Experimentally induced aggressive behavior in subjects with 3,4-methylenedioxy-methamphetamine ("Ecstasy") use history: psychobiological correlates

Glucocorticoids and Aggression: A Tripartite Interaction

The effects of glucocorticoids on aggression can be conceptualized based on its mechanisms of action. These hormones can affect cell function non-genomically within minutes, primarily by affecting the cell membrane. Overall, such effects are activating and promote both metabolic preparations for the fight and aggressive behavior per se. Chronic increases in glucocorticoids activate genomic mechanisms and are depressing overall, including the inhibition of aggressive behavior. Finally, excessive stressors trigger epigenetic phenomena that have a large impact on brain programming and may also induce the reprogramming of neural functions. These induce qualitative changes in aggression that are deemed abnormal in animals, and psychopathological and criminal in humans. This review aims at deciphering the roles of glucocorticoids in aggression control by taking in view the three mechanisms of action often categorized as acute, chronic, and toxic stress based on the duration and the consequences of the stress response. It is argued that the tripartite way of influencing aggression can be recognized in all three animal, psychopathological, and criminal aggression and constitute a framework of mechanisms by which aggressive behavior adapts to short-term and log-term changes in the environment.

Reactive vs proactive aggression: A differential psychobiological profile? Conclusions derived from a systematic review

INTRODUCTION

Scholars have established subcategories of aggressive behavior in order to better understand this construct. Specifically, a classification based on motivational underpinnings makes it possible to differentiate between reactive and proactive aggression. Whereas reactive aggression is characterized by emotional lability, which means it is prone to impulsive reactions after provocation, proactive aggression is driven by low emotionality and high levels of instrumentality to obtain benefits. Some authors have conceived these two types as having a dichotomous nature, but others argue against this conceptualization, considering a complementary model more suitable. Hence, neuroscientific research might help to clarify discussions about their nature because biological markers do not present the same biases as psychological instruments.

AIM

The main objective of this study was to carry out a systematic review of studies that assess underlying biological markers (e.g., genes, brain, psychophysiological, and hormonal) of reactive and proactive aggression.

METHODS

To carry out this review, we followed PRISMA quality criteria for reviews, using five digital databases complemented by hand-searching.

RESULTS

The reading of 3993 abstracts led to the final inclusion of 157 papers that met all the inclusion criteria. The studies included allow us to conclude that heritability accounted for approximately 45% of the explained variance in both types of aggression, with 60% shared by both, especially, for overt and physical expression forms, and 10% specific to each type. Regarding allelic risk factors, whereas low functioning variants affecting serotonin transport and monoaminoxidase increased the risk of reactive aggression, high functioning variants were associated with proactive aggression. Furthermore, brain analysis revealed an overlap between the two types of aggression and alterations in the volume of the amygdala and temporal cortex. Moreover, high activation of the medial prefrontal cortex (PFC) facilitated proneness to both types of aggression equally. Whereas stimulation of the right ventrolateral (VLPFC) and dorsolateral (DLPFC) reduced proneness to aggression, inhibition of the left DLPFC increased it. Finally, psychophysiological and hormonal correlates in general did not clearly differentiate between the two types because they were equally related to each type (e.g., low basal cortisol and vagal variability in response to acute stress) CONCLUSIONS: This study reinforces the complementary model of both types of aggression instead of a dichotomous model. Additionally, this review also offers background about several treatments (i.e., pharmacological, non-invasive brain techniques…) to reduce aggression proneness.

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

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

Glucocorticoid receptor gene (NR3C1) is hypermethylated in adult males with aggressive behaviour

Aggressive behaviour is a serious threat to the personal safety and property of others due to the potential that the assailant may hurt people, himself/herself or objects, and aggression has always been one of the focuses of research and concern. Accumulating evidence suggests that the hypothalamic-pituitary-adrenal (HPA) axis plays a major role in the development, elicitation, enhancement and genetic susceptibility of aggressive behaviour in humans and animals. GR (NR3C1) plays a crucial role in controlling HPA activity, which directly affects aggressive behaviour. Here, we investigated the methylation state of the NR3C1 gene promoter region and its role in aggressive behaviour in adult males for the first time by applying a case-control approach (N = 106 controls, N = 104 patients). Methylation of NR3C1 was measured in peripheral blood samples at exons 1_D, 1_B and 1_F via sodium bisulfite treatment combined with the MethylTarget method. Methylation of the NR3C1 gene was significantly correlated with aggressive behaviour, and the methylation levels of 1_D, 1_B and 1_F were upregulated in the aggressive behaviour group, intentional injury subgroup and robbery subgroup, and the significance varied. In addition, multiple CpG sites were found to be significantly associated with aggressive behaviour. These results suggest that epigenetic aberrations of NR3C1 are associated with aggressive behaviour, and epigenetic processes might mediate aggressive behaviour by affecting the activity of the HPA axis. This correlative study between DNA methylation of the NR3C1 gene and aggressive behaviour in patients may be helpful for forensic assessments.

