Toward a More Valid Assessment of Behavioral Aggression: An Open Source Platform and an Empirically Derived Scoring Method for Using the Competitive Reaction Time Task (CRTT)

While the Competitive Reaction Time Task (CRTT) is the most used behavioral aggression paradigm, it is characterized by methodological heterogeneity and quantification strategies for its' outcome are unstandardized. Therefore, the standards of measuring aggression should be improved. This article contributes on such an improvement by providing: (a) a freely available CRTT online administration program, and (b) a factor-analytically derived scoring method. Based on a combined sample (n = 423), a two-factor model was fit to the 30-trial CRTT version. The first factor included all trial scores subsequent to the first time the participant received aversive feedback (i.e., provoked factor) and the second factor included all trial scores prior to this first aversive feedback (i.e., unprovoked factor). Construct validity was evidenced based on the factors` differential relationship with self-reported aggression and narcissism. Our factor analytic findings empirically support the superiority of one of the existing CRTT scoring methods, that is, separately averaging all preprovocation versus all postprovocation trials. We discuss practical recommendations for CRTT users and outline future empirical avenues. This article aims at stimulating joint efforts to move toward standardization of CRTT implementation and outcome measure analysis.

Cognitive predictors of reactive and proactive aggression in a forensic sample: A comparison with a non-clinical sample

This study aimed at examining cognitive predictors of reactive and proactive aggression in a forensic-psychiatric (n = 80) and a non-clinical sample (n = 98; Brugman et al., 2015). Three different cognitive predictors were incorporated: (1) attentional bias towards aggressive stimuli (measured with Emotional Stroop task) and towards angry faces (measured with a visual search task); (2) interpretation biases (measured with Aggressive Interpretative Bias Task (AIBT) and a vignette task), and (3) implicit self-aggression association (measured with a Single-Target Implicit Association Task). To measure aggression, the Reactive-Proactive Aggression Questionnaire (RPQ) and the Taylor Aggression Paradigm (TAP) were used. An automatic self-aggression association positively predicted proactive aggressive behavior on the TAP in both samples. Furthermore, this self-aggression association predicted, increased self-reported proactive aggression (RPQ) in the forensic sample only. Pain, injury, and danger interpretations reported on the vignettes, negatively predicted self-reported proactive aggression in both samples. A stronger aggressive interpretation bias on the AIBT predicted more reactive aggressive behavior (TAP) in the non-clinical sample only. Taken together, findings show both common and distinct mechanisms in reactively vs. proactively driven aggressive behavior.

Oral cholera vaccination promotes homing of IgA+ memory B cells to the large intestine and the respiratory tract

Oral cholera vaccination is used to induce immune responses in the intestines to protect against cholera infection. However, oral vaccination may also affect immune responses in other mucosal tissues. To study this, tissue-specific homing potential and kinetics of B-cell responses were characterized after oral cholera vaccination. Healthy adult volunteers received two doses of Dukoral® and blood, saliva, nasal wash, and fecal samples were collected over time to detect vaccine-specific antibodies. Additionally, homing potential of lymphocytes to small intestine, colon, airways, skin, and periphery was measured by expression of Integrin β1 and β7, CCR9, CCR10, CCR7, and CLA. After vaccination, antibody responses to cholera toxin B (CTB) and Dukoral® were detected in serum and nasal wash. CTB-specific memory B cells in peripheral blood and tissue homing profiles of memory B cells peaked at day 18. IgA⁺ memory B cells expressed markers that enable homing to the airways and colon, while IgA^- memory B cells primarily expressed small-intestine-homing markers. These data show that oral cholera vaccination has a differential effect on immune responses in various mucosal sites, including the respiratory tract.

