Impulsive and episodic disorders of aggressive behaviour following traumatic brain injury

Pediatric suicide: Review of a preventable tragedy

Concepts of suicide are explored in this issue with a focus on suicide in children and adolescents. The epidemiology of pediatric suicide in the United States is reviewed; also, risk and protective factors, as well as prevention strategies, are discussed. Suicide in the pediatric athlete and the potential protective effect of exercise are examined. In addition, this analysis addresses the beneficial role of psychological management as well as current research on pharmacologic treatment and brain stimulation procedures as part of comprehensive pediatric suicide prevention. Though death by suicide in pediatric persons has been and remains a tragic phenomenon, there is much that clinicians, other healthcare professionals, and society itself can accomplish in the prevention of pediatric suicide as well as the management of suicidality in our children and adolescents.

Social deficits mirror delayed cerebrovascular dysfunction after traumatic brain injury

Traumatic brain injury (TBI) survivors face debilitating long-term psychosocial consequences, including social isolation and depression. TBI modifies neurovascular physiology and behavior but the chronic physiological implications of altered brain perfusion on social interactions are unknown. Adult C57/BL6 male mice received a moderate cortical TBI, and social behaviors were assessed at baseline, 3-, 7-, 14-, 30-, and 60-days post injury (dpi). Magnetic resonance imaging (MRI, 9.4T) using dynamic susceptibility contrast perfusion weighted MRI were acquired. At 60dpi mice underwent histological angioarchitectural mapping. Analysis utilized standardized protocols followed by cross-correlation metrics. Social behavior deficits at 60dpi emerged as reduced interactions with a familiar cage-mate (partner) that mirrored significant reductions in cerebral blood flow (CBF) at 60dpi. CBF perturbations were dynamic temporally and across brain regions including regions known to regulate social behavior such as hippocampus, hypothalamus, and rhinal cortex. Social isolation in TBI-mice emerged with a significant decline in preference to spend time with a cage mate. Cortical vascular density was also reduced corroborating the decline in brain perfusion and social interactions. Thus, the late emergence of social interaction deficits mirrored the reduced vascular density and CBF in regions known to be involved in social behaviors. Vascular morphology and function improved prior to the late decrements in social function and our correlations strongly implicate a linkage between vascular density, cerebral perfusion, and social interactions. Our study provides a clinically relevant timeline of alterations in social deficits alongside functional vascular recovery that can guide future therapeutics.

Social disinhibition in acquired brain injury and neurological disease: a concept analysis

BACKGROUND

Social disinhibition is becoming increasingly recognised in the neuropsychological literature as a complex and debilitating sequalae associated with acquired frontal lobe damage. Despite this, the term has been inconsistently defined and described in both clinical and research contexts. The purpose of this paper was to explore and examine the concept of social disinhibition in the context of brain injury and other organic neurological conditions.

METHOD

A literature search for articles published in the English language from journal inception to June 2021 was conducted using MEDLINE, PsycInfo, Embase, CINAHL and Web of Science. A 'concept analysis' was conducted on the identified literature using Walker & Avant's (2019) framework.

RESULTS

The analysis suggested that while several terms are often used interchangeably with social disinhibition, including impulsivity and behavioural dysregulation, these terms may be differentiated and defined separately within the broader domain of 'behaviours of concern'. Attributes, antecedents and consequences of social disinhibition were also identified and discussed.

CONCLUSIONS

Clarifying the concept of social disinhibition has important implications in both clinical and research contexts, including increased understanding of the behaviours, more accurate estimates of incidence and prevalence, and the development and implementation of targeted rehabilitation programmes.

Intact moral decision-making in adults with moderate-severe traumatic brain injury

Background and aim

Deficits in decision-making are a common consequence of moderate-severe traumatic brain injury (TBI). Less is known, however, about how individuals with TBI perform on moral decision-making tasks. To address this gap in the literature, the current study probed moral decision-making in a sample of individuals with TBI using a widely employed experimental measure.