Of mice and men on MDMA: A translational comparison of the neuropsychobiological effects of 3,4-methylenedioxymethamphetamine ('Ecstasy')

MDMA (3,4-methylendioxymethamphetamine), also known as Ecstasy, is a stimulant drug recreationally used by young adults usually in dance clubs and raves. Acute MDMA administration increases serotonin, dopamine and noradrenaline by reversing the action of the monoamine transporters. In this work, we review the studies carried out over the last 30 years on the neuropsychobiological effects of MDMA in humans and mice and summarise the current knowledge. The two species differ with respect to the neurochemical consequences of chronic MDMA, since it preferentially induces serotonergic dysfunction in humans and dopaminergic neurotoxicity in mice. However, MDMA alters brain structure and function and induces hormonal, psychomotor, neurocognitive, psychosocial and psychiatric outcomes in both species, as well as physically damaging and teratogen effects. Pharmacological and genetic studies in mice have increased our knowledge of the neurochemical substrate of the multiple effects of MDMA. Future work in this area may contribute to developing pharmacological treatments for MDMA-related disorders.

A Failure to Replicate Alcohol-Induced Laboratory Aggression among College Men without Evidence of Personality Disturbance

The effect of acute alcohol intoxication on laboratory-induced aggression among men has been fairly well established. The present study hypothesized that alcohol effects on Point Subtraction Aggression Paradigm (PSAP) responding would not be replicated among “low-risk” college men distinguished by their absence of personality disorder features. Participants were assigned to either Alcohol ( n = 18), Placebo ( n = 7), or Time ( n = 8) comparison groups with each completing 25-min. sessions during the baseline, ascent, peak (70 mg%), and descent (40 mg%) phases of absorption and elimination process. Participants assigned to the Alcohol condition received a .80 ml/kg dose of 95% ethanol mixed with soda in a 1:5 ethanol/soda ratio. As hypothesized, alcohol was associated with stable Point Subtraction Aggression Paradigm responding across the course of absorption, peak, and elimination for all three groups. Aggression Paradigm responding was least variable among the men administered alcohol. The present procedure served to identify a subset of “low-risk” college men whose Point Subtraction Aggression Paradigm responding was not adversely affected by alcohol. The extent to which aggressive personality dispositions contribute to alcohol-induced laboratory aggression remains to be identified. Low-risk college drinkers warrant systematic examination to specify what factors attenuate their reactions to alcohol and other situational provocations.

The effect of acute tryptophan depletion on mood and impulsivity in polydrug ecstasy users

RATIONALE

Several studies suggest users of 3,4-methylenedioxymethamphetamine (ecstasy) have low levels of serotonin. Low serotonin may make them susceptible to lowered mood.

OBJECTIVE

This work aims to study the acute effects on mood and impulsivity of lowering serotonin levels with acute tryptophan depletion in polydrug ecstasy users and to determine whether effects were different in men and women.

METHODS

In a double-blind cross-over study, participants who had used ecstasy at least 25 times (n = 13) and nonuser controls (n = 17) received a tryptophan-deficient amino acid mixture and a control amino acid mixture containing tryptophan, at least 1 week apart. Mood was measured using the profile of mood states, and impulsivity was measured with the Go/No-Go task.

RESULTS

The main result shows that a lowering of mood after acute tryptophan depletion occurred only in female polydrug ecstasy users (n = 7), relative to controls (n = 9). Results from the Go/No-Go task suggested that impulsivity was not increased by acute tryptophan depletion in polydrug ecstasy users.

LIMITATION

The group sizes were small, when males and females were considered separately.

CONCLUSIONS

Women polydrug ecstasy users appear to be more susceptible than men to the effects of lowered serotonin levels. If use of ecstasy alone or in conjunction with other drugs causes progressive damage of serotonin neurons, women polydrug ecstasy users may become susceptible to clinical depression.

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

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

MDMA, serotonergic neurotoxicity, and the diverse functional deficits of recreational 'Ecstasy' users

Serotonergic neurotoxicity following MDMA is well-established in laboratory animals, and neuroimaging studies have found lower serotonin transporter (SERT) binding in abstinent Ecstasy/MDMA users. Serotonin is a modulator for many different psychobiological functions, and this review will summarize the evidence for equivalent functional deficits in recreational users. Declarative memory, prospective memory, and higher cognitive skills are often impaired. Neurocognitive deficits are associated with reduced SERT in the hippocampus, parietal cortex, and prefrontal cortex. EEG and ERP studies have shown localised reductions in brain activity during neurocognitive performance. Deficits in sleep, mood, vision, pain, psychomotor skill, tremor, neurohormonal activity, and psychiatric status, have also been demonstrated. The children of mothers who take Ecstasy/MDMA during pregnancy have developmental problems. These psychobiological deficits are wide-ranging, and occur in functions known to be modulated by serotonin. They are often related to lifetime dosage, with light users showing slight changes, and heavy users displaying more pronounced problems. In summary, abstinent Ecstasy/MDMA users can show deficits in a wide range of biobehavioral functions with a serotonergic component.

