Relationship between levels of testosterone and cortisol in saliva and aggressive behaviors of adolescents

Who is at risk? Applying the biopsychosocial model to explain non-violent and violent delinquency in youth

Research has highlighted the relevance of biological measures in explaining antisocial behavior, but the inclusion of such measures in clinical practice is lagging behind. According to the integrative biopsychosocial model, biological measures should be studied together with psychological and social-environmental factors. In this data-driven study, we applied this comprehensive model to explain non-violent and violent delinquency of 876 at-risk youth (715 male, 9-27 years), by combining nine biological (autonomic-nervous-system; endocrinological), nine psychological, and seven social-environmental measures. Using latent-class-regression analysis we uncovered four distinct psychologically-driven biological clusters, which differed in non-violent and violent delinquency-risk, moderated by social-environmental variables: a biological-psychopathic traits; low problem; high problem; and biological-reactive group. Individual vulnerabilities to (non-)violent delinquency depended on social-environmental context that differed between clusters. These findings highlight the importance of biological and psychological factors, in the context of social-environmental factors, in explaining (non)-violent delinquency.

Salivary markers of aggression - The possible alterations in salivary hormones levels to identify perpetrators of aggression-related violence

Aggression, understood as intentional actions aimed at causing harm, remains in a direct relation with the phenomenon of interpersonal violence, especially its physical form. Creating an objective marker of aggression would be an important tool for preventing, protecting the victims and maintaining control over suspects. There have been attempts to link aggression with shifts in hormone levels, including those that can be measured in saliva, especially testosterone and cortisol. The systematic review aimed to assess changes in salivary hormone levels among perpetrators of violence, with particular emphasis on physical violence, as parameters pointing to perpetrators of violence. Following the inclusion and exclusion criteria, 22 studies were included. Most of the papers included in the analysis came from the USA and Europe. Studies typically included adults as well as children, while focusing mainly on men. Among the hormones, salivary testosterone levels were the ones analyzed most frequently. On the basis of the included studies, a meta-analysis was conducted on the relationship between aggressive behavior and the levels of concentration of testosterone and cortisol measured in saliva. Regardless of gender, individuals exhibiting aggressive behavior were proved to have significantly higher testosterone levels and lower cortisol concentrations in saliva measurements. The obtained results indicate the feasibility of using the examined parameters for initial detection of perpetrators of aggression-related violence. However, further research is necessary to more precisely determine the relationship between aggressive behavior and hormonal changes in order to determine the feasibility of using these parameters as an objective marker for early identification of perpetrators.

Hormone profiles of the African pygmy mouse Mus minutoides, a species with XY female sex reversal

In mammals, most sex differences in phenotype are controlled by gonadal hormones, but recent work on transgenic mice has shown that sex chromosomes can have a direct influence on sex-specific behaviors. In this study, we take advantage of the naturally occurring sex reversal in a mouse species, Mus minutoides, to investigate for the first time the relationship between sex chromosomes, hormones, and behaviors in a wild species. In this model, a feminizing variant of the X chromosome, named X*, produces three types of females with different sex chromosome complements (XX, XX*, and X*Y), associated with alternative behavioral phenotypes, while all males are XY. We thus compared the levels of three major circulating steroid hormones (testosterone, corticosterone, and estradiol) in the four sex genotypes to disentangle the influence of sex chromosomes and sex hormones on behavior. First, we did not find any difference in testosterone levels in the three female genotypes, although X*Y females are notoriously more aggressive. Second, in agreement with their lower anxiety-related behaviors, X*Y females and XY males display lower baseline corticosterone concentration than XX and XX* females. Instead of a direct hormonal influence, this result rather suggests that sex chromosomes may have an impact on the baseline corticosterone level, which in turn may influence behaviors. Third, estradiol concentrations do not explain the enhanced reproductive performance and maternal care behavior of the X*Y females compared to the XX and XX* females. Overall, this study highlights that most of the behaviors varying along with sex chromosome complement of this species are more likely driven by genetic factors rather than steroid hormone concentrations.

Neurobiological correlates of antisociality across adolescence and young adulthood: a multi-sample, multi-method study

BACKGROUND

Antisociality across adolescence and young adulthood puts individuals at high risk of developing a variety of problems. Prior research has linked antisociality to autonomic nervous system and endocrinological functioning. However, there is large heterogeneity in antisocial behaviors, and these neurobiological measures are rarely studied conjointly, limited to small specific studies with narrow age ranges, and yield mixed findings due to the type of behavior examined.

METHODS

We harmonized data from 1489 participants (9-27 years, 67% male), from six heterogeneous samples. In the resulting dataset, we tested relations between distinct dimensions of antisociality and heart rate, pre-ejection period (PEP), respiratory sinus arrhythmia, respiration rate, skin conductance levels, testosterone, basal cortisol, and the cortisol awakening response (CAR), and test the role of age throughout adolescence and young adulthood.

RESULTS

Three dimensions of antisociality were uncovered: 'callous-unemotional (CU)/manipulative traits', 'intentional aggression/conduct', and 'reactivity/impulsivity/irritability'. Shorter PEPs and higher testosterone were related to CU/manipulative traits, and a higher CAR is related to both CU/manipulative traits and intentional aggression/conduct. These effects were stable across age.

