OUTCOME ISSUES IN ADHD: ADOLESCENTAND ADULT LONG-TERM OUTCOME

Sara Ingram,1* Lily Hechtman,2 and Gert Morgenstern,3

1McGill University, Montreal Children’s Hospital, Montreal, Quebec, Canada

2Montreal Children’s Hospital, Child Psychiatry, Montreal, Quebec, Canada

3Douglas Hospital, Psychiatry, Verdun, Quebec, Canada

This article outlines the value and limitations of the researchin the area of long-term outcome of attention deficit and hyperactiv-ity disorder (ADHD). It examines the natural progression of thedisorder, and the factors affecting outcome. Early research findingssince the 1960s have focused on ADHD primarily as a childhooddisorder. More recently, a number of researchers have trackedPatients with ADHD longitudinally. These studies have been able tochart the natural progression of this disorder, ascertaining its contin-ued presence in adolescence and adulthood, as well as to identifystable predictors of outcome. Results of long-term follow-up studiesshowed that in adolescence, most patients (70%–80%) continue toshow symptoms of the disorder and continue to meet the diagnosticcriteria for ADHD. In adulthood, many patients continue to besymptomatic (60%), but fewer meet the diagnostic criteria forADHD. Research in this area is plagued by a number of methodologi-cal difficulties. In addition to the reclassification of the disorder overthe years, differences in study designs have made it difficult toreplicate key findings. Despite these difficulties, a number of consis-tent findings have been documented. The core symptoms of hyperac-tivity–impulsivity tend to decrease over time, although inattentionmay persist. Additional difficulties resulting from secondary prob-lems often develop in later life. These difficulties include lowself-esteem, poor academic performance, and poor interpersonalskills. Antisocial behavior and substance abuse in late adolescenceand adulthood are important problems in some of these patients.The prognosis for these patients is influenced by the severity ofsymptoms, comorbidity, I.Q., family situation such as parental pathol-ogy, family adversity, socioeconomic status, and treatment. Treat-ment, particularly stimulant medication, can be helpful in the shortterm for these patients, but the long-term impact of treatment isunclear. r 1999 Wiley-Liss, Inc.MRDD Research Reviews 1999;5:243–250.

Key Words: attention deficit and hyperactivity disorder; long-termoutcome; predictors of outcome; risk factors

Early research since the 1960s has focused on AttentionDeficit and Hyperactivity Disorder (ADHD) primarily asa childhood disorder. More recently, there is an increased

interest [Barkley,1989; Biederman et al.,1996; Mannuzza andKlein, 1998; Satterfield and Schell,1997; Weiss and Hecht-man,1993] in the long-term outcome for these patients inadolescence and adulthood. Early child studies are evolving intolongitudinal studies.

The following article examines the progression of ADHDin adolescent and adult life, and the role of certain predictivefactors in determining outcome. The necessity of long-term

studies have been outlined by Verhust and Koot [1991].According to these authors, long-term study is needed todetermine the following.

1. Assess which problems in children persist and which donot.

2. Assess which early factors predict adult psychopathol-ogy.

3. Evaluate the necessity and efficacy of treatment andprevention.

4. Reveal causative mechanisms.5. Assess the validity of diagnostic constructs in terms of

outcome.

Most early studies evaluating outcome were retrospective.Presently, a number of prospective longitudinal studies [Barkley,1989; Biederman et al., 1996; Mannuzza and Klein 1998;Weissand Hechtman,1993;Satterfield and Schell,1997] have examinedthe progression of ADHD. This progression from child to adultsymptoms is gradually providing a better long-term picture.These studies [Barkley,1989; Mannuzza and Klein, 1998;Weissand Hechtman,1993; Satterfield and Schell,1997] indicate thatyoung Patients with ADHD have positive and negativeoutcomes, which are influenced by various factors. Prognosticfactors can be grouped into three categories: individualcharacteristics of subjects, family situation, and treatment.Certain factors are stronger predictors of outcome, anddifficulties in these areas can place the patient at higher risk ofnegative outcome. Identification and resolution of high-riskfactors present in the lives of young patients with ADHD areessential for improving long-term outcome. These predictivefactors, as well as the evolution of the clinical pictures in ADHD,will be discussed in detail in a later section.

METHODOLOGICAL ISSUESResearch in the field of ADHD is plagued by a number of

methodological difficulties. These include differences in studydesigns, for example, prospective versus retrospective; as well asthe nonstandard diagnosis applied to patients through the years.

*Correspondence to: Sara Ingram, Department of Child Psychiatry, HyperactivityProgram, Montreal Children’s Hospital, 4018 Ste. Catherine Street West, Westmount,Quebec H3Z 1P2, Canada.