Symptomatological features of patients with and without Ecstasy use during their first psychotic episode

Background: Ecstasy use is generally chosen by adolescents and young adults for its entactogenic properties (the production of feelings of empathy, love, and emotional closeness to others.) Despite this desired and frequently realized outcome, Ecstasy use has often resulted in the genesis of psychotic symptoms and aggressive behaviors, particularly after chronic and/or intensive use. Methods: To explore the negative consequences of Ecstasy use and to examine the aggressive nature oftentimes seen in many Ecstasy users we employed a case-control study model. We compared, by means of validated psychometric tests, the psychopathological symptoms (BPRS), the aggressiveness (OAS) and the social adjustment (DSM-GAF) of psychotic patients with (n = 23) and without (n = 46) recent user of Ecstasy, during their first psychotic episode and hospitalization. All 23 Ecstasy users were Ecstasy users only. Results: Almost all of the psychotic symptoms were of similar severity in both groups. Blunted affect was milder in users than in non-users, whereas hostility and aggressive behavior was significantly more severe in users than in non-users. Conclusions: psychosis with a high level of aggressiveness and violence constitutes an important ‘side-effect’ that surely runs counter to the expected entactogenic action of Ecstasy. At a patient psycho-educational level, this study suggests that the use of Ecstasy may be counterproductive with respect to user expectations.

The relationship between basal and acute HPA axis activity and aggressive behavior in adults

The hypothalamic-pituitary-adrenal (HPA) axis seems to play a major role in the development, elicitation, and enhancement of aggressive behavior in animals. Increasing evidence suggests that this is also true for humans. However, most human research on the role of the HPA axis in aggression has been focusing on highly aggressive children and adolescent clinical samples. Here, we report on a study of the role of basal and acute HPA axis activity in a sample of 20 healthy male and female adults. We used the Taylor Aggression Paradigm to induce and measure aggression. We assessed the cortisol awakening response as a trait measure of basal HPA axis activity. Salivary free cortisol measures for the cortisol awakening response were obtained on three consecutive weekdays immediately following awakening and 30, 45, and 60 min after. Half of the subjects were provoked with the Taylor Aggression Paradigm to behave aggressively; the other half was not provoked. Acute HPA axis activity was measured four times, once before and three times after the induction of aggression. Basal cortisol levels were significantly and negatively related to aggressive behavior in the provoked group and explained 67% of the behavioral variance. Cortisol levels following the induction of aggression were significantly higher in the provoked group when baseline levels were taken into account. The data implicate that the HPA axis is not only relevant to the expression of aggressive behavior in clinical groups, but also to a large extent in healthy ones.

Mechanisms underlying aggressive and hostile behavior in amphetamine users

PURPOSE OF REVIEW

To review current evidence linking amphetamine use with aggression and to consider possible factors that might underlie this association.

RECENT FINDINGS

Although evidence that amphetamine use is related to increased levels of aggression continues to grow, the underlying processes or mechanisms remain somewhat elusive. In this review, three possible underlying factors are considered. Neurotoxic, pharmacological effects of amphetamine on the dopaminergic and serotonergic systems are related to aggressive, hostile behavior in both animal and human studies. Of particular interest is the converging evidence that amphetamine use is related to impairment in executive functions (including self-control) that are regulated by the prefrontal cortex. Taken together, these findings suggest that amphetamine users may have an impaired capacity to control or inhibit aggressive impulses. Furthermore, high levels of impulsivity related to amphetamine use may also play a role. Finally, amphetamine use is associated with increased positive symptoms of psychosis, particularly paranoia, that contribute to a perception of the environment as a hostile, threatening place.

SUMMARY

Taken separately, each of these factors may lead to an increase in aggression with increased use of amphetamine, but their interactive or synergistic effects may be particularly problematic.

An interaction between the norepinephrine transporter and monoamine oxidase A polymorphisms, and novelty-seeking personality traits in Korean females

The personality traits associated with the noradrenergic system have not yet been clearly established. In the present study, we investigated the variable number of tandem repeats (VNTR) polymorphism of the norepinephrine transporter (NET) and monoamine oxidase A (MAOA), which are major components of the adrenergic system, to elucidate their relationship with personality. A total of 245 normal female Koreans (age 23.05+/-3.07 years, mean+/-SD) volunteered to take part in this study. They filled out a Korean version of the Temperament and Character Inventory (TCI) and were genotyped for the NET and MAOA-VNTR; the NET T-182C and MAOA-uVNTR polymorphisms were checked. We found significant main effect of NET genotype on novelty seeking (NS) score (F=5.43, p=0.021) and significant interaction between the NET and MAOA-uVNTR polymorphisms on NS score (F=11.06, p=0.001). However, there were no relationship between MAOA-uVNTR polymorphisms and NS score, and no association with other temperamental dimensions and these two polymorphisms. Our findings suggest that this functional polymorphism in the noradrenergic gene is associated with novelty seeking in Korean females.

A long-term ecstasy-related change in visual perception

RATIONALE

The present study provides the first evidence of the long-term consequences of ecstasy use on visual processes thought to reflect serotonergic functions in the occipital lobe. Methylenedioxymethamphetamine ("ecstasy") is known to cause lasting changes to the serotonin system in animals, and convergent evidence suggests that similar changes occur in human ecstasy users. Other research suggests that serotonin may be involved in lateral inhibition between orientation sensitive neurons in the occipital lobe, and that disruption to the serotonin system causes an increase in the magnitude of the tilt aftereffect illusion that is known depend on those neurons.

OBJECTIVES

The aim of the present study was to determine if ecstasy users have detectable changes in occipital lobe behavioural functioning, as revealed by the tilt aftereffect illusion.