CONCLUSIONS

Across a heterogeneous sample and consistent across development, the CAR may be a valuable measure to link to CU/manipulative traits and intentional aggression, while sympathetic arousal and testosterone are additionally valuable to understand CU/manipulative traits. Together, these findings deepen our understanding of the fundamental mechanisms underlying different components of antisociality. Finally, we illustrate the potential of using current statistical techniques for combining multiple datasets to draw robust conclusions about biobehavioral associations.

Comparable level of aggression between patients with behavioural addiction and healthy subjects

Heightened aggression is identified in several psychiatric disorders, including addiction. In this preliminary study with a relatively small number of samples, aggression in subjects diagnosed with behavioural addiction (BA) was implicitly assessed using the point subtraction aggression paradigm (PSAP) test along with measurements of oxy- and deoxyhaemoglobin dynamics in the prefrontal cortex (PFC) during the test using functional near-infrared spectroscopy. Aggression in BA patients was no higher than that of healthy control (CT) subjects in the PSAP test. Although no apparent increase or decrease in haemoglobin concentrations was observed in the PFC of either BA patients or CT subjects, abnormal correlations within the PFC network were present in BA patients. Consistent with comparable aggression between the groups, blood concentrations of the sex hormone testosterone, which has been shown to be associated with aggressiveness, was even lower in BA patients than in CT subjects. In contrast, when a set of questionnaire surveys for the assessment of aggression were administered, BA patients rated themselves as more aggressive than non-BA subjects. Collectively, these results suggest that aggression may not be heightened in BA, but BA patients may overestimate their aggressiveness, raising concerns about the use of questionnaire surveys for assessments of affective traits such as aggression in behavioural addiction.

Toxoplasma gondii, Suicidal Behavior, and Intermediate Phenotypes for Suicidal Behavior

Within the general literature on infections and suicidal behavior, studies on Toxoplasma gondii (T. gondii) occupy a central position. This is related to the parasite's neurotropism, high prevalence of chronic infection, as well as specific and non-specific behavioral alterations in rodents that lead to increased risk taking, which are recapitulated in humans by T. gondii's associations with suicidal behavior, as well as trait impulsivity and aggression, mental illness and traffic accidents. This paper is a detailed review of the associations between T. gondii serology and suicidal behavior, a field of study that started 15 years ago with our publication of associations between T. gondii IgG serology and suicidal behavior in persons with mood disorders. This "legacy" article presents, chronologically, our primary studies in individuals with mood disorders and schizophrenia in Germany, recent attempters in Sweden, and in a large cohort of mothers in Denmark. Then, it reviews findings from all three meta-analyses published to date, confirming our reported associations and overall consistent in effect size [ranging between 39 and 57% elevation of odds of suicide attempt in T. gondii immunoglobulin (IgG) positives]. Finally, the article introduces certain links between T. gondii and biomarkers previously associated with suicidal behavior (kynurenines, phenylalanine/tyrosine), intermediate phenotypes of suicidal behavior (impulsivity, aggression) and state-dependent suicide risk factors (hopelessness/dysphoria, sleep impairment). In sum, an abundance of evidence supports a positive link between suicide attempts (but not suicidal ideation) and T. gondii IgG (but not IgM) seropositivity and serointensity. Trait impulsivity and aggression, endophenotypes of suicidal behavior have also been positively associated with T. gondii seropositivity in both the psychiatrically healthy as well as in patients with Intermittent Explosive Disorder. Yet, causality has not been demonstrated. Thus, randomized interventional studies are necessary to advance causal inferences and, if causality is confirmed, to provide hope that an etiological treatment for a distinct subgroup of individuals at an increased risk for suicide could emerge.

Effects of Perinatal Cardamom Exposure on Social Behavior, Anxiety, Locomotor Activity, Blood Biochemical Parameters and Brain Acetylcholinesterase of Mice Offspring

BACKGROUND

Cardamom is the flavouring spices mainly cultivated all over the world. Apart from being used as the spice, it has many medicinal values. Therefore, the present study aimed to investigate the potential use of cardamom and its effects on the ability of learning, developmental, and various biochemical factors of Swiss-Webster mice offspring at different stages.

METHODS

In this method, Swiss-Webster mice offspring at different stages were used for the analysis of biochemical factors. After the administration of cardamom orally, the pups were subjected to various tests for determining social and defense behaviors of males and females, anxiety behavior; locomotor and neuromuscular activities, haemotological parameters, and hormonal factors of males and females.

RESULTS

The present findings indicate that the cardamom induced reduction in the social and defense behaviors of males and females, respectively, and also anxiety behavior. Interestingly, locomotor and neuromuscular activities decreased significantly.

DISCUSSION

In addition, the packed cell volume, red blood count, hemoglobin content, AChE in forebrain, the testosterone in males and progesterone in females were observed to increase significantly, whereas the blood platelets and total white blood count decreased non-significantly. Through perinatal exposure, cardamom can pass through the placenta or/and lactation and reaches the fetus. Care must be taken when using cardamom and especially during pregnancy and lactation.

