Self-Reported Inattention, Impulsivity, and Hyperactivity atAges 15 and 18 Years in the General Population

ELIZABETH SCHAUGHENCY, PH.D., ROB McGEE, PH.D., SHYAMALANADA RAJA, M.Se,

MICHAEL FEEHAN, DIP.CLPS., AND PHIL A. SILVA, PH.D.

ABSTRACT

Objective: Prevalence, impact, and continuity of self-reported attention deficit disorder (ADD) symptomology from ages

15 to 18 years were examined in a longitudinal study of a New Zealand birth cohort. Method: At age 15, prevalence of

ADD symptomology was estimated, with no gender differences found in self-reported symptomology. Four adolescents

(0.5%) met full DSM-III criteria for ADD. Adolescents scoring higher than 1.5 SD above the sample mean on total ADD

symptom score were identified as having high levels of ADD symptomology. Results: Male and female adolescents

reporting ADD symptomology with (6% of males; 4% of females) and without history of behavior disorder (6% of males;

7% of females) did not differ in inattention and impulsivity, received more diagnoses other than ADD, and experienced

more adverse educational and social outcomes at 15 and 18 years than did the nonADD group. Conclusions: Findings

pertaining to the ADD with history group were consistent with previous research on the outcome of hyperactive children,

whereas the ADD without history group may be reflecting the onset of other pathology in adolescence. Results suggest

adolescent self-report of attentional difficulties may be a clinically significant marker of adjustment difficulties for both

males and females, but additional information likely is needed for accurate diagnosis. J. Am. Acad. Child Ado/esc.

Psychiatry, 1994, 33, 2:173-184. Key Words: attention deficit disorder, adolescence, early adulthood, continuity,

psychopathology.

The bulk of research on attention-deficit hyperactivitydisorder (ADHD) (American Psychiatric Association,1987) has been conducted on boys aged 6 to 11 years.Although this group is representative of the population

AcceptedJune 22, 1993.Dr. Schaughency is Associate Professor, SchoolPsychology Program, Division

ofSpecial Education and Rehabilitation, College ofEducation, University ofOregon. Dr. McGee is Senior Research Fellow and Mr. Feehan is ResearchFellow, Department of Preventive and Social Medicine, Ms. Nada Raja isJunior Research Fellow and Dr. Silva is Director, Dunedin MultidisciplinaryHealth and Development Research Unit (DMHDRU), Department ofPaediat­rics and Child Health, University of Otago Medical School, New Zealand

The DMHDRU is supported by the Health Research Council of NewZealand. Collection of data at ages 15 and 18 years was partially supportedby grants to Dr. T. Moffitt ftom the Antisocial and Violent Behavior Branchof the U.S. National Institute of Mental Health (I-23-MH42723, ROI­MH43746, ROI-MH-45070). The authors are indebted to many people whomake the longitudinal study possible. This work was conducted while Dr.Schaughency was Visiting Lecturer, Department of Psychology, Universityof Otago.

Reprint requests to Dr. Schaughency, SchoolofPsychology Program, DivisionofSpecial Education and Rehabilitation, College ofEducation, University ofOregon, Eugene, OR 97403.

0890-8567/94/3302-0 173$03.00/0©1994 by the American Academy ofChild and Adolescent Psychiatry.

]. AM. ACAD. CHILD ADOLESC. PSYCHIATRY, 33:2 FEBRUARY 1994

sector most commonly referred for the disorder, thispractice has resulted in limited knowledge of the disor­der in other sectors of the population, particularlyfemales and persons at other developmental levels.

Historically it was thought that children "grew outof' ADHD at puberty, but longitudinal research nowsuggests that these problems continue into adolescenceand beyond (Barkley, 1990; Hechtman, 1991; Kleinand Mannuzza, 1991). Little is known about ADHDin adolescence and adulthood, and what we do knowcomes primarily from follow-up studies of childhoodhyperactivity. The generalizability of these studies toadolescent-referred ADHD is potentially limited (Bark­ley et al., 1991).

Barkley et al. (1991) compared young people diag­nosed with ADHD in adolescence with a similarly agedcontrol group. Their findings were generally consistentwith follow-up studies of child-identified ADHD intoadolescence. Differences found between the adolescent­referred and child-referred ADHD adolescents wereprimarily in the area of treatment use; the adolescent­referred ADHD subjects were less likely to have been

173

SCHAUGHENCY ET AL.

treated with methylphenidate, but more likely to havebeen placed in special education programs for thelearning disabled or to have been retained in grade(Barkley et al., 1991). Because only 10 to 30% ofchildren diagnosed with ADHD are receiving treatmentat any time in the United Sstates (Whalen and Henker,1991), studies of clinical samples of adolescents withADHD could be similarly limited in their applicabilityto the population of adolescents with attentional diffi­culties. Thus, additional research is needed examiningADHD in the general population of adolescents andadults.

The practice of limiting research on ADHD to malesubjects is, in part, based on the often cited statisticthat such difficulties are more common in boys. Girlswith attention problems may be underrecognized, how­ever (c.f., McGee and Feehan, 1992). When girls wereidentified with attentional difficulties relative to same­gender distributions of teacher ratings at ages 9 and11 years, boys and girls identified by teacher ratingswere equally prevalent and displayed similar cognitivedeficits and early history of behavior problems (McGeeet al., 1987). The finding that only two of the 17girls identified by McGee and colleagues met DSM-IIIcriteria for attention deficit disorder (ADD) (AmericanPsychiatric Association, 1980), despite associations withimpairment in functioning, supports the argument thatDSM criteria may underidentify girls with attentionaldifficulties. Research examining the nature of atten­tional difficulties in adolescent girls is virtuallynonexistent.

Particularly problematic for research in ADHD isthe procedure used to identify a case (Taylor et al.,1991). Teachers and parents are seen as the bestinformants on hyperactivity and attention problems inchildren (Loeber et al., in press). In adolescence andadulthood, self-report becomes increasingly weighted inboth research and clinical assessment (Barkley, 1990).