MATERIALS AND METHODS

Thirty ecstasy users and 34 non-drug using controls were compared on the magnitude of the tilt aftereffect illusion following adaptation to stimuli oriented at 15 and 40 degrees from vertical.

RESULTS

Ecstasy users who had not used amphetamines for 115 days or more had a larger average tilt aftereffect than non-drug using controls after adaptation to 40 degrees stimuli but not after adaptation to 15 degrees stimuli. Additionally, there was no difference between non-drug using controls and ecstasy users who had used amphetamines within the last 61 days at either adaptation angle.

CONCLUSIONS

The results were consistent with the proposal that ecstasy-related damage to the serotonin system causes behavioural changes on tests of visual perception processes that are thought to reflect serotonergic functions in the occipital lobe.

The psychotherapeutic potential of MDMA (3,4-methylenedioxymethamphetamine): an evidence-based review

AIMS AND RATIONALE: The purpose of this study was to review whether methylenedioxymethamphetamine (MDMA) has the appropriate pharmacodynamic profile to be a therapeutic agent.

MATERIALS AND METHODS

Empirical descriptions of MDMA's subjective effects in humans will be reviewed to evaluate the proposal that MDMA has psychotherapeutic properties. The focus will be published evidence on its functional effects in therapeutic, medical, and other situations.

RESULTS

MDMA is a powerful central nervous system (CNS) stimulant which affects several neurotransmitter systems and intensifies a range of psychobiological functions. Its acute mood effects can be very positive and life enhancing, and the affirmative cognitions engendered during MDMA therapy may well endure afterwards. However, MDMA also has a number of potential anti-therapeutic characteristics. Acutely, it can also intensify negative cognitions, and these may similarly endure over time. Psychotherapists have found that setting, intention, and expectancy are crucial for a positive outcome, but these factors cannot be guaranteed. Post-MDMA, there is a period of neurotransmitter recovery when low moods predominate, and these may exacerbate psychiatric distress. The explanations proposed for MDMA-assisted therapy are all psychodynamic, and a neurochemical model needs to be outlined. It has been suggested that enduring therapeutic gains can follow a single session, but again, this lacks a clear psychopharmacological rationale. Finally, diathesis-stress models suggest that psychiatric individuals are more prone to acute and chronic abreactions to CNS stimulants such as MDMA.

CONCLUSIONS

There are a number of issues which need to be addressed before it can be argued that MDMA might be clinically useful for psychotherapy.

The effect glucocorticoids on aggressiveness in established colonies of rats

It was repeatedly shown that glucocorticoids increase aggressiveness when subjects are socially challenged. However, the interaction between challenge exposure and glucocorticoid effects was not investigated yet. We studied this interaction by assessing the effects of glucocorticoids in established colonies of rats, i.e. in rats that were not exposed to an acute social challenge. Aggressiveness was high immediately after colony formation but decreased sharply within 4 days and remained stable thereafter. Mild dominance relations were observed in 11 colonies (65%). Approximately three weeks after colony formation, rats remained undisturbed or were injected with vehicle or corticosterone. Routine colony life was followed for 1h after treatments. Injections per se induced a mild and transient behavioral activation: resting was reduced, whereas exploration, social and agonistic interactions were increased. The change lasted about 15min. Corticosterone--although plasma corticosterone levels were increased--had no specific effect, as the behavior of vehicle- and corticosterone-treated rats was similar. Social rank had a minor impact on the results. In contrast, the pro-aggressive effects of corticosterone were robust under conditions of social challenge and were maintained after repeated exposure to aggressive encounters. It occurs that an acute increase in glucocorticoids promotes social challenge-induced aggressiveness, but does not increase aggressiveness under routine conditions. We hypothesize that the pro-aggressive effects of glucocorticoids develop in conjunction with challenge-induced neuronal (e.g. monoaminergic) activation.

Experimentally induced aggressiveness in heroin-dependent patients treated with buprenorphine: comparison of patients receiving methadone and healthy subjects

Objective measures of experimentally induced aggressiveness were evaluated in heroin-dependent patients (HDP), 15 receiving buprenorphine (BUP) and 15 receiving methadone (METH) treatment. HDP were randomly assigned to BUP and METH groups. Fifteen healthy subjects (CONT) were included in the study as controls. During a laboratory task, the Point Subtraction Aggression Paradigm, subjects earned monetary reinforcement and could respond by ostensibly subtracting money from a fictitious subject (the aggressive response). Money-earning (points maintained) responses did not differ in BUP patients and in controls. In contrast, point-maintained responses were significantly lower in the group of HDP treated with METH than in both the BUP and CONT groups. Aggressive responses were significantly higher in the HDP group than in the CONT group. No significant differences in aggressive responses were found between the BUP and METH groups. Baseline concentrations of plasma adrenocorticotropic hormone (ACTH) and cortisol (CORT) were higher in HDP than in CONT. During the experimental task, ACTH and CORT increased significantly less in METH patients than in BUP patients and CONT. Norepinephrine (NE) and epinephrine (EPI) levels increased significantly more in HDP than in CONT, without any difference between the METH and BUP patients. PSAP aggressive responses positively correlated with NE and EPI changes, as well as with Buss-Durkee Hostility Inventory (BDHI) scores in both METH and BUP patients and also in CONT subjects. No correlation was found between the extent of heroin exposure, drug doses and aggressiveness levels. BUP, similarly to METH, does not seem to affect outward-directed aggressiveness, as aggressive responses related more to monoamine levels and personality traits than to the action of opioid agonists. Money-earning responses seemed to be unimpaired in BUP patients.