Lack of correspondence between the reactive proactive questionnaire and the impulsive premeditated aggression scale among forensic psychiatric outpatients

The most studied bimodal classifications of aggressive behavior are the impulsive/premeditated distinction measured with the Impulsive Premeditated Aggression Scale and the reactive/proactive distinction measured with the Reactive Proactive Questionnaire. The terms of these classifications are often used interchangeably, assuming that reactive aggression is equivalent to impulsive aggression and that proactive aggressive behavior is the same as premeditated aggression. The correspondence or discrepancy between both aggression classifications/questionnaires, however, is understudied. Therefore, the current study investigated the correspondence between the RPQ and IPAS in a sample of 161 forensic psychiatric outpatients (FPOs) with severe aggressive behavior. Correlation analysis revealed a limited correspondence between the RPQ and IPAS. Cluster analyses derived three clusters from the RPQ as well as the IPAS: these clusters did not match in 60.3% of the cases. Furthermore, the notion that the RPQ measures trait aggression whereas the IPAS assesses state aggression could not be verified. The present study indicates that aggression subtypes as measured by use of the RPQ and IPAS correspond only partially and should not be used interchangeably. Furthermore, it was suggested that RPQ focuses more on actual aggressive behavior and the IPAS more on emotions and their regulation. Future research is needed to elucidate the applicability of both questionnaires in further detail.

Examining the reactive proactive questionnaire in adults in forensic and non-forensic settings: A variable- and person-based approach

The Reactive Proactive Questionnaire (RPQ) was originally developed to assess reactive and proactive aggressive behavior in children. Nevertheless, some studies have used the RPQ in adults. This study examines the reliability of the RPQ within an adult sample by investigating whether reactive and proactive aggression can be distinguished at a variable- and person-based level. Male adults from forensic samples (N = 237) and from the general population (N = 278) completed the RPQ questionnaire. Variable-based approaches, including factor analyses, were conducted to verify the two-factor model of the RPQ and to examine alternative factor solutions of the 23 items. Subsequently, a person-based approach, i.e., Latent Class Analysis (LCA), was executed to identify homogeneous classes of subjects with similar profiles of aggression in the observed data. The RPQ proved to have sufficient internal consistency. Multiple-factor models were examined, but the original two-factor model was statistically and theoretically considered as most solid and in line with previous research. The multi-level LCA identified three different classes of aggression severity (class 1 showed low aggressive behavior; class 2 subjects displayed modest aggression levels; and class 3 exhibited the highest level of aggressive behavior). In addition, class 1 and 2 showed more reactive than proactive aggression, whereas class 3 displayed comparable levels of reactive/proactive aggression. The RPQ appears to have clinical relevance for adult populations in the way that it can distinguish severity levels of aggression. Before the RPQ is implemented in adult populations, norm scores need to be developed. Aggr. Behav. 43:155-162, 2017. © 2016 Wiley Periodicals, Inc.

The Role of the Insular Cortex in Retaliation

The insular cortex has consistently been associated with various aspects of emotion regulation and social interaction, including anger processing and overt aggression. Aggression research distinguishes proactive or instrumental aggression from retaliation, i.e. aggression in response to provocation. Here, we investigated the specific role of the insular cortex during retaliation, employing a controlled behavioral aggression paradigm implementing different levels of provocation. Fifteen healthy male volunteers underwent whole brain functional magnetic resonance imaging (fMRI) to identify brain regions involved in interaction with either a provoking or a non-provoking opponent. FMRI group analyses were complemented by examining the parametric modulations of brain activity related to the individual level of displayed aggression. These analyses identified a hemispheric lateralization as well as an anatomical segregation of insular cortex with specifically the left posterior part being involved in retaliation. The left-lateralization of insular activity during retaliation is in accordance with evidence from electro-physiological studies, suggesting left-lateralized fronto-cortical dominance during anger processing and aggressive acts. The posterior localization of insular activity, on the other hand, suggests a spatial segregation within insular cortex with particularly the posterior part being involved in the processing of emotions that trigger intense bodily sensations and immediate action tendencies.

