Serotonergic and cognitive impairment in impulsive aggressive personality disordered offenders: are there implications for treatment?

From Physical Aggression to Verbal Behavior: Language Evolution and Self-Domestication Feedback Loop

We propose that human self-domestication favored the emergence of a less aggressive phenotype in our species, more precisely phenotype prone to replace (reactive) physical aggression with verbal aggression. In turn, the (gradual) transition to verbal aggression and to more sophisticated forms of verbal behavior favored self-domestication, with the two processes engaged in a mutually reinforcing feedback loop, considering that verbal behavior entails not only less violence and better survival but also more opportunities to interact longer and socialize with more conspecifics, ultimately enabling the emergence of more complex forms of language. Whereas in the case of self-domestication, sexual selection has been proposed to work against physical aggression traits, in the case of verbal insult, the selection has been proposed to work in favor of verbal aggression. The tension between these two seemingly opposing forces gets resolved/alleviated by a tendency to replace physical aggression with verbal aggression and with verbal behavior more generally. This also helps solve the paradox of the Self-Domestication Hypothesis regarding aggression, more precisely why aggression in humans has been reduced only when it comes to reactive aggression, but not when it comes to proactive aggression, the latter exhibiting an increase in the advent of modern language. We postulate that this feedback loop was particularly important during the time period arguably between 200 and 50 kya, when humans were not fully modern, neither in terms of their skull/brain morphology and their behavior/culture nor in terms of their self-domestication. The novelty of our approach lies in (1) giving an active role to early forms of language in interacting with self-domestication processes; (2) providing specific linguistic details and functions of this early stage of grammar (including insult and humor); (3) supplying neurobiological, ontogenetic, and clinical evidence of a link between (reactive) aggression and (reactive) verbal behavior; (4) identifying proxies of the earlier stages in evolution among cognitive disorders; and (5) identifying specific points of contact and mutual reinforcement between these two processes (self-domestication and early language evolution), including reduction in physical aggression and stress/tension, as well as sexual selection.

Enhancement of Aggression Induced by Isolation Rearing is Associated with a Lack of Central Serotonin

Isolation rearing (IR) enhances aggressive behavior, and the central serotonin (5-hydroxytryptamine, 5-HT) system has been linked to IR-induced aggression. However, whether the alteration of central serotonin is the cause or consequence of enhanced aggression is still unknown. In the present study, using mice deficient in central serotonin Tph2^-/- and Lmx1b^-/-, we examined the association between central serotonin and aggression with or without social isolation. We demonstrated that central serotonergic neurons are critical for the enhanced aggression after IR. 5-HT depletion in wild-type mice increased aggression. On the other hand, application of 5-HT in Lmx1b^-/- mice inhibited the enhancement of aggression under social isolation conditions. Dopamine was downregulated in Lmx1b^-/- mice. Similar to 5-HT, L-DOPA decreased aggression in Lmx1b^-/- mice. Our results link the serotoninergic system directly to aggression and this may have clinical implications for aggression-related human conditions.

Childhood serotonergic function and early adult outcomes in youth with ADHD: A 15-year follow-up study

Longitudinal studies have shown that clinical precursors of antisocial personality disorder (ASPD) include attention-deficit/hyperactivity disorder (ADHD) and more notably comorbid ADHD and conduct disorder (CD). Despite existing evidence for the purported role of abnormal serotonergic function in aggressive youth and adults, little evidence exists on the role of serotonin in the progression from childhood disruptive behavior disorders to adult psychopathology, including ASPD. This study examined the relation between serotonergic function in children diagnosed with ADHD and the development of ASPD in early adulthood. We hypothesized that low serotonin response to a pharmacological probe in childhood would predict the development of adult ASPD. Towards this goal we divided 40 adults (M = 37, F = 3), ages 23-26 (m-24.57, sd-2.33) diagnosed with childhood ADHD into 2 groups: participants with (n = 21) and without (n = 19) ASPD. We used logistic regression to assess whether serotonergic measures in childhood assessed via prolactin and cortisol responses to a fenfluramine challenge, would selectively predict the development of ASPD in early adulthood. Logistic regression models showed that low central serotonergic response in childhood indexed by cortisol response significantly predicted adult ASPD (Wald = 4.427, p = .035) but not ADHD diagnosis in adulthood. Adults without ASPD had the highest serotonergic response whereas adults with adolescent ASPD (i.e. early onset ASPD) had the lowest response. Thus we provide new evidence of the link between low serotonergic function in childhood and the development of ASPD in adulthood, particularly for boys with adolescent onset of ASPD. These findings are relevant for understanding the contribution of childhood neurobiology to risk for later ASPD.

