Antisocial Behavior: More Enduring than Changeable? ROLF LOEBER , PH.D .
Abstract. This paper challenges the notion that many children outgrow early con du~ t p roblem ~ . It explores factors that may have led to resea rchers' underestimating the stability of antisocial behav l ~~s, especially because these behaviors manifest themselves differently in various phases of the life course . In additio n, data suggest that the malleability of child behaviors decreases as children grow older, contributing to a higher continui.ty of a n t~socia l behavior possibly from early adolescenc e onward . Implications are discussed for the study and lnterve~tlon of antisocial behavior. J . Am . Acad . Child Adolesc. Psychiatry. 1991 , 30, 3:393-397. Key Words: conduct disorder , antisocial behavior, development.
Researchers who study antisocial behavior in juv eniles have disagreed about how stable antisocial behavior is over time , and whether or not most youngsters outgrow the behavior (Mischel, 1977, 1978; Olweus, 1979; Patterson, 1982; Robins, 1966). Some studies, using official records , have shown that 50% to 70% of juvenile offenders are arrested again in adulthood (e.g ., McCord, 1979; Osborn and West, 1978; Polk , 1975). Depending upon one's perspecti ve , this proportion mayor may not seem substantial. Eight years ago , Loeber (1982) reported on the continu ity of antisocial behavior; in the interim , there have been several new findings and insights that make it desirabl e to reassess the stability of antisocial behavior. A first concern is whether there are factors that have lowered researchers' estimates of stability in past studies . Second , it often is not recognized that antisocial behavior seems to develop is an orderly manner with different manifestation s succeeding each other over time. Third , given that youngsters differ in the persistence of their symptoms of disruptive/antisocial behavior , it is important to ask which markers differentiate those who are likely to persist from those who are likely to desist. Fourth, antisocial and moral developm ent appear to have a much higher malleability early in life. And last, causal factors affecting stability appear to differ among antisoci al individuals. This paper addresses these issues from a developmental point of view and makes use of several longitud inal studies; although few of these studies have used psychiatric diagnoses of disruptive behavior disorders , they all shed light on the course of this form of psychop athology from childhood onward.
Accepted November 8. i 990 . Dr. Loeber is with th e W estern Psychiat ric Institute an d Clinic .
University of Pittsburgh School of Medicine. Pittsburgh. PA . The author is gratef ul to Carol Baicker-Mckee. Kate Keenan. and Celia Nourse Eatman fo r their comments on an earlier draft of the paper. This paper was written with fin ancial support fro m Grant No . 86-JN-CX-0009 f rom the Office of Juvenile Justice and Delinquency Prevention. Office of Justice Programs, U.S. Department of Justice, and Grant No. MH42529 fr om the National in stitute of Mental Health . Points of view or opinions in this document are those of the author and do not necessarily represent the offi cial position or policies of the U.S . Department of Justice. 0890-8567/91/3003 -0393$03 .OO/O© 1991 by the American Academy of Child and Adolescent Psychiatry . J.Am.A cad . Child Adolesc . Psychiatry , 30 :3, May 1991
Underestimates in Past Research Past research has underestimated the continuity of disruptive/antisocial behavior for the following reasons . First , the manifestation s of these behaviors are highly changeable; therefore , research that has focused on one mode of beha vior, such as aggression (Olweus, 1979) , necess arily. excluded other related manifestations of antisocial beha viors , such as theft . A narrow defin ition of antisocial beha vior tends to artificially reduce cor rect predictions; this can be detected only when a wider array of antisocial outcomes is taken into account. Second, outcome variables often have relied on official records , such as court or arrest records of offenders or on outpatient or hospital records . These records often are far from complete and , in the case of official records of del inquency, are merely a dim reflection of the actual delinquent involvement, as is evident from self-reports. Third, findings on false-positi ve error s in prediction (individuals with early problem behavior who do not become delinquent later) often are interpreted as desistance in antisocial acts. Althou gh this may be true for some individuals, research findings increasingly indicate that disruptive/antisocial behavior often is of an episodic rather than constant nature in some individuals. Thus, studies in which meas urements are taken within a rather narrow time window (such as a year) may conclude that desistance has taken place for a group of formerly antisocial individuals; whereas, the behavior simply may not be apparent for some time , because of a lack of opportunities, incentives, or other factors, and then may reemerge subsequently . Baicker-McKee (1989, unpublished manuscript), for example, reanalyzed the longitudinal data from a community sample of boys from the Cambridge Study in Delinquent Development (West and Farrington, 1973, 1977). The 4 10 boys in this London -based sample were initially studied when they were 8 years old. Baicker-McKee (1989 , unpublished manuscript) found that only 47 .8% of those with an antisocial career by age 18 scored consistently high on measurements with 2-year intervals from age 8 to 18; many other individuals showed a longitudina l pattern of behavior with pauses and relapses. Similarly , Barnett et al. (1989), in an extended follow -up of the same sample, identified a group of juvenile offenders who had no convictions for a period of 7 to 10 years but were subsequently reconvicted in their late twenties .