MENTAL RETARDATION AND DEVELOPMENTAL DISABILITIESRESEARCH REVIEWS 5: 243–250 (1999)

r 1999 Wiley-Liss, Inc.

Studies tend to differ with respect todiagnostic criteria, subject characteristics,as well as assessment methods, andprospective versus retrospective design.The subject age and length of thefollow-up and the use of an appropriatecontrol also vary across studies [Hecht-man, 1992]. These marked methodologi-cal differences in study design contributeto the diverse outcomes pictures found inthe study of the long-term outcome ofADHD. The discontinuity of the disor-der’s professional label and diagnosticcriteria also account for many failures toreplicate key findings, because they donot allow for direct comparisons ofclinical samples.

There have been a number ofdiagnostic labels assigned to childrenexhibiting the hyperactivity, inattention,and impulsivity associated with what ispresently known as ADHD. Reports ofthis disorder have been appeared in theliterature since 1902. The labels appliedto this cluster of symptoms have changedto reflect the views of the time. In the1930s and 1940s, the concept of minimalbrain dysfunction (MBD) had strongetiological implications. This was a broaddiagnostic label, and included a largevariety of people who exhibited behav-ioral or learning difficulties but who didnot exhibit other neurological deficits.By 1957, Laufer and Denhoff termed thesyndrome ‘‘hyperkinetic impulse disor-der.’’ This was a shift from an etiological

viewpoint to one that described the coresymptoms of impulsivity and restlessness.This idea was elaborated by the 1980s inthe DSM-II, and was called the ‘‘hyperki-netic reaction of childhood’’. By theDSM-III, it had changed to ‘‘attentiondeficit with or without hyperactivity’’.This label had shifted back to ‘‘attentiondeficit and hyperactivity disorder’’ by theDSM-IV [American Psychiatric Associa-tion, 1994].

Levy et al.[1997] have suggestedthat ADHD cannot be considered acategorical disorder, but rather a constel-lation of overlapping symptoms. In theirtwin-study, they suggest that ADHDdoes not have discrete determinants, butvaries across the population. This findingmay provide a unifying explanation forthe various case definitions ADHD hashad over the years. However, method-ological problems, discussed above, stillneed to be resolved when examininglong-term outcome. Although researchhas produced a wealth of information,individual studies must be evaluated fortheir values and limitations. The varietyof treatment studies is summarized inTable 1.

NATURAL PROGRESSION OFTHE DISORDER: OUTCOMEPOSSIBILITIES

Early in ADHD research, it washypothesized that affected children wouldsimply outgrow ADHD. Research by

Weiss and Hechtman [1993] showed thatapproximately 25% of children withADHD were not significantly differentfrom normal controls by adolescence. Byadulthood, 30% could not be differenti-ated from the control group. The remain-ing population continued to manifestsymptoms into adulthood. Coping skillsand adaptive functioning may explainsome of the differences. The presence ofthese skills may have a protective influ-ence.

The clinical picture of ADHDvaries over time. Symptom patterns ofADHD tend to vary with age and acrossindividuals. Some core problems evidentin young Patients with ADHD, such ashyperactivity, generally improve by adult-hood, although many other symptoms ofthe disorder persist. The child diagnosis isderived from the DSM-IV criteria, butthese diagnostic criteria are not appropri-ate for adults for a number of reasons.First, the symptoms described reflectchild, not adult, behavior. Second, thenumber of symptoms required for diagno-sis in children may not be applicable toadults. Adults may exhibit fewer symp-toms, but still have the functional impair-ments of ADHD. Third, the DSM-IVrequires that the symptoms be presentbefore the age of 7 years and excludespatients who cannot accurately recallsuch symptoms at that age. These diagnos-tic difficulties contribute to a lack ofconsistency in adult ADHD diagnosis.

Table 1. Treatment Studies of ADHD

Study Design Study Title, Authors Key Findings

Prospective studies Barkley 1990 (8-year prospective follow-up–100 subjects, 60controls)

71.5% hyperactives met ADHD diagnosis at follow-up, 60%ODD, 40% CD

Biederman et al. 1996 (4-year follow-up study of boys 6–17years w/controls)

85% continued to have ADHD, 15% had remitted (1/2 child-hood, 1/2 adolescence)

Gittelman et al. 1995 (prospective follow-up, 16–23 years—101male subjects, 100 matched controls)

68% hyperactives continued to meet ADHD diagnosis in adoles-cence

Satterfield and Schell 1997. Controlled prospective (adoles-cence) (110 male subjects, 88 controls)

By adolescence, 50% of hyperactives had had a felony arrest

Weiss et al. 1971. Controlled prospective 5-year follow-up,10–18 years) (91 subjects with matched controls)

ADHD symptoms still present, hyperactivity diminished. Poorself-esteem and antisocial behavior (25%) elevated vs. controls