Association of aggression and suicide behaviors: A school-based sample of rural Chinese adolescents

BACKGROUND

To determine the prevalence of suicide behaviors and the associations between aggression and suicide behaviors among a nationwide school-based sample of adolescents in rural China.

METHODS

A total of 16,271 students from 24 junior and 23 senior high schools in five provinces of China participated in a self-administered anonymous survey to report suicide ideation, plans, attempts, aggression and other related information. Multivariable logistic regression models were used to investigate the associations between aggression and the risks of suicide behaviors while controlling for potential confounders.

RESULTS

The prevalence of suicide ideation, plans, and attempts during the past one year was 15.1%, 7.2%, and 3.5% respectively. In the fully adjusted model, participants with high level of total aggression had 4.31 times (95% CI, 3.69-5.05), 4.10 times (95% CI, 3.26-5.11), and 3.29 times (95% CI, 2.62-4.93), higher risk of suicide ideation, plans, and attempts, respectively, compared with subjects who had low level of total aggression. Moreover, high levels of all the five dimensions of total aggression also had positive associations with suicide behaviors.

LIMITATIONS

This study was cross-sectional. Hence, the causal link between aggression and suicide behaviors should be verified in the future studies.

CONCLUSIONS

This study suggests that aggression may be a risk factor for suicide behaviors among rural Chinese adolescents. Our findings highlight the importance of aggression treatment in suicide prevention programs. Further longitudinal studies are needed to confirm these associations.

Alterations in brain microstructure in rats that develop abnormal aggression following peripubertal stress

Exposure to early adversity is implicated in the development of aggressive behaviour later in life in some but not all individuals. The reasons for the variability in response to such experiences are not clear but may relate to pre-existing individual differences that influence their downstream effects. Applying structural magnetic resonance imaging (MRI) to a rat model of abnormal aggression induced by peripubertal stress, we examined whether individual differences in the development of an aggressive phenotype following stress exposure were underpinned by variation in the structure of aggression-associated, corticolimbic brain regions. We also assessed whether responsiveness of the hypothalamic-pituitary-adrenal axis to stress was associated with neurobehavioural outcome following adversity. A subset of the rats exposed to peripubertal stress developed an aggressive phenotype, while the remaining rats were affected in other behavioural domains, such as increased anxiety-like behaviours and reduced sociability. Peripubertal stress led to changes in tissue microstructure within prefrontal cortex, amygdala and hippocampal formation only in those individuals displaying an aggressive phenotype. Attenuated glucocorticoid response to stress during juvenility predicted the subsequent development of an aggressive phenotype in peripubertal stress-exposed rats. Our study establishes a link between peripubertal stress exposure in rats and structural deviations in brain regions linked to abnormal aggression and points towards low glucocorticoid responsiveness to stress as a potential underlying mechanism. We additionally highlight the importance of considering individual differences in behavioural response to stress when determining neurobiological correlates.

Psychotic-spectrum symptoms, cumulative adversity exposure and substance use among high-risk girls

AIM

Psychotic-spectrum symptoms are linked to trauma, substance/alcohol use (SAU), criminality/violence and poor functional outcomes, supporting the need for early detection in vulnerable populations. To better understand high-risk girls' mental health, we assessed: (1) psychotic-spectrum symptoms; (2) cumulative trauma, adversity and loss exposures (C-TALE) and adversity-indicators (symptoms, maladaptive coping, stressor-reactivity); and SAU risk-factors; and (3) relationships among psychotic-spectrum symptoms, adversity-indicators and SAU risk-factors.