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Fourth, the intermittent, and at the same time continuous, nature of disruptive/antisocial behavior may be explained in terms of underlying propensities and skills acquisition. Loeber and Le Blanc (1990) have posed that once individuals have learned antisocial skills (such as decreasing the detection of theft, conning schemes, or safe cracking), such skills tend to remain in their repertoire for a long time and may reemerge under the right circumstances of need and opportunity . Finally, conclusions about continuity often have been based on correlational evidence (e.g., Olweus, 1979). There are at least two important caveats, however. In studies on antisocial behavior, the frequency of a predictor (called the selection ratio) often is much higher than the frequency of the outcome (called the base rate). It is not often recognized that in a two-by-two prediction table, where there is a difference in the selection ratio and the base rate, only a proportion of all subjects can be accurately predicted (Loeber and Dishion, 1983). For that reason, observed correlation coefficients in prediction studies, such as phi, often have an upper limit that is not equal to one (phi is comparable to a product-moment correlation coefficient but, unlike the latter, applies to two-by-two tables). Consequently, a reported phi may represent an underestimate and, for that reason, must be corrected to reflect its ceiling (Farrington and Loeber, 1989). In addition, authors have argued that, for example, a correlation of 0.29 accounts for less than 9% of the variance in the outcome variable and is, therefore, of little significance. In a two-by-two prediction table, however , a phi of 0.29 can mean that 37 .5% of the predicted delinquents actually become delinquent, in contrast to only 12.5% of those predicted to be nondelinquent (Farrington and Loeber, 1989). Interpreted in this manner, prediction results are comparable with those found in many areas of medicine and certainly have clinical and practical utility .
An Orderly Change of Manifestations? Manifestations of disruptive/antisocial behavior in childhood and adolescence may appear unpredictable to the adults confronted with them. Youngsters may startle their parents by displaying a succession of seemingly unrelated behaviors-fire setting, theft , vandalism , assault, to mention only a few. It may be difficult for adults to see a pattern in such behaviors. Cross-sectional and longitudinal studies, however, increasingly are clarifying developmental patterns in the manifestations of disruptive/antisocial behavior as they occur over time, although some details remain to be uncovered. One major finding is that, as a rule, less and more serious problem behaviors do not occur randomly but tend to take place in an orderly fashion. Overall, less serious problem behavior tends to precede more serious problem behaviors; less serious behaviors , therefore, appear as a necessary step toward more serious acts (Loeber, 1990; Patterson, 1982). This seems to hold for the development of problem behaviors from the preschool to the elementary school age period as well as for delinquent behaviors that tend to emerge in late childhood and early adolescence. For example, LeBlanc and Frechette (1989) followed up a sample of adolescent 394
delinquents in the province of Quebec. Based on the youngsters' recall of the age of first criminal activities, the authors documented an orderly sequence from less to more serious types of delinquent acts. The understanding, however, is that few youngsters progress to the most serious acts (rape, homicide), that other youngsters stop at intermediate levels, and that some of these subsequently desist. Desistance, however, is inversely related to the degree of progression (Loeber, 1988). Another major finding concerns changes in the nature of the problem behavior . Studies show that the prevalence of confrontive or overt problem behavior tends to decrease from the preschool period; whereas, most concealing or covert behaviors tend to increase from the elementary school age period into adolescence (Loeber, 1982). Thus, it is likely that a shift takes place from overt to covert problem behaviors before adolescence. This may imply that some formerly aggressive youngsters change the pattern of their problem behavior to include lying and theft . Loeber et aI., (1989), in a follow-up of a group of highly disruptive boys from kindergarten onward, found that 75% of the stable fighters (i.e., over a period of 4 years) developed covert behaviors as well, compared with only 8% of those boys who stopped fighting in the interim . In addition, some youngsters, who are not aggressive or otherwise seriously problematic earlier in life, develop concealing acts later (Loeber, 1988; Loeber and Schmaling, 1985). Some tentative advances are being made in formulating different pathways to antisocial outcomes, rather than continuing to assume that there is only a single pathway (Loeber, 1988). Disruptive/antisocial behavior tends to be activated in the period from preschool to midadolescence. Onset after that age is very uncommon (Baicker-Mcls.ee, 1989, unpublished manuscript; Robins, 1966). Among those youngsters who develop symptoms before midadolescence are those who initiate problem behavior very early in life . Children in this group often display hyperactive and inattentive symptoms as well and are less likely to outgrow these conduct problems than children with a later onset. They appear to be especially at risk for an antisocial career characterized by high rate, "versatile" forms of offending (property, violent, and other offenses), often accompanied by substance abuse . The desistance rate appears relatively low in this group. Loeber (1988) called this the aggressive/ versatile path and contrasted it with the nonaggressive path . Youngsters in the latter category begin relatively late, are more likely to be females than those in the aggressive/ versatile path, and display primarily concealing, nonaggressive forms of conduct problems including delinquency, with or without substance use. Compared with the aggressive/versatile path, however, the desistance rate is higher in the nonaggressive path . The formulation of the different pathways, although based on various empirical studies, awaits further refinement and confirmation.