Little research has been conducted evaluating self­reported symptoms ofADHD in adolescence or adult­hood (Barkley, 1990). Barkley and colleagues (1991)found that adolescent-referred teenagers with ADHDreported less serious adjustment difficulties relativeto parents' and teachers' ratings and concluded thatclinicians should not rely heavily on the self-reports ofadolescents. Agreeing that adolescents may underreportsymptoms, Dulcan (1986) reached a different conclu­sion. When adolescents endorsed symptoms, they werelikely to be clinically significant (Dulcan, 1986).

The shift in weighting of informants parallels theshift in referral agent over development. Children arebrought to the clinic by their parents; in adulthood,clients are self-referred. Because the referral agent influ­ences who does and does not seek treatment, additionalresearch is needed that examines self-report of ADHDsymptoms in adolescence and adulthood for clinicalas well as methodological reasons.

This study examined the prevalence, nature, andcourse of self-reported inattention, impulsivity, andhyperactivity at age 15 years in a large sample ofadolescents from the general population. At the age15 assessment, DSM-III criteria were used to defineADD. Adolescents reporting elevated ADD symp­tomology with and without a history of childhoodbehavior disorder were compared with adolescents whodid not report elevated ADD symptomology on self­reported and parent-reported indices of ADD symp­tomology, behavioral correlates of ADD, academicachievement, and other indices of social adjustment(e.g., help-seeking, medication use). These adolescentswere followed-up at age 18 years to examine continuityof attentional and associated impairment into youngadulthood, with self-reported and external, other-re­ported indices of adjustment.

Sufficient numbers of male and female subjectsallowed for exploration of relevant gender differences;use of external and self-report allowed for examinationof the validity of self-report of attentional difficultiesat these ages.

METHOD

Sample

Participants were enrolled in the Dunedin MultidisciplinaryHealth and Development Study (DMHDS), a longitudinal investi­gation of health and development. Silva (1990) presents a fulldescription of sample history. Briefly, participants in the DMHDSbelonged to the cohort born at Queen Mary Hospital, Dunedin,Otago between April 1, 1972 and March 31, 1973 and living inOtago at the first assessment at age 3 years. Of the 1,139 childreneligible for inclusion, 1,037 enrolled in the study, the remaindereither traced too late for the age 3 assessment or not having parentalpermission to participate. The sample was reassessed every 2 yearsto age 15 and then at 18 years on a variery of measures. Comparedwith the remainder of New Zealand, the Dunedin sample scoredsomewhat higher on socioeconomic status (Elley and Irving, 1972)and is underrepresented in children of Maori and other Polynesiandescent (New Zealand Department of Statistics, 1983). Overall,the sample is comparable with those from English-speaking West­ern cultures.

174 j. AM. ACAD. CHILD ADOLESC. PSYCHIATRY, 33:2, FEBRUARY 1994

Sample characteristics at age 15 years are described by McGeeet al. (1990) and at 18 by Feehan et al. (1993). FollowingMcGee et al. (1990), participants were included in analyses if childdiagnostic interview and parent rating scale information wereavailable at age 15, resulting in a sample size of 943 (483 boysand 460 girls) at age 15. At age 18 years, age 15 subjects wereincluded if they had mental health data available at 18 years,following Feehan et al. (1993), resulting in a sample size of 890(453 males; 437 females) at age 18.

Measures: Age 15 Years

Mental Health Interview. Adolescents were administered a modi­fied version of the Diagnostic Interview Schedule for Children(DISC-C) (Costello er aI., 1982), abbreviated to include only thoseitems with the highest item-total correlation with each DSM-IIIcriterion symptom as described by McGee et al. (1990). DISC-Citems were scored for symptom endorsement for use in diagnosticdecision-making and quantitatively to create psychometric scalesof ADD, anxiety, depression, and conduct disorder. Individualdiagnoses were grouped into categories of internalizing (anxietyand depressive) and externalizing (i.e., disruptive; conduct andoppositional) disorders, excluding ADD. The interview also in­cluded items that assessed perceived course of the disorder, help­seeking and medication (prescription or nonprescription) fortheir difficulties.

Parent Questionnaire. Parents completed the Revised BehaviorProblem Checklist (RBPC) (Quay and Peterson, 1987), a 77-itemrating scale comprising factors labeled conduct disorder, socializedaggression, anxiety-withdrawal, attention problem-immaturity, mo­tor excess, and psychotic behavior. The parent questionnaire alsoincluded items assessing help-seeking and police contact regardingtheir child's difficulties.

Academic Achievement. Reading recognition was assessed via theBurt Word Reading Test-1974 revision (BWRT) (Scottish Councilfor Research in Education, 1976), a measure used extensively withthis New Zealand population. Information also was obtained onthe adolescents' performance on the national School Certificateexamination, typically taken at Form 5 (approximately age 15years). Not all New Zealand young people take this examination,only those seeking a school certificate. Scores on the English subtestwere chosen because they share the greatest correlation with thetotal score and the English subtest is compulsory for everyonetaking the school certificate examination (Trainor, personal commu­nication, 1992). Because other subtesrs are elective, total scoreswould be based on different subtest scores for different students.Scores represent grades assigned by the New Zealand QualificationsAuthority. For analyses, grades were divided into three categories:good (grades of AI, Az), average (B" Bz)' and poor (C" Cz, D).

Measures: Age 18 Years

Mental Health Interview. At 18 years, participants were inter­viewed with a modified version of the Diagnostic Interview Sched­ule, version three-revised (DIS-IlI-R) (Robins et aI., 1989).Modifications to the DIS-III-R are described by Feehan er al.(1993). Items were added to assess the continuity of childhooddisorders (specifically ADD) and the adolescents' perceptions ofimpairment due to endorsed symptoms, course of symptomology,help-seeking, and medication (prescription and nonprescription)use.

Significant Other Report. At age 18, a "significant other" nomi­nated by the subject completed a questionnaire that included itemsassessingADD. For the 930 18 years olds with mental health data,

ADD SYMPTOMOLOGY IN ADOLESCENCE

830 (89%) completed questionnaries. Half were completed by aparent and 30% by a close friend (Feehan et aI., 1993).