Methods/hypothesis

We administered a set of 50 trolley-type dilemmas to 31 individuals with TBI and 31 demographically matched, neurotypical comparison participants. We hypothesized that individuals with TBI would be more likely to offer utilitarian responses to personal dilemmas than neurotypical peers.

Results

In contrast to our hypothesis, we observed that individuals with TBI were not more likely to offer utilitarian responses for personal dilemmas.

Conclusion

Our results suggest that moral decision-making ability is not uniformly impaired following TBI. Rather, neuroanatomical (lesion location) and demographic (age at injury) characteristics may be more predictive of a disruption in moral decision-making than TBI diagnosis or injury severity alone. These results inform the neurobiology of moral decision-making and have implications for characterizing patterns of spared and impaired cognitive abilities in TBI.

Mediating effects of impulsivity and alexithymia in the association between traumatic brain injury and aggression in incarcerated males

Studies suggest both alexithymia and impulsivity (partially) explain aggressive behavior in traumatic brain injury (TBI) patients, but none of these studies use both questionnaire and performance-based measures as recommended, nor simultaneously investigate both impulsivity and alexithymia. The available studies therefore likely miss part of the constructs of alexithymia and impulsivity, and do not comprehensively assess the mediating effects of both constructs in the relationship between TBI and aggression. A sample of N = 281 incarcerated individuals were recruited from Dutch penitentiary institutions, and completed the Buss Perry Aggression Questionnaire (aggression), BIS-11 (impulsivity) and Toronto Alexithymia Scale-20 (alexithymia) questionnaires, as well as a stop-signal task and an emotion recognition paradigm. Several multiple mediation analyses were conducted using structural equation modelling, to assess the viability of a causal theoretical model of aggression. The final planned models were the original models with a good fit with the data (comparative fit index > 0.95, root mean square error of approximation and Standardized root mean square residual < 0.05), and results indicate that only questionnaire-based impulsivity mediated the relationship between TBI and aggression. TBI was unrelated to alexithymia, stop-signal or emotion recognition performance. Aggression was predicted by both alexithymia and impulsivity, but not by the performance measures. Post hoc analyses shows that alexithymia moderates the relationship between impulsivity and aggression. These results imply that aggressive incarcerated individuals showing impulsive behavior should be screened for TBI, since TBI is often overlooked or misdiagnosed, and indicate that both impulsivity and alexithymia are potential focus points for aggression reduction treatment in TBI patients.

Psychiatric sequelae of traumatic brain injury - future directions in research

Despite growing appreciation that traumatic brain injury (TBI) is an important public health burden, our understanding of the psychiatric and behavioural consequences of TBI remains limited. These changes are particularly detrimental to a person's sense of self, their relationships and their participation in the wider community, and they continue to have devastating individual and cumulative effects long after TBI. This Review relates specifically to TBIs that confer objective clinical or biomarker evidence of structural brain injury; symptomatic head injuries without such evidence are outside the scope of this article. Common psychiatric, affective and behavioural sequelae of TBI and their proposed underlying mechanisms are outlined, along with a brief overview of current treatments. Suggestions for how scientists and clinicians can work together in the future to address the chasms in clinical care and knowledge are discussed in depth.

Executive functioning as mediator of the association between traumatic brain injury and prison bullying

OBJECTIVE

This study examined whether executive functioning (EF) mediated the relationship between childhood traumatic brain injury (TBI) and engaging in bullying in prison (BP).

PARTICIPANTS

A sample of male adults in custody in Uruguay (N = 236), drawn from five prisons.

METHODS

Inmates filled out self-report questionnaires examining TBI (Head Injury Questionnaire), EF (Behavior Rating Inventory of Executive Function Adult, BRIEF-A) and bullying in prison (Direct and Indirect Prisoner Behavior Checklist - revised, SCALED, DIPC-SCALED-r).

RESULTS

Findings showed that TBI was associated with prison bullying after controlling for age, level of education, socioeconomic status, and civil status. The mediation analysis indicated that the relationship between TBI and bullying was fully mediated via executive impairment, especially through the behavioral regulation component (mainly inhibition and emotional control).