CONCLUSION

The administration of cardamom enhances the ability of social, developmental, and various biochemical factors of Swiss-Webster mice offspring at different stages.

Monoamine and neuroendocrine gene-sets associate with frustration-based aggression in a gender-specific manner

Investigating phenotypic heterogeneity in aggression and understanding the molecular biological basis of aggression subtypes may lead to new prevention and treatment options. In the current study, we evaluated the taxonomy of aggression and examined specific genetic mechanisms underlying aggression subtypes in healthy males and females. Confirmatory Factor Analysis (CFA) was used to replicate a recently reported three-factor model of the Reactive Proactive Questionnaire (RPQ) in healthy adults (n = 661; median age 24.0 years; 41% male). Gene-set association analysis, aggregating common genetic variants within (a combination of) three molecular pathways previously implicated in aggression, i.e. serotonergic, dopaminergic, and neuroendocrine signaling, was conducted with MAGMA software in males and females separately (total n = 395) for aggression subtypes. We replicate the three-factor CFA model of the RPQ, and found males to score significantly higher on one of these factors compared to females: proactive aggression. The genetic association analysis showed a female-specific association of genetic variation in the combined gene-set with a different factor of the RPQ; reactive aggression due to internal frustration. Both the neuroendocrine and serotonergic gene-sets contributed significantly to this association. Our genetic findings are subtype- and sex-specific, stressing the value of efforts to reduce heterogeneity in research of aggression etiology. Importantly, subtype- and sex-differences in the underlying pathophysiology of aggression suggest that optimal treatment options will have to be tailored to the individual patient. Male and female needs of intervention might differ, stressing the need for sex-specific further research of aggression. Our work highlights opportunities for sample size maximization offered by population-based studies of aggression.

Biomarkers in aggression

Aggressive behavior exerts an enormous impact on society remaining among the main causes of worldwide premature death. Effective primary interventions, relying on predictive models of aggression that show adequate sensitivity and specificity are currently lacking. One strategy to increase the accuracy and precision of prediction would be to include biological data in the predictive models. Clearly, to be included in such models, biological markers should be reliably associated with the specific trait under study (i.e., diagnostic biomarkers). Aggression, however, is phenotypically highly heterogeneous, an element that has hindered the identification of reliable biomarkers. However, current research is trying to overcome these challenges by focusing on more homogenous aggression subtypes and/or by studying large sample size of aggressive individuals. Further advance is coming by bioinformatics approaches that are allowing the integration of inter-species biological data as well as the development of predictive algorithms able to discriminate subjects on the basis of the propensity toward aggressive behavior. In this review we first present a brief summary of the available evidence on neuroimaging of aggression. We will then treat extensively the data on genetic determinants, including those from hypothesis-free genome-wide association studies (GWAS) and candidate gene studies. Transcriptomic and neurochemical biomarkers will then be reviewed, and we will dedicate a section on the role of metabolomics in aggression. Finally, we will discuss how biomarkers can inform the development of new pharmacological tools as well as increase the efficacy of preventive strategies.

Systematic review and meta-analysis of basal cortisol levels in Borderline Personality Disorder compared to non-psychiatric controls

OBJECTIVE

Borderline personality disorder (BPD) is a prevalent, complex, and serious mental disorder involving multiple symptoms and maladaptive behaviour. The underlying psychobiological mechanisms involved are not yet fully understood, but increasing evidence indicates that changes in hypothalamic-pituitary-adrenal stress axis (HPA) activity may contribute to BPD. Whilst various studies have demonstrated elevated levels of cortisol (the end-product of the HPA axis) in BPD sufferers, others have presented opposite findings. Inconsistent findings may be attributable to comorbidities, collection and measurement methods, gender, and sample size. Considering these discrepancies, the aim of this systematic review and meta-analysis was to assess available studies in the scientific literature examining basal/ baseline cortisol levels in patients diagnosed with borderline personality disorder compared to non-psychiatric controls.

METHODS

A systematic literature review was conducted with descriptions of primary studies in addition to a meta-analysis of studies with a control group. Meta-analysis was performed using Comprehensive Meta-analysis software (CMA version 2). The effect size (Hedges' g) was calculated with random-effect model.

RESULTS

A systematic literature search identified 16 studies that met the eligibility criteria from a total of 1076 unique records initially examined. Twelve studies (N = 546; 278 borderline personality disorder and 268 non-psychiatric controls) fulfilled the inclusion criteria for meta-analysis. The standardised mean difference (Hedges' g) of basal cortisol level between BPD and control groups was -0.32 (pooled data from 12 studies; 95% confidence interval -0.56 to -0.06, p = 0.01), indicating significantly lower mean cortisol level for the BPD group.

CONCLUSION

Cortisol as a biomarker of the HPA axis is an important and helpful measure in the study of stress disorders such as BPD. However, considerations of potential confounding factors must be considered.