METHODS

We administered the Structured Clinical Interviews for Psychotic Spectrum, and Trauma and Loss Spectrum to 158 adolescent delinquent girls.

RESULTS

Girls' psychotic-spectrum profiles were similar to previously reported adult psychotic patients and characterized by typical symptoms (hallucinations/delusions, reported largely SAU-independent), interpersonal sensitivity, schizoid traits and paranoia (over-interpretation, anger over-reactivity, hypervigilance). Auditory/visual hallucinations (55.7%), delusions (92.4%), ideas of reference (96.8%) and adversity (90.0% ≥10/24 C-TALE-types) were common. Mean loss (4) and trauma (8) onset-age occurred before SAU-onset (12). Significant positive correlations were found among psychotic-spectrum symptoms, stressor-reactivity, C-TALE, adversity-indicators; and number of SAU-types; and a negative correlation occurred between psychotic-spectrum symptoms and earlier alcohol use onset. After controlling for number of SAU-types, stressor-reactivity and adversity-related numbing individually had the largest associations with total psychotic-spectrum symptoms (b = 2.6-4.3). Girls averaged more than 4 maladaptive coping strategies (e.g., 24.8% attempted suicide) in response to adversity, amplifying potential health-disparities. No racial/ethnic differences emerged on psychotic-spectrum symptoms.

CONCLUSIONS

This symptom constellation during adolescence likely interferes with social and academic functioning. Whether representing a prodromal phase, trauma-response or cross-diagnostic psychopathology, accurate early detection and appropriate treatment of psychotic-spectrum symptoms are warranted to improve functional outcomes in vulnerable populations.

General Habit Propensity Relates to the Sensation Seeking Subdomain of Impulsivity But Not Obesity

According to dual-system theory, instrumental learning and performance depend on the balance between goal-directed and habitual action control. Overreliance on habits has been argued to characterize clinical conditions such as drug addiction or obsessive-compulsive disorder as well as obesity and excessive impulsivity. A tendency toward habitual action control in obesity has already been indicated in the food domain. However, impairments might not be restricted to eating behavior. This has been suggested by domain-general obesity-associated disturbances in executive function as well as alterations in corticostriatal circuits underlying the goal-directed and habitual systems. In this study we examined the balance of goal-directed and habitual action control in a sample of normal-weight, overweight, and obese participants (n = 105) using the slips-of-action test in a non-food context. We tested for continuous or group-based associations between body weight status (BMI) and the devaluation sensitivity index (DSI), a parameter representing the balance of the goal-directed and habitual systems in action control. As personality differences in the domain of impulsivity might affect this relationship, we also examined whether the interaction between BMI and self-reported impulsivity, based on the UPPS Impulsive Behavior Scale, was related to the DSI. In addition to that, we tested for direct, i.e., weight status independent, relationships between UPPS subdomains of impulsivity and the DSI. We failed to find evidence for a relationship between weight status and sensitivity to devaluation as indexed by the DSI. However, independent of weight status, we observed lower sensitivity to devaluation in sensation seekers, a subtype of impulsivity. To conclude, behavioral flexibility in the sense of disturbances in the balance between the habitual and goal-directed systems seems to be unaffected by weight status in a non-food context. Consequently, stimuli and behavior might not be generally excessively linked in overweight or obesity. However, according to ceiling effects we cannot rule out subtle effects the paradigm was not able to disentangle. Further, future studies are needed to clarify the role of specific subtypes of obesity (e.g., food addiction). The indicated habit propensity in sensation seekers may account for previous reports of weak avoidance behavior and risky decision making.