Plasma serotonin levels in young violent offenders: Aggressive responding and personality correlates

70 young male violent offenders and 30 normal controls in Hunan, China were interviewed and assessed by the Minnesota Multiphasic Personality Inventory (MMPI), Point Subtraction Aggression Paradigm (PSAP) and plasma serotonin (5-HT) level. Compared to the normal controls, the violent offenders had significantly higher plasma 5-HT levels; higher scores on the MMPI subscale Pd (P < 0.01), Pa (P < 0.05); and higher PSAP-B responding and lower PSAP-C responding (P < 0.05). There was a positive correlation between the MMPI Pd score and the PSAP B response, but no significant correlation was found between Pd score and plasma 5-HT level, or between PSAP B response and plasma 5-HT level. Our data suggest that the young violent offenders are more aggressive than the normal control. But this study did not demonstrate that the plasma 5-HT level had a correlation with the PSAP aggressive response. The relationship between the aggressiveness and impulsivity in the violent behavior needs further study.

Personality and aggressive behavior under provoking and neutral conditions: A meta-analytic review

The authors conducted a comprehensive review to understand the relation between personality and aggressive behavior, under provoking and nonprovoking conditions. The qualitative review revealed that some personality variables influenced aggressive behavior under both neutral and provocation conditions, whereas others influenced aggressive behavior only under provocation. Studies that assessed personality variables and that directly measured aggressive behavior were included in the quantitative review. Analyses revealed that trait aggressiveness and trait irritability influenced aggressive behavior under both provoking and neutral conditions but that other personality variables (e.g., trait anger, Type A personality, dissipation-rumination) influenced aggressive behavior only under provoking conditions. The authors discuss possible relations between these patterns of aggressive behavior and the personality dimensions of Agreeableness and Neuroticism and consider implications for theories of aggression.

Trait modulation of alcohol-induced laboratory aggression

Modest alcohol and aggressive trait effects on laboratory-induced aggression among men have been reported with some consistency in the literature. Relationships between aggressive personality traits and laboratory-induced aggression appear to become less consistent under the influence of alcohol. Several research teams have found suggestions that the effects of alcohol on laboratory aggression may be reduced or even reversed among individuals with aggressive personality traits. This study examined the effects of alcohol on the aggressive responding on the Point Subtraction Aggression Paradigm (PSAP) of eight undergraduate men who generated evidence on the Million Clinical Multiaxial Inventory-II (MCMI-II) of sadistic-aggressive personality disorder features. This sample was compared with a group of 18 undergraduate male peers without MCMI-II elevations described in a previous study. Neither alcohol ingestion (0.8 ml/kg) nor aggressive personality traits predicted laboratory behavior in isolation, but alcohol was found to selectively attenuate (d = 0.75) PSAP responding for the sadistic-aggressive as opposed to the control subjects (i.e., a significant aggressive trait by alcohol interaction). The possible value of this counterintuitive response tendency in identifying men at elevated risk for alcohol-related aggression was discussed. Large, immediate reductions in laboratory-based aggressive responding while under the influence of alcohol might provide a paradoxical high risk indicator that has not been previously identified.

Mechanisms differentiating normal from abnormal aggression: glucocorticoids and serotonin

Psychopathology-associated human aggression types are induced by a variety of conditions, are behaviorally variable, and show a differential pharmacological responsiveness. Thus, there are several types of abnormal human aggression. This diversity was not reflected by conventional laboratory approaches that focused on the quantitative aspects of aggressive behavior. Recently, several laboratory models of abnormal aggression were proposed, which mainly model hyperarousal-driven aggressiveness (characteristic to intermittent explosive disorder, post-traumatic stress disorder, depression, chronic burnout, etc.) and hypoarousal-driven aggressiveness (characteristic mainly to antisocial personality disorder and its childhood antecedent conduct disorder). Findings obtained with these models suggest that hyperarousal-driven aggressiveness has at its roots an excessive acute glucocorticoid stress response (and probably an exaggerated response of other stress-related systems), whereas chronic hypoarousal-associated aggressiveness is due to glucocorticoid deficits that affect brain function on the long term. In hypoarousal-driven aggressiveness, serotonergic neurotransmission appears to lose its impact on aggression (which it has in normal aggression), certain prefrontal neurons are weakly activated, whereas the central amygdala (no, or weakly involved in the control of normal aggression) acquires important roles. We suggest that the specific study of abnormal aspects of aggressive behavior would lead to important developments in understanding the specific mechanisms underlying different forms of aggression, and may ultimately lead to the development of better treatment approaches.