Markers There are several known markers that predict continuity of behavior: frequency, multiple settings, variety, early onset, and hyperactivity (Loeber, 1982). First, youngsters who l.Am.Acad .Child Adolesc. Psychiatry, 30:3, May 1991
LONGITUDINAL RESEARCH: ANTISOCIAL BEHAVIOR
display high rates of problem behavior early in life are more at risk for later antisocial behavior than those who display low-rate problem behavior. This certainly applies to symptoms of conduct disorder but may also apply to symptoms of oppositional defiant disorder as early as the preschool period in the case of extremely high frequency and intensity of oppositional behaviors . Second, children displaying problem behavior in more than one setting are thought to be more likely to continue displaying the problem behavior than children whose problem behavior is confined to one setting only. (It should be noted, however, that this conclusion may be affected by informant effects [Costello and Loeber, in press]). Third, a high variety of problem behavior (e.g., theft and aggression) is associated with a higher risk for continuity than a low variety (e.g ., theft only) . Fourth, children who experience a precocious onset of conduct problems are at a much higher risk for later antisocial behavior than those who begin displaying conduct problems at a more normative age. Lastly, youngsters who are also hyperactive and have attention deficits are much more at risk to develop serious and lasting antisocial behavior than those without these early symptoms (e.g., Farrington et al., 1990; Gittelman et al., 1985; Glueck and Glueck , 1966; Weiss and Hechtman, 1986). These seemingly disparate findings on markers can be integrated as follows: age at onset , variety, frequency, and seriousness are highly correlated, at least in the domain of delinquency (Le Blanc and Frechette, 1989). Moreover, the presence of hyperactivity often is associated with early onset of disruptive behavior (Offord et al., 1979), while the development of disruptive/antisocial behaviors takes place primarily through accretion rather than succession of different behaviors over time. Thus, this deviancy process is characterized by a diversification of the problem behaviors as youngsters grow older (Loeber, 1990), with more serious behaviors following less serious ones in an additive fashion . This may explain why early variety is an important marker. In addition, the likelihood that youngsters will begin displaying a new problem behavior is related to the frequency of existing problem behaviors (Loeber , 1988); this underscores the importance of frequency as a marker. Decreasing Malleability Reference was made earlier to the relationship between children's advancement to serious acts and the reduced likelihood of their desistance. This relationship is confounded by the fact that serious acts are usually displayed by older youngsters . The question can be raised, therefore, whether disruptive/antisocial behavior, like other personality characteristics, tends to stabilize as youngsters grow older. For example , findings in the area of moral development and the development of intelligence indicate that test-retest coefficients become higher after the latency period (Bloom, 1964; Colby et al., Lieberman , 1983; Kohlberg et al., 1984). In addition, cross-sectional and longitudinal studies on aggression indicate that stability coefficients tend to increase with age, particularly from early adolescence onward (Loeber, 1982; Olweus, 1979). Recently, Baicker-McKee (1989 , unpublished manul.Am .Acad. Child Adolesc . Psychiatry, 30 :3, May 1991
script), in her reanalysis of the Cambridge study, adopted a comprehensive definition of different manifestations of disruptive/antisocial behavior at different ages. Once again, she found that the stability coefficients steadily increased in magnitude between the ages of 8 and 16. In summary, there is evidence that disruptive/antisocial behaviors' 'crystallize" and become more stable as children become older. This implies that malleability decreases with age, which may explain why it is difficult to turn around antisocial teenagers with a long and extensive history of problem behavior. Multiple Causality Space allows only a sketching of some important causal patterns . Certain logical conclusions may be drawn from the preceding about the causality of disruptive/antisocial behavior. First, it seems highly likely that for those youngsters with an onset of disruptive behavior in the preschool years, the causes of the onset of the disorder must lie either in that early period or in genetic factors. In contrast, for those whose onset is later, the causal factors associated with onset must necessarily lie in that later period (this does not exclude the possibility that genetic factors are activated later in life). Second, given that the onset of patterns of physical aggression is unusual in adolescence; the origins of aggression must also be sought primarily in the preadolescent period. Third, it likewise is highly unusual for hyperactivity and attention deficits, often associated with oppositional defiant disorder and conduct disorder, to appear after the age of 9 or 10. Again , their causes must be situated in childhood or in genetic factors. Parents and children's peers have been mentioned frequently as important social influences for the acquisition of antisocial behaviors (e.g . , Elliott et aI., 1985). The majority of the studies concern family influences. Loeber and Stouthamer-Loeber's (1986) metanalysis of cross-sectional and longitudinal studies showed the high degree of agreement among studies that certain parent-ehild interactions (such as chronic conflict and neglect) appear associated with disruptive child behavior at different ages. It has also been shown that disruptions in child-earetaker continuity during the preschool period, rather than later , are associated with disruptive child behavior; this suggests that another form of vulnerability operates at that time. Again, potential social causes can be seen in a developmental perspective where familial influences occur first, and peer influences become apparent later but continue to operate side by side for a number of years. A common element between the two spheres of influence is that some forms of social interaction facilitate youngsters' learning of antisocial behavior. Even when narrowed down to certain age ranges , it is easy to oversimplify the causes of disruptive/antisocial behavior. There is a consensus among many scholars that a single cause perspective is naive; instead, it is likely that there are multiple causes including both biological and social components (e.g., Jenkins et aI., 1985; Rutter and Giller, 1983). The biological components do not necessarily refer only to genetic effects but may include neurotoxins (such as lead) that decrease intelligence, attention capabilities, and