Social/Educational Disadvantage. A five-point index of self-re­ported disadvantage was used based on number of the following:left school with fewer than 3 years secondary schooling, havingno academic qualifications, perceived difficulty in supporting them­selvesfinancially, the participant (or their partner) having/expectinga dependent child, and being unemployed (Feehan et aI., 1993).

ProceduresProcedures were similar at both assessments. Subjects were invited

to the Research Unit for assessments near to their l Srh and l Sthbirthdays, respectively. Descriptions of procedures and consentforms were mailed before the assessment date. At age 15 years,parental and adolescent written consent were obtained; adolescentconsent was sought at 18 years old. Efforts were made to interviewelsewhere those who could not attend the unit.

RESULTS

Dimensional variables were analyzed using analysisof variance (ANOVA) procedures. Groups of three ormore related variables were analyzed using multivariateanalyses of variance (MANOVA). Significant MANO­VAs were followed by univariate ANOVAs. Otherbetween group comparisons were conducted using AN­OVAs or ttests. Significant ANOVAswere followed bypost hoc analyses using Scheffe's procedure. Categoricalvariables were analyzed using chi-square procedures.Significant overall chi squares were followed by compar­isons of each pair of groups, and significant resultsfollowed by appropriate post-hoc pairwise comparisons.When previous research or preliminary analyses sug­gested possible gender effects, data were analyzed sepa­rately by gender when appropriate.

Prevalence of Attentional Difficulties at Age 15 Years

Information on self-reported symptoms of ADD wasobtained via ADD items on the DISC-C; parent ratingswere obtained via the attention problems-immaturity(AP-I) and motor excess (ME) factors of the RBPC.Table 1 presents the prevalence estimates for eachself-reported item assessing attentional difficulties andhyperactivity, for the whole sample and separately bygender. Symptom endorsement was defined as a ratingof 2, "yes, certainly applies." There were no genderdifferences in prevalence of self-reported symptoms ofADD, p > .05. Differences were found in the expecteddirections for parent ratings of items most directlyrelating to attentional difficulties (short attention span:males: 7.25%, females: 3.48%, distractible: males:

]. AM. ACAD. CHILD ADOLESC. PSYCHIATRY, 33:2, FEBRUARY 1994 175

SCHAUGHENCY ET AL.

TABLE 1Prevalence (%) of Self-Reported Symptoms' of Attention Deficit Disorder at Age 15 Years

Often start on schoolwork and not finishHave trouble paying attention when people are talkingHard time doing schoolwork with noises/other things going onTeacher says nor keeping mind on workHard to finish something enjoyRush into doing things without thinking what may happenTrouble organizing schoolworkTeacher has to remind whar to do again and againTrouble waiting turn or push ahead in lineRun around alot inside home or school when not supposed toHard to sit stillHard to sit through something

EntireSample

(n = 943)

15.383.18

19.837.537.85

17.297.743.293.615.307.329.65

Males(n = 483)

13.662.69

21.336.007.25

19.467.872.483.936.007.048.90

Females(n = 460)

17.173.70

18.269. 138.48

15.007.614.133.264.577.61

10.43

2.230.771.393.310.493.280.022.010.310.970.110.63

p

.14

.38

.24

.07

.48

.07

.88

.16

.58

.32

.74

.43

• From Diagnostic Interview Schedule for Children (Costello er aI., 1982).

8.49%, females: 3.26%), mororic restlessness (males:6.42 %, females: 2.61%), and sloppy school work(males: 5.18%, females: 0.43%), p < .01.

Four adolescents currently met full DSM-III criteriafor ADD using the confirmation procedures describedby McGee et al. (1990), too few cases for data analyses.However, the DSM criteria have not been establishedempirically for diagnosis of ADD in adolescents, andlower cutoff scores might be appropriate given thereported decline in prevalence of ADHD symptomsin the normal population at this age (Barkley, 1990).Given this and the polythetic approach taken in theDSM-III-R criteria for ADHD, a psychometric ap­proach was taken to examine additionally the natureof attentional difficulties in adolescence.

Total scores were calculated for the DISC-C ADDitems and RBPC AP-I factor. Males and females didnot differ in self-reported total symptom rating (males,M = 7.33, SD = 4.65; females, M = 7.03, SD = 4.85;t = -.98, NS), although receiving different ratings fromtheir parents (males, M = 5.14, SD = 5.12; females,M = 3.75, SD = 4. 19; t= -4.52, P < .0001). Self-ratedand parent-rated characteristics of ADD correlatedmodestly and did not differ by gender (inattention:males, r (483) = .29, P < .0001; females, r(460) =

.29, P < .0001 ; motor excess: males, r(483) = .23, P< .0001; females, r(457) = .20, P < .0001).

Adolescents were identified as experiencing ADDsymptomology if they obtained scores higher than 1.5SD above the mean on the DISC-C ADD and RBPCAP items. Because no gender differences were obtained

on self-reported attent ion problems, cutoffs were estab­lished relative to the entire sample for the DISC-Cscores whereas same-gender ratings were used to estab­lish cutoffs on the RBPC following recommendationsby McGee and Feehan (1992). Fifry-eight boys(12.01%) and 47 girls (10.22%) met criteria for self­reported ADD symptoms; 45 boys (9.32%) and 47 girls(10.22%) met criteria for parent-reported attentionaldifficulties. As predicted given the modest correlationbetween self-report and parent-report, the overlap be­tween self-report and parent-identified adolescents wassmall: 12 boys and eight girls. Three of the fourchildren who met DSM-III criteria were identifiedvia self-report; only one of the four ident ified viaparent- report.

ADD is conceptualized as a developmental disorder(Barkley, 1990). Therefore, a significant number ofthe children identified as experiencing ADD symp­tomology at 15 years old would be expected to exhibita behavior disorder in childhood or preadolescence.Whether there also exists a "late onset" pattern ofattentional difficulties is unclear. History of disorderwas defined as ident ification of disorder from ages 3to 13 years (Anderson et aI., 1987; McGee et al., 1991,1993). Fifry percent (n = 29) of boys and 37% (n =17) of girls reporting ADD symptomology at age 15possessed an early history of behavior disorder. Earlierassessment data for the remaining 29 boys (50%) and30 girls (64%) who reported ADD symptomology didnot indicate early mental health disorder.

