Walter Matthys

Salivary cortisol and cardiovascular activity during stress in oppositional-defiant disorder boys and normal controls

BACKGROUND Arousal-regulating mechanisms are important in explaining individual differences in antisocial behavior. METHODS Alterations in salivary cortisol concentration and cardiovascular activity were studied in 21 boys with oppositional defiant disorder (ODD) and 31 normal controls (NC) during a 2-hour stressful procedure involving frustration and provocation. RESULTS Baseline levels of heart rate (HR) were significantly lower in the ODD group, but their HR levels were higher during provocation and frustration. Cortisol levels in the ODD group were overall lower than those of the NC group, and the effect of stress seemed to be minimal and similar for both groups; however, individual differences were large. Since anxiety plays an important mediating role in cortisol response, subjects were divided into one of four groups based on the intensity of their externalizing behavior and anxiousness. Cortisol increase due to stress exposure was strongest in highly externalizing and highly anxious subjects; cortisol decrease was strongest in those subjects who were high in externalizing behavior and low in anxiousness. CONCLUSIONS The results of the study support an important role for hypothalamic-pituitary-adrenal axis sympathetic autonomic functioning in persistent antisocial behavior in young boys.

Reactive and proactive aggression in children--a review of theory, findings and the relevance for child and adolescent psychiatry.

The clinical population of aggressive children diagnosed as having an oppositional defiant disorder (ODD) or a conduct disorder (CD) is heterogeneous, both with respect to behaviour and aetiology. Recently, the following distinction has been proposed that might further clarify this heterogeneity: reactive aggression is an aggressive response to a perceived threat or provocation, whereas proactive aggression is defined as behaviour that anticipates a reward. In this article we examine various aspects of this distinction. We will [1] examine the evidence that reactive and proactive aggression are distinct phenomena by discussing the theories underlying the distinction between the subtypes in humans and we briefly review evidence for a similar distinction in animals; [2] we critically review the literature on the measurement in children via questionnaires and behavioural observations; we then point out that the correlation observed between the subtypes is due to the fact that many children show both types of aggression; [3] we review the literature on specific characteristics of the subtypes giving attention to social information processing, peer status, biological correlates and developmental history, and demonstrate that there is some evidence to suggest that reactive and proactive aggression are distinct dimensions; [4] we discuss the relevance of the distinction between reactive and proactive aggression for child and adolescent psychiatry.

Hypothalamic-pituitary-adrenal axis and autonomic nervous system activity in disruptive children and matched controls.

OBJECTIVES To investigate whether a pattern of lower autonomic nervous system (ANS) and hypothalamic-pituitary-adrenal (HPA) axis activity is found in children with disruptive behavior disorders (DBD) under nonstressful and stressful conditions, and whether such a pattern would correspond with their feelings of control and negative emotionality. METHOD The effects of stress were studied by comparing cortisol response, heart rate (HR), skin conductance level (SCL), and subjective feelings of 26 children with DBD and 26 matched normal controls. An additional 12 normal control children were studied in a nonstress control condition. RESULTS Baseline HR and SCL but not cortisol were lower in the DBD group. Stress significantly affected cortisol, HR, SCL, and negative moods, although children with DBD showed a weaker HPA stress response and the difference between the groups was greater under stress. CONCLUSIONS Children with DBD are characterized by lower ANS activity and HPA axis responsivity, but higher levels of emotional arousal. It is possible that in children with DBD the HPA axis and ANS, on the one hand, and their emotional arousal, on the other, are less well coordinated. It is speculated that this could be due to differences in genetic makeup or to stressful conditions during pre- or postnatal life.