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increase overactivity in youngsters (Needleman and Bellinger, 1981). It is likely that a child 's central nervous system is particularly vulnerable to neurotoxins during the first years of life; this is consistent with the findings on early onset. Investigative Methods
The preceding comments implied that cross-sectional research only sheds limited light on changes in antisocial behavior as they occur over time. Instead , longitudinal studies are especially likely to produce new insights about orderly sequences in the changing behaviors. Longitudinal data are also more likely to identify shifts in the causes of antisocial behavior as youngsters grow older (Farrington et aI., 1986). What types of longitudinal studies will be most useful? First, prospective rather than retrospective studies are needed, because it cannot be assumed that causal processes and changing manifestations can be adequately recalled by informants over long periods of time . Also, in prospective studies one might adjust the frequency of assessments to reflect the speed of change in developmental processes. Widely spaced assessments are likely to miss crucial periods of change. Third , given that the most deviant individuals are often the most unreliable informants, it is necessary to include other informants, such as parents, peers, teachers, or, in the case of older target individuals, their significant others. Fourth, given that the prevalence of individuals displaying serious antisocial behavior is relatively low, it may be advisable to do a screening procedure at the beginning of a study in order to enhance the base rate of individuals at high risk for antisocial careers. Fifth, many of the most deviant individuals, when followed up, often lead a highly irregular life; they may move often and sometimes are on the run from credit agencies or justice officials. Therefore,
in order to enhance participation, it is extremely important that prospective studies have an efficient tracking system, and that contact procedures with the target subjects are tailored to their needs and characteristics (Stouthamer-Loeber et aI., in press). Conclusion
This sketch on the stability of disruptive/antisocial behavior has made several important points . The behavior is particularly virulent; once in full bloom, it is difficult to eliminate through currently available intervention techniques. In that sense, disruptive behavior disorder is very enduring; it is also changeable, however, especially in the first 12 or so years of life. Many of the initial causes of the disorder operate during childhood when children's behavior tends to be most malleable. It is toward that developmental period that we need to shift resources if we are truly serious about combating this epidemic disorder in which youngsters victimize others and , generally, fail to live fulfilling lives. The challenge is to create intervention programs that can truly interrupt the deviancy processes spoken of before. Several approaches operating in tandem may be required. On the one hand, interventions should be aimed at reducing behaviors that appear to be keystones for further deviant behavior, such as physical aggression, hyperactivity , and
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behaviors reflecting attention deficits . However, the elimination or reduction of these behaviors will probably not be sufficient by themselves . Almost invariably, the development of antisocial behavior is accompanied by emerging social and academic deficits. Creating options for success in these areas of vulnerability very well may be a necessary prerequisite for more normative development. Also, youngsters ' attachment to deviant peer groups is much more likely in households and schools characterized by neglect or repressive interactions with adults . Adults' investment in time and frequent, positive interactions with these youngsters are most likely the breeding ground for more prosocia! developments.
References Barnett, A., Blumstein, A. & Farrington, D. P. (1989), A prospective test of a criminal career model. Criminology , 27:373-388 . Bloom , B. S. (1964), Stability and Change in Human Characteristics . London: Wiley . Colby , A. , Kohlberg, L., Gibbs, J. & Lieberman, M. (1983), A longitudinal study of moral judgement. Mongr . Soc . Res . Child Dev.• 4:1-2 . Costello, J. & Loeber, R. (in press), Pervasive and situational hyperactivity-confounding effect of informant. J. Child Psychol. Psychiatry. Elliott, D . S., Huizinga, D. & Ageton, S. S. (1985), Explaining Delinquency and Drug Use. Beverly Hills : Sage Publications. Farrington, D. P. & Loeber , R. (1989), RIOC & Phi as measures of predictive efficiency and strength of association in 2 X 2 tables. Journal of Quantitative Criminology, 5:201-213. ----Van Kammen , W . B. (1990), Long term criminal outcomes of hyperactivity-impulsivity-attention deficit and conduct problems in childhood. In: Straight and Devious Pathways to Adulthood, eds . L. N. Robins & M. R. Rutter. New York: Cambridge University Press , pp . 62-81. - - Ohlin . L. E. & Wilson, J. Q. (1986) , Understanding and Controlling Crime : Toward a New Research Strategy. New York : Springer-Verlag. Gittelman, R., Mannuzza, S., Shenker, R. & Bonagura, N. (1985), Hyperactive boys almost grown up. Arch. Gen. Psychiatry, 42:937947. Glueck, E. T. & Glueck , S. (1966), Identification of potential delinquents at 2-3 years of age . Int. J. Soc. Psychiatry. 