176 ] . AM. ACAD . C H ILD ADOLESC. PSYCHIAT RY, 33 :2 , FEBRUARY 1994

ADD SYMPTOMOLOGY IN ADOLESCENCE

Nature of Self-Reported Symptoms of ADD

at Age 15 Years

Pattern of ADD Symptoms. Adolescents reponingADD symptomology with (early ADD) and withouta history of mental health disorder (late ADD) andadolescents without ADD (no ADD) were comparedon symptom totals for the DSM-III symptom clustersof inattention, impulsivity, and hyperactivity, total self­reponed ADD symptom score, and parent ratings onthe AP-I and ME factors of the RBPC. Means andstandard deviations by group and gender are presentedin Table 2.

Comparisons on DSM-III symptom clusters usinga 3 (group) X 2 (gender) MANOVA produced asignificant model, F(6,937) '" 149.41, P < .0001, forgroup but not gender. Univariate analyses revealedmain effects for group for all three symptom clusters,inattention, F(2,937) '" 224.10,p< .0001; impulsivity:F(2,937) '" 270.86, P < .0001; hyperactivity:F(2,937) '" 259.66, P < .0001. Adolescents in boththe ADD groups obtained higher scores than did thesample remainder on all three symptom constructs,as expected, given procedures for group formation.Adolescents in the two ADD groups also differedon hyperactivity.

Group X gender interactions were found for impul­sivity and hyperactivity; impulsivity, F(2,937) '" 5.63,P < .005; hyperactivity, F(2,937) '" 6.19, P < .005.Therefore, additional analyses will be reponed sepa­rately by gender. As Table 2 shows, differences were

found between the groups on all three symptom clustersfor both boys and girls. Boys and girls in both ADDgroups reponed higher inattention and impulsivitythan did their same-gender peers in the nonADDgroup but did not differ from each other. The resultsdiffered between the genders for hyperactivity. Boysin the early ADD group reponed more hyperactivitythan did boys in the late ADD group, who in turnreponed more hyperactivity than did boys withoutADD symptomology. For girls, both ADD groupsreponed more hyperactivity than the nonADD groupbut did not differ from each other.

Significant effects were found for both boys andgirls for total ADD score, but with somewhat differentresults for the two genders: adolescent boys in the earlyADD group reponed more ADD symptoms than didthose in the late ADD group and those without ADD,and those in the late ADD group reponed more ADDsymptoms than those without ADD. Adolescent girlsin both ADD groups reponed greater ADD symp­tomology than did those without ADD but did notdiffer from each other.

Boys and girls differed in parent-rated inattention,whereas only boys differed in motor excess. Adolescentboys in the early ADD group had the highest parent­rated inattention, with those in the late ADD groupnot differing fromthose without ADD. Only adoles­cent girls in the late ADD group received higherinattention ratings than those without ADD. For motorexcess, parents rated boys in both ADD groups as

TABLE 2Pattern of Attention Deficit Disorder (ADD) Symptoms at Age 15 Years

Males Females

Early ADD(n = 29)M (SD)

Late ADD(n = 29)M (SD)

No ADD(n = 425)M (SD) F(2)

Early ADD(n = 17)M (SD)

Late ADD(n = 30)M (SD)

No ADD(n = 413)M (SD) F(2)

5.67 (2.07)' 1.84 (1.8W 89.74*5.23 (2.30)' 1.17 (1.2W 156.98*3.20 (1.58)' 0.56 (0.91)' 141.37*

18.43 (4.19)' 5.73 (3.0W 314.40*

5.60 (3.55),b 3.52 (4.16)' 6.00*0.93 (1.60) 0.60 (1.09) 2.37, NS

1.74 (1.7W 137.66* 5.89 (2.00)'1.39 (1.3W 120.58* 4.59 (2.18)'0.56 (0.96)' 126.19* 3.00 (1.54)'6.01 (2.96)' 339.44* 17.19 (3.31)'

5.86 (2.10)' 5.83 (2.33)'5.03 (2.18)' 4.17 (2.09)'3.41 (1.86)' 2.31 (l.4W

18.18 (3.89)' 15.93 (1.84)b

Self-report!InattentionImpulsivityHyperactivityTotal ADD symptoms

Parent reporr'Attention problems-immaturity 9.90 (5.40)' 6.21 (4.25)b 4.74 (4.9W 15.33* 5.94 (4.76)"Motor excess 1.59 (1.21)' 1.31 (1.37)' 0.74 (1.14)b 9.85* 1.06 (1.25)

Note: Cells with different superscript letters are significantly different at the p < .05 level.! From Diagnostic Interview Schedule for Children (Costello et aI., 1982).2 Revised Behavior Problem Checklist (Quay and Peterson, 1987).*p < .001, **p < .01.

]. AM. ACAD. CHILD ADOLESC. PSYCHIATRY, 33:2, FEBRUARY 1994 177

SCHAUGHENCY ET AL.

displaying more motor excess than did the sampleremainder.

Perceived Course of ADD Symptomology. The twoADD groups were compared on their response to aquestion asking whether they perceive their symptomsofADD to be "getting better, about the same, or gettingworse," analyzed separately by gender. Differences werefound between the two groups of boys reporting ADD,X2 (2) = 6.65, P < .05. More boys in the early ADDgroup reported perceiving their symptoms of ADD tobe getting better, 60% versus 24%; X2 (2) = 6.65, P~ .01, consistent with the conceptualization of residualADD in adolescents and adulthood, while for girls,no differences were found between the two groups,23% versus 24%; X2 (2) = 0.04, NS.

Impairment Associated with Self-Reported Symptoms of

ADD at Age 15 Years

Behavioral Correlates and Comorbidity. Correlationsbetween self-reported ADD symptomology and self­reported and parent-rated adjustment difficulties arepresented in Table 3. Adolescent self-ratings of ADDsymptomology correlated with all other self-ratings onthe DISC-C scales and parent-ratings on the RBPCfor both boys and girls.

