Serotonergic and cardiac correlates of aggression in children

Children with developmental dyslexia show elevated parasympathetic nervous system activity at rest and greater cardiac deceleration during an empathy task

Reading difficulties are the hallmark feature of dyslexia, but less is known about other areas of functioning. Previously, we found children with dyslexia exhibited heightened emotional reactivity, which correlated with better social skills. Whether emotional differences in dyslexia extend to the parasympathetic nervous system-an autonomic branch critical for attention, social engagement, and empathy-is unknown. Here, we measured autonomic nervous system activity in 24 children with dyslexia and 24 children without dyslexia, aged 7 - 12, at rest and during a film-based empathy task. At rest, children with dyslexia had higher respiratory sinus arrhythmia (RSA) than those without dyslexia. Cardiac deceleration during the empathy task was greater in dyslexia and correlated with higher resting RSA across the sample. Children with dyslexia produced more facial expressions of concentration during film-viewing, suggesting greater engagement. These results suggest elevated resting parasympathetic activity and accentuated autonomic and behavioral responding to others' emotions in dyslexia.

Neurobiological factors as predictors of cognitive-behavioral therapy outcome in individuals with antisocial behavior: a review of the literature

This review focuses on the predictive value of neurobiological factors in relation to cognitive-behavioral therapy outcome among individuals with antisocial behavior. Ten relevant studies were found. Although the literature on this topic is scarce and diverse, it appears that specific neurobiological characteristics, such as physiological arousal levels, can predict treatment outcome. The predictive value of neurobiological factors is important as it could give more insight into the causes of variability in treatment outcome among individuals with antisocial behavior. Furthermore, results can contribute to improvement in current treatment selection procedures and to the development of alternative treatment options.

Biological sensitivity to context: the interactive effects of stress reactivity and family adversity on socioemotional behavior and school readiness

This study examined the direct and interactive effects of stress reactivity and family adversity on socioemotional and cognitive development in three hundred and thirty-eight 5- to 6-year-old children. Neurobiological stress reactivity was measured as respiratory sinus arrhythmia and salivary cortisol responses to social, cognitive, sensory, and emotional challenges. Adaptation was assessed using child, parent, and teacher reports of externalizing symptoms, prosocial behaviors, school engagement, and academic competence. Results revealed significant interactions between reactivity and adversity. High stress reactivity was associated with more maladaptive outcomes in the context of high adversity but with better adaption in the context of low adversity. The findings corroborate a reconceptualization of stress reactivity as biological sensitivity to context by showing that high reactivity can both hinder and promote adaptive functioning.

Selective breeding for infant rat separation-induced ultrasonic vocalizations: developmental precursors of passive and active coping styles

Human depression and anxiety disorders show inherited biases across generations, as do antisocial disorders characterized by aggression. Each condition is preceded in children by behavioral inhibition or aggressive behavior, respectively, and both are characterized by separation anxiety disorders. In affected families, adults and children exhibit different forms of altered autonomic nervous system regulation and hypothalamic-pituitary-adrenal activity in response to stress. Because it is difficult to determine mechanisms accounting for these associations, animal studies are useful for studying the fundamental relationships between biological and behavioral traits. Pharmacologic and behavioral studies suggest that infant rat ultrasonic vocalizations (USV) are a measure of an early anxiety-like state related to separation anxiety. However, it was not known whether or not early ultrasound emissions in infant rats are markers for genetic risk for anxiety states later in life. To address these questions, we selectively bred two lines of rats based on high and low rates of USV to isolation at postnatal (P) 10 days of age. To our knowledge, ours is the only laboratory that has ever selectively bred on the basis of an infantile trait related to anxiety. The High and Low USV lines show two distinct sets of patterns of behavior, physiology and neurochemistry from infancy through adulthood. As adults High line rats demonstrate "anxious"/"depressed" phenotypes in behavior and autonomic nervous system (ANS) regulation to standard laboratory tests. In Lows, on the other hand, behavior and autonomic regulation are consistent with an "aggressive" phenotype. The High and Low USV lines are the first genetic animal models implicating long-term associations of contrasting "coping styles" with early attachment responses. They thus present a potentially powerful model for examining gene-environment interactions in the development of life-long affective regulation.

Externalizing and internalizing problems in relation to autonomic function: a population-based study in preadolescents

OBJECTIVE

To investigate whether externalizing and internalizing problems are related to lower and higher heart rate (HR), respectively, and to explore the relationship of these problems with respiratory sinus arrhythmia (RSA) and baroreflex sensitivity (BRS). Moreover, to study whether problems present at both preschool and preadolescent age show stronger associations with autonomic function than those that were not.