Executive Functions in Preschool Children with Aggressive Behavior: Impairments in Inhibitory Control

The question whether executive function (EF) deficits in children are associated with conduct problems remains controversial. Although the origins of aggressive behavior are to be found in early childhood, findings from EF studies in preschool children with aggressive behavior are inconsistent. The current study aimed to investigate whether preschool children with aggressive behavior show impairments in EF. From a population-based sample, 82 preschool children who were showing aggressive behavior as indicated by scores at or above the 93rd percentile on the Aggressive Behavior Scale of the CBCL 1 1/2-5 were selected. These children with aggressive behavior were matched on IQ to a group of typically developing control children (N = 99). Six neuropsychological tasks were administered to assess set shifting, inhibition, working memory and verbal fluency. A factor analysis was conducted which yielded one clear factor: inhibition. Aggressive preschool children showed poorer performance on this inhibition factor than control children and boys performed worse on this factor than girls. This association between aggressive behavior and inhibition deficits was maintained after controlling for attention problems. In addition, gender differences in all EFs measured were found with boys exhibiting more impairment in EF than girls. These findings demonstrate that preschool children with aggressive behavior show impairments in inhibition, irrespective of attention problems.

Effectiveness of the Incredible Years parent training to modify disruptive and prosocial child behavior: a meta-analytic review.

The present meta-analytic review examined effectiveness of the Incredible Years parent training (IYPT) regarding disruptive and prosocial child behavior, and aimed to explain variability in intervention outcomes. Fifty studies, in which an intervention group receiving the IYPT was compared to a comparison group immediately after intervention, were included in the analyses. Results showed that the IYPT is an effective intervention. Positive effects for distinct outcomes and distinct informants were found, including a mean effect size of d=.27 concerning disruptive child behavior across informants. For parental report, treatment studies were associated with larger effects (d=.50) than indicated (d=.20) and selective (d=.13) prevention studies. Furthermore, initial severity of child behavior revealed to be the strongest predictor of intervention effects, with larger effects for studies including more severe cases. Findings indicate that the IYPT is successful in improving child behavior in a diverse range of families, and that the parent program may be considered well-established.

Adrenal androgens and aggression in conduct disorder prepubertal boys and normal controls

BACKGROUND The evidence for a role of androgens in human aggression is less convincing than in animals. We examined the relationship between androgens and aggression in prepubertal boys who were diagnosed as suffering from severe aggression and antisocial behavior. METHODS Plasma levels of testosterone (T), androstenedione (A), and dehydroepiandrosterone sulphate (DHEAS) were measured in 15 boys with a conduct disorder (CD) and 25 normal control (NC) boys. Parents and teachers of the children rated the intensity of aggression and delinquency over the last 6 months. RESULTS CD boys had significantly higher levels of DHEAS and marginally significantly higher levels of A; there were no differences in T. Moreover, DHEAS levels were significantly positively correlated with the intensity of aggression and delinquency as rated by both parents and teachers. CONCLUSIONS The results suggest that adrenal androgen functioning plays an important role in the onset and maintenance, of aggression in young boys.

Stress responsivity in children with externalizing behavior disorders

Patterns of lower autonomic nervous system (ANS) and hypothalamic-pituitary-adrenal (HPA) axis activity have been found in children with oppositional defiant disorder (ODD). The aim of the present study was to investigate whether children with attention-deficit/hyperactivity disorder (ADHD) differ from ODD children with (OD/AD) or without comorbid ADHD in ANS and HPA axis activity under baseline and stressful conditions. The effects of stress on cortisol, heart rate (HR), and skin conductance level (SCL) were studied in 95 children (26 normal control [NC] children and 69 child psychiatric patients referred for externalizing behavior problems [15 ODD, 31 OD/AD, and 23 ADHD]). No baseline differences were found in cortisol between the four groups. However, the ODD and OD/AD groups showed a significantly weaker cortisol response to stress compared to the ADHD and NC groups; the ADHD group had a similar cortisol response as the NC group. Within the ODD group this pattern of low cortisol responsivity was most clearly present in the more severely affected inpatients. With respect to HR, the ODD group had a significantly lower HR during baseline and stressful conditions. The higher HR levels in the OD/AD and ADHD groups were likely to be caused by methylphenidate. The externalizing groups had significantly lower SCL levels, and no differences were found between these groups. It was concluded that differences in cortisol responsivity during stress exposure are important in distinguishing within a group of children with externalizing behavior between those with ODD and ADHD.

