,children with ADD/W0 may have a singular deficiency in the arousal (per-ceptual-responsivity) system, a hypothesis supported by behavioral evidenceof a more sluggish tempo exhibited by this group (Lahey, Schaughency,Frame, & Strauss, 1985; Lahey, Schaughency, Strauss, & Frame, 1984;Neeper, 1985).

Furthermore, the differential attentional system hypothesis is also sup-ported by results of animal model studies indicating that different neuro-transmitters may be involved in attention processing (Shaywitz, Shaywitz,Cohen, & Young, 1983; Zametkin & Rapoport, 1986). Two of the most-often-implicated neurotransmitters thought to be involved are the catechola-mines, dopamine (DA) and norepinephrine (NE). As Schaughency andHynd (1989) suggest, the catecholamine hypothesis of ADD was based onbehavioral observations suggesting that many children with ADD/H im-proved clinically following treatment with stimulant medication. Stimulantmedication is thought to achieve its pharmacological effect by potentiatingthe effects of DA (Robbins, 1984) as well as possibly both DA and NE(Shekim, Javaid, Dekirmenjian, Chapel, & Davis, 1982). Furthermore, DAis the precursor of NE, although it is also believed that NE mechanisms mayhave a modulating effect on DA (Robbins, 1984). There is substantial evi-dence that DA is related to anterior (motor) processing, whereas NE isrelated to posterior (sensory) processing.Further, Shaywitz et al. (1983) found the developmental course of DA-depleted rat pups to be similar to that seen with children with ADD/H. Thepups were found to be significantly more active than litter-mate controlsduring the developmental period, paralleling the developmental course thathas been found in children with ADD/H (Hechtman & Weiss, 1983; Hecht-man, Weiss, & Perlman, 1984). In addition, when the DA-depleted rat pupswere treated with stimulant medication, there was a decrease in activity level,a response that has also been observed in many children with ADD/H


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122 A. R. Lorys, G. W Hynd, and B. B. LuheyZametkin & Rapoport, 1986; Shaywitz, Teicher, Cohen, Anderson, Young,& Levitt, 1983).

Also supporting the possible involvement of DA in ADD/H, Ginsburg,Becker, Trattner, and Bareggi (1984) used hyperactive dogs who werefound to be favorable responders to stimulant medication as well as othernonresponders to stimulant medication and a control group, comparingthem on behavioral and neurochemical indices. Results indicated that whenusing an inhibitory training task involving a stay-sit paradigm, the controlslearned the task readily, while the experimental group was described asdistractible, having a higher activity level, and unable to maintain the sittingposition for comparable lengths of time. Following the administration of D-amphetamine, 5 of the 14 experimental dogs improved dramatically.

Consistent with these findings, results of Shaywitz, Teichner, Cohen,Anderson, Young, and Levitt (1984) comparing DA-depleted, NE-depleted,and both DA- and NE-depleted rat pups (CA) to normal controls alsoindicated DA-depleted pups exhibited more activity than controls as well asNE- or CA-depleted pups. These findings lend support to the hypothesisregarding DA and ADD/H as well as NE and its involvement in ADD.

Regarding NE, it has also suggested to be involved in ADD (Zametkin &Rapoport, 1986), with results of animal studies supporting the idea that NEis involved in selective attention (Mason, 1980; Mason & Fibinger, 1979).Mason concluded that learning deficits as manifested in resistance to extinc-tion, distractibility, decreased habituation, and impairments in selective at-tention displayed in NE-depleted rats reflect the sole of NE in attention.Mason concluded that NE was involved with sensory, but not motor habitu-ation. Therefore, in consideration of Lurias (1980) conceptualization ofbrain-behavior relations, deficits in sensory-attentional mechanisms wouldbe consistent with a deficient sensory-input unit, or in more neuroanatomi-cal terms, cortical structures associated with the temporal, parietal, andoccipital regions. In summary, support for an anterior-posterior gradienthypothesis regarding ADD/H and ADD/W0 can be found in animal studieswhich are consistent with clinical studies of children with ADD (Schaughen-cy & Hynd, 1989).