Testosterone-cortisol dissociation in children exposed to prenatal maternal stress, and relationship with aggression: Project Ice Storm

Prenatal maternal stress (PNMS) has been associated with postnatal behavioral alterations that may be partly explained by interactions between the hypothalamic-pituitary-adrenal (HPA) and hypothalamic-pituitary-gonadal (HPG) axes. Yet it remains unclear whether PNMS leads to enduring HPA-HPG alterations in the offspring, and whether HPA-HPG interactions can impact behavior during development, in particular levels of aggression in childhood. Here we investigated the relationship between a marker for HPG axis function (baseline testosterone) and a marker for HPA axis response (cortisol area under the curve) in 11½-year-olds whose mothers were exposed to the 1998 Quebec ice storm during pregnancy (n = 59 children; 31 boys, 28 girls). We examined (a) whether the degree of objective or subjective PNMS regulates the testosterone-cortisol relationship at age 11½, and (b) whether this testosterone-cortisol relationship is associated with differences in aggressive behavior. We found that, at lower levels of subjective PNMS, baseline testosterone and cortisol reactivity were positively correlated; in contrast, there was no relationship between these hormones at higher levels of subjective PNMS. Cortisol response moderated the relationship between testosterone and aggression. These results support the notion PNMS may explain variance in fetal HPA-HPG interactions, and that these interactions may be associated with aggressive behavior in late childhood.

Differences in serum steroid hormones concentrations in Spontaneously Hypertensive Rats (SHR) - an animal model of Attention-Deficit/Hyperactivity Disorder (ADHD)

Spontaneously hypertensive rats are the most common animal model used to study attention deficit hyperactivity disorder (ADHD). The present study investigated the levels of steroid hormones in the bloodstream of hypertensive rats and its normotensive control strain, Wistar-Kyoto rats, to check if there are any hormonal differences between both strains at the onset of ADHD. Plasma samples were collected from young (5-week-old) and mature (10-week-old) male hypertensive and normotensive rats to determine the serum level of testosterone, 17beta-estradiol, free estriol, progesterone, corticosterone and cortisol using ELISA kits. The results showed statistically significant increases in serum levels of testosterone and free estriol in 10-week-old hypertensive and normotensive rats when compared to 5-week-old animals. Moreover, the concentrations of progesterone, corticosterone and cortisol were significantly elevated in 10-week-old hypertensive rats when compared to 5-week-old animals of both strains as well as 10-week-old normotensive rats. Hormonal differences observed between 10-week-old hypertensive and normotensive rats were also accompanied by differences in the volumes of lateral ventricles as well as the third ventricle and cerebral aqueduct. In conclusion, elevated contents of progesterone, corticosterone and cortisol in hypertensive rats may be associated not only with ADHD but also with developing hypertension. This question needs further study.

The Neural Mechanisms of Sexually Dimorphic Aggressive Behaviors

Aggression is a fundamental social behavior that is essential for competing for resources and protecting oneself and families in both males and females. As a result of natural selection, aggression is often displayed differentially between the sexes, typically at a higher level in males than females. Here, we highlight the behavioral differences between male and female aggression in rodents. We further outline the aggression circuits in males and females, and compare their differences at each circuit node. Lastly, we summarize our current understanding regarding the generation of sexually dimorphic aggression circuits during development and their maintenance during adulthood. In both cases, gonadal steroid hormones appear to play crucial roles in differentiating the circuits by impacting on the survival, morphology, and intrinsic properties of relevant cells. Many other factors, such as environment and experience, may also contribute to sex differences in aggression and remain to be investigated in future studies.

Use of anti-gonadotropin-releasing hormone vaccines in African elephants (Loxodonta africana): A review

Background: Androgen-related aggressive behaviour and musth cause serious problems in captive African elephant bulls and often lead to human and animal injuries, and damage to property.Objectives: To review the work carried out with anti-gonadotropin-releasing hormone (GnRH) vaccines to control androgen-related behaviour and fertility in captive and free-ranging elephant bulls and the induction of anoestrus in elephant cows.Method: In the first study, an anti-GnRH vaccine from Pepscan was tested in six bulls (four captive and two free-ranging). Once the vaccine Improvac® became available, the effect on behaviour, the reproductive organs and semen quality was tested. Improvac® was also used to attempt induction of anoestrus in elephant cows.Results: The first study proved that aggressive behaviours are significantly associated with increased faecal androgen concentrations. Musth (n = 1) and aggressive behaviour (n = 2) were down regulated and correlated with a decline in faecal androgen concentrations. Aggression and musth could be controlled with Improvac® (600 µg), but were more consistent when the dose was increased to 1000 µg administered every five to six months. The same dose down regulated testicular function and bulls (n = 17) were rendered infertile within 12 months after commencement of treatment. Initial attempts to induce anoestrous with 600 µg in free-ranging elephant cows gave inconclusive results, but 1000 µg in captive cows delivered five-monthly was successful.Conclusion: The treatment of elephant bulls with Improvac® resulted in the successful down-regulation of androgen-related behaviour and sperm production in captive and wild elephant bulls of various ages (≤ 34 years). Preliminary studies to induce anoestrus in cows with Improvac® appear to be successful.