The association between suicidality and serotonergic dysfunction in depressed patients

The loudness dependence of auditory evoked potentials (LDAEP) has been proposed as a reliable indicator of central serotonin system activity in animal and some human studies. Since low central serotonergic activity is related to suicidality, it is possible that the LDAEP can be used to predict suicidality. The aim of the present study was to determine whether there is an association between suicidality and LDAEP in a depressed Korean population. Data from 38 depressive subjects (10 males, 28 females; mean age: 40.79 years) were analyzed. The subjects were divided into two groups: with prior suicide attempts (SA; n=17) and no prior suicide attempts (NSA; n=21). The LDAEP was evaluated by measuring auditory event-related potentials. Peak-to-peak N1/P2 amplitudes were calculated at five stimulus intensities, and the LDAEP was calculated as the slope of the linear-regression curve. The LDAEP values differed significantly between the SA and NSA groups. Depressed subjects with a history of suicide attempts seem to be characterized by large LDAEP values, indicating low serotonergic activity. The findings of the present study support the view that low serotonergic activity is related to the suicidality of depressed subjects. Thus, LDAEP, which can reflect serotonergic activity, may be a practical biological marker for suicidality.

Neuroimaging and neurocognitive correlates of aggression and violence in schizophrenia

Individuals diagnosed with major mental disorders such as schizophrenia are more likely to have engaged in violent behavior than mentally healthy members of the same communities. Although aggressive acts can have numerous causes, research about the underlying neurobiology of violence and aggression in schizophrenia can lead to a better understanding of the heterogeneous nature of that behavior and can assist in developing new treatment strategies. The purpose of this paper is to review the recent literature and discuss some of the neurobiological correlates of aggression and violence. The focus will be on schizophrenia, and the results of neuroimaging and neuropsychological studies that have directly investigated brain functioning and/or structure in aggressive and violent samples will be discussed as well as other domains that might predispose to aggression and violence such as deficits in responding to the emotional expressions of others, impulsivity, and psychopathological symptoms. Finally gender differences regarding aggression and violence are discussed. In this context several methodological and conceptional issues that limited the comparison of these studies will be addressed.

The neuropsychology of prefrontal function in antisocial personality disordered offenders with varying degrees of psychopathy

BACKGROUND

Despite methodological differences between studies, it has been suggested that psychopathy may be associated with a ventromedial prefrontal cortex (VMPFC) deficit and antisocial personality disorder (ASPD), as classified in the DSM-IV, with a broader range of deficits in dorsolateral prefrontal cortex (DLPFC) and VMPFC function.

METHOD

Ninety-six male offenders with ASPD who were assessed using the psychopathy checklist: screening version (PCL:SV) and 49 male right-handed healthy controls (HCs), matched for age and IQ, completed a neuropsychological test battery.

RESULTS

Offenders with ASPD displayed subtle impairments on executive function tasks of planning ability and set shifting and behavioural inhibition compared to HCs. However, among the offenders with ASPD there was no significant association between executive function impairment and scores on the measure of psychopathy.

CONCLUSIONS

Psychopathic traits in offenders with ASPD are not associated with greater executive function impairment.

Impulsivity and the modular organization of resting-state neural networks

Impulsivity is a complex trait associated with a range of maladaptive behaviors, including many forms of psychopathology. Previous research has implicated multiple neural circuits and neurotransmitter systems in impulsive behavior, but the relationship between impulsivity and organization of whole-brain networks has not yet been explored. Using graph theory analyses, we characterized the relationship between impulsivity and the functional segregation ("modularity") of the whole-brain network architecture derived from resting-state functional magnetic resonance imaging (fMRI) data. These analyses revealed remarkable differences in network organization across the impulsivity spectrum. Specifically, in highly impulsive individuals, regulatory structures including medial and lateral regions of the prefrontal cortex were isolated from subcortical structures associated with appetitive drive, whereas these brain areas clustered together within the same module in less impulsive individuals. Further exploration of the modular organization of whole-brain networks revealed novel shifts in the functional connectivity between visual, sensorimotor, cortical, and subcortical structures across the impulsivity spectrum. The current findings highlight the utility of graph theory analyses of resting-state fMRI data in furthering our understanding of the neurobiological architecture of complex behaviors.

Dopamine, serotonin and impulsivity

Impulsive people have a strong urge to act without thinking. It is sometimes regarded as a positive trait but rash impulsiveness is also widely present in clinical disorders such as attention deficit hyperactivity disorder (ADHD), drug dependence, mania, and antisocial behaviour. Contemporary research has begun to make major inroads into unravelling the brain mechanisms underlying impulsive behaviour with a prominent focus on the limbic cortico-striatal systems. With this progress has come the understanding that impulsivity is a multi-faceted behavioural trait involving neurally and psychologically diverse elements. We discuss the significance of this heterogeneity for clinical disorders expressing impulsive behaviour and the pivotal contribution made by the brain dopamine and serotonin systems in the aetiology and treatment of behavioural syndromes expressing impulsive symptoms.

