Effect of D-amphetamine on emotion-potentiated startle in healthy humans: implications for psychopathy and antisocial behaviour

Dental injuries in Swiss soccer supporters: A comparative study of regular fans, ultras, and hooligans for public health strategies

OBJECTIVES

Violence among soccer supporters continues to pose a significant public health concern in many parts of the world. In Switzerland, hooliganism is largely uninvestigated. This study aimed to examine incidents of violence and associated dental injuries among different groups of soccer supporters, as well as assess the impact of intoxicants on their behavior, using survey data from regular fans, ultras, and hooligans in the Swiss Football League.

MATERIAL AND METHODS

A cross-sectional survey using a standardized questionnaire was conducted among distinct factions of soccer supporters in the Swiss Football League in 2022. A total of 165 participants self-identified as belonging to one of three subgroups: "regular fan," "ultra," or "hooligan." Data were gathered on physical altercations, dental injuries, possession of mouthguards, intoxicant use, and medical assistance. Descriptive statistics, logistic regression models, and significance tests were used for data analysis (α = .05).

RESULTS

Hooligans had a higher frequency of dental injuries resulting from fights than ultras and regular fans. Hooligans with 11-20 fights per soccer season had a 9.6 times higher probability of dental trauma than those with 0-5 fights (p = .048). Possession of a mouthguard was associated with a lower risk of dental injuries for hooligans but an increased risk for ultras. Additionally, hooligans were found to differ significantly from other groups in their consumption of amphetamines and cocaine (p < .001).

CONCLUSIONS

The study found a strong link between physical altercations and dental injuries among soccer supporters. To promote better prevention, there is a necessity for enhanced educational initiatives facilitated by dentists to amplify the dissemination of mouthguards. Furthermore, it is crucial to raise awareness regarding their proper fitting to minimize the occurrence of combat-related dental injuries. Health authorities and other stakeholders should take a comprehensive approach to addressing some of the root causes of violent behavior, which include alcohol abuse and illicit substance consumption.

Reduced emotional responsiveness in individuals with marginal elevation in blood pressure within the normal range: Evidence from altered affect-modulated startle response

Reduced responsiveness to emotional stimuli ('emotional dampening') has been observed in normotensives with elevated blood pressure (BP) and hypertensives but it is not known whether this is due to aberrant responding to emotional information at the involuntary level and whether it is also associated with minimal elevations in BP in the normal range. In this study, we examined emotional dampening using the affect-modulated startle paradigm given its proven sensitivity to motivational states of approach and withdrawal, typically independent of conscious intentional control. Acoustically elicited startle eye-blink modulation was measured using electromyography of the orbicularis oculi muscle beneath the left eye in 59 healthy individuals while they viewed pleasant, unpleasant and neutral standardized pictures. The expected startle attenuation to pleasant pictures, and startle potentiation to unpleasant pictures, relative to neutral pictures, was found in people in the comparison (N = 29) but not elevated BP (N = 30) group. This finding was further supported by significant moderating effect (assessed using ANCOVA and sub-sample analysis) of BP on valence-startle amplitude relationship. The comparison BP group also showed slower latencies to response onset for pleasant stimuli compared to neutral and unpleasant, with no effect of valence in the elevated BP group. However, BP did not moderate the valence-onset latency relationship. Our findings indicate that previously reported emotional dampening associated with elevated BP extends to reduced involuntary emotional reactivity and to individuals with even minimal BP elevations (i.e. higher but still within the normal range). Future research needs to confirm these findings in hypertensive individuals, preferably using within-subjects designs.

Intoxicated aggression: Do alcohol and stimulants cause dose-related aggression? A review

RATIONALE

Violence and drug use are significant public health challenges that are strongly linked. It is known that alcohol plays a major role in the causation of unnatural deaths and that stimulants like cocaine and amphetamine are often implicated in aggressive acts or violence. However, a clear causal relationship between these substances and aggression, and more specifically a blood concentration threshold at which intoxicated aggression emerges is lacking. In case of a crime and subsequent law enforcement, knowledge about dose-response relationships could be of pivotal importance when evaluating the role of alcohol and drugs in aggressive offences.

AIMS

The present review aimed to determine whether there is a causal relation between intoxication with these psychoactive substances and aggression, and to define blood concentration thresholds above which these substances elicit aggression.

METHODS

Empirical articles published between 2013 and 2017 and review papers containing the predefined search strings were identified through searches in the PubMed and Embase databases and additional reference list searches. The complete search query yielded 1578 publications. Initially all articles were manually screened by title and abstract. Articles with irrelevant titles, given the selected search terms and review aims were discarded. Remaining articles were carefully studied and those that did not comply with the main objectives of this review were discarded. At the end of this process, 167 titles were found eligible for review.

FINDINGS AND CONCLUSION

While placebo-controlled experimental studies clearly showed a causal link between alcohol and aggression, it is evident that such a link has not yet been established for cocaine and amphetamines. In case of alcohol, it is clear that there are various individual and contextual factors that may contribute to the occurrence of an aggressive act during intoxication. A clear threshold blood alcohol concentration has not been defined yet for alcohol, but a statistically significant increase of aggression has been demonstrated at a dose of 0.75 g/kg and higher. Future studies into intoxicated aggression should include multiple doses of alcohol and stimulants and take into account individual and contextual factors.