The Role of the Lateral Hypothalamus in Violent Intraspecific Aggression-The Glucocorticoid Deficit Hypothesis

This review argues for a central role of the lateral hypothalamus in those deviant forms of aggression, which result from chronic glucocorticoid deficiency. Currently, this nucleus is considered a key region of the mechanisms that control predatory aggression. However, recent findings demonstrate that it is strongly activated by aggression in subjects with a chronically downregulated hypothalamus-pituitary-adrenocortical (HPA) axis; moreover, this activation is causally involved in the emergence of violent aggression. The review has two parts. In the first part, we review human findings demonstrating that under certain conditions, strong stressors downregulate the HPA-axis on the long run, and that the resulting glucocorticoid deficiency is associated with violent aggression including aggressive delinquency and aggression-related psychopathologies. The second part addresses neural mechanisms in animals. We show that the experimental downregulation of HPA-axis function elicits violent aggression in rodents, and the activation of the brain circuitry that originally subserves predatory aggression accompanies this change. The lateral hypothalamus is not only an integral part of this circuitry, but can elicit deviant and violent forms of aggression. Finally, we formulate a hypothesis on the pathway that connects unfavorable social conditions to violent aggression via the neural circuitry that includes the lateral hypothalamus.

Acute Stress and Anxiety in Medical Residents on the Emergency Department Duty

The objectives of this longitudinal study were to compare salivary cortisol release patterns in medical residents and their self-perceived anxiety levels between a regular working day and a day when on call in the emergency department (ED-duty day) and to determine any differences in cortisol release pattern as a function of years of residency or sex. The study included 35 residents (physicians-in-training) of the Granada University Hospital, Granada, Spain. Acute stress was measured on a regular working day and an ED-duty day, evaluating anxiety-state with the Spanish version of the State-Trait Anxiety Inventory. Physiological stress assessment was based on salivary cortisol levels. Cortisol release concentrations were higher on an ED-duty day than on a regular working day, with a significantly increased area under the curve (AUC) (p < 0.006). This difference slightly attenuated with longer residency experience. No gender difference in anxiety levels was observed (p < 0.001). According to these findings, the hypothalamic-pituitary-adrenal axis activity and anxiety levels of medical residents are higher on an ED-duty day than on a regular working day.

A sex-specific dose-response curve for testosterone: could excessive testosterone limit sexual interaction in women?

Testosterone treatment increases sexual desire and well-being in women with hypoactive sexual desire disorder; however, many studies have shown only modest benefits limited to moderate doses. Unlike men, available data indicate women show a bell-shaped dose-response curve for testosterone, wherein a threshold dosage of testosterone leads to desirable sexual function effects, but exceeding this threshold results in a lack of further positive sexual effects or may have a negative impact. Emotional and physical side-effects of excess testosterone, including aggression and virilization, may counteract the modest benefits on sexual interaction, providing a possible explanation for a threshold dose of testosterone in women. In this commentary, we will review and critically analyze data supporting a curvilinear dose-response relationship between testosterone treatment and sexual activity in women with low libido, and also explore possible explanations for this observed relationship. Understanding optimal dosing of testosterone unique to women may bring us one step closer to overcoming regulatory barriers in treating female sexual dysfunction.

The role of trauma in the hormonal interplay of cortisol, testosterone, and oxytocin in adolescent aggression

Although numerous studies have examined the neuroendocrinology of aggression, the findings are mixed and focused on cortisol and testosterone. We argue that past findings remain inconclusive partly because the key roles of oxytocin and trauma have not been systematically integrated yet. Oxytocin is associated with social behavior and interacts with cortisol and testosterone, whereas trauma is a crucial risk factor of aggression that strongly affects hormonal activity. In this review, we investigate the role of trauma in the hormonal interplay of cortisol, testosterone, and oxytocin in aggression during adolescence. We first discuss how these hormones interact with each other and how trauma influences these interactions and then we propose a model that highlights the role of trauma in the hormonal interplay in aggression. We suggest that the timing of trauma has a distinct effect on hormonal activity and it should be integrated into any comprehensive model. Current trauma is linked to different levels of oxytocin, cortisol, testosterone, and testosterone/cortisol ratio than childhood trauma, but this distinction is also influenced by gender and type of aggression. We conclude that in order to better understand the neuroendocrinology of aggression, it is crucial to incorporate the investigation of oxytocin and trauma in future research.

Aggression as an independent entity even in psychosis - The role of cortisol

Aggression is a common entity in psychiatric disorders, particularly psychotic disorders. Glucocorticoid hypofunction has been linked to abnormal forms of aggressive behavior in various studies in a 'possibly causal' role. We hypothesise that aggression, even among those having psychosis is associated with glucocorticoid alterations similar to those who are aggressive but not psychotic. To our knowledge, this is the first study attempting to look at the cortisol functioning in relation to both aggression and psychosis. The present study included 80 participants divided into four groups depending upon presence or absence of aggression and psychosis. Morning cortisol, afternoon cortisol and their variability were measured using ELISA. The groups were compared on measures of aggression, psychosis, morning cortisol, afternoon cortisol and their variability using standard statistical instruments. The present study found lower levels of morning cortisol, afternoon cortisol and cortisol variability among the aggressive group (vs. non aggressive group) and among the diseased group (vs. non diseased group). The differences were most marked for cortisol variability which was related to both aggression and psychosis independently. There were statistically significant correlation between cortisol variability and aggression, which was retained even after controlling for psychosis. There was no significant correlation of cortisol variability with psychosis severity (after controlling for aggression score) or with age, gender or duration of psychosis. We conclude that aggression, even among patients with psychosis, is an independent entity characterized by lower levels of morning cortisol and cortisol variability. The etio-pathology may lie in some altered neuro-immune parameters executed by cortisol and psychosis as trigger.

