It is well established that core ADHD symptoms (i.e., inattention, impulsivity and hyperactivity) place children at substantial risk for developing serious conduct problems.  The development of serious conduct problems does not occur in all children with ADHD, however, suggesting that social experiences may contribute to amplifying impulsivity and inattention into persisting conduct problems such as aggression, defiance, and lying in some children but not in others.  Identifying the social experiences/processes that contribute to such differential outcomes is important because this may provide an opportunity to prevent the development of serious conduct problems in many children.

A study published in the Journal of Abnormal Child Psychology (Snyder, et al., (2004). Child Impulsiveness-inattention, early peer experiences, and the development of early onset conduct problems) provides an excellent example of research directed towards understanding the interplay of biological and social factors in children's development.  The authors begin their study by noting that not all children who display impulsive, hyperactive and inattentive behavior also show the early emergence, persistence and growth of conduct problems such as aggression, defiance, lying, and stealing.  Thus, although core ADHD symptoms are important risk factors for the development of these behaviors, this risk is not always realized.  Why does this occur for some children but not others?

To begin answering this question, their study explores the role that peer relationships play in the early onset of conduct problems among children characterized by impulsive-inattentive behavior.  Two interrelated sets of findings led the authors to hypothesize that peer relationship processes link impulsive-inattentive behavior (i.e., behaviors symptomatic of ADHD) to the emergence and persistence of serious conduct problems.  First, it has been clearly established that difficulties in peer relationships contribute substantially to the persistence and growth of conduct problems.

Second, ADHD symptoms place children at considerable risk for being disliked by peers.  As the authors note "...deficits in self-regulatory capacities may be associated with unskilled, socially uncoordinated, and high amplitude means of relating to peers, interfering with efforts to successfully establish and sustain constructive play and social interaction.  Impulsivity and inattention may also lead to increasing reliance on coercive and aggressive means of negotiating disagreement and conflict."  Thus, as children with high levels of impulsive and inattentive behaviors enter formal schooling, they may be poorly equipped to negotiate the new sets of social challenges that they face.

In sum, the authors propose a model in which impulsive/inattentive behaviors place children at risk for aggressive and coercive interactions with peers, and which eventuate their being disliked.  These social experiences, in turn, provide a context in which serious conduct problems emerge, intensify, and persist.  In sum, they suggest that biological risk factors, i.e., ADHD symptoms, in conjunction with negative social experiences that such risk factors engender, are necessary to explain the origin and maintenance of serious conduct problems.

To test this developmental model, the authors conducted a longitudinal study in which they examined the associations between impulsive-inattentive behavior, peer relationships, and conduct problems over a 2-year period.  Participants were 133 girls and 134 boys whose mean age was 5.3 years at the beginning of the study (entry into kindergarten) and 7.2 years at the last data collection point (exit from first grade).  The school that participants attended served a well-defined, low socioeconomic neighborhood in a city with a population of 450,000.

Measures

Impulsivity-inattention - Children in this study were not formally diagnosed with ADHD; instead, multiple measures collected at kindergarten entry were used to assess the degree of impulsive-inattentive behaviors in all participants.  This included parent ratings of ADHD symptoms, neuropsychological tests, and observations of children's behavior in the classroom.  These different measures were combined to create a single indicator of impulsivity-inattention for each child.

Peer-Social Processes - Peer social-relationship processes were measured in the fall and spring of kindergarten.  At these periods, the behavior that each child directed toward peers and that peers directed toward each child were collected on multiple occasions by trained observers.  On 6 separate occasions during the fall and spring, the behavior of participating children was observed on the playground for a 5-minute period.  Each 5-minute observation period was divided into 30 10-second segments, and for each segment, observers noted whether the child had been physically or verbally aggressive towards a peer, or had been the victim of physical or verbal aggression by a peer.  Thus, these observations provide an indication of the frequency with which each child was engaged in negative interactions with peers.

In addition to this observational data, children were asked to nominate 3 classmates that they especially liked to play with and 3 classmates that they did not like to play with.  These ratings were used to compute popularity scores for each study participant that were based on the number of "like to play with" and "don't like to play with" nominations that each child received from his or her classmates.

Child Outcomes: Conduct Problems - Teacher ratings of conduct problems were obtained in the fall and spring of kindergarten and in the fall and spring of first grade.  Ratings of conduct problems were made using the Teacher Report Form, a standardized behavior and nationally normed rating scale.  Parent ratings of their child's conduct problems were made at comparable time points using the parent version of the same scale.