Neurogenetics and Epigenetics in Impulsive Behaviour: Impact on Reward Circuitry

Adverse, unfavourable life conditions, particularly during early life stages and infancy, can lead to epigenetic regulation of genes involved in stress-response, behavioral disinhibition, and cognitive-emotional systems. Over time, the ultimate final outcome can be expressed through behaviors bedeviled by problems with impulse control, such as eating disorders, alcoholism, and indiscriminate social behavior. While many reward gene polymorphisms are involved in impulsive behaviors, a polymorphism by itself may not translate to the development of a particular behavioral disorder unless it is impacted by epigenetic effects. Brain-derived neurotrophic factor (BDNF) affects the development and integrity of the noradrenergic, dopaminergic, serotonergic, glutamatergic, and cholinergic neurotransmitter systems, and plasma levels of the neurotrophin are associated with both cognitive and aggressive impulsiveness. Epigenetic mechanisms associated with a multitude of environmental factors, including premature birth, low birth weight, prenatal tobacco exposure, non-intact family, young maternal age at birth of the target child, paternal history of antisocial behavior, and maternal depression, alter the developmental trajectories for several neuropsychiatric disorders. These mechanisms affect brain development and integrity at several levels that determine structure and function in resolving the final behavioral expressions.

What imaging tells us about violence in anti-social men

This paper provides an overview of imaging studies in samples of men with personality disorder (PD) who have been violent. Mention is also made of the work of two groups that have looked at the neural correlates of violence across diagnostic categories, including schizophrenia and anti-social PD given their relevance in the field. The paper focuses on the notion that aggressive behaviour can be conceptualised in terms of at least two types, reactive and pro-active, and that few studies separate them. The neuro-anatomical basis of aggression and associated neurobehavioural theories are discussed in relation to clinical disorders (mainly anti-social personality pathology) associated with these different types of aggressive behaviour. Structural (computed tomography, magnetic resonance imaging) and functional (positron emission tomography, fMRI, single-photon emission tomography) studies with violent people variously characterised as anti-social or having psychopathy will be critically reviewed.

Aggression, psychopathy and brain imaging - Review and future recommendations

Violent behavior appears to result from a complex web of interacting genetic as well as environmental factors. Psychopathy is a strong predictor for relapse in violent acts. The current review shed light on rapidly expanding knowledge in brain imaging related to violent behavior and psychopathy. A literature search was performed in PubMed, Cochrane and PsycInfo combining the key words: mentally disordered offender/aggression/violence/ crime/forensic psychiatry/brain imaging neuroimaging/fMRI/MRI/PET/SPECT/lack of empathy/psychopathy and antisocial personality disorder. The reviewed material, which consisted of 48 articles, indicates a rather strong consensus on the connection between dysfunctional parts of the frontal and temporal lobes and violent antisocial behavior and psychopathy. In future studies, it would be useful to focus on the limbic system and to investigate which parts of the frontal lobes and cerebral networks that are of interest in the psychopathic personality. Moreover, the reviewed material highlights some of the methodological difficulties in this area of research such as selection bias in the recruitment of patients, inadequate matching of control subjects, and sometimes incongruous results. In the future we hope that brain imaging can be used to map biological deviations in different offenders in order to try to learn more about the different mechanisms behind violent behaviors.