Weiss and Hechtman 1985. Controlled prospective 5, 10,15-year follow-up, 1st assessed at 6–12 years—103 subjects,matched controls)

Hyperactives fared worse than controls, by adulthood 23% anti-social personality disorder, 66% troubled by at least one coresymptom, more symptoms and psychiatric diagnosis

Retrospective studies Borland and Heckman 1976 (20 men, avg. 30 years, comparedto brothers)

Found subjects were employed, self-supporting, but more emo-tional and work problems than brothers

Feldman et al. 1975 (10–12 year retrospective follow-up, 48men avg. 21 years, previously diagnosed hyperactive, com-pared to siblings)

91% hyperactives working or in school. Lower educationalachievement, poor self-esteem, more drug use than siblings

Family studies Biederman et al. 1987 (1st-degree relatives of 22 ADHD sub-jects and 29 controls)

64% of ADHD subjects had ODD or CD. Relatives of thisgroup had more antisocial disorder, ODD, CD, overanxiousdisorder vs. controls

Morrison et al. 1971, 1980 (compared families of ADHDpatients to families with children w/other psychiatric illness)

Parents of hyperactives had significantly more antisocial person-ality disorder, and hysteria

Higher incidence of unipolar affective disorder in 2nd-degreerelatives of hyperactives

ODD, oppositional defiant disorder; CD, conduct disorder.

244 MRDD RESEARCH REVIEWS • OUTCOME ISSUES IN ADHD • INGRAM ET AL.

This article undertakes to provide theprogression of the clinical picture ofADHD and to identify the factors thatinfluence long-term outcome. The evo-lution of the disorder can be charted fromchildhood to adulthood.

CLINICAL PICTURE OFCHILDHOOD ADHD

ADHD has been described as aproblem in motivation and behavioralregulation [Barkley et al., 1990]. Earlyinattention and impulsivity lay the foun-dation for later difficulties, such as poorself-esteem, learning problems, and delin-quent behavior, which can make itdifficult for the ADHD patient to suc-ceed.

Children with ADHD often showoppositional or conduct problems(,50%), because of their impulsivity andinability to follow rules. Depending onseverity of symptoms, oppositional defi-ant disorder (ODD) or conduct disorders(CD) may be diagnosed [Ross andRoss,1982]. Whalen and Henker [1985]suggest there are several components tothe social behavioral problems of childrenwith ADHD. Inappropriate and sociallyawkward behavior has high negativesocial impact. Children with ADHD areoften intrusive in social interactions,which can result in rejection by otherchildren [Flicek, 1992; Pope et al., 1987].The tendency of these children to belouder and more forceful than their peersmay be perceived as verbal and physicalaggressiveness. These behavioral ele-ments create social difficulties duringinteractions. Given these considerations,the commonly resultant conduct prob-lems in children with ADHD are notunexpected.

Inattention, difficulty in finishingtasks, and disruptive classroom behaviorpresent in ADHD contribute to thechild’s academic difficulties. Childrenwith ADHD often do poorly in school[Barkley, 1989], although academic fail-ure is not attributed to intelligencedeficits, but underachievement becauseof behavioral or attentional difficulties[Cantwell,1986]. Learning disabilitiesclinically co-occur frequently (20%–50%)[Anastapoulos and Barkley,1992; Rob-ins,1992]. Problems evident in school arealso seen at home.

SUMMARYThe clinical picture of ADHD in

childhood is a combination of the exces-sive activity, poor sustained concentra-tion, disorganization, and poor socialskills associated with ADHD [Whalenand Henker, 1985]. These difficulties

significantly contribute to academic fail-ure and problematic interpersonal rela-tionships. The social and academic diffi-culties experienced by the child frequentlylead to poor self-esteem [Weiss et al.,1985]. These deficits in adaptive function-ing (relative to IQ) in socialization,communication, and daily life are prob-able contributors to the poor long-termprognosis [Stein et al., 1995].

CLINICAL PICTUREIN ADOLESCENCE

Despite reports of overall improve-ment in functioning by adolescence,ADHD generally perseveres. Social andacademic problems continue to affect thelife of the child [Faigel et al., 1995].Fischer and colleagues [1993] found that50% to 80% of patients with ADHDcontinued to display problems into adoles-cence. The later manifestation of ADHDis often a perseverance of earlier symp-toms, such as poor sustained attention,impulsivity and restlessness, and residualsecondary problems [Hechtman andWeiss, 1983]. Secondary problems in-clude the emergence of new comorbidi-ties, such as depression, conduct prob-lems, antisocial behavior, substance use,social problems, low self-esteem, andemotional problems [Fischer et al., 1993;Slomkowski et al., 1995]. Maladjustmentcan become more evident with age, andproblem behavior often leads to difficul-ties in school, with peers, and at home.Patients with ADHD usually appear moreimmature, with lower self-esteem thantheir peers.