CONCLUSION

These findings suggested that compensating for EF difficulties in adult inmates with brain injuries might help to decrease the bullying in prison.

Functional brain activity constrained by structural connectivity reveals cohort-specific features for serum neurofilament light chain

Background

Neuro-axonal brain damage releases neurofilament light chain (NfL) proteins, which enter the blood. Serum NfL has recently emerged as a promising biomarker for grading axonal damage, monitoring treatment responses, and prognosis in neurological diseases. Importantly, serum NfL levels also increase with aging, and the interpretation of serum NfL levels in neurological diseases is incomplete due to lack of a reliable model for age-related variation in serum NfL levels in healthy subjects.

Methods

Graph signal processing (GSP) provides analytical tools, such as graph Fourier transform (GFT), to produce measures from functional dynamics of brain activity constrained by white matter anatomy. Here, we leveraged a set of features using GFT that quantified the coupling between blood oxygen level dependent signals and structural connectome to investigate their associations with serum NfL levels collected from healthy subjects and former athletes with history of concussions.

Results

Here we show that GSP feature from isthmus cingulate in the right hemisphere (r-iCg) is strongly linked with serum NfL in healthy controls. In contrast, GSP features from temporal lobe and lingual areas in the left hemisphere and posterior cingulate in the right hemisphere are the most associated with serum NfL in former athletes. Additional analysis reveals that the GSP feature from r-iCg is associated with behavioral and structural measures that predict aggressive behavior in healthy controls and former athletes.

Conclusions

Our results suggest that GSP-derived brain features may be included in models of baseline variance when evaluating NfL as a biomarker of neurological diseases and studying their impact on personality traits.

Neurofilament light chain (NfL) is a marker released into the blood as a result of central nervous system damage or neurodegeneration. However, we know little about how NfL levels relate to brain structure and activity. Here, we use imaging data and advanced statistical methods to look at the relationship between brain activity and structure in healthy people and former athletes with a history of multiple concussions, and determine whether these can predict NfL levels in the blood. We find the relationship between brain activity and structure and NfL levels is different between the two groups. Our findings help us to understand how brain injury might impact NfL levels and their relationship with brain activity, and could guide how NfL and imaging data are used as tools in research and in the clinic.

Sihag et al. analyse brain imaging data, circulating neurofilament light chain levels and personality scores in a cohort of former athletes with a history of concussions. The authors use graph signal processing to identify brain structural and connectivity features associated with neurofilament levels and with aggressive behaviour.

A global collaboration to study intimate partner violence-related head trauma: The ENIGMA consortium IPV working group

Intimate partner violence includes psychological aggression, physical violence, sexual violence, and stalking from a current or former intimate partner. Past research suggests that exposure to intimate partner violence can impact cognitive and psychological functioning, as well as neurological outcomes. These seem to be compounded in those who suffer a brain injury as a result of trauma to the head, neck or body due to physical and/or sexual violence. However, our understanding of the neurobehavioral and neurobiological effects of head trauma in this population is limited due to factors including difficulty in accessing/recruiting participants, heterogeneity of samples, and premorbid and comorbid factors that impact outcomes. Thus, the goal of the Enhancing NeuroImaging Genetics through Meta-Analysis (ENIGMA) Consortium Intimate Partner Violence Working Group is to develop a global collaboration that includes researchers, clinicians, and other key community stakeholders. Participation in the working group can include collecting harmonized data, providing data for meta- and mega-analysis across sites, or stakeholder insight on key clinical research questions, promoting safety, participant recruitment and referral to support services. Further, to facilitate the mega-analysis of data across sites within the working group, we provide suggestions for behavioral surveys, cognitive tests, neuroimaging parameters, and genetics that could be used by investigators in the early stages of study design. We anticipate that the harmonization of measures across sites within the working group prior to data collection could increase the statistical power in characterizing how intimate partner violence-related head trauma impacts long-term physical, cognitive, and psychological health.