Comorbidity with other disorders is presented inTable 4. As correlational analyses predict, self-reportedADD was associated with likelihood of other disorder,X2(2) = 111.50, P < .001. For the entire sample, 33

TABLE 3Correlations between Self-Reported Symptoms of ADD andSelf-Reported and Parent-Reported Adjustment Difficulties

Total Sample Males FemalesBehavioral Dimension (n = 943) (n = 483) (n = 460)

Self-report'Conduct disorder .52* .51* .55*Anxiety .34* .40* .31*Depression .30* .27* .34*

Parent-report"Conduct disorder .23* .23* .24*Socialized aggression .26* .27* .25*Anxiety-withdrawal .10** .09*** .11***Psychotic behavior .18* .19* .16*

'From Diagnostic Interview Schedule for Children (Costelloet al., 1982).

b Revised Behavior Problem Checklist (Quay and Peterson,1987).

* P < .001, **P < .01, *** P < .05.

(72%) of adolescents in the early ADD group and 26(46%) of adolescents in the late ADD group displayeda comorbid disorder (i.e., diagnosis other than ADD),compared with 130 (16%) of those without ADD.

The pattern of comorbidity for males was similarto those obtained for the entire sample, early ADD:66% (19/29); late ADD: 34% (10/29); no ADD: 12%(52/425), X2 (2) = 62.15, P < .001. Boys in the earlyADD group were more likely than were boys in thelate ADD group to receivea diagnosis other than ADDx2 (1) = 5.59, P < .05, and boys in the late ADDgroup were more likely to receive a diagnosis otherthan ADD than were those not reporting ADD X2 (1) =

11.40, P < .001. For girls, the pattern of comorbiditywas generally similar early ADD: 82% (14/17); lateADD: 63% (19/30); no ADD: 19% (78/413), X2 (2) =

62.87, P < .001. Adolescent girls in both ADD groupswere more likely to receive a diagnosis of a disorderother than ADD than were girls without ADD x2 (1 ) =

39.11, P < .01, X2 (1) = 32.31, P < .001, respectively,but did not differ from each other, x2 (1) = 1.88, P =

.17. Additional analyses conducted to examine possibledifferences in types of pathology experienced by adoles­cents in the two ADD groups revealed no significantrisk for internalizing versus externalizing disorder forboys or girls.

Academic Achievement. Educational indices of im­pairment are presented by group and gender in Table5. The results of a 3 (group) X 2 (gender) ANOVAcomparing performance on the BWRT were significant,F(5,932) = 4.75, P < .0005. Main effectswere obtainedfor both group, F(2,932) = 5.02, P < .01, and gender,F(1,932) = 12.88, P < .0005, with no group X

gender interaction. Adolescents in the earlyADD groupperformed more poorly on the BWRT than did adoles­cents in the late ADD group or those without ADD,and girls performed better on the BWRT than didboys. Separate analyses conducted by gender revealedno significant effects.

Academic achievement was examined additionallyvia analysis of the school certificate examination inEnglish. Male and female adolescents in the earlyADDgroup were lesslikely to have taken the school certificateexamination in English than were adolescents withoutADD. The proportion of adolescents in the late ADDgroup who took the school certificate examination inEnglish fell between the other two groups and did notdiffer from either.

178 J. AM. ACAD. CHILD ADOLESC. PSYCHIATRY, 33:2, FEBRUARY 1994

ADD SYMP T OMOLOGY IN ADOLESCENCE

TABLE 4Comorbidity of Adolescent-Reported Symptoms of ADD at Age 15 Years

Codiagnoses"

Early AD D(n = 29)

Frequency (%)

Males Females

Late AD D No ADD Early ADD Late ADD(n = 29) (n = 425) X' (n = 17) (n = 30)

Frequency (%) Frequency (%) (8 dfJ Frequen cy (%) Frequency (%)

No ADD(n = 4 13)

Frequen cy (%)x'

(8 dfJ

ExternalizingInternalizingMixed

104I

(34.48)(13.79)

(3.45)

442

(13.79)(13.79)

(6.90)

20242

(4.71)(5.56)(0.47)

85.03*482

(23.53)(47.06)(11.76)

964

(30.00)(20.00)(13 .33)

20497

(4.84)(11.86)

(1.69)

80.75*

, After McGee et al. (1990).

* P < .000 1.

Differences in performance on the school certificateexamination in English were found for boys but notgirls (p = .07). Differences in performance were foundonly between boys in the early AD D group and boyswithout ADD, X2 (2) = 6.82, P < .05. More boys inthe early ADD group performed poorly on the schoolcertificate examination in English than did boys with­out ADD, x2 (l ) = 6.73, P < .01, results consistentwith their lower performance on the BWRT.

Other Social Indicators of Impairment. Differenceswere found for adolescent boys and girls for self­reported help-seeking and medication use, shown inTable 6. Boys and girls in both AD D groups reportedseeking help more frequently than did their same­gender peers in the nonADD group but did not differfrom each other.

A somewhat different pattern was observed for self­reported medication use. Male and female adolescentsin the late AD D group were more likely to report takingsomething for their difficulties than were adolescents

without ADD, with none of the other compansonsreaching significance .

Between-group comparisons for parents seeking helpfor their sons failed to reach significance, p = .07, butdifferences were found for parents seeking help fortheir daughters. Parents of girls in the late AD D groupwere more likely to have sought help for their daughtersthan were parents of girls in the nonADD group, withnone of the other comparisons achieving significance.

Differences were found in parent-reported policecontact for their sons but not for their daughters.Parents of boys in the early ADD group reported moreoften that their sons had contact with the police thandid parents of boys in the late ADD or nonADDgroups, who did not differ from each other.