Pattern of cannabis use in ecstasy polydrug users: moderate cannabis use may compensate for self-rated aggression and somatic symptoms

Cannabis is one of the most common 'co-drugs' for ecstasy users. The aim of the present study was to explore self-reported psychobiological problems in ecstasy polydrug users in relation to their pattern of cannabis use. Two hundred and eighty ecstasy polydrug users were allocated into five cannabis groups according to the frequency of their cannabis use. The control group comprised 121 alcohol-tobacco users. There were no significant group differences with regard to age, diagnosed family psychiatric history and level of self-rated stress experienced during 6 months prior to the study. The present study produced three main findings: (a) Ecstasy users with no concomitant use of cannabis displayed more self-rated aggression and somatic symptoms compared with ecstasy users who were smoking cannabis on a monthly or weekly basis. (b) Ecstasy users who reported heavy cannabis use in the past displayed higher paranoid symptoms compared with ecstasy weekly and daily cannabis users. (c) Former heavy cannabis users were the most likely to complain of a variety of ecstasy related long-term problems. In conclusion, moderate cannabis use may help to ameliorate or mask MDMA-induced aggressivity and somatic symptoms. However, this study confirms that heavy cannabis and ecstasy use is associated with several psychobiological problems, which may emerge after a period of abstinence from both drugs.

Decreased pain tolerance and mood in recreational users of MDMA

RATIONALE

3,4-Methylenedioxymethamphetamine (MDMA) is known to affect brain serotonin (5-HT) neurons in experimental animals. However, its effects on humans are more difficult to infer. Serotonin is implicated in the body's ability to modulate the effects of pain and to regulate mood.

OBJECTIVE

The aim of this research is to test nociceptive responses and mood in MDMA users as an index of central 5-HT function.

METHOD

Measurements of pain tolerance were obtained using the cold-pressor test for 15 polydrug users who regularly use MDMA, 3-4 days after the most recent usage, and ten matched polydrug users who do not use MDMA. A rating on mood was obtained for each participant using the Nowlis Mood Adjective checklist.

RESULTS

Measurements of pain tolerance and mood were significantly lower in the MDMA group. A positive correlation between mood and pain tolerance was found in the MDMA group, whereas no correlation was found between these variables in the non-MDMA group

CONCLUSION

This study found an association between pain tolerance and MDMA usage and confirmed the association between MDMA and depressed mood. The current results suggest that MDMA, at least in the short term, may cause serotonin-mediated alterations in pain sensitivity.

Simultaneous liquid chromatographic analysis of catecholamines and 4-hydroxy-3-methoxyphenylethylene glycol in human plasma

The comparison of two HPLC methods, one with electrochemical detection and the other with coulometric detection, for the simultaneous analysis of catecholamines and 4-hydroxy-3-methoxyphenylethylene glycol (MHPG) in human plasma is presented. The careful pre-treatment of plasma samples is based on an innovative two-step procedure by means of solid-phase extraction (SPE) which uses one single hydrophilic-lipophilic balance cartridge. The extraction yield values found were higher than 85% for epinephrine, norepinephrine and MHPG, and higher than 70% for dopamine. The assays carried out on real plasma samples with the coulometric system gave good results in terms of sensitivity (limits of quantitation: 0.10-0.15 ng ml(-1) for catecholamines, 0.6 ng ml(-1) for MHPG) and selectivity, while interference was sometimes found when using the amperometric system. Precision was also satisfactory, with relative standard deviation values for intermediate precision always lower than 6%. The HPLC method with coulometric detection coupled to a novel SPE procedure is thus suitable for the simultaneous determination of catecholamines and MHPG in plasma of volunteers subjected to experimental stress.

Substance use among high-school students: relationships with temperament, personality traits, and parental care perception

Alcohol use, "alcohol abuse," and illicit drug use were investigated in a representative sample of 1076 urban, northern Italian high school students aged 14 to 19 years in 2001. In addition to questions on substance use, the participants were asked about school achievements and perceived substance use among friends. All the students were submitted to Zuckerman Sensation Seeking Scale (SSS) scale, Eysenck Personality Questionnaire (EPQ), Buss-Durkee Hostility Inventory (BDHI), and Parental Bonding Instrument (PBI). Lifetime alcohol use was found in 80.5%, "alcohol abuse" in 37.7%, cannabis use in 26.2%, ecstasy in 2.8%, heroin in 3.8%, and cocaine in 8.3% of the students: gender differences were significant for alcohol use, "alcohol abuse" and ecstasy use, with male subjects outnumbering females, but not for reported cannabis, heroin, and cocaine use. Early substance use onset among adolescents aged 14-16 years was detected. Higher sensation seeking on SSS, social coping impairment on EPQ, direct aggressiveness on BDHI, poor school achievements, and lower parental care on PBI were found associated with illicit drug use and "alcohol abuse" (multiple drugs users). Increased levels of aggressiveness and sensation seeking were evidenced both in minimal experimenters (ME) and habitual users (HU), without any significant difference, in comparison with abstinent students. Similarly, ME scored higher than abstinent subjects on EPQ for social coping impairment, but lower than HU. Parental care perception was lower in HU, but not in ME with, respect to abstinent subjects. Pearson inverse correlation was demonstrated between PBI scores and EPQ maladaptation and BDHI aggressiveness. Data from this preliminary pilot study suggest that temperamental traits and personality changes may be associated to early substance use "proneness" and reduced perception of parental care.