Cognitive predictors of violent incidents in forensic psychiatric inpatients

This study tested the predictive value of attentional bias, emotion recognition, automatic associations, and response inhibition, in the assessment of in-clinic violent incidents. Sixty-nine male forensic patients participated and completed an Emotional Stroop to measure attentional bias for threat and aggression, a Single Target - Implicit Association Task to assess automatic associations, a Graded Emotional Recognition Task to measure emotion recognition, and an Affective Go/NoGo to measure response inhibition. Violent incidents were derived from patient files and scored on severity level. The predictive value of level of psychopathy was tested with the Psychopathy Checklist - Revised (PCL-R). Generalized linear mixed model analyses showed that increased attention towards threat and aggression, difficulty recognizing sad faces and factor 2 of the PCL-R predicted the sum of violent incidents. Specifically, verbal aggression was predicted by increased attention towards threat and aggression, difficulty to recognize sad and happy faces, and PCL-R factor 2; physical aggression by decreased response inhibition, higher PCL-R factor 2 and lower PCL-R factor 1 scores; and aggression against property by difficulty recognizing angry faces. Findings indicate that cognitive tasks could be valuable in predicting aggression, thereby extending current knowledge on dynamic factors predicting aggressive behavior in forensic patients.

No Effects of Bilateral tDCS over Inferior Frontal Gyrus on Response Inhibition and Aggression

Response inhibition is defined as the capacity to adequately withdraw pre-planned responses. It has been shown that individuals with deficits in inhibiting pre-planned responses tend to display more aggressive behaviour. The prefrontal cortex is involved in both, response inhibition and aggression. While response inhibition is mostly associated with predominantly right prefrontal activity, the neural components underlying aggression seem to be left-lateralized. These differences in hemispheric dominance are conceptualized in cortical asymmetry theories on motivational direction, which assign avoidance motivation (relevant to inhibit responses) to the right and approach motivation (relevant for aggressive actions) to the left prefrontal cortex. The current study aimed to directly address the inverse relationship between response inhibition and aggression by assessing them within one experiment. Sixty-nine healthy participants underwent bilateral transcranial Direct Current Stimulation (tDCS) to the inferior frontal cortex. In one group we induced right-hemispheric fronto-cortical dominance by means of a combined right prefrontal anodal and left prefrontal cathodal tDCS montage. In a second group we induced left-hemispheric fronto-cortical dominance by means of a combined left prefrontal anodal and right prefrontal cathodal tDCS montage. A control group received sham stimulation. Response inhibition was assessed with a go/no-go task (GNGT) and aggression with the Taylor Aggression Paradigm (TAP). We revealed that participants with poorer performance in the GNGT displayed more aggression during the TAP. No effects of bilateral prefrontal tDCS on either response inhibition or aggression were observed. This is at odds with previous brain stimulation studies applying unilateral protocols. Our results failed to provide evidence in support of the prefrontal cortical asymmetry model in the domain of response inhibition and aggression. The absence of tDCS effects might also indicate that the methodological approach of shifting cortical asymmetry by means of bilateral tDCS protocols has failed.

Reducing proactive aggression through non-invasive brain stimulation

Aggressive behavior poses a threat to human collaboration and social safety. It is of utmost importance to identify the functional mechanisms underlying aggression and to develop potential interventions capable of reducing dysfunctional aggressive behavior already at a brain level. We here experimentally shifted fronto-cortical asymmetry to manipulate the underlying motivational emotional states in both male and female participants while assessing the behavioral effects on proactive and reactive aggression. Thirty-two healthy volunteers received either anodal transcranial direct current stimulation to increase neural activity within right dorsolateral prefrontal cortex, or sham stimulation. Aggressive behavior was measured with the Taylor Aggression Paradigm. We revealed a general gender effect, showing that men displayed more behavioral aggression than women. After the induction of right fronto-hemispheric dominance, proactive aggression was reduced in men. This study demonstrates that non-invasive brain stimulation can reduce aggression in men. This is a relevant and promising step to better understand how cortical brain states connect to impulsive actions and to examine the causal role of the prefrontal cortex in aggression. Ultimately, such findings could help to examine whether the brain can be a direct target for potential supportive interventions in clinical settings dealing with overly aggressive patients and/or violent offenders.