Continuity of ADD Symptomology from

Ages 15 to 18 Years

Pattern of ADD Symptomology at 18. At 18 yearsinformation on ADD symptomology was obtained

TABLE 5Educational Indicators of Impairment at Age 15 Years

Males Females

Early ADD Late AD D No AD D Early ADD Late ADD No ADD(n = 29) (n = 29) (n = 425) Tes t (n = 17) (n = 30) (n = 413) T est

M (SO) M (SO) M (SO) Statistic M (SO) M (SO) M (SO) Statistic

BWRT 1 81.96 (20.50 88.59 (11.13) 88.59 (14.36) 2.67,NS 86.65 (19.92) 95.47 (11.13) 92 .55 (13.87) 2.14, NS

Schoo l Certifica teEnglish' Frequency (%) Frequency (%) Frequency (%) Frequency (%) Frequency (%) Frequency (%)

Students taking exam 11 (45.83)' 16 (66.67)'" 28 1 (83.88) ' X' (2) = 9 (60.00)' 16 (76 .19)'" 304 (88.37)' X'(2 ) =23.66* 12.02***

Poor performance 7 (63.64) 8 (50.00) 80 (28.4 7) X' (4) = 4 (44.44) 4 (25.00) 50 (16.45) X' (4) =(C I, C2 . 0 ) 9.62** 8.6 1,NS

No": Cells with different superscript letters are significantly different at the p < .05 level.I Burt Word Reading T est - 1974 Revision (Scottish Council for Research in Education, 1976)., School Certificate , English (New Zealand Q ualifications Authority).* p < .001, **P < .01, *** P < .05.

] . AM . ACAO. CHILD A O O L ES C . PSYC H IAT RY, 33:2, F EBRUARY 19 94 179

SCHAUGHENCY ET AL.

TABLE 6Social Indicators of Impairment at Age 15 Years

Early ADD(n = 29)

Frequency (%)

Males

Late ADD(n = 29)

Frequency (%)

No ADD(n = 425)

Frequency (%) X' (2)

Early ADD(n = 17)

Frequency (%)

Females

Late ADD(n = 30)

Frequency (%)

No ADD(n = 413)

Frequency (%) X' (2)

Self-report'Help seeking (17.24)" 6 (20.69)' 30 (7.09)' 9.44* 6 (35.29)" 9 (30.00)' 54 (13.11)' 11.92*Medication use (3.45)" 2 (6.09)"' 2 (0.47)' 12.63* 2 (l1.7W 11 (36.67)" 16 (3.87)' 51.81**

Parent report'Help seeking 7 (24.14) 2 (7.14) 45 (10.64) 4.46, NS 4 (23.53)" 11 (36.67)"' 47 (11.44)' 16.71**Police contact 10 (34.38)' 3 (10.71)' 37 (8.73)' 19.34** 1 (5.88) 2 (6.67) 22 (5.35) 0.10, NS

Note: Cells with different superscript letters are significantly different at the p < .05 level., McGee et al., 1990.

* P < .01, ** P < .001.

via the mental health interview with the subject andquestionnaire completed by a "significant other." Thesedata were analyzed both for the whole sample andseparately by gender.

Subjects were asked if they experienced each coresymptom of ADD as conceptualized by the DSM-III,i.e., inattention, impulsivity, hyperactivity. The groupsidentified at age 15 were compared on their total scorefor these core symptoms at 18 using a 3 (group) X

2 (gender) ANOVA. The ANOVA for the wholesample comparison produced a significant model,F(5,884) = 10.54, P < .0001, with significant effectsobtained for group, F(2,884) = 20.29, P < .0001,gender, F(l,884) = 5.02, P < .05, and a group X

gender interaction, F(2,884) = 3.54, P < .05. BothADD groups continued to report higher levels ofADDsymptomology at age 18 than did young adults withoutADD symptomology at 15 years. At age 18 malestended to report higher levels of symptomology thandid females, although the degree of disparity betweenmales and females differed for the three groups. TotalADD scores for males and females who did not reportADD symptomology at 15 are very similar, with in­creased divergence in the late ADD and early ADDgroups, respectively. Differences were found for bothmales and females in same gender analyses. For males,the pattern of results was the same as had been foundfor the entire sample, whereas for females, no differenceswere obtained in post hoc analyses.

The groups did not differ on others' ratings ofattentional difficulties for the sample as a whole, butdiffered in impulsivity as reported by the significantother, X2(2) = 6.12, P < .05. Young adults in the lateADD group at 15 received more ratings of impulsivitythan did young adults without ADD at 15 years,

x2 (l ) = 5.87, P < .05, with no other compansonsreaching significance.

Too few subjects were given ratings of 2, "yes,certainly applies" to use this conservative criterionfor symptom endorsement in separate comparisons bygender. Therefore, symptom presence was defined asratings of 1 or 2. The groups differed on inattentionand impulsivity for both males and females, shown inTable 7. Only young men from the late ADD groupreceived higher inattention and impulsivity ratings thandid the nonADD group. Young women in both ADDgroups received higher ratings of impulsivity than didthose in the nonADD group. Women in the earlyADD group also received more inattention ratingsthan those in the nonADD group, with no othercomparisons achieving significance.

Perceived Impairment and Course at Age 18. Youngadults endorsing ADD symptomology were asked torate their degree of impairment on a 5 point scale.Ratings of 4 or 5 were classified as a high degree ofimpairment. The groups differed for the whole sample,X2 (2) = 8.96,p < .01. Sixteen percent (6/38) of youngadults in the early ADD group at 15 and 14% (6/42)of young adults in the late ADD group at age 15indicated a high level of impairment from ADD symp­tomology, compared with 6% (27/470) ofyoung adultswithout ADD at age 15. Both ADD groups differedfrom the nonADD group, early ADD history versusnonADD, x2 (l ) = 5.84, P < .05; late ADD versusnonADD, x2 (l ) = 4.67, P < .05, who did not differfrom each other. As Table 7 shows, when analyzedseparately by gender, neither comparison reachedsignificance.