12:5-16 . Jenkins, R. L., Heidemann, P. H. & Caputo, J . A. (1985), No Single Cause: Juvenile Delinquency and the Search for Effective Treatment. College Park, MD: American Correctional Association . Kohlberg , L., Ricks, D. & Snarey , J. (1984) , Childhood development as a predictor of adaptation in adulthood . Genetic Psychology Monographs. 110:91-172. Le Blanc, M. & Frechette, M . (1989), Male Offending from Latency to Adulthood. New York : Springer-Verl ag . Loeber , R. (1982) , The stability of antisocial and delinquent child behavior: a review . Child Dev .• 53:1431-1446. - - (1988), The natural histories of juvenile conduct problems, substance use and delinquency: evidence for developmental progressions . In: Advances in Clinical Child Psychology. Vol. II, eds. B. Lahey , & A. E. Kazdin. New York: Plenum, pp. 73-124. - - (1990), Development and risk factors of juvenile antisocial behavior and delinquency. Clinical Psychology Review, 10:1-41. - - Dishion, T . J. (1983) , Early predictors of male delinquency: a review . Psychol. Bull .• 94:68-99 . - - Schmaling, K. B. (1985) , The utility of differentiating between mixed and pure forms of antisocial child behavior. J. Abnorm. Child Psychol ., 13:315-336 . - - Stoutharner-Loeb er, M. (1986), Family factors as correlates and predictors of juvenile conduct problems and delinquency. In: Crime and Justice: An Annual Review of Research, Vol. 7, eds . N. Morris
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LO NG ITUDINAL RESEARCH : ANT ISOC IAL BEHAVIOR
& M. Ton ry. Chicago: University of Chicago Press, pp. 29- 149. - Le Blanc , M. ( 1990), Toward a developm enta l crim inology. In: Crime and Ju stice , eds. M. Tonry & N. Morris . Chicago: Universi ty of Chicago Press , pp . 375-473 . - - Trembl ay, R. E ., Gagnon , C. & Charlebois, P. (1989), Continuity and desistance in disrupti ve boys' early fighting in school. Developm ent and Psychopathology , 1:39-50 . McCord , 1. (1979), Some child-rearing antecedents of criminal behavior in adult men . J . Pers . Soc . Psychol ., 9:1477-1486. Mischel , W . (1977), The interact ion of person and situation. In: Personality at the Crossroads: Current Issues ill Interactional Psychology, eds . D. Magnusson & N. S. Endler. Hillsdale , NJ: Lawrence Erlbaum, pp. 333-352. - - (1978), On the interface of cog nition and personal ity. Am. Psy chol., 34:740-754 . Needleman, H. L. & Bellinger, D . C. (198 1), The epidem iology of low-level lead exposure in childhood. J . Child Psychiatry , 20 :496512. Offord, D. R., Sullivan, K., Allen, N. & Abrams, N. (1979), Delinquency and hyperactivity . J. Nerv. M ent. Dis., 167:734-741. Olweus , D. (1979), Stabi lity of aggress ive reaction patterns in males: -
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a review. Psychol. Bull., 86:852-857. Osborn, S . G. & West , D. J . (1978), The effec tiveness of various predicto rs of criminal careers . J . Adolesc ., 1:101-117 . Patterson , G. R. (1982), Coercive Family Interactions , Eugene, OR: Castalia Press. Polk, K. (1975) , Schools and the delin quency experience . Crimina l Justice & Behavior , 2:3 15-338 . Robins , L. N. (1966), Deviant Children Grow Up: A Sociolog ical and Psychiatric Study of Sociopathic Personality. Baltimore: Williams & Wilkins. Rutter, M . & Giller, H. (198 3), Juvenile Delin quency : Tre nds and Perspectives , Harmondsworth , U.K. : Penguin. Stouthamer-Loeber , M. , Van Kamm en , W. B. & Loeber, R. (in press), The Nuts and Bolts of Impleme nting Large Sc ale Longitud inal Studies. Yio lence and Victims . Weiss , G. & Hechtman , L. T . (1986), Hyperactive Children Grow Up. New York: Guilford Press. West, D. J. & Farrington , D. P. (1973), Who Becomes D elinquent? London: Heinemann. - - -- (1977), The Delinquent Way of Life . London: Heine mann.
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Abstract. This paper challenges the notion that many children outgrow early con du~ t p roblem ~ . It explores factors that may have led to resea rchers' underestimating the stability of antisocial behav l ~~s, especially because these behaviors manifest themselves differently in various phases of the life course . In additio n, data suggest that the malleability of child behaviors decreases as children grow older, contributing to a higher continui.ty of a n t~socia l behavior possibly from early adolescenc e onward . Implications are discussed for the study and lnterve~tlon of antisocial behavior. J . Am . Acad . Child Adolesc. Psychiatry. 1991 , 30, 3:393-397. Key Words: conduct disorder , antisocial behavior, development.
Researchers who study antisocial behavior in juv eniles have disagreed about how stable antisocial behavior is over time , and whether or not most youngsters outgrow the behavior (Mischel, 1977, 1978; Olweus, 1979; Patterson, 1982; Robins, 1966). Some studies, using official records , have shown that 50% to 70% of juvenile offenders are arrested again in adulthood (e.g ., McCord, 1979; Osborn and West, 1978; Polk , 1975). Depending upon one's perspecti ve , this proportion mayor may not seem substantial. Eight years ago , Loeber (1982) reported on the continu ity of antisocial behavior; in the interim , there have been several new findings and insights that make it desirabl e to reassess the stability of antisocial behavior. A first concern is whether there are factors that have lowered researchers' estimates of stability in past studies . Second , it often is not recognized that antisocial behavior seems to develop is an orderly manner with different manifestation s succeeding each other over time. Third , given that youngsters differ in the persistence of their symptoms of disruptive/antisocial behavior , it is important to ask which markers differentiate those who are likely to persist from those who are likely to desist. Fourth, antisocial and moral developm ent appear to have a much higher malleability early in life. And last, causal factors affecting stability appear to differ among antisoci al individuals. This paper addresses these issues from a developmental point of view and makes use of several longitud inal studies; although few of these studies have used psychiatric diagnoses of disruptive behavior disorders , they all shed light on the course of this form of psychop athology from childhood onward.
Accepted November 8. i 990 . Dr. Loeber is with th e W estern Psychiat ric Institute an d Clinic .