Neurocognitive differences between pedophilic and nonpedophilic child molesters

Although some evidence exists that child molesters may be characterized by structural and functional brain abnormalities, findings across studies are inconsistent. Past cognitive research in this area has been extensively criticized for relying on conceptually weak batteries, measures of questionable reliability, and poorly defined samples (i.e., failing to distinguish between pedophilic and nonpedophilic child molesters). The present study aimed to address the weaknesses of past research by comparing 40 child molesters (20 pedophilic and 20 nonpedophilic) and 20 demographically matched nonoffender controls on six well-defined neurocognitive composite scores of comparable reliability (i.e., semantic knowledge, executive functioning, processing speed, motor speed, auditory memory, and visual memory). Results indicated that pedophilic child molesters exhibit slower processing speed, nonpedophilic child molesters exhibit poorer semantic knowledge, and both molester groups exhibit executive weaknesses as compared to nonoffender controls. This study is the first to compare the two molester types on neurocognitive functions. The observed differences between the molester groups help explain inconsistencies in past research and demonstrate the need to distinguish between the two types of child molesters when studying neurobiologic underpinnings of sexual offending.

Facial and prosodic affect recognition among pedophilic and nonpedophilic criminal child molesters

The present study compared facial and prosodic affect recognition abilities among pedophilic and nonpedophilic child molesters and community-dwelling controls. Pedophilic child molesters are characterized by primary sexual interest in prepubescent children, whereas nonpedophilic child molesters are characterized by offending against children despite being primarily sexually attracted to adults. The results showed that nonpedophilic child molesters made more errors in recognizing both facial and prosodic affect, performing more poorly than both controls and pedophilic child molesters. These findings are consistent with greater psychopathic tendencies among nonpedophilic molesters as well as with prior findings of smaller amygdala volume among child molesters.

Neuroscience, moral reasoning, and the law

Modern advancements in functional magnetic resonance imaging (fMRI) technology have given neuroscientists the opportunity to more fully appreciate the brain's contribution to human behavior and decision making. Morality and moral reasoning are relative newcomers to the growing literature on decision neuroscience. With recent attention given to the salience of moral factors (e.g. moral emotions, moral reasoning) in the process of decision making, neuroscientists have begun to offer helpful frameworks for understanding the interplay between the brain, morality, and human decision making. These frameworks are relatively unfamiliar to the community of forensic psychologists, despite the fact that they offer an improved understanding of judicial decision making from a biological perspective. This article presents a framework reviewing how event-feature-emotion complexes (EFEC) are relevant to jurors and understanding complex criminal behavior. Future directions regarding converging fields of neuroscience and legal decision making are considered.

Serotonergic function, two-mode models of self-regulation, and vulnerability to depression: what depression has in common with impulsive aggression

Evidence from diverse literatures supports the viewpoint that two modes of self-regulation exist, a lower-order system that responds quickly to associative cues of the moment and a higher-order system that responds more reflectively and planfully; that low serotonergic function is linked to relative dominance of the lower-order system; that how dominance of the lower-order system is manifested depends on additional variables; and that low serotonergic function therefore can promote behavioral patterns as divergent as impulsive aggression and lethargic depression. Literatures reviewed include work on two-mode models; studies of brain function supporting the biological plausibility of the two-mode view and the involvement of serotonergic pathways in functions pertaining to it; and studies relating low serotonergic function to impulsiveness, aggression (including extreme violence), aspects of personality, and depression vulnerability. Substantial differences between depression and other phenomena reviewed are interpreted by proposing that depression reflects both low serotonergic function and low reward sensitivity. The article closes with brief consideration of the idea that low serotonergic function relates to even more diverse phenomena, whose natures depend in part on sensitivities of other systems.

Brain anatomy of persistent violent offenders: more rather than less

Most violent crimes in Western societies are committed by a small group of men who display antisocial behavior from an early age that remains stable across the life-span. It is not known if these men display abnormal brain structure. We compared regional brain volumes of 26 persistently violent offenders with antisocial personality disorder and substance dependence and 25 healthy men using magnetic resonance imaging volumetry and voxel-based morphometry (VBM). The violent offenders, as compared with the healthy men, had markedly larger white matter volumes, bilaterally, in the occipital and parietal lobes, and in the left cerebellum, and larger grey matter volume in right cerebellum (effect sizes up to 1.24, P<0.001). Among the offenders, volumes of these areas were not associated with psychopathy scores, substance abuse, psychotropic medication, or global IQ scores. By contrast, VBM analyses of grey matter revealed focal, symmetrical, bilateral areas of atrophy in the postcentral gyri, frontopolar cortex, and orbitofrontal cortex among the offenders as compared with the healthy men (z-scores as high as 5.06). Offenders with psychopathy showed the smallest volumes in these areas. The larger volumes in posterior brain areas may reflect atypical neurodevelopmental processes that underlie early-onset persistent antisocial and aggressive behavior.