Subjects were again asked to indicate whether theyperceived their ADD symptomology to be getting

180 ]. AM. ACAD. CHILD ADOLESC. PSYCHIATRY, 33:2, FEBRUARY 1994

ADD SYMPTOMOLOGY IN ADOLESCENCE

TABLE 7Continuity of Attentional Difficulties at Age 18 Years

Early ADD(II = 29)

M SO

Males

Late ADD(n = 27)

M SO

No ADD(n = 397)

M SOTest

Statistic

Early ADD(n = 16)

M SO

Females

Late ADD(n = 27)

M SO

No ADD(n = 394)

M SOTest

Statistic

Self-reportTotal core ADD 5.17 (2.74)' 4.93 (2.74)' 2.52 (2.46)' F (2) = 3.00 (2.53) 3.74 (3.43) 2.52 (2.46) F (2) =

symptoms! 19.86* 3.16**

Frequency (%) Frequency (%) Frequency (%) Frequency (%) Frequency (%) Frequency (%)

Impairment (19.23)' 3 (13.04) 17 (7.17) 4.85, NS (8.33) 3 (15.79) 10 (4.29) 5.85, NSSignificant other report"

Inattention 10 (45.45)" 14 (63.64)" 133 (36.94)' X' (2) = 8 (61.54)' 12 (52.17)' 119 (33.33)' X' (2) =6.64** 7.38**

Impulsivity 11 (50.00)" 17 (77.27)" 166 (45.73)' X' (2) = 12 (85.71)' 15 (68.18)' 149 (41.62)' X' (2) =8.32** 15.81*

Note: Cells with different superscript letters are significanrly different at the p < .05 level.1 From Diagnostic Interview Schedule (Robins er al., 1989).z Freehan et al. (in press).

* p < .001, **P < .05.

better, staying the same, or getting worse. The groupsdid not differ on perceived course for either the sampleas a whole or separately by gender.

Comorbidity at Age 18

For the entire sample, ADD symptomology at 15years was again found to be associated with higherlevelsof morbidity for other psychiatric diagnoses, earlyADD: x2 (1 ) = 13.60, P < .001; late ADD: X2 (1) =

19.78, P < .001, but did not differ from each other.Sixty percent (27/45) of young adults from the earlyADD group and 63% (34/54) from the late ADDgroup met criteria for a disorder at 18, compared with33% (262/791) from the nonADD group. Youngadults in the early ADD group were more likely toexperience an externalizing versus an internalizing dis­order (24% externalizing) than young adults from thenonADD group (6% externalizing), x2 (1 ) = 10.06, P< .005. The occurrence of an externalizing vs. inter­nalizing disorder did not differ between young adultsfrom the late ADD (13% externalizing) and non­ADD groups.

Somewhat different results were obtained for malesand females, shown in Table 8. For males, both ADDgroups were found to differ from the nonADD group,early ADD versus nonADD: X2 (3) = 31.56, P < .001;late ADD versus nonADD: x2 (3) = 13.39, P < .005,but did not differ from each other. For females, onlythe late ADD group differed from the nonADD group,

x2 (3) = 26.44, P < .001. For males, both ADD groupsmet criteria for a disorder more often, early ADD:66% (19/29); late ADD: 56% (15127); nonADD: 26%(105/397). As with the whole sample, young men fromthe early ADD were more likely to experience anexternalizing versus internalizing disorder than weremen from the nonADD group, x2 (1 ) = 4.70, P < .05,with those from the late ADD group not differingfrom either the early ADD or nonADD groups.

Young women from the late AD 0 group were morelikely than the nonADD group to experience a disorder,late ADD: 70% (19/27); nonADD: 40% (157/394);X2 (1) = 9.68, P< .005. Small cell frequencies precludedadditional analysis by disorder type separately forwomen. The relatively high proportion of mixed (i.e.,internalizing + externalizing) diagnoses for the lateADD group (30%) suggests these young women may beat risk for both internalizing and externalizing disorders.

Academic/Occupational Attainment at Age 18. Com­parisons on the total disadvantage index producedsignificant results for both males and females. Formales, both ADD groups differed from the nonADDgroup, early ADD versus nonADD: males: X2 (2) =

27.74, P < .001; late ADD versus nonADD: males:X2(2) = 17.74, P < .001, but did not differ from eachother. For females, the late ADD group differed fromthe nonADD group, X2(2) = 14.31, P < .001, withno other comparisons reaching significance. Youngmen in both ADD groups experienced two or moreelements of disadvantage than did their nonADD peers

j. AM. ACAD. CHILD ADOLESC. PSYCHIATRY, 33:2, FEBRUARY 1994 181

SCHAUGHENCY ET AL.

TABLE 8Associated Impairment at Age 18 Years

Males Females

Early ADD Lare ADD No ADD Early ADD Late ADD No ADD(n = 29) (n = 27) (n = 397) (n = 16) (n = 27) (n = 394)

Frequency (%) Frequency (%) Frequency (%) X' Frequency (%) Frequency (%) Frequency (%) X'

Codiagnoses' X'(6) = X'(6) =39.63* 26.97*

Externalizing 10 (34.48) 7 (25.93) 36 (9.07) 1 (6.25) 0 (0.00) 15 (3.81)Imernalizing 4 (13.79) 5 (18.52) 53 (13.25) 5 (31.25) II (40.74) 120 (30.46)Mixed 5 (17.24) 3 (11.11) 16 (4.03) 2 (I 2.50) 8 (29.63) 22 (5.58)

Disadvantage'Disadvanrage Index II (37.93) 9 (33.30) 33 (8.31) X'(4) = 8 (50.00) 8 (29.63) 35 (8.88) X'(4) =

(> 2 elements) 38.13* 8.21*< 3 years secondary 8 (27.59>' 7 (25.93)' 29 (7.30)' X' (2) = 3 (18.75) 4 (14.81) 33 (8.38) X'(2) =

education 21.28* 3.10, NSNo school II (37.93)" 6 (22.22)" 30 (7.56)' X' (2) = 4 (25.00)' (18.52)' 25 (6.35)' X' (2) =

qualification 31.15* 12.08**Unemployed 13 (44.83)" 7 (25.93)"' 58 (14.61)' X' (4) = 6 (37.50)" 9 (33.33)' 55 (13.96)' X' (4) =

19.02* 14.16**Difficulry supporting 3 (10.34) (18.52) 36 (9.07) X'(2) = 0 (0.00) (18.52) 43 (10.91) X'(2) =

self 2.59, NS 3.54, NSTeen parent (17.24)' 2 (7.41)' 6 (1.5 I)' X' (2) = (6.25)" 4 (14.81)' 13 (3.30)' X' (2) =

26.11 * 8.68***Medication use' 4 (13.79)" 8 (29.63)" 48 (12.09)' x' (2) = 3 (18.75)M (29.63)" 44 (11.17)' X'(2) =

6.78* 8.40***

Note: Cells with different superscript letters are significanrly different at the p < .05 level.1 Feehan et al. (1993).