Biederman and colleagues [1998]looked at a group of male patients withADHD (ages 6–17) to determine whetherthere are differences in the clinicalexpression and correlates of ADHD inchildhood and adolescence. They haveshown that there is a diagnostic continu-ity between child and adolescent ADHD.This recent finding supports the inclusionof adolescents in the research protocol forADHD and confirms that ADHD contin-ues into adolescence, although the particu-lar manifestations of the disorder changeslightly because of the developmentalstage.

By adolescence, response to stimu-lant treatment is still sufficient, althoughmany teenagers elect to discontinuemedication. With medication and appro-priate counseling, many adolescents withADHD can be treated and succeed atlevels comparable to that of their peers[Faigel, 1995].

The majority of patients withADHD, however, are at risk of a negativeoutcome, including pervasive full-symp-

tom patterns and antisocial behavior[Hinshaw, 1994]. In a recent study byBiederman et al.[1996], a group of malechildren with ADHD were evaluated at4-year follow-up. The patient outcomewas varied, as was expected, based on theliterature. Of Biederman’s follow-upgroup (6–17 years old), it was found that85% of the subjects still met the criteriafor ADHD at 4 years, whereas 15% hadremitted. This remission figure is lowerthan the percentage documented byHechtman and Weiss [1983]. To under-stand what differentiates this small groupof patients from the majority, furtherresearch into developmental pathways isrequired.

SUMMARYThe adolescent clinical picture is

characterized by the perseverance of theearly symptoms of inattention and impul-sivity. There is a small portion (,15%–20) of the patient population who nolonger meet the criteria for ADHD byadolescence. The remainder of the pa-tient population continues show ADHDsymptoms. Hyperactive behavior hasusually decreased by adolescence. Second-ary difficulties and comorbid disorders arepresent in the adolescent patient popula-tion. Many adolescents with ADHDcontinue to demonstrate academic diffi-culties and exhibit poor social skills andimmaturity. This often results in poorrelationships with peers, teachers, andfamily members. The prevalence ofantisocial behavior in adolescents withADHD is also high. These problems canincrease the risk of negative outcome.

CLINICAL PICTUREIN ADULTHOOD

ADHD often progresses into adult-hood. Research indicates that 50% to65% of adult patients with ADHD stilldemonstrate deficits, such as impairedsocial relationships, depression, low self-concept, antisocial behavior, drug use,and education and occupational disadvan-tages [Barkley, 1990a; Weiss and Hecht-man,1993]. The symptom patterns mayimprove over time, but the effects of earlydifficulties may continue to be problem-atic in the adult patient.

The recognition of ADHD symp-toms in adulthood has only recentlyevolved. By adulthood, many of thehyperactivity symptoms fade, makingADHD more difficult to identify inabsence of the symptoms visible inchildren in more structured situations. Toobtain the diagnosis of ADHD in adult-hood, there must be a pervasiveness ofsymptoms, and considerations to the

MRDD RESEARCH REVIEWS • OUTCOME ISSUES IN ADHD • INGRAM ET AL. 245

degree of impairment. According toresearch by Hechtman and Weiss [1983],the adult outcome of the patients withADHD may be grouped into threeclusters:

1. Those hyperactive young adultswhose functioning in manyspheres is fairly normal.

2. Those hyperactive young adultswho continue to have symp-toms of the syndrome andsignificantly more social, emo-tional, and impulsive problemsthan matched controls butwhose difficulties are not suffi-ciently severe to reflect markedpsychiatric or antisocial pathol-ogy.

3. Those hyperactive individualswho clearly constitute a signifi-cantly disturbed group requir-ing psychiatric hospitalizationand/or adult jails.

The distribution of the patients isnot equal across the three outcomepossibilities. The majority (50% to 60%)of patients continue to exhibit varioussymptoms as young adults, whereas only afew (10%) become grossly disturbed[Hechtman and Weiss, 1983]. Theseresearchers also found that patients withADHD are at a lower risk of antisocial orcriminal behavior by adulthood, despiteslightly elevated levels of these behaviorsduring adolescence. However, Bieder-man et al. [1995], in comparing clinicallyreferred adults with ADHD and adultswithout ADHD, found a significantlyhigher lifetime risk of substance usedisorder in these adults with ADHD(52% vs. 27%). He encouraged theexploration of risk and protective factors.Such factors were delineated by Gittel-man and colleagues [1995] and Mannuzzaet al. [1991], when they showed thatsubjects who continued to have ADHDsymptoms in adulthood and had comor-bid CD or antisocial disorders were at riskof substance abuse. Other research find-ings suggest that the risk of other ongoingdifficulties is not as significant as previ-ously thought. Gittelman et al. [1985]and Mannuzza et al. [1991] did not findany elevated risk of anxiety or mooddisorders in adult probands.