Beyond Sensation Seeking: A Conceptual Framework for Individual Differences in Psychostimulant Drug Effects in Healthy Humans

Psychostimulant addiction is an important, relapsing condition for which there is no effective pharmacological treatment. Countering this problem requires an understanding of the specific risk factors that predispose individuals to initial misuse of these drugs. Healthy individuals display marked individual differences in emotional, behavioral and brain responses to low and moderate doses of stimulant drugs. These between-person differences have been most often studied using personality measures of sensation seeking. However, a growing body of work in healthy adults indicates potentially unique sources of variance in these responses that are related to four dissociable personality domains: extraversion, fearlessness, impulsivity and absorption. These four domains are empirically dissociable and can serve as endophenotypic markers of dopamine, norepinephrine and serotonin function in healthy individuals. The relationship between normal variation in these traits and the pharmacological effects of these drugs is here proposed as a framework for better understanding the specific sources of between-person variation in stimulant drug effects on mood, behavior and brain responses in healthy humans.

Effects of d-amphetamine upon psychosocial stress responses

Psychostimulant drugs alter the salience of stimuli in both laboratory animals and humans. In animals, stimulants increase rates of responding to conditioned incentive stimuli, and in humans, amphetamine increases positive ratings of emotional images. However, the effects of stimulants on real-life emotional events have not been studied in humans. In this study, we examined the effect of d-amphetamine on responses to acute psychosocial stress using a public speaking task. Healthy volunteers (N=56) participated in two experimental sessions, one with a psychosocial stressor (the Trier Social Stress Test) and one with a non-stressful control task. They were randomly assigned to receive d-amphetamine (5 mg n=18, 10 mg n=20) or placebo (n=18) on both sessions under double blind conditions. Salivary cortisol, subjective mood, and vital signs were measured at regular intervals during the session. Subjects also provided cognitive appraisals of the tasks before and after their performances. Amphetamine produced its expected mood and physiological effects, and the Trier Social Stress Test produced its expected effects on cortisol and mood. Although neither dose of amphetamine altered cardiovascular or hormonal responses to stress, amphetamine (10 mg) increased participants' pre-task appraisals of how challenging the task would be, and it increased post-task ratings of self-efficacy. Paradoxically, it also increased ratings of how stressful the task was, and prolonged aversive emotional responses. These findings suggest that amphetamine differentially affects stress response components: it may increase participants' appraisals of self-efficacy without dampening the direct emotional or physiological responses to the stress.

Mesocorticolimbic dopamine functioning in primary psychopathy: A source of within-group heterogeneity

Despite similar emotional deficiencies, primary psychopathic individuals can be situated on a continuum that spans from controlled to disinhibited. The constructs on which primary psychopaths are found to diverge, such as self-control, cognitive flexibility, and executive functioning, are crucially regulated by dopamine (DA). As such, the goal of this review is to examine which specific alterations in the meso-cortico-limbic DA system and corresponding genes (e.g., TH, DAT, COMT, DRD2, DRD4) might bias development towards a more controlled or disinhibited expression of primary psychopathy. Based on empirical data, it is argued that primary psychopathy is generally related to a higher tonic and population activity of striatal DA neurons and lower levels of D2-type DA receptors in meso-cortico-limbic projections, which may boost motivational drive towards incentive-laden goals, dampen punishment sensitivity, and increase future reward-expectancy. However, increasingly higher levels of DA activity in the striatum (moderate versus pathological elevations), lower levels of DA functionality in the prefrontal cortex, and higher D1-to-D2-type receptor ratios in meso-cortico-limbic projections may lead to increasingly disinhibited and impetuous phenotypes of primary psychopathy. Finally, in order to provide a more coherent view on etiological mechanisms, we discuss interactions between DA and serotonin that are relevant for primary psychopathy.

Multilevel impact of the dopamine system on the emotion-potentiated startle reflex

RATIONALE/OBJECTIVES

The pathogenetic mechanism of emotion-related disorders such as anxiety disorders is considered to be complex with an interaction of genetic, biochemical, and environmental factors. Particular evidence has accumulated for alterations in the dopaminergic system-partly conferred by catechol-O-methyltransferase (COMT) gene variation-and for distorted emotional processing to constitute risk factors for anxiety and anxiety-related disorders.

METHODS

Applying a multilevel approach, we analyzed the main and interactive effects of the functional COMT val158met polymorphism and L-dopa (single-dose 50 mg levodopa and 12.5 mg carbidopa; double-blind, placebo-controlled design) on the emotion-potentiated (unpleasant, neutral, and pleasant IAPS pictures) startle response as an intermediate phenotype of anxiety in a sample of 100 healthy probands (f = 52, m = 48).

RESULTS

The COMT 158val allele was associated with an increased startle potentiation by unpleasant stimuli as compared with neutral stimuli irrespective of L-dopa or placebo intervention. COMT 158met/met genotype carriers, while displaying no difference in startle magnitude in response to unpleasant or neutral pictures in the placebo condition, showed startle potentiation by unpleasant pictures under L-dopa administration only.

CONCLUSIONS

The present proof-of-concept study provides preliminary support for a complex, multilevel impact of the dopaminergic system on the emotion-potentiated startle reflex suggesting increased phasic dopamine transmission driven by the more active COMT 158val allele and/or a single dose of L-dopa to predispose to maladaptive emotional processing and thereby potentially also to anxiety-related psychopathological states.