Workplace Violence and Long-term Sickness Absence: Assessment of the Potential Buffering Effect of Social Support in Two Occupational Cohort Studies

OBJECTIVES

We aimed to determine the effect of workplace violence on long-term sickness absence, and whether social support from supervisors and colleagues buffer this effect.

METHODS

Information on workplace violence and social support were derived from the Danish Work Environment Cohort Study in 2000, 2005, and 2010 and the Swedish Longitudinal Occupational Survey of Health in 2006 and 2008. Individual- and joint-effects on register-based long-term sickness absence were determined using logistic regression models for repeated measurements. Cohort-specific estimates were combined in random effect meta-analyses.

RESULTS

Workplace violence and low social support were independently associated with a higher risk of long-term sickness absence, and we did not find evidence of an interaction.

CONCLUSION

Exposure to workplace violence is a risk factor for long-term sickness absence while social support is associated with a lower risk of long-term sickness absence.

Maladaptive Aggression: With a Focus on Impulsive Aggression in Children and Adolescents

Objective: Aggressive behavior is among the most common reasons for referral to psychiatric clinics and confers significant burden on individuals. Aggression remains poorly defined; there is currently no consensus on the best ways to recognize, diagnose, and treat aggression in clinical settings. In this review, we synthesize the available literature on aggression in children and adolescents and propose the concept of impulsive aggression (IA) as an important construct associated with diverse and enduring psychopathology. Methods: Articles were identified and screened from online repositories, including PubMed, PsychInfo, the Cochrane Database, EMBase, and relevant book chapters, using combinations of search terms such as "aggression," "aggressive behavio(u)r," "maladaptive aggression," "juvenile," and "developmental trajectory." These were evaluated for quality of research before being incorporated into the article. The final report references 142 sources, published from 1987 to 2019. Results: Aggression can be either adaptive or maladaptive in nature, and the latter may require psychosocial and biomedical interventions when it occurs in the context of central nervous system psychopathology. Aggression can be categorized into various subtypes, including reactive/proactive, overt/covert, relational, and IA. IA in psychiatric or neurological disorders is reviewed along with current treatments, and an algorithm for systematic evaluation of aggression in the clinical setting is proposed. Conclusions: IA is a treatable form of maladaptive aggression that is distinct from other aggression subtypes. It occurs across diverse psychiatric and neurological diagnoses and affects a substantial subpopulation. IA can serve as an important construct in clinical practice and has considerable potential to advance research.

Executive (dys)function after traumatic brain injury: special considerations for behavioral pharmacology

Executive function is an umbrella term that includes cognitive processes such as decision-making, impulse control, attention, behavioral flexibility, and working memory. Each of these processes depends largely upon monoaminergic (dopaminergic, serotonergic, and noradrenergic) neurotransmission in the frontal cortex, striatum, and hippocampus, among other brain areas. Traumatic brain injury (TBI) induces disruptions in monoaminergic signaling along several steps in the neurotransmission process - synthesis, distribution, and breakdown - and in turn, produces long-lasting deficits in several executive function domains. Understanding how TBI alters monoamingeric neurotransmission and executive function will advance basic knowledge of the underlying principles that govern executive function and potentially further treatment of cognitive deficits following such injury. In this review, we examine the influence of TBI on the following measures of executive function - impulsivity, behavioral flexibility, and working memory. We also describe monoaminergic-systems changes following TBI. Given that TBI patients experience alterations in monoaminergic signaling following injury, they may represent a unique population with regard to pharmacotherapy. We conclude this review by discussing some considerations for pharmacotherapy in the field of TBI.