METHOD

In a population cohort of 10- to 13-year-old children (N = 931; 11.6 +/- 0.5 years; 47% boys), autonomic measurements in supine and standing position were performed at school. RSA and BRS were determined by spectral analysis. Current externalizing and internalizing problems were assessed by the Child Behavior Checklist and problems at age 4 to 5 retrospectively by the Preschool Behavior Questionnaire.

RESULTS

At supine rest, current externalizing problems were associated with lower HR and higher RSA, but not with BRS and current internalizing problems with higher HR and lower RSA, but not with BRS. These results were specifically found in children with problems that were retrospectively reported to have been also present at preschool age. Standing-induced changes in autonomic parameters were unrelated to the behavioral dimensions.

CONCLUSIONS

Externalizing and internalizing problems are associated with divergent autonomic patterns, suggesting autonomic underarousal and overarousal, respectively. Problems starting early in life may specifically account for this. This should be confirmed in prospective studies.

Omega-3 fatty acid deficiencies in neurodevelopment, aggression and autonomic dysregulation: opportunities for intervention

Mechanisms by which aggressive and depressive disorders may be exacerbated by nutritional deficiencies in omega-3 fatty acids are considered. Early developmental deficiencies in docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) may lower serotonin levels at critical periods of neurodevelopment and may result in a cascade of suboptimal development of neurotransmitter systems limiting regulation of the limbic system by the frontal cortex. Residual developmental deficits may be manifest as dysregulation of sympathetic responses to stress including decreased heart rate variability and hypertension, which in turn have been linked to behavioral dysregulation. Little direct data are available to disentangle residual neurodevelopmental effects from reversible adult pathologies. Ensuring optimal intakes of omega-3 fatty acids during early development and adulthood shows considerable promise in preventing aggression and hostility.

The roles of marriage and anger dysregulation in biobehavioral stress responses

Physiological and behavioral correlates of anger dysregulation in adults were evaluated in the context of marital stress. Fifty-four married couples participated in a series of laboratory procedures that included electrocardiogram measures during a 15-min marital conflict interaction and an interview assessing their inability to regulate anger (anger dysregulation). Results from the multivariate regression analyses indicated that the nature of the couple's relationship, rather than individual levels of anger dysregulation, predicted lower parasympathetic cardiac activity (indexed by high-frequency heart period variability) and shorter cardiac interbeat intervals. Anger dysregulation, rather than the dyadic relationship, was predictive of greater displays of angry behavior during the marital conflict interaction. The importance of contextual factors in stress processes, such as stress due to marriage, are discussed in light of research linking poor marital quality to greater health risks for women than for men.

Irritability in pediatric mania and other childhood psychopathology

Irritability is an important symptom in childhood psychopathology that has received relatively little research attention. Recent controversy concerning the diagnosis of mania in children has focused attention on how little is known about how to assess irritability in a systematic way, and about its diagnostic associations. For example, subtyping irritability according to course (chronic vs. episodic), precipitants, and family history may facilitate the identification of psychopathology and the study of pathophysiology. While normative and pathologic irritability can be differentiated reliably, the validity of the distinction is unclear. In addition, there is a need for scales designed to measure the severity of irritability in children with mood and anxiety disorders. In order to facilitate research, we propose a definition of irritability from the perspective of affective neuroscience. Because reactive aggression may be a helpful animal model for irritability, we review the neural circuitry mediating this behavior. Behavioral paradigms that evoke frustration, as well as those that assess the ability to inhibit a prepotent motor response, maintain attentional focus, execute response reversal, recognize angry faces, and regulate emotional responses, may be useful in the study of irritability. Examples of such paradigms are described, and the pharmacology of irritability is reviewed briefly.

Annotation: the role of prefrontal deficits, low autonomic arousal, and early health factors in the development of antisocial and aggressive behavior in children

BACKGROUND

This article selectively reviews the biological bases of antisocial and aggressive behavior in children with a focus on low autonomic functioning, prefrontal deficits, and early health factors.

RESULTS

Low resting heart rate is thought to be the best-replicated biological correlate of antisocial and aggressive behavior in child and adolescent populations and may reflect reduced noradrenergic functioning and a fearless, stimulation-seeking temperament. Evidence from neuropsychological, neurological, and brain imaging studies converges on the conclusion that prefrontal structural and functional deficits are related to antisocial, aggressive behavior throughout the lifespan. A prefrontal dysfunction theory of antisocial behavior is advanced. This argues that social and executive function demands of late adolescence overload the late developing prefrontal cortex, giving rise to prefrontal dysfunction and a lack of inhibitory control over antisocial, violent behavior that peaks at this age. Birth complications and minor physical anomalies are selectively associated with later violent behavior, especially when combined with adverse psychosocial risk factors for violence. Cigarette smoking during pregnancy may increase the risk for antisocial and violent behavior in later life by disrupting noradrenergic functioning and enhancement of cholinergic receptors that inhibit cardiac functioning. Malnutrition during pregnancy is associated with later antisocial behavior and may be mediated by protein deficiency.