Results

Gender Differences in Inattention-Impulsivity and Peer Difficulties - Prior to examining the study's major hypotheses, the authors tested for gender differences in impulsive-inattentive behavior and peer relationship difficulties.  Not surprisingly, boys had significantly higher scores on the composite measure of impulsive-inattentive behavior than girls.  In addition, at each observation point, boys were engaged in significantly higher rates of peer aggression and victimization than girls.

Is the link between impulsive-inattentive behavior and the development of conduct problems explained by peer relationship difficulties? - Testing this central study hypothesis requires 3 steps.  First, it must be shown that impulsive-inattentive behavior predicts the growth of conduct problems over time.  Second, it must be established that peer relationship difficulties also predict the escalation of conduct problems over time.  Finally, it needs to be demonstrated that when impulsive-inattentive behavior and peer relationship difficulties are simultaneously examined as predictors of growth in conduct problems, only peer relationship difficulties remain a significant predictor.

This pattern of results would demonstrates that the process by which impulsive-inattentive behavior leads to conduct problems is through the influence that such behavior has on children's peer relationship.  In "statistical" language, this is described as demonstrating that peer difficulties "mediate" the relationship between impulsive-inattentive behavior and growth in conduct problems; i.e., impulsive-inattentive behavior does not directly produce an escalation in conduct problems, but does so by creating peer relationship difficulties for children, which, in turn, eventuate an escalation in conduct problems.

The first step in this sequence was supported: for both boys and girls, impulsive-inattentive behavior predicted an increase in both parents' and teachers' ratings of conduct problems over time; this pattern was equally strong for boys and girls.

Support was also found for the second step in this sequence; that is, peer relationship difficulties predicted growth in conduct problems over time.  For boys and girls, popularity with peers was consistently negatively associated with teachers' ratings of children's conduct problems (i.e., the higher children's popularity, the lower their conduct problems at school).  In addition, aggression on the playground was positively related to conduct problems for both genders.  Boys and girls who were "tough" enough to dish out aggression towards peers while avoiding being targets of aggression themselves were at particular risk for developing serious conduct problems; this was especially true for girls.  This suggests that although being aggressed against by peers is an aversive experience, it may actually protect against the increasing escalation of conduct problems.

For the final step in the sequence, a somewhat different pattern of results emerged for boys and girls.  For boys, the significant relationship between impulsive-inattentive behavior and growth in conduct problems at home and school was no longer evident when peer relationship processes were added as a predictor of conduct problems.  As noted above, this suggests that impulsive-inattentive behavior effects the development of conduct problems in boys through the adverse impact such behavior exerts on children's peer relationships.

For girls, a similar pattern was found for the prediction of parents' report of conduct problems, but not for teachers where impulsive-inattentive behavior and peer relationship problems were found to have an additive effect.

Summary and Implications

Although the statistical analyses in this study are complicated, the results illustrate a simple and important point - both biological and social factors play an important role in the development of children with ADHD.   Specifically, results from this study suggest that one important mechanism by which ADHD symptoms may influence the development of serious conduct problems is through the adverse impact that such symptoms have on the quality of children's relations and experiences with peers.  According to the authors, "Coercive peer processes and peer rejection engendered by early child impulsivity and inattention appear to facilitate the occurrence and growth of overt (aggression, defiance) and covert (stealing, lying) conduct problems."

This study examined the interplay of ADHD symptoms, peer processes, and conduct problems in children just beginning formal schooling.  In addition, children in this study did not have a formal diagnosis of ADHD; in fact, children showing a broad spectrum of impulsive-inattentive behavior were included.  It is well established, however, that ADHD is an important factor for rejection by peers.  It is also well established, that peer rejection is an important risk for a variety of negative developmental outcomes ranging from mental health difficulties to serious antisocial behavior.  Both these relations have been found in older children/adolescents.  Thus, the relationships among ADHD symptoms, peer relationship difficulties, and conduct problems are likely to characterize older children and adolescents as well.

The value of incorporating an exploration of social processes into efforts to understand the development of individuals with ADHD is that it broadens our understanding of the multiple influences that shape children's path through life.  To a certain extent, an emphasis on identifying the biological underpinnings of ADHD - although extremely valuable - can inhibit efforts to examine other important factors in whether children with ADHD develop in healthy vs. problematic ways.  Such work also opens up other pathways for intervening to promote healthy developmental outcomes in addition to treatments such as medication that are intended to ameliorate core ADHD symptoms that may be quite helpful.  Hopefully, more effective ways to promote the healthy, successful development of individuals with ADHD will be an important outcome of this interesting research approach.