SUMMARYThe adult clinical picture diverges

into one of three outcomes. The portionof the patient population who has shownremittance of the disorder has increasedby adulthood. This group may continueto experience mild symptoms of thedisorder. The problems experienced by

the remaining population vary from mildfunctional difficulties to severe onesrequiring hospitalization and/or jails.Adult difficulties include inattention andimpulsivity, which can affect relation-ships and employment, and extend tocomorbidities. As was the case in adoles-cence, the hyperactive behavioral ele-ment has decreased significantly by adult-hood. These findings highlight the factthere is a varied picture of ADHD inadulthood.

PREDICTIVE FACTORSThe varied long-term outcome of

ADHD is related to certain risk factors.These may be grouped into three catego-ries: individual characteristics, which in-clude severity and type of symptomsexhibited, comorbidity, and IQ; familysituation; and treatment. Certain factorsserve as better predictors of outcome thando others. Significant impairment inadaptive functioning in patients withADHD increases the morbidity of thedisorder and has a poor prognosis [Steinet al., 1995]. Individual characteristicssuch as IQ, comorbidity, oppositionality,aggression [Johnson et al. 1994], emo-tional state, and peer relationships can actsingly or in combination to influenceadaptive functioning and outcome. Indi-vidual characteristics will be examinedseparately in the next section.

COMORBIDITYADHD occurring comorbidly with

conduct, mood, and anxiety disorders isusually associated with a negative progno-sis [Huesmann et al., 1984; Parker andAsher, 1987]. A number of studies haveevaluated risk factors associated withcomorbid disorders. At a 10-year follow-

up, Hechtman [1986] similarly found thatantisocial behavior in the child served asan important predictor of outcome.

Since many studies (Biederman etal., 1996; Satterfield and Schell, 1997;Weiss and Hechtman et al., 1993, Bark-ley et al., 1990) support previous findingsthat children with ADHD develop co-morbid disorders at significantly higherrates than do control subjects, thesecomorbidities need to be assessed.

Individual impairments in variousareas need to be investigated as they maybe early warning signs of later psychopa-thology.

A subgroup of patients may notmeet the full diagnostic criteria for aparticular comorbid condition, but stillhave symptoms of the comorbid condi-tion and have significant functional im-pairments. These impairments can beconsidered a type of comorbidity in itself,because they affect overall functioning inhome, school, and social environments.These patients often also require addi-tional interventions [Aman et al., 1996].

Many studies [Biederman etal.,1996; Satterfield and Schell, 1997;Weiss and Hechtman, 1993; Barkley etal., 1990] thus support previous findingsthat children with ADHD develop co-morbid disorders at significantly higherrates than do control subjects. Further-more, comorbid disorders significantlyaffect long-term outcome. Consequently,these comorbidities need to be assessed.Individual impairments in various areasneed to be investigated as they may beearly warning signs of later psychopathol-ogy.

COMORBID AFFECTIVE/MOODDISORDERS ANDANXIETY DISORDERS

Emergence of comorbid anxietyand mood disorders is generally seen assecondary to repeated social and aca-demic failures. The resultant low self-esteem and concomitant depression some-times seen in patients with ADHD istherefore not unexpected [Campbell etal., 1978]. Patients with ADHD are at riskof comorbid anxiety and affective/mooddisorders. Biederman and colleagues[1991] found the approximate rate ofcomorbidity with ADHD to be 25% withoveranxious disorder, separation anxiety,and phobic disorders. Comorbid anxietydisorders require special attention, be-cause they appear to have reducedresponsiveness to stimulant treatment[Pliszka, 1987].

The rates of comorbidity of affec-tive or mood disorders is a disputed topic.Although some studies have not found

The varied long-termoutcome of ADHD isrelated to certain riskfactors. These may be

grouped into threecategories: individualcharacteristics, which

includes severity and typeof symptoms exhibited,comorbidity, and IQ;family situation; and

treatment.

246 MRDD RESEARCH REVIEWS • OUTCOME ISSUES IN ADHD • INGRAM ET AL.

any affective disorders [Gittelman et al.,1995; Lahey et al., 1988], others assertthat the comorbidity does exist, and canbe as high as 30% [Biederman et al.,1991].