Executive function deficits in preschool children with ADHD and DBD.

BACKGROUND  Impairments in executive functions (EF) are consistently associated with attention deficit hyperactivity disorder (ADHD) and to a lesser extent, with disruptive behavior disorder (DBD), that is, oppositional defiant disorder or conduct disorder, in school-aged children. Recently, larger numbers of children with these disorders are diagnosed earlier in development, yet knowledge about impairments in clinically diagnosed preschool children and the role of comorbidity is limited. Therefore, the aim of the current study was to examine EF in clinically referred preschool children with a clinical diagnosis of ADHD, DBD and ADHD + DBD. METHOD Participants were 202 children aged 3.5-5.5 years, 61 with ADHD only, 33 with DBD only, 52 with comorbid ADHD + DBD and 56 typically developing children. Five EF tasks were administered. RESULTS Confirmatory factor analysis showed that the two-factor model (inhibition and working memory) fit the data better than a one-factor model in this clinical sample. Preschoolers with ADHD displayed inhibition deficits, also after controlling for IQ. Likewise, preschoolers with DBD displayed impaired inhibition, but when IQ was controlled differences were carried mostly by the effect on the task where motivational demands were high (i.e. when tangible rewards were used). This pattern was also found in the interaction between ADHD and DBD; impaired inhibition in the comorbid group, however, was more severe than in the DBD group. Regarding working memory, few group differences were found. CONCLUSIONS Clinically diagnosed preschool children with ADHD showed robust inhibition deficits, whereas preschool children with DBD showed impaired inhibition especially where motivational incentives were prominent. Severity of inhibition impairment in the comorbid group was similar to the ADHD group.

The dominance of behavioural activation over behavioural inhibition in conduct disordered boys with or without attention-deficit hyperactivity disorder

On the basis of Grays theory, Quay suggested that conduct disorder (CD) is associated with a Behavioural Activation System (BAS) that dominates over the Behavioural Inhibition System (BIS), whereas attention deficit hyperactivity disorder (ADHD) is characterised by an underactive BIS. Two studies were conducted to test the hypothesis that the dominance of the BAS over the BIS is more pronounced in CD comorbid with ADHD (CD/ADHD) than in CD alone. First of all, a response perseveration task was used, i.e. the door-opening task (Daugherty & Quay, 1991). In this game, the subject chooses either to open the next door or to stop playing; there is a steadily increasing ratio of punished responses to rewarded responses and a large number of doors opened is indicative of response perseveration. As expected, a steady increase in the number of doors opened was found across normal control (NC) boys, CD boys, and CD/ADHD boys (NC < CD < CD/ADHD). Second, the dominance of the BAS over the BIS was examined by observing the social behaviour of the child in interaction with a research assistant who alternately activated the BAS and the BIS while a game was played. The behaviour of the children was analysed according to ethological methods. Group differences in the frequencies of three out of five behavioural categories were in line with the results of the door-opening task (NC < CD < CD/ADHD).

Verbal, Facial and Autonomic Responses to Empathy-Eliciting Film Clips by Disruptive Male Adolescents with High Versus Low Callous-Unemotional Traits

This study examined empathy-related responding in male adolescents with disruptive behavior disorder (DBD), high or low on callous-unemotional (CU) traits. Facial electromyographic (EMG) and heart rate (HR) responses were monitored during exposure to empathy-inducing film clips portraying sadness, anger or happiness. Self-reports were assessed afterward. In agreement with expectations, DBD adolescents with high CU traits showed significantly lower levels of empathic sadness than healthy controls across all response systems. Between DBD subgroups significant differences emerged at the level of autonomic (not verbal or facial) reactions to sadness, with high CU respondents showing less HR change from baseline than low CU respondents. The study also examined basal patterns of autonomic function. Resting HR was not different between groups, but resting respiratory sinus arrhythmia (RSA) was significantly lower in DBD adolescents with high CU traits compared to controls. Results support the notion that CU traits designate a distinct subgroup of DBD individuals.