Structural brain abnormalities in psychopaths-a review

The biological basis of psychopathy has not yet been fully elucidated. Few studies deal with structural neuroimaging in psychopaths. The aim of this article is to review these studies in order to contribute to our understanding of the biological basis of psychopathy. Data in the literature report a reduction in prefrontal gray matter volume, gray matter loss in the right superior temporal gyrus, amygdala volume loss, a decrease in posterior hippocampal volume, an exaggerated structural hippocampal asymmetry, and an increase in callosal white matter volume in psychopathic individuals. These findings suggest that psychopathy is associated with brain abnormalities in a prefrontal-temporo-limbic circuit-i.e. regions that are involved, among others, in emotional and learning processes. Additionally, data indicate that psychopathic individuals cannot be seen as a homogeneous group. The associations between structural changes and psychopathic characteristics do not enable causal conclusions to be drawn, but point rather to the important role of biological brain abnormalities in psychopathy. To gain a comprehensive understanding of this, psychopathy must be viewed as a multifactorial process involving neurobiological, genetic, epidemiological and sociobiographical factors.

Treatment consideration and manifest complexity in comorbid neuropsychiatric disorders

Psychiatric disorders may co-occur in the same individual. These include, for example, substance abuse or obsessive-compulsive disorder with schizophrenia, and movement disorders or epilepsy with affective dysfunctional states. Medications may produce iatrogenic effects, for example cognitive impairments that co-occur with the residual symptoms of the primary disorder being treated. The observation of comorbid disorders in some cases may reflect diagnostic overlap. Impulsivity, impulsiveness or impulsive behaviour is implicated in a range of diagnostic conditions including substance abuse, affective disorder and obsessive-compulsive disorder. These observations suggest a need to re-evaluate established diagnostic criteria and disorder definitions, focusing instead on symptoms and symptom-profiles.

Impulsivity, aggressiveness, and DSM-IV personality disorders

The aim of this study is to assess whether impulsive and aggressive traits can be placed on a continuum with DSM-IV Cluster B Personality Disorders (PDs) and to determine if different aspects of these personality traits are specifically associated with individual Cluster B PDs. The study group comprised 461 outpatients admitted consecutively to a clinic that specializes in the diagnosis and treatment of PDs. Principal component analyses clearly suggested a five-factor structure of both normal and psychopathological personality traits. Importantly, measures of impulsivity, aggressiveness and novelty seeking formed a part of the principal component that clustered all Cluster B PDs. Regression analyses indicated that impulsive traits were selectively associated with Borderline PD whereas different aspects of aggressiveness were useful in discriminating Narcissistic PD from Antisocial PD. Sensation seeking traits formed a part of Histrionic PD. These results indicate that impulsive/aggressive traits may be useful in explaining both why Cluster B PDs tend to covary, and why they frequently differ in clinical pictures and courses.

Relations of serotonin function to personality: current views and a key methodological issue

Studies of biological underpinnings of personality suggest that serotonergic functioning relates to certain personality traits. However, how to interpret the findings depends partly on assumptions about how personality is organized. These assumptions are reflected in the assessment devices used and also in how the data are examined. Review of evidence to date appears to link serotonin function to impulsivity and, to some extent, to hostility. The relation of serotonin function to anxiety proneness is far more questionable. Indeed, when such a relation occurs, it often takes a form opposite to the direction argued by theory. It is recommended that research use measures that discriminate adequately among personality qualities reflecting incentive sensitivity, threat sensitivity, and impulsiveness. Indeed, it is highly desirable to examine facets of each of these qualities separately.