* P < .001, **P < .01, ***P <'05.

more often, earlyADD versus nonADD: x2 (l ) = 28.80,P < .001; late ADD versus nonADD: x2 (l ) = 16.50,P < .001. Young women in the late ADD group alsoexperienced two or more elements of disadvantagemore often than did their nonADD peers, X2 (l) =14.54, P < .001.

Between-group differences were found for each ele­ment of disadvantage except difficulty supporting self,results varying somewhat by gender and element ofdisadvantage (Table 8). Young men from both ADDgroups were more likely to have completed fewer than3 years of secondary education, to have no schoolqualification, and to be a teen parent than were youngmen without ADD, but they did not differ from eachother. Young men from the early ADD group werealso more likely to be unemployed than were youngmen from the nonADD group.

Although the groups did not differ on proportionof young women with less than 3 years of secondaryeducation, both ADD groups were more likely to haveno school qualification and to be unemployed thanwere young women in the nonADD group. Youngwomen in the late ADD group were also more likelyto be a teen parent than were young women in thenonADD group.

Other Social Indicators ofImpairment. Subjects wereasked to indicate whether they had sought help fortheir difficulties at age 18. The groups did not differon seeking help from a health professional, other re­source (e.g., support group), family, or friend foranalysesconducted using the entire sample or separatelyby gender. Differences were found for medication usefor the whole sample, X2(2) = 14.85, P < .001, andmales and females separately (Table 8). Both male andfemale young adults from the late ADD group weremore likely to report having taken either prescriptionor nonprescription medication for their difficulties thanwere those from the nonADD group, with no othercomparisons reaching significance.

DISCUSSION

These findings are consistent with follow-up researchof hyperactive boys. They additionally suggest thatgirls reporting ADD symptomology in adolescencewith a history of behavior disorder are likely to havesimilar outcomes, although no differences were foundin parent reported attentional difficulties and help­seeking for girls in the ADD with history and nonADDgroups. However, adolescents also were identified whoreported ADD symptomology in the absence of a

182 J. AM. ACAD. CHILD ADOLESC. PSYCHIATRY, 33:2, FEBRUARY 1994

history of behavior disorder. No differences were foundbetween these two groups in self-reported inattentionor impulsivity. These adolescents also were more likelyto experience adjustment difficulties at age 15, and tocontinue to experience ADD symptomology, adjust­ment difficulties, and social disadvantage at 18 years.

How can these findings be reconciled with theconceptualization ofADD as a developmental disorder?Findings for the ADD with history group are mostconsistent with research on ADD and consonant withthe conceptualization of ADD as a developmentaldisorder, especially for boys. For example, adolescentswho reported ADD symptomology with a history ofbehavior disorder were more likely to experience aca­demic difficulties at age 15, and boys in this groupwere also more likely to have had contact with thepolice. Findings for the ADD without history groupmay be more parsimoniously conceptualized as indica­tive of general pathology rather than reflective of aspecific ADD syndrome. Concentration difficulties aresymptomatic of a wide-range of psychopathology (e.g.,anxiety, depression, psychosis), and not unique toADD. Impuls ivity, likewise, is characteristic of a num­ber of forms of psychopathology as well as ADD (e.g.,conduct disorder, mania).

Importantly, for both these groups of young people,self-report of attentional difficulties at 15 years wasassociated with continued symptoms at 18, associatedadjustment difficulties, and adverse outcomes. Thesefindings highlight the issuessurrounding the proceduresfor case identification. The findings provide supportfor both the use of lower, empirically established cutoffscores in the identification of ADD in adolescence andthe validity of self-report in identifying adolescentadjustment difficulties. These analysesprovide no infor­mation on the issue of whether adolescents, particularlyadolescents with ADD, are likely to underreport theirsymptomology. However, consistent with the viewtaken by Dulcan (1986) , these analyses suggest thatwhen adolescents do report attentional difficulties, thesedifficulties are likely to be of clinical significance.Therefore, adolescent self-report should be consideredin assessment and diagnostic decision making.

If adolescents in the ADD with history group reflectcases of "true" ADD whereas adolescents in the ADDwithout history group reflect other psychopathology,these findings also point to the role of multimethod

ADD SYMPTOMOLOGY IN ADOLES CEN CE

assessment in accurate case conceptualization: adoles­cent self-report of attentional difficulties may be agood marker of adolescent adjustment difficulties, butadditional information from parents and teachers maybe needed for differential diagnosis. Moreover, theincreased risk for disorders other than ADD for bothgroups of adolescents reporting ADD symptomologysuggests that the clinician should conduct a comprehen­sive assessment for accurate case conceptualization andtreatment planning.

Finally, these findings urge caution in the exclusionof female subjects in future research of ADD in adoles­cence based on the assumption of a large male-to­female gender ratio. There were no gender differencesis prevalence of self-reported attentional difficulties.These findings may reflect true differences in genderratios from childhood to adolescence. Epidemiolog icalresearch suggests a decline in prevalence of ADDHfrom childhood to adolescence, especially in boys,which could effectively reduce the male to femalegender ratio in adolescence (Szatmari et aI., 1989).These findings point to the potential for underrecogniz­ing adolescent females with attentional difficulties.Whereas no gender differences were found in self­reported attentional difficulties, sex differences werefound in parent-reported attentional difficulties, despitethe similarity in the association between self-reportedattentional difficulties and impairment for boys andgirls.

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