Brain injury, behaviour support, and family involvement: putting the pieces together and looking forward

Purpose: (1) to provide insight into the family's experience and support needs following acquired brain injury (ABI) specific to behavioural changes; (2) to provide an overview of empirically-based behaviour support approaches for individuals with ABI; and (3), to examine family involvement in implementing behavioural interventions.Methods: Review of the literature.Results: Family members experience significant distress resulting from neurobehavioural changes in relatives with ABI, and report unmet informational and practical support needs regarding this issue. The importance of utilising family expertise within the rehabilitation process is widely acknowledged, with the increasing involvement of family members being promoted. There is growing evidence supporting the use of positive behaviour support approaches for individuals with ABI in community settings, and evidence supporting the involvement of family within behavioural interventions.Conclusions: This review suggests the need to develop alternative support models that shift the focus towards building competence in everyday support people rather than dependency on the service system. A bottom-up approach is recommended, with the aim of addressing unmet support needs and increasing the competence of family members in supporting behaviour change in individuals with ABI. Recommendations are provided in informing an optimal community-based neurobehavioural support model. Implications for RehabilitationPositive behaviour support is recommended in supporting behavioural changes following brain injury, with family expertise utilised in this process.Evidence suggests that family members can be effectively trained in developing and implementing behaviour support strategies.Family involvement in behavioural interventions may address unmet support needs and increasing the competence of family members in supporting behavioural changes following brain injury.

Alexithymia is associated with aggressive tendencies following traumatic brain injury

OBJECTIVE

Aggressive behavior is a frequent legacy of traumatic brain injury (TBI). This study explores the question of how alexithymia, which is associated with deficits in social cognition and empathy, may predispose individuals to aggressive tendencies after head trauma.

METHOD

A total of 47 individuals referred for routine neuropsychological assessment and advice on the management of long-term neuropsychological sequelae after TBI and 72 demographically matched controls completed the 20-Item Toronto Alexithymia Scale (TAS-20) and Buss Perry Aggression Questionnaire (BPAQ; self and proxy).

RESULTS

The incidence of alexithymia and aggressive tendencies was significantly higher in the group with TBI. After controlling for covariates, alexithymia explained an additional 29% of variance in BPAQ total scores in the group with TBI and 11.1% in the control group. Of the three TAS-20 sub-scales, 'difficulty describing feelings' emerged as a consistent unique predictor of aggression scores.

CONCLUSIONS

Higher levels of alexithymia are associated with greater aggressive tendencies post-TBI. The findings offer important theoretical and empirical insights into the prediction of aggression after TBI.

Neuropsychological correlates of self-reported impulsivity and informant-reported maladaptive behaviour among veterans with posttraumatic stress disorder and traumatic brain injury history

OBJECTIVE

Frontal lobe deficits resulting from traumatic brain injury (TBI) and/or posttraumatic stress disorder (PTSD) have been linked to impulsive behaviour. We sought to examine whether neuropsychological performance predicted self-reported impulsivity and informant-reported maladaptive behaviour.

METHOD

We administered the Delis-Kaplan Executive Function System (D-KEFS) to 116 Iraq/Afghanistan-era veterans diagnosed with a history of TBI and PTSD.

RESULTS

Poorer performance on D-KEFS Stroop Task (both colour and word, separately) and Trail making (letter sequencing and motor speed) tasks and higher PTSD symptom severity were associated with higher self-reported impulsivity. Trail making letter sequencing performance was negatively associated with informant-reported maladaptive behaviour. Regression analyses revealed PTSD symptom severity and Trail making letter sequencing best predicted self-reported impulsivity, even when accounting for age, sex, and education. Only Trail making letter sequencing predicted informant-reported maladaptive behaviour when accounting for other variables in the model.

CONCLUSIONS

Attention and processing speed impairments and PTSD symptom severity appear to be important predictors of impulsivity and problematic behaviour among veterans. Findings have implications for theoretical models of aggression and violence and inform the assessment and treatment of individuals with TBI and PTSD.