Validation of Turkish and English Versions of the Schizotypal Personality Questionnaire-B

Abstract. We present normative data for a Turkish translation of the Schizotypal Personality Questionnaire-B (SPQ-B). The SPQ-B is a brief, self-report screening instrument developed by Raine and Benishay (1995) and is used to evaluate respondents for the presence of schizotypal personality features. We describe the internal consistency and test-retest reliability of the Turkish instrument and report intercorrelations among subfactors and total SPQ-B score. For comparison purposes, we present normative data for the SPQ-B (English version) from two studies examining schizotypy among nonclinical student samples in the United States. We report α coefficients and assess the convergent validity of the SPQ-B by examining the relationship between scores on the SPQ-B and performance on two existing measures of schizotypy and schizophrenic-spectrum personality disorders. Central tendency, distribution of scores, factor structure, and intercorrelations in both Turkish and US samples were similar, suggesting that our Turkish translation of the SPQ-B is a culturally valid instrument.

Neural Substrates Underlying Impulsivity

Attention deficit hyperactivity disorder (ADHD) is a neuropsychiatric disorder whose three main symptoms are impulsiveness, inattention, and hyperactivity. Although ADHD is an early developmental disorder, it may persist into adulthood, resulting in deficits associated with poor academic performance, frequent job changes, poor and unstable marriages, and increases in motor vehicle accidents. Of the three primary symptoms of ADHD, deficits in impulse control are the most challenging to the social network and the judicial system. While the etiology of ADHD remains unknown, recent work suggests that the central deficits in ADHD may be due to poor response inhibition that is linked to monoamine and prefrontal lobe deficiencies. In the past, preclinical studies designed to understand the lack of impulse control have generally been relegated to studies linked to aggression and drug abuse. With the use of innovative noninvasive techniques, like anatomical and functional magnetic resonance imaging, selective neurochemical and behavioral paradigms have converged with preclinical reports and lend support to the premise that monoaminergic neurotransmitter systems and the cortico-striatal circuitry are essential to impulse control. Furthermore, new emerging data on neural substrates underlying impulsivity have incorporated brain regions involved in reinforcement, reward, and decision making such as the nucleus accumbens, cerebellum, and amygdala. As noninvasive brain imaging, neurochemical, and behavioral approaches are combined, our knowledge of the neural networks underlying impulsivity will hopefully give rise to therapeutic approaches aimed at alleviating this disorder.

Depression and antisocial personality disorder: two contrasting disorders of 5HT function

Impaired 5HT functioning has been implicated in two very different psychiatric syndromes: antisocial personality disorder and depression. In both, reduced csf concentration of 5HIAA and blunted circulating hormone responses to 5HT drug challenge have been described. The paradox can be resolved by the theory that the two main ascending 5HT pathways mediate adaptive responses to future and current adversity. Projections of the anterior group of raphe 5HT cells (dorsal raphe nucleus) oppose the action of dopamine and mediate avoidance of threats. Impaired function sensitises the dopamine system resulting in impulsivity and drug addiction. Posterior 5HT cells (median raphe nucleus) innervate hippocampus and cingulate gyrus and suppress memory and awareness of current and past adversity. Impaired function results in low mood, low self-esteem, hopelessness and pessimism. Modern imaging methods are providing startling corroboration of these ideas.

Neuroimaging studies of violence and antisocial behavior

The neurobiological basis of violence and antisocial behavior is poorly understood. Lesion studies have implicated the frontal and temporal lobes in such phenomena. Recent neuroimaging studies have provided more detailed information on the neurobiological correlates of violence and antisocial behavior. Moreover, the results of such imaging studies extend findings from prior lesion studies. These results suggest that violent and antisocial behavior is associated with disruptions in frontotemporal neural systems. This article reviews the neuroimaging literature on violence and antisocial behavior and discusses the strengths and weaknesses of the different methods that have been used in such studies. The author reviews findings from cerebral psychophysiology studies (electroencephalographic studies and evoked potentials), as well as from studies using positron emission tomography (PET), single photon emission computed tomography (SPECT), and magnetic resonance imaging (MRI). The article concludes with a discussion of useful directions for future research. It is clear that the use of neuroimaging methods in combination offers the greatest promise for progress in the understanding of the neural basis of violence and antisocial behavior.