CONCLUSIONS

It is argued that early health intervention and prevention studies may provide the most effective way of reversing biological deficits that predispose to antisocial and aggressive behavior in children and adults.

ADHD, aggression, and antisocial behavior across the lifespan. Interactions with neurochemical and cognitive function

The progression to adult antisocial behavior is the least desirable developmental trajectory for children with ADHD. An unremitting pattern of physical aggression appears of great import when predicting long-term outcome. However, a profile characterized by behavioral and cognitive impulsivity and emotional lability may indicate a greater likelihood of the progression to adult antisocial behavior and violent impulse-control disorders. This constellation of behaviors appears to be, at least in part, mediated by brain serotonergic systems. The contribution of cognitive impairments, as manifested by executive function deficits, diminished moral reasoning, and impaired empathic ability, to the emergence and persistence of antisocial behavior has yet to be discerned.

Serotonin and aggression in children

Research consistently indicates that in animals and adults, reduced central serotonergic (5-HT) function is associated with increased aggression. This relationship has been elucidated via cerebrospinal fluid monoamine metabolite levels, hormonal responses to pharmacologic challenge using serotonergic probes, platelet receptor binding studies, and, more recently, through molecular genetic approaches. In contrast, studies examining the relationship of 5-HT to aggression in children have been characterized by inconsistent findings. The literature examining the relationship between central 5-HT function and aggression is reviewed. Several hypotheses that might account for the discrepancies in the child literature are examined.

Peripheral serotonin measures in prepubertal psychiatric inpatients and normal children: associations with suicidal behavior and its risk factors

BACKGROUND

This study reports relationships between suicidal behavior and its risk factors in prepubertal children and whole blood and platelet serotonin-related measures.

METHODS

Seventy-five prepubertal psychiatric inpatients including 23 (30.7%) nonsuicidal, 32 (42.7%) with suicidal ideation, and 20 (26.6%) with a suicide attempt were compared to 35 normal prepubertal controls with regard to platelet serotonin content, serotonin-amplified platelet aggregation, and whole blood tryptophan.

RESULTS

Mean whole blood tryptophan content was significantly lower among inpatient children with a recent suicide attempt than among normal controls or inpatients with suicidal ideation (F = 3.94, df = 3.54, p < or = .01). Inpatient children with a mood disorder had significantly higher platelet serotonin content than inpatients without a mood disorder (F = 3.86, df = 2.80, p < or = .03). Racial/ethnic differences were also observed for inpatients and normal controls, with whites having significantly lower levels of platelet serotonin (expressed as ng/mL blood or ng/10(9) platelets) than blacks or Latinos. Blacks had significantly higher levels of whole blood tryptophan than other racial/ethnic groups.

CONCLUSIONS

The results suggest that whole blood tryptophan and platelet serotonin content should be studied for their predictive validity as risk factors for suicidal behavior in youth while controlling for racial/ethnic differences.

Serotonin, aggression, and parental psychopathology in children with attention-deficit hyperactivity disorder

OBJECTIVE

To explore the relationship between central serotonergic (5-HT) function and history of parental aggression in aggressive and nonaggressive boys with attention-deficit hyperactivity disorder (ADHD).

METHOD

History of psychiatric symptoms was assessed in the biological parents of 41 boys with ADHD. The relationship between 5-HT function in aggressive and nonaggressive probands, as assessed via the prolactin response to fenfluramine (FEN) challenge, and parental history of aggression was examined.

RESULTS

Aggressive boys with a parental history of aggressive behavior had a significantly lower prolactin response to FEN challenge than aggressive boys without a parental history of aggression. Nonaggressive boys had a prolactin response midway between those of the two aggressive subgroups, and their prolactin response did not vary as a function of parental aggression. Children subdivided on the basis of parental history of other psychiatric symptoms did not differ in their response to the FEN challenge.

CONCLUSIONS

These data indicate an association between parent aggressive behavior and lower 5-HT function in aggressive boys with ADHD but do not indicate the extent to which this association is environmentally and/or genetically transmitted. There may be different neurochemical mechanisms in familial and nonfamilial aggressive children, which have clinical implications for pharmacological interventions.