Potential role of pre- and postnatal testosterone levels in attention-deficit/hyperactivity disorder: is there a sex difference?

OBJECTIVE

Both prenatal testosterone (T) exposure and postnatal T levels have been associated with developing neural circuitry and behavioral systems. This study examined the potential correlation between pre- and postnatal T levels and behavioral and neurocognitive profiles of children with attention-deficit/hyperactivity disorder (ADHD).

METHODS

Two hundred ADHD patients with a mean age of 8.7±2.0 years (158 boys and 42 girls) were recruited. The ratio of the length of the right index finger (2D) to that of the right ring finger (4D) (2D/4D ratio) served as a surrogate of prenatal T exposure, and postnatal T was determined using salivary T concentration. Behavioral symptoms were evaluated using the Swanson, Nolan, and Pelham - Version IV Scale for ADHD (SNAP-IV). Neurocognitive function was assessed using the Wechsler Intelligence Scale for Children - Fourth Edition (WISC-IV) and Conners' Continuous Performance Test (CPT).

RESULTS

Lower 2D/4D ratios were associated with comorbid disruptive behavior disorders (t=2.15, P=0.033) in all participants. Among the boys with ADHD, neither 2D/4D ratios nor salivary T levels were associated with behavioral symptoms or neurocognitive function. Among the girls with ADHD, the salivary T level was positively correlated with the Perceptual Reasoning Index of the WISC-IV (r=0.48, P=0.001) and the Confidence Index (r=0.37, P=0.017) and Omission Errors of the CPT (r=0.62, P<0.001).

CONCLUSION

Findings suggest that a higher prenatal T exposure is associated with a greater risk of developing disruptive behavior disorders, and T may exert differential neurocognitive effects between boys and girls with ADHD. However, the neurobiological mechanisms of T involved in the pathogenesis of ADHD warrant further investigation.

Discovery of biochemical biomarkers for aggression: A role for metabolomics in psychiatry

Human aggression encompasses a wide range of behaviors and is related to many psychiatric disorders. We introduce the different classification systems of aggression and related disorders as a basis for discussing biochemical biomarkers and then present an overview of studies in humans (published between 1990 and 2015) that reported statistically significant associations of biochemical biomarkers with aggression, DSM-IV disorders involving aggression, and their subtypes. The markers are of different types, including inflammation markers, neurotransmitters, lipoproteins, and hormones from various classes. Most studies focused on only a limited portfolio of biomarkers, frequently a specific class only. When integrating the data, it is clear that compounds from several biological pathways have been found to be associated with aggressive behavior, indicating complexity and the need for a broad approach. In the second part of the paper, using examples from the aggression literature and psychiatric metabolomics studies, we argue that a better understanding of aggression would benefit from a more holistic approach such as provided by metabolomics. © 2016 Wiley Periodicals, Inc.

The neurobiological basis of human aggression: A review on genetic and epigenetic mechanisms

Aggression is an evolutionary conserved behavior present in most species including humans. Inadequate aggression can lead to long-term detrimental personal and societal effects. Here, we differentiate between proactive and reactive forms of aggression and review the genetic determinants of it. Heritability estimates of aggression in general vary between studies due to differing assessment instruments for aggressive behavior (AB) as well as age and gender of study participants. In addition, especially non-shared environmental factors shape AB. Current hypotheses suggest that environmental effects such as early life stress or chronic psychosocial risk factors (e.g., maltreatment) and variation in genes related to neuroendocrine, dopaminergic as well as serotonergic systems increase the risk to develop AB. In this review, we summarize the current knowledge of the genetics of human aggression based on twin studies, genetic association studies, animal models, and epigenetic analyses with the aim to differentiate between mechanisms associated with proactive or reactive aggression. We hypothesize that from a genetic perspective, the aminergic systems are likely to regulate both reactive and proactive aggression, whereas the endocrine pathways seem to be more involved in regulation of reactive aggression through modulation of impulsivity. Epigenetic studies on aggression have associated non-genetic risk factors with modifications of the stress response and the immune system. Finally, we point to the urgent need for further genome-wide analyses and the integration of genetic and epigenetic information to understand individual differences in reactive and proactive AB. © 2015 Wiley Periodicals, Inc.

"Latent" infection with Toxoplasma gondii: association with trait aggression and impulsivity in healthy adults

BACKGROUND

Latent chronic infection with Toxoplasma gondii (T. gondii), a common neurotropic pathogen, has been previously linked with suicidal self-directed violence (SSDV). We sought to determine if latent infection with T. gondii is associated with trait aggression and impulsivity, intermediate phenotypes for suicidal behavior, in psychiatrically healthy adults.