University of Pittsburgh School of Medicine. Pittsburgh. PA . The author is gratef ul to Carol Baicker-Mckee. Kate Keenan. and Celia Nourse Eatman fo r their comments on an earlier draft of the paper. This paper was written with fin ancial support fro m Grant No . 86-JN-CX-0009 f rom the Office of Juvenile Justice and Delinquency Prevention. Office of Justice Programs, U.S. Department of Justice, and Grant No. MH42529 fr om the National in stitute of Mental Health . Points of view or opinions in this document are those of the author and do not necessarily represent the offi cial position or policies of the U.S . Department of Justice. 0890-8567/91/3003 -0393$03 .OO/O© 1991 by the American Academy of Child and Adolescent Psychiatry . J.Am.A cad . Child Adolesc . Psychiatry , 30 :3, May 1991
Underestimates in Past Research Past research has underestimated the continuity of disruptive/antisocial behavior for the following reasons . First , the manifestation s of these behaviors are highly changeable; therefore , research that has focused on one mode of beha vior, such as aggression (Olweus, 1979) , necess arily. excluded other related manifestations of antisocial beha viors , such as theft . A narrow defin ition of antisocial beha vior tends to artificially reduce cor rect predictions; this can be detected only when a wider array of antisocial outcomes is taken into account. Second, outcome variables often have relied on official records , such as court or arrest records of offenders or on outpatient or hospital records . These records often are far from complete and , in the case of official records of del inquency, are merely a dim reflection of the actual delinquent involvement, as is evident from self-reports. Third, findings on false-positi ve error s in prediction (individuals with early problem behavior who do not become delinquent later) often are interpreted as desistance in antisocial acts. Althou gh this may be true for some individuals, research findings increasingly indicate that disruptive/antisocial behavior often is of an episodic rather than constant nature in some individuals. Thus, studies in which meas urements are taken within a rather narrow time window (such as a year) may conclude that desistance has taken place for a group of formerly antisocial individuals; whereas, the behavior simply may not be apparent for some time , because of a lack of opportunities, incentives, or other factors, and then may reemerge subsequently . Baicker-McKee (1989, unpublished manuscript), for example, reanalyzed the longitudinal data from a community sample of boys from the Cambridge Study in Delinquent Development (West and Farrington, 1973, 1977). The 4 10 boys in this London -based sample were initially studied when they were 8 years old. Baicker-McKee (1989 , unpublished manuscript) found that only 47 .8% of those with an antisocial career by age 18 scored consistently high on measurements with 2-year intervals from age 8 to 18; many other individuals showed a longitudina l pattern of behavior with pauses and relapses. Similarly , Barnett et al. (1989), in an extended follow -up of the same sample, identified a group of juvenile offenders who had no convictions for a period of 7 to 10 years but were subsequently reconvicted in their late twenties .
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Fourth, the intermittent, and at the same time continuous, nature of disruptive/antisocial behavior may be explained in terms of underlying propensities and skills acquisition. Loeber and Le Blanc (1990) have posed that once individuals have learned antisocial skills (such as decreasing the detection of theft, conning schemes, or safe cracking), such skills tend to remain in their repertoire for a long time and may reemerge under the right circumstances of need and opportunity . Finally, conclusions about continuity often have been based on correlational evidence (e.g., Olweus, 1979). There are at least two important caveats, however. In studies on antisocial behavior, the frequency of a predictor (called the selection ratio) often is much higher than the frequency of the outcome (called the base rate). It is not often recognized that in a two-by-two prediction table, where there is a difference in the selection ratio and the base rate, only a proportion of all subjects can be accurately predicted (Loeber and Dishion, 1983). For that reason, observed correlation coefficients in prediction studies, such as phi, often have an upper limit that is not equal to one (phi is comparable to a product-moment correlation coefficient but, unlike the latter, applies to two-by-two tables). Consequently, a reported phi may represent an underestimate and, for that reason, must be corrected to reflect its ceiling (Farrington and Loeber, 1989). In addition, authors have argued that, for example, a correlation of 0.29 accounts for less than 9% of the variance in the outcome variable and is, therefore, of little significance. In a two-by-two prediction table, however , a phi of 0.29 can mean that 37 .5% of the predicted delinquents actually become delinquent, in contrast to only 12.5% of those predicted to be nondelinquent (Farrington and Loeber, 1989). Interpreted in this manner, prediction results are comparable with those found in many areas of medicine and certainly have clinical and practical utility .