Identifying cognitive predictors of reactive and proactive aggression

The aim of this study was to identify implicit cognitive predictors of aggressive behavior. Specifically, the predictive value of an attentional bias for aggressive stimuli and automatic association of the self and aggression was examined for reactive and proactive aggressive behavior in a non-clinical sample (N = 90). An Emotional Stroop Task was used to measure an attentional bias. With an idiographic Single-Target Implicit Association Test, automatic associations were assessed between words referring to the self (e.g., the participants' name) and words referring to aggression (e.g., fighting). The Taylor Aggression Paradigm (TAP) was used to measure reactive and proactive aggressive behavior. Furthermore, self-reported aggressiveness was assessed with the Reactive Proactive Aggression Questionnaire (RPQ). Results showed that heightened attentional interference for aggressive words significantly predicted more reactive aggression, while lower attentional bias towards aggressive words predicted higher levels of proactive aggression. A stronger self-aggression association resulted in more proactive aggression, but not reactive aggression. Self-reports on aggression did not additionally predict behavioral aggression. This implies that the cognitive tests employed in our study have the potential to discriminate between reactive and proactive aggression. Aggr. Behav. 41:51-64 2015. © 2014 Wiley Periodicals, Inc.

Out of control: evidence for anterior insula involvement in motor impulsivity and reactive aggression

Inhibiting impulsive reactions while still defending one's vital resources is paramount to functional self-control and successful development in a social environment. However, this ability of successfully inhibiting, and thus controlling one's impulsivity, often fails, leading to consequences ranging from motor impulsivity to aggressive reactions following provocation. Although inhibitory failure represents the underlying mechanism, the neurocognition of social aggression and motor response inhibition have traditionally been investigated in separation. Here, we aimed to directly investigate and compare the neural mechanisms underlying the failure of inhibition across those different modalities of self-control. We used functional imaging to reveal the overlap in neural correlates between failed motor response inhibition (measured by a go/no-go task) and reactive aggression (measured by the Taylor aggression paradigm) in healthy males. The core overlap of neural correlates was located in the anterior insula, suggesting common anterior insula involvement in motor impulsivity as well as reactive aggression. This evidence regarding an overarching role of the anterior insula across different modalities of self-control enables an integrative perspective on insula function and a better integration of cognitive, social and emotional factors into a comprehensive model of impulsivity. Furthermore, it can eventually lead to a better understanding of clinical syndromes involving inhibitory deficits.

Restoration of impaired intestinal barrier function by the hydrolysed casein diet contributes to the prevention of type 1 diabetes in the diabetes-prone BioBreeding rat

AIMS/HYPOTHESIS

Impaired intestinal barrier function is observed in type 1 diabetes patients and animal models of the disease. Exposure to diabetogenic antigens from the intestinal milieu due to a compromised intestinal barrier is considered essential for induction of the autoimmune process leading to type 1 diabetes. Since a hydrolysed casein (HC) diet prevents autoimmune diabetes onset in diabetes-prone (DP)-BioBreeding (BB) rats, we studied the role of the HC diet on intestinal barrier function and, therefore, prevention of autoimmune diabetes onset in this animal model.

METHODS

DP-BB rats were fed the HC diet from weaning onwards and monitored for autoimmune diabetes development. Intestinal permeability was assessed in vivo by lactulose-mannitol test and ex vivo by measuring transepithelial electrical resistance (TEER). Levels of serum zonulin, a physiological tight junction modulator, were measured by ELISA. Ileal mRNA expression of Myo9b, Cldn1, Cldn2 and Ocln (which encode the tight junction-related proteins myosin IXb, claudin-1, claudin-2 and occludin) and Il-10, Tgf-ß (also known as Il10 and Tgfb, respectively, which encode regulatory cytokines) was analysed by quantitative PCR.

RESULTS

The HC diet reduced autoimmune diabetes by 50% in DP-BB rats. In DP-BB rats, prediabetic gut permeability negatively correlated with the moment of autoimmune diabetes onset. The improved intestinal barrier function that was induced by HC diet in DP-BB rats was visualised by decreasing lactulose:mannitol ratio, decreasing serum zonulin levels and increasing ileal TEER. The HC diet modified ileal mRNA expression of Myo9b, and Cldn1 and Cldn2, but left Ocln expression unaltered.