METHODS

Traits of aggression and impulsivity were analyzed in relationship to IgG antibody seropositivity for T. gondii and two other latent neurotropic infections, herpes simplex virus 1 (HSV1) and cytomegalovirus (CMV). One thousand community-residing adults residing in the Munich metropolitan area with no Axis I or II conditions by SCID for DSM-IV (510 men, 490 women, mean age 53.6 ± 15.8, range 20-74). Plasma samples were tested for IgG antibodies to T. gondii, HSV-1 and CMV by ELISA. Self-reported ratings of trait aggression scores (Questionnaire for Measuring Factors of Aggression [FAF]) and trait impulsivity (Sensation-Seeking Scale-V [SSS-V]) were analyzed using linear multivariate methods.

RESULTS

T. gondii IgG seropositivity was significantly associated with higher trait reactive aggression scores among women (p < .01), but not among men. T. gondii-positivity was also associated with higher impulsive sensation-seeking (SSS-V Disinhibition) among younger men (p < .01) aged 20-59 years old (median age = 60). All associations with HSV-1 and CMV were not significant.

CONCLUSIONS

Aggression and impulsivity, personality traits considered as endophenotypes for SSDV, are associated with latent T. gondii infection in a gender and age-specific manner, and could be further investigated as prognostic and treatment targets in T. gondii-positive individuals at risk for SSDV.

Testosterone and its effects on human male adolescent mood and behavior: a systematic review

PURPOSE

During human puberty, there is an approximate 30-fold increase in testosterone production in boys. This increase is often linked to changes in mood and behavior in adolescence such as aggression, an increase in risk taking, and depression. The aim of this systematic review was to determine what evidence exists on the effects of endogenous testosterone on behavior and mood in males during adolescence.

METHODS

The following databases were searched: MEDLINE, Pre-MEDLINE, Education Resources Information Centre, PsycINFO, EMBASE, Scopus, and Web of Science. Only human studies were included. The study is community based, and the participants were healthy male adolescents within the age range of 9-18 years. Studies were required to have a validated mood and/or behavior assessment contemporaneous with a timed testosterone measurement.

RESULTS

A total of 27 studies met the inclusion criteria of which only one was a longitudinal study. The remaining 26 studies were cross sectional in their analysis. As a variety of measurement tools were used, no meta-analysis was possible. Most studies focused on aggression. The one longitudinal study looking at testosterone and aggression showed little relationship with concurrent changes in aggression. Most of the cross-sectional studies of adolescent males observed relationships between aggression and testosterone levels. With respect to other behaviors and moods and/or affect, no consistent relationships with testosterone were observed in cross-sectional studies.

CONCLUSIONS

This systematic review concludes that there are insufficient longitudinal data of high methodological quality to currently confirm that changing testosterone levels during puberty are significantly associated with mood and behavior in adolescent males. To discount these findings is to risk apportioning blame inappropriately and missing other important diagnoses in adolescent males.

The glucocorticoid/aggression relationship in animals and humans: an analysis sensitive to behavioral characteristics, glucocorticoid secretion patterns, and neural mechanisms

Glucocorticoids control a wide array of biological processes from glucose homeostasis to neuronal function. The mechanisms mediating their effects are similarly varied and include rapid and transient nongenomic effects on calcium trafficking, various neurotransmitter receptors, and other membrane/cytoplasmic proteins, as well as slowly developing but durable genomic effects that are mediated by a large number of glucocorticoid-sensitive genes that are affected after variable lag-times. Given this complexity, we suggest that the aggression/glucocorticoid relationship cannot be reduced to the simple "stimulation/inhibition" question. Here, we review the effects of glucocorticoids on aggression by taking into account the complexities of glucocorticoid actions. Acute and chronic effects were differentiated because these are mediated by different mechanisms. The effects of chronic increases and decreases in glucocorticoid production were discussed separately, because the activation of mechanisms that are not normally activated and the loss of normal functions should not be confounded. Findings in healthy/normal subjects and those obtained in subjects that show abnormal forms of behavior or psychopathologies were also differentiated, because the effects of glucocorticoids are indirect, and largely depend on the properties of neurons they act upon, which are altered in subjects with psychopathologies. In addition, the conditions of glucocorticoid measurements were also thoroughly evaluated. Although the role of glucocorticoids in aggression is perceived as controversial by many investigators, a detailed analysis that is sensitive to glucocorticoid and behavioral measure as well as to the mediating mechanism suggests that this role is rather clear-cut; moreover, there is a marked similarity between animal and human findings.

Youth bullying: a review of the science and call to action

Recognized as a critical public health problem, youth bullying is reportedly experienced by approximately 20% of today's youths. In the last decade, attention to bullying has increased and the scientific knowledge base relevant for practitioners who treat youths, research their issues, and create policy has expanded. The purpose of this review is to highlight key developments related to the health effects of bullying, interventions aimed at curbing bullying behaviors, the measurement of bullying, and nursing's disciplinary response to this phenomenon. A call to action for nurses involved in caring for youths across settings and roles is offered and strategic actions for nursing professionals are provided.