An Orderly Change of Manifestations? Manifestations of disruptive/antisocial behavior in childhood and adolescence may appear unpredictable to the adults confronted with them. Youngsters may startle their parents by displaying a succession of seemingly unrelated behaviors-fire setting, theft , vandalism , assault, to mention only a few. It may be difficult for adults to see a pattern in such behaviors. Cross-sectional and longitudinal studies, however, increasingly are clarifying developmental patterns in the manifestations of disruptive/antisocial behavior as they occur over time, although some details remain to be uncovered. One major finding is that, as a rule, less and more serious problem behaviors do not occur randomly but tend to take place in an orderly fashion. Overall, less serious problem behavior tends to precede more serious problem behaviors; less serious behaviors , therefore, appear as a necessary step toward more serious acts (Loeber, 1990; Patterson, 1982). This seems to hold for the development of problem behaviors from the preschool to the elementary school age period as well as for delinquent behaviors that tend to emerge in late childhood and early adolescence. For example, LeBlanc and Frechette (1989) followed up a sample of adolescent 394
delinquents in the province of Quebec. Based on the youngsters' recall of the age of first criminal activities, the authors documented an orderly sequence from less to more serious types of delinquent acts. The understanding, however, is that few youngsters progress to the most serious acts (rape, homicide), that other youngsters stop at intermediate levels, and that some of these subsequently desist. Desistance, however, is inversely related to the degree of progression (Loeber, 1988). Another major finding concerns changes in the nature of the problem behavior . Studies show that the prevalence of confrontive or overt problem behavior tends to decrease from the preschool period; whereas, most concealing or covert behaviors tend to increase from the elementary school age period into adolescence (Loeber, 1982). Thus, it is likely that a shift takes place from overt to covert problem behaviors before adolescence. This may imply that some formerly aggressive youngsters change the pattern of their problem behavior to include lying and theft . Loeber et aI., (1989), in a follow-up of a group of highly disruptive boys from kindergarten onward, found that 75% of the stable fighters (i.e., over a period of 4 years) developed covert behaviors as well, compared with only 8% of those boys who stopped fighting in the interim . In addition, some youngsters, who are not aggressive or otherwise seriously problematic earlier in life, develop concealing acts later (Loeber, 1988; Loeber and Schmaling, 1985). Some tentative advances are being made in formulating different pathways to antisocial outcomes, rather than continuing to assume that there is only a single pathway (Loeber, 1988). Disruptive/antisocial behavior tends to be activated in the period from preschool to midadolescence. Onset after that age is very uncommon (Baicker-Mcls.ee, 1989, unpublished manuscript; Robins, 1966). Among those youngsters who develop symptoms before midadolescence are those who initiate problem behavior very early in life . Children in this group often display hyperactive and inattentive symptoms as well and are less likely to outgrow these conduct problems than children with a later onset. They appear to be especially at risk for an antisocial career characterized by high rate, "versatile" forms of offending (property, violent, and other offenses), often accompanied by substance abuse . The desistance rate appears relatively low in this group. Loeber (1988) called this the aggressive/ versatile path and contrasted it with the nonaggressive path . Youngsters in the latter category begin relatively late, are more likely to be females than those in the aggressive/ versatile path, and display primarily concealing, nonaggressive forms of conduct problems including delinquency, with or without substance use. Compared with the aggressive/versatile path, however, the desistance rate is higher in the nonaggressive path . The formulation of the different pathways, although based on various empirical studies, awaits further refinement and confirmation.
Markers There are several known markers that predict continuity of behavior: frequency, multiple settings, variety, early onset, and hyperactivity (Loeber, 1982). First, youngsters who l.Am.Acad .Child Adolesc. Psychiatry, 30:3, May 1991
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display high rates of problem behavior early in life are more at risk for later antisocial behavior than those who display low-rate problem behavior. This certainly applies to symptoms of conduct disorder but may also apply to symptoms of oppositional defiant disorder as early as the preschool period in the case of extremely high frequency and intensity of oppositional behaviors . Second, children displaying problem behavior in more than one setting are thought to be more likely to continue displaying the problem behavior than children whose problem behavior is confined to one setting only. (It should be noted, however, that this conclusion may be affected by informant effects [Costello and Loeber, in press]). Third, a high variety of problem behavior (e.g., theft and aggression) is associated with a higher risk for continuity than a low variety (e.g ., theft only) . Fourth, children who experience a precocious onset of conduct problems are at a much higher risk for later antisocial behavior than those who begin displaying conduct problems at a more normative age. Lastly, youngsters who are also hyperactive and have attention deficits are much more at risk to develop serious and lasting antisocial behavior than those without these early symptoms (e.g., Farrington et al., 1990; Gittelman et al., 1985; Glueck and Glueck , 1966; Weiss and Hechtman, 1986). These seemingly disparate findings on markers can be integrated as follows: age at onset , variety, frequency, and seriousness are highly correlated, at least in the domain of delinquency (Le Blanc and Frechette, 1989). Moreover, the presence of hyperactivity often is associated with early onset of disruptive behavior (Offord et al., 1979), while the development of disruptive/antisocial behaviors takes place primarily through accretion rather than succession of different behaviors over time. Thus, this deviancy process is characterized by a diversification of the problem behaviors as youngsters grow older (Loeber, 1990), with more serious behaviors following less serious ones in an additive fashion . This may explain why early variety is an important marker. In addition, the likelihood that youngsters will begin displaying a new problem behavior is related to the frequency of existing problem behaviors (Loeber , 1988); this underscores the importance of frequency as a marker. Decreasing Malleability Reference was made earlier to the relationship between children's advancement to serious acts and the reduced likelihood of their desistance. This relationship is confounded by the fact that serious acts are usually displayed by older youngsters . The question can be raised, therefore, whether disruptive/antisocial behavior, like other personality characteristics, tends to stabilize as youngsters grow older. For example , findings in the area of moral development and the development of intelligence indicate that test-retest coefficients become higher after the latency period (Bloom, 1964; Colby et al., Lieberman , 1983; Kohlberg et al., 1984). In addition, cross-sectional and longitudinal studies on aggression indicate that stability coefficients tend to increase with age, particularly from early adolescence onward (Loeber, 1982; Olweus, 1979). Recently, Baicker-McKee (1989 , unpublished manul.Am .Acad. Child Adolesc . Psychiatry, 30 :3, May 1991