The present study investigated the hypothesis that reliably diagnosed andbehaviorally defined groups such as ADD/H and ADD/W0 could also bedifferentiated using measures that appraise selected mechanisms of atten-tion. The delineation of differential attentional systems as described aboveand their potential relationship to these behaviorally characterized clinicalsyndromes could, if substantiated through empirical research, lead to amore comprehensive understanding of the neuropsychological constructsmanifested in these attentional syndromes. Thus, studies that examine dif-ferential performance of children comprising ADD subtypes on cognitive


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and attentional tasks will not only provide validation of the subtypes butwill contribute to a developing framework integrating behavioral and neuro-psychological perspectives.

According to the conceptual framework proposed by Schaughency andHynd (1989), children with ADD/H are most likely to be most severelyaffected on measures tapping both perceptual arousal and motor regulatoryprocesses, particularly in the latter sense, for example, on reaction-timemeasures since these are thought to represent more anterior processing, Incontrast, children diagnosed as ADD/W0 are most likely to be Iess severelyaffected in these motor regulatory processes, as their deficient neurocogni-tive processes would primarily manifest in the arousal (perceptual-respon-sivity) posterior system and not additionally in the motor-regulatory systemas in ADD/H. A clinic control (CC) population with no documented atten-tional deficiencies should perform significantly better than either ADDgroup on a battery of such measures.

Consequently, on the battery of neurocognitive measures tapping verbaland perceptual-motor regulatory processes and attentional and relatedmemory abilities, used in the present study, it was expected that an order ofdeficient performance would be evident between groups of children withADD/H, ADD/WO, and a CC group.

METHOD

SubjectsSubjects were 100 children referred to an outpatient diagnostic and refer-ral clinic in the Psychology Department of a large southeastern university.

The clinic served children aged 6-l 3 years referred for psychological evalua-tion. The 100 children were taken from 112 consecutive referrals to the clinicover a three-year period (1984-1987). Subjects and a mean age of 9 years, 2months (SD= 1 year, 8 months), and showed no evidence of overt neurologi-cal disorder, psychotic disorder, or mental retardation (FSIQ > 70). Socio-economic status ranged across ail IeveIs although there was a tendency forsubjects families to fall within the lower-middle and lower ranks of theMyers and Bean (1968) index of socioeconomic status. Current grade place-ments ranged from first to sixth grade. Subjects were predominantly Cauca-sian (87 white, 12 black, 1 Hispanic) and male (79 males, 21 females).Diagnostic Procedures

Each subject and at least one parent (predominantly mothers) were inter-viewed separately using the Schedule for Affective Disorders and Schizo-phrenia for School-Age Children (K-SADS) (Puig-Antich & Chambers,


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124 A. R . Lorys , G. FK Hy nd, and B. B. Luhey1978) updated to include all symptoms used in the DSM-III (APA, 1980) forthe following syndromes: Conduct Disorder (CD) (all subtypes), AttentionDeficit Disorder with and without Hyperactivity (ADD/H, ADD/WO),Overanxious Disorder, Separation-Anxiety Disorder, Major Depressive Epi-sode (MDE), Dysthymic Disorder, Oppositional Disorder, Simple Phobia,Obsessive-Compulsive Disorder, and Schizophrenia. Both the Conners Par-ent Rating Scale (Conners, 1973) and the Revised Behavior Problem Check-list (Quay & Peterson, 1983) were also completed by the parent.