Surging Hormones: Brain-Behavior Interactions During Puberty

In this paper we discuss the surging hormones of puberty and their influences on adolescent behavior. We describe why these issues represent an interesting and important area of investigation, emphasizing their contributions to a specific set of developmental processes at the heart of the transition from childhood to adolescence. We briefly review the neuroendocrine underpinnings of human puberty. Our review focuses on evidence for behavioral (and neurobehavioral) effects of gonadal hormones, and emphasizes the social and affective dimensions of these hormonal effects. More broadly, we consider how these hormonal events contribute to brain-behavior interactions that can bias early adolescent trajectories in both positive and negative directions, and in ways that may begin as small influences, but can spiral into large-scale effects over time. These influences also appear to play an important role in functional and structural brain development during adolescence. Finally we offer some thoughts on directions for future research in these areas.

Childhood bullying: a review of constructs, concepts, and nursing implications

Bullying among children as a pervasive problem has been increasingly recognized as an important public health issue. However, while much attention has been given to understanding the impact of bullying on victims, it is equally important to examine predictors of bullying and potential outcomes for bullies themselves. The current literature on bullying lacks consensus on a utilizable definition of bullying in research, which can vary by theoretical framework. In an attempt to bridge the gaps in the literature, this article will provide a review of the state of the science on bullying among children, including the major theoretical constructs of bullying and their respective viewpoints on predictors and correlates of bullying. A secondary aim of this article is to summarize empirical evidence for predictors of bullying and victimization, which can provide strategies for intervention and prevention by public health nursing professionals. By calling attention to the variability in the bullying literature and the limitations of current evidence available, researchers can better address methodological gaps and effectively move toward developing studies to inform nursing treatment programs and enhance public health initiatives that reduce violence in school settings.

Genetic determinants of aggression and impulsivity in humans

Human aggression/impulsivity-related traits have a complex background that is greatly influenced by genetic and non-genetic factors. The relationship between aggression and anxiety is regulated by highly conserved brain regions including amygdala, which controls neural circuits triggering defensive, aggressive, or avoidant behavioral models. The dysfunction of neural circuits responsible for emotional control was shown to represent an etiological factor of violent behavior. In addition to the amygdala, these circuits also involve the anterior cingulated cortex and regions of the prefrontal cortex. Excessive reactivity in the amygdala coupled with inadequate prefrontal regulation serves to increase the likelihood of aggressive behavior. Developmental alterations in prefrontal-subcortical circuitry as well as neuromodulatory and hormonal abnormality appear to play a role. Imbalance in testosterone/serotonin and testosterone/cortisol ratios (e.g., increased testosterone levels and reduced cortisol levels) increases the propensity toward aggression because of reduced activation of the neural circuitry of impulse control and self-regulation. Serotonin facilitates prefrontal inhibition, and thus insufficient serotonergic activity can enhance aggression. Genetic predisposition to aggression appears to be deeply affected by the polymorphic genetic variants of the serotoninergic system that influences serotonin levels in the central and peripheral nervous system, biological effects of this hormone, and rate of serotonin production, synaptic release and degradation. Among these variants, functional polymorphisms in the monoamine oxidase A (MAOA) and serotonin transporter (5-HTT) may be of particular importance due to the relationship between these polymorphic variants and anatomical changes in the limbic system of aggressive people. Furthermore, functional variants of MAOA and 5-HTT are capable of mediating the influence of environmental factors on aggression-related traits. In this review, we consider genetic determinants of human aggression, with special emphasis on genes involved in serotonin and dopamine metabolism and function.

Androgen levels and anger and impulsivity measures as predictors of physical, verbal and indirect aggression in boys and girls

Previous studies indicate that androgen levels and certain psychological characteristics such as anger and impulsivity are related to the development and maintenance of aggression. Further studies are required to analyze the potential predictor role of the interaction of said factors on aggressive behavior. 90 nine-year-old children (44 boys and 46 girls) were assessed in relation to their levels of physical, verbal and indirect aggression, using a peer-rating technique. Testosterone and androstenedione levels were analyzed using an enzymoimmunoassay technique in saliva samples. Anger (state and trait) and anger control were measured using the STAXI-NA, and impulsivity was measured through the MFF-20. A General Linear Model revealed that sex was the best predictor for aggression measures, with boys scoring higher than girls in physical, verbal and indirect aggression; after sex, testosterone was found to be the best predictor (in a positive sense) of all three types of aggressive behavior studied. In addition to observing a main effect of androstenedione on physical and verbal aggression, a 'state anger*androstenedione' interaction was found to predict these types of aggression, with androstenedione acting as a moderator (inhibitor) of the effects of anger on these behaviors; also, a 'state anger*testosterone' interaction was found to predict verbal aggression. The results support the idea that, after sex, androgens constitute a biological marker to be taken into consideration in relation to individual differences in aggressive behavior. It is possible that at the age of 9, testosterone tends to increase aggression, while androstenedione tends to moderate (inhibit) the effects of anger on aggression.