COMORBID CONDUCTDISORDER, OPPOSITIONALDEFIANT DISORDER, ANDANTISOCIAL BEHAVIOR

The risk of a poor long-termoutcome is increased when ADHDoccurs comorbidly with CD and ODD.Satterfield and Schell’s work [1997]focused on the adverse effects of comor-bid CD in adolescent patients withADHD. They documented a higherincidence of arrest in patients withADHD demonstrating antisocial behav-ior consistent with CD than in patientswith ADHD who did not have CD.They suggest that minor antisocial mani-festations, such as defiance and aggressive-ness, can be primary indicators of CD andeventual criminality, and should there-fore be monitored. Patients with ADHDwho do not demonstrate these types ofbehaviors also need to be assessed forserious antisocial behavior in later life[Satterfield and Schell, 1997].

Biederman and colleagues [1996]have also examined the prevalence of CDand ODD in patients with ADHD. At4-year follow-up, children diagnosedwith ADHD also showed higher preva-lence of ODD (65%) and CD (22%) thandid controls [Biederman et al., 1996].

COMORBID SUBSTANCE ABUSEDrug and alcohol abuse can be

seriously deleterious to the patient withADHD, and decrease the likelihood of apositive outcome. There is further con-cern that the inclination for drug andalcohol use results from the early stimu-lant medication treatment. Several studiesof patients with ADHD [Blouin et al.,1978; Satterfield and Schell, 1997] havefound increased use of intoxicating sub-stances in adolescence and adulthood.Beck and colleagues [1975] and Henkeret al. [1981] are not in agreement withthese conclusions, because they did notfind a higher incidence of drug use inhyperactive individuals. Controlled pro-spective long-term follow-up studies areneeded to provide a more accuratepicture of alcohol and substance abuse, asthey control for use in the generalpopulation at a particular point in time.

Prospective follow-up studies haveevaluated drug and alcohol use on acontinuum. Several studies [Borland andHeckman, 1976; Milman, 1979] havefound an increase in drug and alcohol use

in hyperactive individuals, but this usewas not significantly different from thecontrol groups. Gittelman’s [1985] pro-spective study, however, found that thehyperactive subjects showed a 12% in-creased prevalence of substance abusedisorder. There were indications that thesubstance abuse emerged concurrentlywith the conduct problems and continu-ing symptoms of the disorder.

Despite the contradictory studyresults, it appears that the majority ofhyperactive individuals do not use drugsor alcohol at significantly higher levelsthan controls by adulthood [Weiss andHechtman, 1993]. In adolescence, levelsof nonmedical drug use in hyperactiveteens may be slightly elevated, but this isnot apparent by adulthood. The differ-ences across studies may be accounted forby the possible existence of a smallsubgroup of hyperactive patients who userecreational drugs and alcohol exces-sively. If this subgroup is oversampled,negative outcome in adulthood could bemore apparent, as was found by Robins[1992] The presence of such a subgroup isof concern, because the prognosis of sucha group is quite negative. Such subgroupsmay be seen in newly referred adults withADHD seen by the Biederman group[1995].

IQ: MENTAL RETARDATIONPatients exhibiting mental retarda-

tion (MR) and ADHD tend to have apoorer prognosis than individuals exhibit-ing ADHD alone. Low IQ is associatedwith less adaptive functioning and in-creased impairment [Aman, 1996].

In a four-year follow-up of chil-dren with low intelligence and ADHDAman et al. [1993] found that significantbehavioral and emotional problems con-tinued into adolescence, as is common inADHD. Certain qualitative differences,such as elevated levels of psychotropicdrug use, and continued problems withADHD, CD, and separation anxietydisorder, may be present and more severewhen compared to children with ADHDand normal IQ [Aman et al., 1993].Stimulants have useful clinical effects inthese children as well.

Children with MR and ADHDoften have selective attention difficulties,such as being unable to refocus attentionaway from the most salient dimension[Pearson et al., 1996]. This study alsosuggests that girls with MR may be at ahigher risk of ADHD when compared toa non-MR population. This is an interest-ing finding, because ADHD is moreprevalent in boys in the general popula-tion [Pearson et al. 1996].

The cumulative data in this areaindicate that improvement is relative toIQ. IQ is one of the most importantpredictive factors in outcome. This iswhy children with ADHD and MR tendto have a poorer long-term outcome, butthose with less impairment have a similaroutcome to children with ADHD only.The diagnosis of comorbid MR must beconsidered on a continuum, with regardand relative to severity. The ADHDaspect of their behavior has been docu-mented to improve with traditionalADHD treatment. These cases requirespecial attention because of their high riskof poor outcome [Aman et al., 1993].

FAMILY ENVIRONMENTFamily environment and socioeco-

nomic status (SES) appear have an effecton the overall adjustment of the patientwith ADHD [Weiss and Hechtman,1993]. Minde and colleagues [1972]followed families of hyperactive childrenover time. They found that families ofchildren with positive outcome im-proved over time, whereas the families ofchildren exhibiting a more negativeoutcome deteriorated over time. Thereasons for this are unclear, but deteriora-tion appears to be a result of a negativevicious cycle.