In addition to parental rating scales, each childs teacher was contactedand completed an interview based on the K-SADS, as well as the ConnersTeacher Rating Scale (Conners, 1969), the Child Behavior Rating Scale(Neeper & Lahey, 1986), and the SNAP Checklist (Pelham, Atkins, &Murphy, 1981). Each teacher was also asked to complete a sociometricmeasure in the classroom in order to obtain peer-rating data. Combining allsources of information, decisions regarding the presence or absence of eachDSM-III symptom were made, resulting in diagnostic classifications foreach child. To assess the reliability of clinical diagnoses, a second diagnosti-cian gave an independent diagnosis of the child based on consideration of allrating scales as well as observation of both parent and child interviewsthrough a one-way mirror. Interdiagnostician reliability for each diagnosiswas computed using Cohens Kappa (Spitzer, Cohen, Fleiss, & Endicott,1967). Kappa for ADD/H was .79 and .77 for ADD/WO. Final DSM-IIIdiagnoses reflected interdiagnostician resolution and were used for groupingfor all analyses.

Three experimental groups were formed on the basis of DSM-III diag-noses. Forty-eight children with a clinical diagnosis of ADD/H (Group l),26 children with a diagnosis of ADD/W0 (Group 2), and 26 children with adiagnosis of a depressive or anxiety disorder as well as children with noclinical diagnosis (Group 3) were identified. The third group was included asa clinic control (CC) group. Inclusion of this last group was deemed essen-tial in providing evidence as to the uniqueness of deficits characteristic ofADD/H or ADD/W0 children in relation to other clinic-referred childrenwith psychiatric disorders. It should be noted that both ADD groups con-tained children with sole diagnoses of ADD/H and ADD/W0 as well asother children with codiagnoses of conduct disorder in addition to an ADDdiagnosis.

InstrumentationInstrumentation chosen for inclusion in the present research was selected

from the comprehensive battery administered as part of the psychologicalevaluation conducted with each subject. Previous research with the mea-sures chosen for use in the present study indicated their usefulness in tap-


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Neurocognitiv e Measures and ADD 125ping attentional constructs, and suggested their potential ability to differen-tiate children with ADD/H from ADD/W0 children and other clinicreferred children.

Instrumentation included the Wechsler Intelligence Scale for Children-Revised (WISC-R), from which the three factors identified by Kaufman(1975) were used as variables [Verbal-Comprehension (VC), Perceptual-Or-ganization (PO), and Freedom from Distractibility (FFD)], as well as thescaled score of the Digit Span (DS) subtest by itself. All three WISC-Rfactors were used in the present study due to results of a previous study bySemrud-Clikeman and Lorys-Vernon (1988) comparing children with ADD/H, ADD/H+CD, and a clinic control population. Results indicated thatalthough both the VC and PO factors significantly distinguished betweengroups, the FFD factor did not. However, it was noted children with ADD/WO were not considered in that study, but such a group was included in thepresent study. DS was used separately because it had been noted by Stewartand Moely (1983) to be the one subtest of the three comprising the FFDfactor that may be the most dependent on attention since it most purelytapped serial memory skills in children. It was considered to be an auditorysequential memory task.

Additional variables were chosen from the Luria-Nebraska Neuropsycho-logical Battery-Childrens Revision (LNNB-CR). Item 128 of the MemoryScale was used as well as Item 65 of the Visual Scale. Item 128 is a serialword-learning task comprised of a repetition-remembering process fromwhich the number of trials and the number of errors committed by eachsubject before reaching criterion was recorded for use in data analyses. Theresults of Felton, Wood, Brown, and Campbell (1987) indicated that chil-dren with ADD could be distinguished from Reading Disabled childrenthrough deficits in serial learning and memory. Item 65 is a visual-spatialorientation task from which the number of incorrect responses to 10 itemswas recorded and used in analyses.Furthermore, Items 41 and 42 of the Rhythm Scale of the LNNB-CRwere selected. These auditory sequential/motor regulatory items are slightlydifferent from one another, but were presumed to tap perceptual-sensitivityprocessing skills, as well as motor regulatory skills. The total score for thetwo items combined (0, 1, 2, 3, or 4) was recorded. Lastly from the LNNB-CR, Items 16 and 17 from the Motor Scale were considered as variables.These items are motor-regulatory in nature. Again, the total score for thetwo items combined (0, 1, 2, 3, or 4) was recorded.