Gene-environment interplay in alcoholism and other substance abuse disorders: expressions of heritability and factors influencing vulnerability

Factors that confer predisposition and vulnerability for alcoholism and other substance abuse disorders may be described usefully within the gene-environment interplay framework. Thus, it is postulated that heritability provides a major contribution not only to alcohol but also to other substances of abuse. Studies of evoked potential amplitude reduction have provided a highly suitable and testable method for the assessment of both environmentally-determined and heritable characteristics pertaining to substance use and dependence. The different personal attributes that may co-exist with parental influence or exist in a shared, monozygotic relationship contribute to the final expression of addiction. In this connection, it appears that personality disorders are highly prevalent co-morbid conditions among addicted individuals, and, this co-morbidity is likely to be accounted for by multiple complex etiological relationships, not least in adolescent individuals. Co-morbidity associated with deficient executive functioning may be observed too in alcohol-related aggressiveness and crimes of violence. The successful intervention into alcohol dependence and craving brought about by baclofen in both human and animal studies elucidates glutamatergic mechanisms in alcoholism whereas the role of the dopamine transporter, in conjunction with both the noradrenergic and serotonergic transporters, are implicated in cocaine dependence and craving. The role of the cannabinoids in ontogeny through an influence upon the expression of key genes for the development of neurotransmitter systems must be considered. Finally, the particular form of behaviour/characteristic outcome due to childhood circumstance may lie with biological, gene-based determinants, for example individual characteristics of monoamine oxidase (MAO) activity levels, thereby rendering simple predictive measures both redundant and misguiding.

Aggressive responding in abstinent heroin addicts: neuroendocrine and personality correlates

Objective measures of experimentally induced aggressiveness were evaluated in 20 abstinent heroin-dependent subjects, in comparison with 20 normal healthy male subjects. All the subjects were preliminarily submitted to DSM-IV interviews, Buss-Durkee Hostility Inventory (BDHI) and Minnesota Multiphasic Personality Inventory (MMPI II). During a laboratory task, the Point Subtraction Aggression Paradigm (PSAP), subjects earned monetary reinforcers with repeated button presses and were provoked by the subtraction of money, which was attributed to a fictitious other participant. Subjects could respond by ostensibly subtracting money from the fictitious subject (the aggressive response). Money-earning responses were not different in drug-free heroin addicts and controls during the first two sessions and significantly lower during the third session in heroin-dependent subjects (t=2.99, P<.01). Aggressive responses were significantly higher (F=4.9, P<.01) in heroin addicted individuals, in comparison with controls. During the experimentally induced aggressiveness, plasma adrenocorticotropic hormone (ACTH) and cortisol (CORT) concentrations increased less significantly, and norepinephrine (NE) and epinephrine (EPI) levels, together with heart rate (HR), increased more significantly in abstinent heroin-dependent subjects than in healthy subjects. PSAP aggressive responses positively correlated with catecholamine changes, BDHI "direct" and "irritability" scores, MMPI "psychopathic deviate" scores in heroin-dependent subjects and controls, and with CORT responses only in healthy subjects. No correlation was found between heroin-exposure extent (substance abuse history duration) and aggressiveness levels. The present findings suggest that heroin-dependent patients have higher outward-directed aggressiveness than healthy subjects, in relation with monoamine hyperreactivity, after long-term opiate discontinuation. Aggressiveness in heroin addicts seems to be related more to the personality traits than to drug effects. The impairment of hypothalamus-pituitary-adrenal (HPA) axis in abstinent addicted individuals could be due to a long-lasting action exerted by opiates on proopiomelanocortin (POMC) or to a premorbid psychobiological condition, in association with increased sympathetic arousal.

Drugs of abuse and the elicitation of human aggressive behavior

The drug-violence relationship exists for several reasons, some direct (drugs pharmacologically inducing violence) and some indirect (violence occurring in order to attain drugs). Moreover, the nature of that relationship is often complex, with intoxication, neurotoxic, and withdrawal effects often being confused and/or confounded. This paper reviews the existing literature regarding the extent to which various drugs of abuse may be directly associated with heightened interpersonal violence. Alcohol is clearly the drug with the most evidence to support a direct intoxication-violence relationship. The literatures concerning benzodiazepines, opiates, psychostimulants, and phencyclidine (PCP) are idiosyncratic but suggest that personality factors may be as (or more) important than pharmacological ones. Cannabis reduces likelihood of violence during intoxication, but mounting evidence associates withdrawal with aggressivity. The literature on the relationship between steroids and aggression is largely confounded, and between 3,4-methylenedioxymethamphetamine (MDMA) and aggression insufficient to draw any reasonable conclusions. Conclusions and policy implications are briefly discussed.