Family problems or unstable situa-tions have been cited as potential aggrava-tors of the symptoms of ADHD. Familiesof many ADHD adolescents tend to bemore disharmonious than normal con-trols. In these families, there also appearsto be a greater risk of parental separationor divorce [Barkley et al., 1991].

Parental psychopathology tends tonegatively contribute significantly to theoutcome [Hechtman et al., 1984; Loneyet al., 1981]. Morrison [1980] found ahigh prevalence of sociopathy, hysteria,and alcoholism in the parents of childrenwith ADHD. The mental health of familymembers serves as a fairly good predictorof outcome. Other predictors of persis-tence are prevalence of ADHD in thefamily and psychosocial adversity [Bieder-man et al., 1996].

The stability of emotional andpsychological aspects of home life andSES can help distinguish between highand low functioning individuals [Hecht-man, 1991]. Milman [1979] showed atrend indicating that lower SES couldnegatively affect global outcome, but itdid not meet statistical significance. SESusually exerts its influence in conjunctionwith other factors and is less predictive byitself [Loney et al., 1981; Weiss et al.,1985; Satterfield and Schell, 1997].

MRDD RESEARCH REVIEWS • OUTCOME ISSUES IN ADHD • INGRAM ET AL. 247

TREATMENTTreatment studies provide immedi-

ate information on response to treatment,but limited information on the overalloutcome and maintenance of gains.There is evidence [Anastapoulos et al.,1996; Varley, 1983; Hinshaw et al., 1992;Douglas et al., 1988] that treatment canimprove the likelihood of a positiveoutcome and reduce the negative conse-quences of ADHD symptoms in the shortterm. Positive outcome is usually deter-mined by alleviation of the symptoms,and overall adaptive functioning. Presenttreatments [Hechtman et al., 1984; forreview see Barkley, 1990] have notshown long-term effects. The treatmentrationale is that by improving functioningearly in life, and addressing presentproblems, the patient will develop fewerprimary and secondary difficulties later inlife.

PHARMACOLOGICALTREATMENT

The bulk of the research focuses onthe nature and outcome of pharmacologi-cal treatment of the disorder. Standardstimulant treatments for ADHD includeRitalin or Dexedrine. Stimulant therapyis effective in the short term, buttreatment by a single modality has beendocumented to have very little impact inthe long term [Hechtman et al., 1984;Paternite and Loney, 1980;Weiss andHechtman, 1993].

Stimulants improve behavior andADHD symptoms [Varley, 1983; Hin-shaw et al., 1992; Douglas et al., 1988],but residual benefits may subside whenthe medication is discontinued [Ross andRoss, 1982]. Gains in social skills andself-esteem may persist when medicationis discontinued, but attentional difficultiesreturn [Hechtman et al., 1981]. In theacademic realm, there is much contro-versy regarding the effects of stimulantmedication and the maintenance of gains.Research [Hechtman et al., 1984] hasshown that there is little real improve-ment on academic achievement measureswhen comparing a medicated group anda nonmedicated group at 5-year fol-low-up without medication. However,the overall adjustment of the childrenwho received the medication appears tobe better.

The treatment results of patientswith ADHD and MR are not consistentwith the treatment results of patients withADHD only [Handen et al., 1994].However, within the MR group, chil-dren with higher IQs, i.e., closer to therange of children with ADHD only, tendto respond better than those with lower

IQs (less than 45) [Aman et al., 1993].Children with ADHD and MR mayrequire supplemental programming, suchas behavioral interventions, to trulybenefit from stimulant medication[Handen et al., 1996].

The adult response to treatment ispresently being studied. In severe cases,stimulants are used to ameliorate symp-toms [Wilens, 1995]. Adults appear torespond well to stimulant treatment. Theadult pharmacotherapy parallels the treat-ments used with children. Stimulantsreduce the ‘‘core’’ symptoms of ADHDin adults, such as restlessness, irritability,inability to concentrate, and impulsive-ness.

To date, few studies that havelooked at the long-term impact oftreatment on outcome. Loney et al.[1981] followed patients who receivedstimulant medication as children. Weissand Hechtman [1993] followed hyperac-tive adults who received long-term stimu-lant treatment. They found no differencebetween the hyperactive group whoreceived medication and the hyperactivegroup who did not, although the hyperac-tive group fared significantly worse thannormal controls. This implies that stimu-lant treatment does not affect hyperactivepatients in the long term.

The discontinuity between theshort-term gains of stimulant treatmentand long-term overall improvement isevident in the research. The long-termefficacy of pharmacological interventionsrequires further research. To date, there isno evidence that stimulants alter thecourse of ADHD or improve long-termoutcome. The discontinuation of stimu-lant medication and other treatments mayaccount for the absence of long-termbenefits. Ongoing treatment may berequired to affect long-term outcome.