In addition to the LNNB-CR, most of the subjects completed four reac-tion time (RT) tasks similar to those employed by Posner (1978) in a para-digm where same/different decisions were required. A simple reaction RTtask and three graded speeded classification tasks were administered. Con-sidering the results of a previous RT study which yielded significant differ-


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126 A. R . Lorys , G. FE Hynd, and B. B. Luheyences between a separate but overlapping sample of children with ADD/Hand ADD/W0 on three-letter nonsense-word matching (Hynd, Nieves, Con-nors, Stone, Town, Becker, Lahey, & Lorys-Vernon, 1989), only the three-letter string-match RT task (LSRT) was included in this study, with the meanRT being used as the variable of analysis.

Completing the mini-battery selected for use in the present research,performance on a sensory localization task (finger agnosia) was chosen as avariable. This measure was presumed to tap perceptual-sensory processing(Luria, 1980). The total number of errors made on the right hand (FAR), thetotal number of errors made on the left hand (FAL) as well as the totalnumber of errors overall (FAT) were recorded and used in the analyses (10items for each hand, 20 total possible).

RESULTSThe following types of analyses were performed: (a) Correlational analy-

ses to determine which variables were to be used as covariates (yielding Full-Scale Intelligence Quotent (FSIQ), Chronological Age (CA), and number ofconduct disorder symptoms (NCD) as covariates); and (b) a series of analy-ses of covariance (ANCOVAs) using the three WISC-R factors (VC, PO, andFFD), as well as ANCOVAs using the LNNB-CR variables (Items 128, 65,41/42, 16117) with FSIQ, CA, and NCD as covariates, followed by the sameseries of ANCOVAs using the same factors with only CA and NCD ascovariates.

The means and standard deviations for all variables by groups are pre-sented in Table 1. Table 1 includes the WISC-R IQ scores and related factorand subtest variables as well as NCD, and the LNNB-CR-related variablesas well as FAR, FAL, FAT, and LSRT.

Correlational AnalysesCorrelations using Pearsons product-moment coefficient were computed

for the total sample as well as for individual groups, after variable meansand standard deviations were obtained. Significant correlations @< .Ol)were obtained between all WISC-R-related variables (VIQ, PIQ, FSIQ, VC,PO, FFD, and DS), as expected since the WISC-R is a measure of generalintelligence and individual scores yielded by the various parts of the testshould be correlated.

In addition, significant correlations (p< .Ol) were obtained betweenFSIQ and all other variables with the exceptions of FAR, FAL, and FAT. Itappeared that all variables except those related to FA were related to generalintellectual ability. It was reasoned that since FSIQ correlated significantlywith 11 of the 14 variables, it should be used as a covariate.


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Neurocognitive Measures and ADDTABLE 1

Variable Means/(Standard Deviations)

I27

Group 1 Group 2(ADD/H) (ADD/WO)

Group 3(CC)

WISC-R VariableChronological AgeVerbal IQPerformance IQ

Full-Scale IQVerbal-Comprehension FactorPerceptual-Organization FactorFreedom From Distractibility FactorDigit SpanNumber of Conduct Disorder Symptoms

LNNB-CR-Related VariablesItem 128 (# of trials)Item 128 (errors)Item 65 (# errors)Items 41/42 (total)Items 16/17 (total)Finger Agnosia-RightFinger Agnosia-LeftFinger Agnosia-TotalLetter String Reaction Time

104.42(18.76)101.29(16.77)99.57

(15.13)100.47(16.19)10.44(2.89)10.10(2.51)9.32

(2.61)8.88

(3.11)2.81

(2.90)

3.55(1.48)6.71

(5.85)3.95

(2.74)1.48

(1.35)1.88

(1.38)0.67

(1.14)0.81

(1.25)1.48

(1.90)2.31

(0.93)

124.50(16.62)97.65

(14.75)98.08

(18.16)97.69

(15.80)9.90

(2.65)9.92

(2.97)8.48

(1.65)8.23

(2.37)1.15

(1.17)