CONCLUSIONS/INTERPRETATION

Improved intestinal barrier function might be an important intermediate in the prevention of autoimmune diabetes by the HC diet in DP-BB rats. Effects on tight junctions, ileal cytokines and zonulin production might be important mechanisms for this effect.

Prolonged exclusive breastfeeding reduces autoimmune diabetes incidence and increases regulatory T-cell frequency in bio-breeding diabetes-prone rats

BACKGROUND

Previously, we reported that exclusive breastfeeding delayed and partially protected bio-breeding diabetes-prone (BBDP) rats from spontaneous autoimmune diabetes development. To investigate whether this protection results from modulation of the (mucosal) immune system, the present study was designed to analyse the effect of nutrition early in life on the immune status of BBDP rats.

METHODS

The breastfeeding period of BBDP pups was extended or not, while allowing half of the pups to eat during that period whereas the other half received only breast milk. Cytokine profiles as well as naturally occurring regulatory T-cell frequencies were measured over time in the mesenteric lymph nodes (MLNs) and spleen.

RESULTS

Prolonged exclusive breastfeeding partially protects against autoimmune diabetes development and resulted in elevated levels of natural regulatory T cells (CD4(+) CD25(+) FoxP3(+)) in MLNs and spleen directly after weaning and throughout life. Stimulation of MLN cells from rats that ingested solid food during the nursing period showed massive secretion of interferon gamma (IFN-gamma), interleukin (IL)-4 and IL-10, whereas MLN cells from exclusive breastfed rats did not. In contrast, transforming growth factor beta (TGF-ss) was secreted equally by all groups.

CONCLUSIONS

Prolonged exclusive breastfeeding partially protects BBDP rats from autoimmune diabetes development. Interestingly, ingestion of solid food during the weaning period completely abolishes this protective effect. The protective effect of exclusive breastfeeding correlates with higher levels of naturally occurring regulatory T cells throughout life and low cytokine secretion at weaning.

Antibiotic treatment partially protects against type 1 diabetes in the Bio-Breeding diabetes-prone rat. Is the gut flora involved in the development of type 1 diabetes?

AIMS/HYPOTHESIS

Accumulating data suggest that the gut immune system plays a role in the development of type 1 diabetes. The intestinal flora is essential for the development of the (gut) immune system and the establishment of tolerance. It has been reported that oral administration of food and bacterial antigens early in life suppresses later development of diabetes in the Bio-Breeding diabetes-prone (BB-DP) rat. This study was designed to investigate the possible relationship between the development of diabetes and the composition of intestinal flora.

MATERIALS AND METHODS

The intestinal flora of BB-DP rats, a rat model for type 1 diabetes, was characterised long before the clinical onset of diabetes by fluorescent in situ hybridisation. In a separate experiment, BB-DP rats were treated with antibiotics and the effect on diabetes incidence and level of insulitis was analysed.

RESULTS

We observed a difference in bacterial composition between rats that eventually did and those that did not develop diabetes. This difference was detectable long before clinical onset of the disease. Rats that did not develop diabetes at a later age displayed a lower amount of Bacteroides sp. Modulation of the intestinal flora through antibiotic treatment decreased the incidence and delayed the onset of diabetes. A combination of antibiotic treatment and a protective hydrolysed casein diet completely prevented diabetes in the BB-DP rat.

CONCLUSIONS/INTERPRETATION

Our data suggest that the intestinal flora is involved in the development of type 1 diabetes. Factors influencing composition of the intestinal flora could be a target for therapeutic intervention.

Neonatal oral administration of DiaPep277, combined with hydrolysed casein diet, protects against Type 1 diabetes in BB-DP rats. An experimental study

AIMS/HYPOTHESIS

Environmental factors such as diet and bacterial antigens play an important role in the onset of Type 1 diabetes. Different self-antigens are suggested to play a role in the development of diabetes. Antibodies against the 60-kDa heat shock protein 60, which have a high homology to bacterial heat shock protein 65, have been found in the circulation at the onset of diabetes in humans and in pre-diabetic NOD-mice. One of the immunodominant epitopes in autoimmune diabetes is p277, a specific peptide of human heat shock protein 60 corresponding to positions 437-460. In this study we investigated whether neonatal oral administration of DiaPep277 (a synthetic peptide analogue of p277) affected the development of diabetes in the BioBreeding-Diabetes Prone (BB-DP) rat, and whether this could potentiate the effect of a protective hydrolysed casein-diet.