PSYCHOSOCIAL TREATMENTAlthough stimulant therapy is the

most prevalent treatment in the clinicalmanagement of ADHD [for systematic

review see Barkley, 1990; Gadow, 1992],psychosocial treatment is also used. Psy-chosocial treatments can provide bothparents and children a feeling of greatercontrol over behavior. These interven-tions can help to alleviate and managestressors that are present, improve behav-ior, and affect outcome [Anastapoulos etal., 1996].

Psychosocial options include par-ent training, problem-solving communi-cation training, and structural familytherapy [Anastapoulos et al., 1996]. Paren-tal behavioral management training pro-grams have been developed, but familialdifficulties can limit the success of theseprograms because of inconsistent applica-tion [Dangel and Polster, 1984]. Parentaltraining techniques improve overall homefunctioning when the difficulties arerelated to the consequences of ADHD.

These psychosocial treatment stud-ies [Anastapoulos et al., 1996] showfavorable outcome at the end of thestudy, and at 3-month follow-up. Theshort-term benefits in the area of psycho-social functioning are significantly visibleafter treatment. However, long-termeffects are not seen when this interven-tion is administered singly [Hinshaw,1994].

MULTIMODAL TREATMENTRecent advances in the treatment

of ADHD combine several treatmentapproaches, known as multimodal treat-ment. Medication, parental training, so-cial skills, study skills training, andremediation are all part of the treatmentprogram. The first project completed in1996 by Abikoff, Hechtman, and col-leagues compared a multimodal treat-ment group to a baseline medicationgroup and an attention control group,also receiving medication. At the end ofthe 2-year treatment period, there was nosignificant difference between the threegroups [Abikoff and Hechtman, 1996].This result suggests that multimodaltreatment is not a significant improve-ment over methylphenidate alone. Afollow-up is currently under way toinvestigate whether any differences willbecome apparent between the groups atfollow-up. This is necessary to determineoutcome on a longer-term basis.

Cooperation across researchers willhopefully lead to more integrated andinformative results. Treatment can be animportant factor in determining ADHDoutcome. It is hoped that with furtherresearch, these treatment programs willcontinue to explore and increase the oddsof a positive long-term outcome for

Identification andresolution of high-riskfactors present in youngPatients with ADHD’

lives is essential forimproving long-term

outcome.

248 MRDD RESEARCH REVIEWS • OUTCOME ISSUES IN ADHD • INGRAM ET AL.

patients with ADHD in adolescence andadulthood.

CONCLUSIONA number of the studies discussed

[Barkley et al., 1991; Biederman et al.,1998; Hechtman, 1992; Mannuzza et al.,1991; Satterfield and Schell, 1997] havetracked patients with ADHD longitudi-nally. These studies have charted thenatural progression of this disorder, ascer-taining its continued presence in adoles-cence and adulthood, and have identifiedstable predictors of outcome.

There are a number of method-ological problems in ADHD research.These include:

1. Nonstandard diagnosis appliedto patients over time.

2. Studies differing with respect todiagnostic criteria, subject char-acteristics, and assessment meth-ods.

3. The age and length of thefollow-up.

4. The use of an appropriate con-trol, which also varies acrossstudies.

The marked methodological differ-ences across studies contribute to thediverse outcome pictures found in thelong-term study of ADHD.

Results of long-term follow-upstudies showed that in adolescence, mostpatients continue to show symptoms ofthe disorder and continue to meet thediagnostic criteria for ADHD (70%–80%). In adulthood, many patients con-tinue to be symptomatic (60%), but fewermeet the diagnostic criteria for ADHD.

Although some core symptoms ofthe disorder tend to decrease over time[Faigel, 1995], additional difficulties fromsecondary problems develop in later life[Hechtman and Weiss, 1983]. Thesedifficulties include low self-esteem, pooracademic performance, and poor interper-sonal skills. Antisocial behavior and sub-stance abuse in late adolescence andadulthood are important problems insome of these patients [Weiss and Hecht-man, 1993]. The prognosis for thesepatients is influenced by the severity ofsymptoms, comorbidity, IQ, family situa-tion, parental pathology, family adversity,SES, and treatment.

Treatment, particularly stimulantmedication, can be helpful in the shortterm for these patients [Varley, 1983;Hinshaw et al., 1992; Douglas et al.,1988], but the long-term impact oftreatment is unclear. The continuation oftreatment may be crucial in influencingpositive outcome. Research in ADHD

continues to evolve. New findings willhopefully continue to improve bothquality of life for the patient and thefamily, and long-term outcome.j

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