Hypothalamic-pituitary-adrenal axis responses to stress in subjects with 3,4-methylenedioxy-methamphetamine ('ecstasy') use history: correlation with dopamine receptor sensitivity

Fifteen 3,4-methylenedioxymethamphetamine (MDMA, 'ecstasy') users who did not have other drug dependencies or prolonged alcohol abuse and 15 control subjects were studied. All the subjects were exposed to the same psychosocial stressor (Stroop Color-Word Interference Task, public speaking and mental arithmetic in front of an audience) 3 weeks after MDMA discontinuation. Plasma concentrations of adrenocorticotropic hormone (ACTH) and cortisol were measured immediately before the tests began and at their end, 30 min later. Growth hormone (GH) responses to the dopaminergic agonist bromocriptine and psychometric measures (Tridimensional Personality Questionnaire, Minnesota Multiphasic Personality Inventory, Buss-Durkee Hostility Inventory) were also obtained 4 weeks after MDMA discontinuation for the same subjects. ACTH and cortisol basal levels were significantly higher in ecstasy users than in control subjects. In contrast, ACTH and cortisol responses to stress were significantly blunted in MDMA users. The sensitivity of dopamine D2 receptors, reflected by GH responses to bromocriptine challenge, was reduced in MDMA users compared with controls. The responsiveness of the hypothalamic-pituitary-adrenal (HPA) axis (ACTH and cortisol delta peaks) correlated directly with GH areas under curves in response to bromocriptine, and inversely with psychometric measures of aggressiveness and novelty seeking. No correlation was found between hormonal measures and the extent of MDMA exposure. Reduced D2 receptor sensitivity, HPA basal hyperactivation and reduced responsiveness to stress may represent a complex neuroendocrine dysfunction associated with MDMA use. The present findings do not exclude the possibility that dopamine dysfunction partly predated MDMA exposure.

Neuroendocrine responses to experimentally-induced emotions among abstinent opioid-dependent subjects

The present study investigated neuroendocrine and cardiovascular changes during experimentally-induced affective states in abstinent heroin-dependent subjects and healthy controls. The procedure for eliciting emotions in all subjects used pleasant and unpleasant stimuli that did not differ in subjective arousal properties. We investigated whether the valence of the stimuli differentially affected neuroendocrine responses by comparing neutral, pleasant and unpleasant pictures on heart rate (HR), systolic (SBP) and diastolic blood pressure (DBP), methyl-OH-phenyl-glycol (MHPG), norepinephrine (NE), epinephrine (EPI), adrenocorticotrophic hormone (ACTH) and cortisol (CORT) plasma levels. Twelve abstinent heroin-dependent subjects, in comparison with 12 control subjects, were submitted to three experimental sessions, each on one of three experimental days a week apart, in counterbalanced order: day 1=unpleasant pictures, day 2=pleasant pictures, day 3=neutral pictures. In the rating of subjective arousal pleasant and unpleasant stimuli received the same high score in comparison with neutral stimuli; a different cardiovascular and neuroendocrine pattern was obtained in healthy subjects: unpleasant stimuli elicited increases in HR, SBP, MHPG, NE, ACTH, CORT, whereas neutral and pleasant stimuli did not induce any significant response in hormonal levels. In contrast, in heroin addicts, despite increased perceptions of unpleasantness, HR, SBP, MHPG and NE levels did not increase after disliked stimuli; these subjects also reported increased arousal during exposure to neutral stimuli. In comparison with controls, addicted individuals showed higher CORT and ACTH basal levels, and a consequent lack of response to unpleasant stimuli. The results indicate that neuroendocrine and cardiovascular systems respond selectively to affective, motivationally relevant stimuli, and that substance use disorders may be associated with dysregulation of emotion-processing mechanisms.

Altered states: the clinical effects of Ecstasy

Ecstasy is the second most widely abused illegal drug in Europe. Ecstasy is the colloquial name for 3,4-methylenedioxymethamphetamine (MDMA), but not all Ecstasy tablets contain MDMA. When taken in hot, crowded environments, Ecstasy/MDMA users have developed acute complications that have had fatal consequences. Epidemiological evidence indicates that adverse reactions to Ecstasy/MDMA intoxication are rare and idiosyncratic. Potential mechanisms of action are reviewed. In animal studies, MDMA damages serotonergic fibres and reduces the number of serotonin transporter sites within the CNS. Demonstration of neurotoxicity in human users of Ecstasy is hampered by a number of confounds that the majority of published studies have failed to address. These confounds are reviewed and their impact is discussed.

Acute and carryover effects in mice of MDMA ("ecstasy") administration during periadolescence

In spite of the increasing evidence concerning its neurotoxicity, young human individuals are often involved in the recreational use of amphetamine-type stimulants such as 3,4-methylenedioxymethamphetamine (MDMA or "ecstasy"). A study aimed to investigate short- and long-term consequences of a repeated and intermittent MDMA administration (0, 5 or 10 mg/kg i.p., 3 days treatment history) was conducted in mice. Mice were injected at different phases in development, namely at early (28 days old), middle (38 days old) or late (52 days old) adolescence. When assessed for nociceptive response, a dose-dependent analgesia was found in middle and late adolescent mice. Carryover consequences of previous MDMA treatment were then investigated at adulthood (80 days old). In a social interaction test, levels of environment exploration and social behaviour resulted markedly increased in drug-free state as a function of drug exposure during development, whereas others behaviours were reduced. MDMA challenge (5-mg/kg dose) produced the expected hyperactivity, as well as a marked increment of hypothalamic serotonin (5-hydroxyhyptamine, 5-HT) levels. Mice treated chronically with MDMA during middle and late adolescence were associated with important reductions of the indoleamine. As a whole, these results indicate a differential long-term vulnerability to behavioural and neurotoxicant effects of MDMA as a function of the developmental stage of exposure.