A multifactorial and integrative approach to impulsivity in neuropsychology: insights from the UPPS model of impulsivity

Risky and excessive behaviors, such as aggressive and compulsive behaviors, are frequently described in patients with brain damage and have dramatic psychosocial consequences. Although there is strong evidence that impulsivity constitutes a key factor at play in these behaviors, the literature about impulsivity in neuropsychology is to date scarce. In addition, examining and understanding these problematic behaviors requires the assumption that impulsivity is a multidimensional construct. Consequently, this article aims at shedding light on frequent risky and excessive behaviors in patients with brain damage by focusing on a unified, comprehensive, and well-validated model, namely, the UPPS model of impulsivity. This model considers impulsivity as a multidimensional construct that includes four facets: urgency, (lack of) premeditation, (lack of) perseverance, and sensation seeking. Furthermore, we discuss the psychological mechanisms underlying the dimensions of impulsivity, as well as the laboratory tasks designed to assess each mechanism and their neural bases. We then present a scale specifically designed to assess these four dimensions of impulsivity in patients with brain damage and examine the data regarding this multidimensional approach to impulsivity in neuropsychology. This review supports the need to adopt a multifactorial and integrative approach toward impulsive behaviors, and the model presented provides a valuable rationale to disentangle the nature of brain systems and mechanisms underlying impulsive behaviors in patients with brain damage. It may also foster further relevant research in the field of impulsivity and improve assessment and rehabilitation of impulsive behaviors in clinical settings.

Improving Traumatic Brain Injury Outcomes: The Development of an Evaluation and Referral Tool at Groote Schuur Hospital

BACKGROUND

The Western Cape Province of South Africa has a great shortage of diagnostic expertise, rehabilitative infrastructure, and support services for patients with traumatic brain injury (TBI). The neurosurgical outpatient setting is busy and often chaotic, and patients are frequently lost to follow-up. This study sought to continue with the design and development of a comprehensive, yet brief tool to aid patient referrals and ensure that no consequence of TBI is left unidentified and unaddressed.

METHODS

There were 47 patients with TBI (mean age, 35 years; range, 18-75 years) assessed. The study was designed in 3 distinct phases, each representing a different stage in the tool's development.

RESULTS

The Groote Schuur Traumatic Brain Injury Evaluation was shortened and simplified. Overall, 81% of the participants indicated cognitive dysfunction. There was a high prevalence of psychological/psychiatric sequelae, with 85% of participants reporting at least 1 such problem.

CONCLUSIONS

The findings further highlight the prevalence of the cognitive, behavioral, and psychological consequences of TBI and shed additional light on the particular types of problems that patients with TBI face. Following the identified changes, the questionnaire and algorithm combination are now ready to be validated in the neurosurgical clinical setting.

Sex differences in orbitofrontal connectivity in male and female veterans with TBI

More female soldiers are now serving in combat theaters than at any other time. However, little is known about possible sex differences underlying the neuropathology and manifestation of one of modern war’s signature injuries, traumatic brain injury (TBI). The paucity of information regarding sex differences in TBI is particularly evident when examining changes in executive function and emotion regulation associated with post concussive events. The current study objective was to observe whether patterns of orbitofrontal (OFC) functional connectivity would differ between female veterans with TBI and their male counterparts. The study further sought to determine whether OFC connectivity might be differentially associated with clinical measures of aggression and hostility. Seventeen female veterans and 24 male veterans, age 18 to 25, who met criteria for TBI completed resting state magnetic resonance imaging (MRI) and clinical assessment measures. Imaging data were analyzed using left and right seed regions of the OFC, and regression analyses were conducted to observe the relationship between resting state connectivity and self-reported aggression. Females and males in this study differed in OFC connectivity, with females demonstrating greater connectivity between left and right OFC and parietal and occipital regions and males demonstrating greater connectivity between left and right OFC and frontal and temporal regions. Significant associations between resting state connectivity and clinical measures were found only in male veterans. These findings suggest that TBI may interact with sex-specific patterns of brain connectivity in male and female veterans and exert divergent effects on clinical profiles of aggression post-injury.