METHODS

BB-DP rats were orally inoculated once per day with placebo or DiaPep277 at days 4, 5, 6 and 7 of life. At the age of 21 days rats were weaned on to a conventional, cereal-based diet or on to the hydrolysed casein-diet.

RESULTS

The development of diabetes in animals receiving DiaPep277 in combination with the hydrolysed casein-diet was delayed by 17 days, and a relative reduction of the incidence by 64% was seen. Non-diabetic animals did not show any sign of insulitis.

CONCLUSIONS/INTERPRETATION

Short-term neonatal feeding with p277 in early life, combined with diet adaptation, appears to provide a procedure to significantly reduce the development of Type 1 diabetes in later life.

Combined blockade of both micro - and kappa-opioid receptors prevents the acute orexigenic action of Agouti-related protein

Agouti-related protein (AgRP) is an endogenous antagonist at the melanocortin 3 and 4 receptor in the hypothalamus. Central administration of AgRP produces a robust increase in food intake, and this effect can be blocked by administration of nonspecific opioid receptor antagonist. Such results implicate opioid receptors as critical to mediating the effects of AgRP. To determine which opioid receptor subtype is critical, we first determined the highest i3vt (administered into the third ventricle) dose of two specific opioid antagonists, nor-Binaltorphine or beta-funaltrexamine, that did not influence food intake on their own. Then, rats were pretreated with either of these two antagonists before i3vt AgRP and access to a high-fat diet. For neither the kappa- nor the micro -specific antagonist was there any effect to block the effects of AgRP on food intake. However, administration of both the kappa- and micro -receptor antagonists does significantly reduce the effect of AgRP. The current results implicate opioid receptors as critical downstream mediators of the potent effects of AgRP to increase food intake but indicate that either micro - or kappa-receptor activation is sufficient for AgRP's effect.

Psychological and family characteristics of adolescents with vocal cord dysfunction

Vocal cord dysfunction (VCD) is a respiratory disorder often confused with asthma. Although previous case reports have implicated family and/or individual psychopathology in the etiology of this condition, this is the first paper to present prospective, case-control empirical data on a group of pediatric patients with VCD. A case-control methodology was employed to examine patients in terms of both family and individual functioning. Results indicate that patients with VCD were not different from asthmatic controls on measures of family functioning. However, they did experience significantly higher levels of anxiety and received a higher number of anxiety-related diagnoses such as separation anxiety and generalized anxiety disorder on a structured psychiatric interview. The nature of the relation between VCD and psychological symptoms in children is discussed. Etiologic and treatment issues are examined in the context of the findings.

Laparoscopic fundoplication to enhance pulmonary function in children with severe reactive airway disease and gastroesophageal reflux disease

BACKGROUND

The relationship between severe reactive airway disease (RAD) and gastroesophageal reflux disease (GERD) has been noted but the relationship is poorly understood. This study reports our experience with laparoscopic fundoplication and its effect on the pulmonary status of children with severe steroid-dependent reactive airway disease.

METHODS

Fifty-six patients with severe steroid-dependent RAD and medically refractory GERD underwent laparoscopic Nissen fundoplications. Mean age was 7 years and mean weight was 20 kg. All patients had the procedure completed successfully laparoscopically with an average operative time of 62 min. Average hospital stay was 1.6 days.

RESULTS

Forty-eight of 56 patients noted significant improvement in their respiratory symptoms in the first week. Fifty of 56 patients have been weaned off their oral steroids and four others have had a greater than 50% decrease in their dose. Sixteen patients had a documented increase in their FEV1 in the initial postoperative period (avg. 26%).

CONCLUSION

Patients with steroid-dependent RAD and GERD refractory to medical management show improvement in their respiratory status following fundoplication and the majority can be weaned off of their oral steroids. Laparoscopic techniques allow this procedure to be performed safely even in this high-risk group of patients.