3.23(1.10)4.00

(2.40)3.36

(3.04)0.96

(1.11)1.73

(1.37)0.42

(0.76)0.31

(0.55)0.73

(1.19)1.66

(0.50)

108.27(19.77)107.23(13.26)103.12(15.84)105.88(14.24)11.32(2.11)11.22(2.40)9.43

(2.14)9.92

(2.69)0.81

(1.63)

3.10(1.04)3.90

(2.02)3.55

(2.70)0.50

(0.80)1.55

(1.41)0.40

(1.26)0.48

(0.96)0.88

(1.81)1.77

(0.71)

In addition, because CA also correlated with performance on the LNNB-CR variables, it was used as a covariate. Lastly, NCD symptoms were usedas a covariate based on the negative additive influence of conduct disorderon performance of children with ADD/H (Lahey, Schaughency, Hynd,Carlson, Nieves, 1987; Walker, Lahey, Hynd, & Frame, 1987; Hynd, Nieves,Connor, Stone, Town, Becker, Lahey, & Lorys-Vernon, 1989). As stated


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128 A. R. Lorys, G. IK Hynd, and B. B. Luheyearlier, both ADD groups contained some children with codiagnoses of CD.In summary, analyses were conducted using FSIQ, CA, and NCD as covari-ates and then using only CA and NCD as covariates.

ANCOVAs- WISC-R-Related VariablesThe ANCOVAs examining the three WISC-R factor scores using FSIQ as

a covariate resulted in nonsignificant group effects @> .05). Similar resultswere found using NCD as a covariate @> .05). Thus, it appeared the threeWISC-R factors and NCD failed to distinguish between groups.

Auditory Sequential Memory (OS)Table 1 presents the group means and standard deviations for DS, which

were not significantly different between groups. When the ANCOVAswere computed, no significant group differences emerged on any of theANCOVAs.

ANCOVAs- LNNB-CR-Related VariablesSerial learning (Item 128). As seen in Table 1, there was virtually no differ-ence between the mean performance of the ADD/H, ADD/WO, and CCgroups on Item 128. All groups took approximately three trials to correctlylearn to criterion the serially presented list of words. When FSIQ, CA, andNCD were used as covariates, again no significant group effect was noted(p> .05). It appeared that deficits in serial learning did not differentiateADD/H or ADD/W0 children from a CC group. Furthermore, althoughthe means of the number of errors were in the expected direction (ADD/H =6.71, ADD/WO=4.00, CC=3.90), no significant group effect emergedfrom the ANCOVA.

In further analyses in which FSIQ was eliminated using only CA andNCD as covariates, there are still no significant group effect. However, onthe ANCOVA using only CA, a near-significant effect emerged (F=3.03,p < .0537).

Visual-Spatial Orientation (Item 65)Considering the means and standard deviations presented in Table 1, in

addition to the results of the ANCOVAs, no significant group effectsemerged for this variable. It appeared that performance on a visual-spatialorientation task did not differentiate ADD/H or ADD/W0 children fromthe CC group, in contrast to the earlier stated hypothesis.


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Neurocognitive Measures and ADD 129Auditory-Sequential/Motor Regulatory Processing (Items 41/42)

Referring to Table 1 which presents means and standard deviations forthis task, it appeared there were slight differences between groups for thecombined scores of these two items. The ADD/H groups mean (1.48) wasalmost three times that of the CC groups (0.50). Keeping in mind that ahigher score on these tasks indicated poorer performance, it appeared thatthe ADD/H group performed poorer on this task. Nonetheless, furtheranalyses using FSIQ, CA, and NCD as covariates did not yield any signifi-cant group effects @> .05). However, when FSIQ and NCD were eliminatedas covariates and only CA was used, a significant effect was obtained (F=3.46, p< .04).