Holistic Practice in Traumatic Brain Injury Rehabilitation: Perspectives of Health Practitioners

Given that the literature suggests there are various (and often contradictory) interpretations of holistic practice in brain injury rehabilitation and multiple complexities in its implementation (including complex setting, discipline, and client-base factors), this study aimed to examine the experiences of practitioners in their conceptualization and delivery of holistic practice in their respective settings. Nineteen health practitioners purposively sampled from an extensive Brain Injury Network in Queensland, Australia participated in individual interviews. A systematic text analysis process using Leximancer qualitative analysis program was undertaken, followed by manual thematic analysis to develop overarching themes. The findings from this study have identified several items for future inter-professional development that will not only benefit the practitioners working in brain injury rehabilitation settings, but the patients and their families as well.

Remission of lifelong episodic dyscontrol after bilateral dorsolateral temporal lobe damage

A 45-year-old married woman with fits of episodic dyscontrol since an early age suffered a bilateral injury of the dorsolateral temporal lobe after which such episodes vanished for good. The remission of her lifelong proneness to aggression was so remarkable that her relatives and friends unanimously welcomed her "new personality". The post-traumatic taming in this case was an unanticipated collateral effect of brain damage with a salutary change of personality. This change possibly resulted from the release, due to the bitemporal injury, of inclinations that had not hitherto been fully expressed in the patient's mind and behavior due to the overriding influence of episodic dyscontrol on her ordinary conduct.

Frontotemporal correlates of impulsivity and machine learning in retired professional athletes with a history of multiple concussions

The frontotemporal cortical network is associated with behaviours such as impulsivity and aggression. The health of the uncinate fasciculus (UF) that connects the orbitofrontal cortex (OFC) with the anterior temporal lobe (ATL) may be a crucial determinant of behavioural regulation. Behavioural changes can emerge after repeated concussion and thus we used MRI to examine the UF and connected gray matter as it relates to impulsivity and aggression in retired professional football players who had sustained multiple concussions. Behaviourally, athletes had faster reaction times and an increased error rate on a go/no-go task, and increased aggression and mania compared to controls. MRI revealed that the athletes had (1) cortical thinning of the ATL, (2) negative correlations of OFC thickness with aggression and task errors, indicative of impulsivity, (3) negative correlations of UF axial diffusivity with error rates and aggression, and (4) elevated resting-state functional connectivity between the ATL and OFC. Using machine learning, we found that UF diffusion imaging differentiates athletes from healthy controls with significant classifiers based on UF mean and radial diffusivity showing 79–84 % sensitivity and specificity, and 0.8 areas under the ROC curves. The spatial pattern of classifier weights revealed hot spots at the orbitofrontal and temporal ends of the UF. These data implicate the UF system in the pathological outcomes of repeated concussion as they relate to impulsive behaviour. Furthermore, a support vector machine has potential utility in the general assessment and diagnosis of brain abnormalities following concussion.

Definition of Impulsivity and Related Terms Following Traumatic Brain Injury: A Review of the Different Concepts and Measures Used to Assess Impulsivity, Disinhibition and other Related Concepts

Impulsivity is a common and debilitating sequela following traumatic brain injury (TBI), but there is no consensual definition or measure to assess this construct. The following review aims to elucidate the differences and resemblances between impulsivity, disinhibition and other related terms following brain injury and the instruments that are commonly used to measure these constructs. To do so, a search through different databases was conducted in order to find articles that mention and define impulsivity, disinhibition, impulse control, regulation deficits, dyscontrol and risky behavior. The concepts that stand out from the literature, the measures used, the similarities, the differences between these concepts are observed. The fit with the UPPS model of impulsivity, according to which impulsivity is a multidimensional concept composed of four distinct dimensions (urgency, perseverance, premeditation and sensation-seeking) is discussed.

Emotional and behavioral dyscontrol after traumatic brain injury

Emotional and behavioral dyscontrol are relatively common neuropsychiatric sequelae of traumatic brain injury and present substantial challenges to recovery and community participation. Among the most problematic and functionally disruptive of these types of behaviors are pathologic laughing and crying, affective lability, irritability, disinhibition, and aggression. Managing these problems effectively requires an understanding of their phenomenology, epidemiology, and clinical evaluation. This article reviews these issues and provides clinicians with brief and practical suggestions for the management of emotional and behavioral dyscontrol.