script), in her reanalysis of the Cambridge study, adopted a comprehensive definition of different manifestations of disruptive/antisocial behavior at different ages. Once again, she found that the stability coefficients steadily increased in magnitude between the ages of 8 and 16. In summary, there is evidence that disruptive/antisocial behaviors' 'crystallize" and become more stable as children become older. This implies that malleability decreases with age, which may explain why it is difficult to turn around antisocial teenagers with a long and extensive history of problem behavior. Multiple Causality Space allows only a sketching of some important causal patterns . Certain logical conclusions may be drawn from the preceding about the causality of disruptive/antisocial behavior. First, it seems highly likely that for those youngsters with an onset of disruptive behavior in the preschool years, the causes of the onset of the disorder must lie either in that early period or in genetic factors. In contrast, for those whose onset is later, the causal factors associated with onset must necessarily lie in that later period (this does not exclude the possibility that genetic factors are activated later in life). Second, given that the onset of patterns of physical aggression is unusual in adolescence; the origins of aggression must also be sought primarily in the preadolescent period. Third, it likewise is highly unusual for hyperactivity and attention deficits, often associated with oppositional defiant disorder and conduct disorder, to appear after the age of 9 or 10. Again , their causes must be situated in childhood or in genetic factors. Parents and children's peers have been mentioned frequently as important social influences for the acquisition of antisocial behaviors (e.g . , Elliott et aI., 1985). The majority of the studies concern family influences. Loeber and Stouthamer-Loeber's (1986) metanalysis of cross-sectional and longitudinal studies showed the high degree of agreement among studies that certain parent-ehild interactions (such as chronic conflict and neglect) appear associated with disruptive child behavior at different ages. It has also been shown that disruptions in child-earetaker continuity during the preschool period, rather than later , are associated with disruptive child behavior; this suggests that another form of vulnerability operates at that time. Again, potential social causes can be seen in a developmental perspective where familial influences occur first, and peer influences become apparent later but continue to operate side by side for a number of years. A common element between the two spheres of influence is that some forms of social interaction facilitate youngsters' learning of antisocial behavior. Even when narrowed down to certain age ranges , it is easy to oversimplify the causes of disruptive/antisocial behavior. There is a consensus among many scholars that a single cause perspective is naive; instead, it is likely that there are multiple causes including both biological and social components (e.g., Jenkins et aI., 1985; Rutter and Giller, 1983). The biological components do not necessarily refer only to genetic effects but may include neurotoxins (such as lead) that decrease intelligence, attention capabilities, and
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increase overactivity in youngsters (Needleman and Bellinger, 1981). It is likely that a child 's central nervous system is particularly vulnerable to neurotoxins during the first years of life; this is consistent with the findings on early onset. Investigative Methods
The preceding comments implied that cross-sectional research only sheds limited light on changes in antisocial behavior as they occur over time. Instead , longitudinal studies are especially likely to produce new insights about orderly sequences in the changing behaviors. Longitudinal data are also more likely to identify shifts in the causes of antisocial behavior as youngsters grow older (Farrington et aI., 1986). What types of longitudinal studies will be most useful? First, prospective rather than retrospective studies are needed, because it cannot be assumed that causal processes and changing manifestations can be adequately recalled by informants over long periods of time . Also, in prospective studies one might adjust the frequency of assessments to reflect the speed of change in developmental processes. Widely spaced assessments are likely to miss crucial periods of change. Third , given that the most deviant individuals are often the most unreliable informants, it is necessary to include other informants, such as parents, peers, teachers, or, in the case of older target individuals, their significant others. Fourth, given that the prevalence of individuals displaying serious antisocial behavior is relatively low, it may be advisable to do a screening procedure at the beginning of a study in order to enhance the base rate of individuals at high risk for antisocial careers. Fifth, many of the most deviant individuals, when followed up, often lead a highly irregular life; they may move often and sometimes are on the run from credit agencies or justice officials. Therefore,
in order to enhance participation, it is extremely important that prospective studies have an efficient tracking system, and that contact procedures with the target subjects are tailored to their needs and characteristics (Stouthamer-Loeber et aI., in press). Conclusion
This sketch on the stability of disruptive/antisocial behavior has made several important points . The behavior is particularly virulent; once in full bloom, it is difficult to eliminate through currently available intervention techniques. In that sense, disruptive behavior disorder is very enduring; it is also changeable, however, especially in the first 12 or so years of life. Many of the initial causes of the disorder operate during childhood when children's behavior tends to be most malleable. It is toward that developmental period that we need to shift resources if we are truly serious about combating this epidemic disorder in which youngsters victimize others and , generally, fail to live fulfilling lives. The challenge is to create intervention programs that can truly interrupt the deviancy processes spoken of before. Several approaches operating in tandem may be required. On the one hand, interventions should be aimed at reducing behaviors that appear to be keystones for further deviant behavior, such as physical aggression, hyperactivity , and
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behaviors reflecting attention deficits . However, the elimination or reduction of these behaviors will probably not be sufficient by themselves . Almost invariably, the development of antisocial behavior is accompanied by emerging social and academic deficits. Creating options for success in these areas of vulnerability very well may be a necessary prerequisite for more normative development. Also, youngsters ' attachment to deviant peer groups is much more likely in households and schools characterized by neglect or repressive interactions with adults . Adults' investment in time and frequent, positive interactions with these youngsters are most likely the breeding ground for more prosocia! developments.
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