Nonetheless, it is of interest to note that when post-hoc group compari-sons were made using age adjusted means, the comparison between theADD/H group and the CC group was significant (p < .0117). Thus, it mightbe concluded that when age adjusted scores were examined, there weresignificant differences in the performance of the ADD/H group comparedto that of the CC population. However, it appeared that the number of CDsymptoms exhibited by a child exerted a significant influence on poor per-formance on this cross-modal auditory/motor task.

Motor Regulatory (Items 16/I 7)Table 1 presents the means and standard deviations for the combinedtotal scores for items 16/17. As can be seen, there were no differencesbetween the performances of the three groups. In addition, when FSIQ,CA, and NCD were used as covariates then CA individually, and then onlyCA and NCD in further analyses, again no significant group effects wereindicated. Thus, it appeared ADD/H and ADD/W0 children did not differin their performance on the motor regulatory task, contrary to the statedhypothesis.

Motor Regulatory (LSRT)Referring once again to Table 1, group means and standard deviations for

the LSRT task appear to be nondistinguishable between the three groups.Covariate analyses using FSIQ, CA, and NCD, indicated no significantgroup differences on this variable (p> .05). Additional covariate analysesusing only CA and then both CA and NCD also indicated no significantgroup differences @> .05). However, post-hoc comparisons between groupsdid indicate a significant comparison between the ADD/H and CC groups(PC .0363). Therefore, it appeared that when general intellectual function-ing level was not taken into account, the ADD/H children did perform


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130 A. R. Lorys, G. FK Hynd, and B. B. Luheydifferently than CC children. However, this effect was eliminated whenFSIQ was introduced as a covariate.

Sensory Localization (Finger Agnosia)As seen in Table 1, the group means and standard deviations of errors on

this task for the right hand, the left hand, and also the total number oferrors for these tasks appeared to be virtually similar with the exception ofFAL. For this variable, the mean of the ADD/H group (.81) was slightlymore than two times greater than the mean for the ADD/W0 group (.31).Although this appeared to be contrary to stated hypotehses, it may havebeen that the cross-modal nature of the task obscured any possible deficitthat may have been present. The results of further analyses using FSIQ, CA,and NCD as covariates indicated no significant @ > .OS) group effect for anyof the FA variables.

Of interest, when only CA was used as a covariate, the group effect didapproach significance @> .0541) but when NCD was added with CA as acovariate, this trend toward significance was eliminated. Post-hoc tests be-tween group comparisons using age adjusted means did indicate a signifi-cant comparison between the ADD/H and ADD/W0 groups (p< .0197).However, as noted earlier, no significant group effects could be seen. Thus,children with ADD/H and children with ADD/W0 did not appear to per-form differently on the FA task.

SummaryIn general, these results indicated children with ADD/H and children

with ADD/W0 cannot be differentiated from each other on the neurocogni-tive tasks considered in the present study. Although there did appear to besome differences between the three groups in the predicted direction on acouple of the variables, when general intellectual functioning was used as acovariate, any potentially significant effects were eliminated.

DISCUSSIONThe purpose of this study was to explore whether reliably diagnosed and

behaviorally defined groups comprised of children with ADD/H and chil-dren with ADD/W0 could also be differentiated using neurocognitive mea-sures that presumably appraise selected mechanisms of attention. Specifical-l,y, it was hypothesized that differences would be found between childrenwith ADD/H and those with ADD/W0 on motor regulatory and perceptu-al-sensory tasks. It was expected that ADD/Hs would perform more poorly


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Neurocognitiv e Measures and ADD 131

than ADD/WOs or a CC group on motor regulatory tasks while ADD/WOswould perform more poorly than ADD/Hs or a CC group on perceptual-sensory tasks.

These hypotheses were based on Schaughency and Hynds (1989) argu-ment that children with ADD/H may have disturbances in the activation ormotor control-readiness system as outlined by Tucker and Williamson(1984), while children with ADD/W0 may have a singular deficiency in thearousal (perceptual-responsivity) system. In general, results were contraryto stated hypotheses with a couple of exceptions.

Overall, the major findings of the present study can be summarized asfollows.

1. FSIQ, as measured by the WISC-R, correlated significantly with theneuropsychological measures employed in this study.2. The three factors derived by Kaufman (1975) which underlie the

WISC-R did not appear to differentiate ADD/H children, ADD/W0children, or a clinic control group such as the one included in thepresent study nor the DS subtest individually.

3. Contrary to stated hypotheses generated from the results of Felton etal. (1987), serial learning and memory tasks did not discriminateADD/H from ADD/W0 children, or a CC group.

4. On a visual-orientation task presumably assessing the posterior-visualassociation areas, there were no differences between ADD/H andADD/W0 children or a CC group.

5. On measures using auditory-sequential memory/motor skills, therewas a significant difference that was consistent with the hypothesesstated earlier between ADD/H and ADD/W0 children, but the effectwas eliminated when FSIQ was introduced as a covariate.

6. There was no difference between children with ADD/H, children withADD/WO, or CC children motor-regulatory measures.

7. Performance on a tactile-sensory localization measure did not discrim-inate ADD/H and ADD/W0 children from each other or from a CCgroup.

The results of the present study do not support the anterior-posteriorgradient hypothesis for ADD/Hs and for ADD/WOs. However, althoughsupport for Schaughency and Hynd (1989) was lacking, the idea that theADD groups are not discrete groups but are just different in the motorregulatory domain still exists.

As for the present studys contribution to the developing conceptualframework integrating behavioral and neuropsychological perspectives, it


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132 A. R. Lorys, G. FK Hynd, and B. B. Luheydid not provide substantial findings aside from the notion that FSIQ had apowerful influence on results of neuropsychological measures with thesechildren. This finding is consistent with many studies in which clinical neu-ropsychological measures correlate significantly with measures of generalintelligence (Hynd, Snow, & Becker, 1986).

This study also suggests that other neuropsychological measures that maytap more discrete neurocognitive processes (e.g., dichotic listening, event-related potentials) may avoid possible ceiling effects which may have influ-enced the results of this study (particularly on the LNNB-CR tasks) andprovide a more sensitive test of the issues addressed in this study. Morespecific tests of visual-perceptual sensitivity, orientation, recognition, andassociation may provide differentiating results not found in this study.

For example, Chelune et al. (1986) found that ADD/H children differedsignificantly from normals on the Wisconsin Card Sort Test. This and otherbehavioral measures that presumably tap frontal inhibitory processes (seeBecker, Isaac, & Hynd, 1987; Passler, Isaac, & Hynd, 1985) may providediscrimination between the subtypes of ADD addressed in this study. How-ever, the recent results of Linz, Hynd, Isaac, and Gibson (1989) suggest thatthese tasks may not be as sensitive in distinguishing between the behaviorallydifferentiated subtypes of ADD/H and children with conduct disorder. Thismost recent study underscores the potential importance of other moreneuropsychologically oriented paradigms in addressing the hypotheses ex-amined here. In this context, the recent report by Voeller and Heilman(1988) suggests that measures of motor impersistence may hold promise indistinguishing children with ADD. Further, they propose that children withADD/H may suffer deficits in right hemispheric processes, possibly right-anterior functioning.

It is still important to investigate whether the behaviorally defined sub-types of ADD can be differentiated through other psychometric or neuro-cognitive measures. At this point, it may be suggested that somewhat circu-lar reasoning characterizes this literature in that only through behavioralmeasures can these subtypes be significantly and consistently differentiated,and behavioral measures are the means by which the subtypes were initiallydiagnosed. In other words, the majority of the studies that investigate thepotentially different performance of ADD/H and ADD/W0 children onmeasures independent of those used in initial diagnosis fail to find valida-tion as to the independence of the ADD subtypes (e.g., Maurer & Stewart,1980; Hynd, Nieves, Connor, Stone, Town, Becker, Lahey, & Lorys-Vernon,1989). Therefore, at present, the ability to reliably characterize children intoADD subtypes exceeds the ability to understand in a conceptually meaning-ful way what neural structures and neuropsychological processes may bedifferentially involved.


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