Mechanisms underlying aggressive and hostile behavior in amphetamine users

Identifying neurofunctional domains across substance use disorders

Background: Substance use disorders (SUDs) are heterogeneous across multiple functional domains. Various frameworks posit that domains (e.g., executive function) contribute to the persistence of SUDs; however, the domains identified in different studies vary.Objectives: We used factor analysis to identify the underlying latent domains present in a large sample (N = 5,244, 55.8% male) with a variety of SUDs to yield findings more generalizable than studies with a narrower focus.Method: Participants (1,384 controls and 3,860 participants with one or more SUDs including alcohol, cocaine, cannabis, and/or opioid use disorders) completed the Semi-Structured Assessment for Drug Dependence and Alcoholism, the NEO Personality Inventory, and the Wisconsin Card Sorting Test. Exploratory factor analysis (EFA) and fit indices (root mean-squared error of approximation (RMSEA), Comparative Fit Index (CFI), and Tucker-Lewis Index (TLI)) were used to examine different latent variable models. A multiple indicators, multiple causes (MIMIC) approach-tested associations of the latent variables with sociodemographics, substance use, and a history of abuse/neglect.Results: A six-factor model (predominant alcohol, predominant cocaine, predominant opioid, externalizing, personality, and executive function) provided the best fit [RMSEA = 0.063 (90% CI 0.060, 0.066), CFI = 0.98, TLI = 0.96]. All factors were moderately correlated (coefficient = 0.25-0.55, p < .05) with the exception of executive function. MIMIC analysis revealed different patterns of associations (all p < .0001) with sociodemographics, substance use, and a history of abuse/neglect among the factors.Conclusions: The domains identified, particularly executive function, were parallel to those observed previously. These factors underscore the heterogeneous nature of SUDs and may be useful in developing more targeted clinical interventions.

Psychostimulants and social behaviors

Mounting evidence from animal models and human studies indicates that psychostimulants can significantly affect social behaviors. This is not surprising considering that the neural circuits underlying the regulation and expression of social behaviors are highly overlapped with those targeted by psychostimulants, which in most cases have strong rewarding and, consequently, addictive properties. In the present work, we provide an overview regarding the effects of illicit and prescription psychostimulants, such as cocaine, amphetamine-type stimulants, methylphenidate or modafinil, upon social behaviors such as social play, maternal behavior, aggression, pair bonding and social cognition and how psychostimulants in both animals and humans alter them. Finally, we discuss why these effects can vary depending on numerous variables such as the type of drug considered, acute versus long-term use, clinical versus recreational consumption, or the presence or absence of concomitant risk factors.

Effects of resilience on impulsivity, cognition and depression during protracted withdrawal among Chinese male methamphetamine users

BACKGROUND

Methamphetamine (METH) dependence is a complex and dynamic public health problem. Long-term abuse of METH can increase numerous risks of mental and physical problems. Currently, the methods to reduce METH dependence and improve the withdrawal symptoms are limited and ineffective. Resilience is seen as a multidimensional and dynamic capability to recover or bounce back from stressful events and is also generally considered as a protective factor against mental dysfunction.

METHODS

One hundred thirty-four males with METH dependence were consecutively recruited from Huanglong Compulsory Isolated Detoxification Center between 2019 and 2021, of whom 112 were into the group. The Connor-Davidson Resilience Scale (CD-RISC), Self-rating depression scale (SDS), Self-rating anxiety scale (SAS), Barratt Impulsiveness Scale-11(BIS-11), and the Repeatable Battery for the Assessment of Neuropsychological Status (Rbans) were used to evaluate resilience, depression, anxiety, impulsivity, and cognition respectively.

RESULTS

The results mainly indicated that high resilience group showed lower SDS, SAS and BIS-11 scores than low resilience group (all p < 0.05). Besides, the total scores of Rbans were higher in high resilience groups than low resilience group (both p < 0.05). Moreover, linear regression results showed that resilience may be influenced by the scores of SDS and SAS.

CONCLUSIONS

Resilience is negatively correlated with impulsivity and depression. Besides, it is also positively associated with cognitive function. Drug users with higher resilience may have a strong ability to mobilize psychological resources to create a good psychological environment, which may have a positive effect on the relief or improvement of symptoms.

A systematic literature review and narrative synthesis of effective interventions for family and caregivers of people who use methamphetamine

Background: Methamphetamine is a highly addictive central nervous stimulant associated with numerous adverse health, psychological, and social impacts. Family and friends of people who use methamphetamine often take on a crucial caregiving role in supporting their loved one. Consequently, they can experience a range of psychosocial challenges themselves. This review aimed to identify and assess the effectiveness of interventions designed to support caregivers of people who use methamphetamine. Methods: A systematic search of relevant literature published in the English language was conducted. Of 2257 records identified, only 2 evaluation studies examined interventions specifically designed for caregivers of people who use methamphetamine. Additionally, four qualitative accounts described experiences of caring for people who use methamphetamine. These accounts were summarized narratively to provide a more complete picture of family and caregiver experiences and coping strategies. Results: Effective treatment components included tending to caregiver concerns and providing training to enhance informational support and problem-solving skills. Qualitative accounts uncovered a range of challenges experienced by caregivers, such as emotional distress, concern for the person using methamphetamine, disrupted family structures, and financial difficulties. Coping strategies included attempts at managing and supporting the person using methamphetamine while protecting the overall cohesion and wellbeing of the family unit. Conclusions: This review highlighted a lack of evidence-based interventions for caregivers of people who use methamphetamine. More research is needed to clarify concerns that may be particularly relevant for those in a caregiving role.

The contribution of methamphetamine use to crime: Evidence from Australian longitudinal data

BACKGROUND

To quantify the extent to which methamphetamine use is associated with increases in crime net of any premorbid risk of criminality among people who use the drug.

METHODS

Four one-month data panels from 469 participants dependent on methamphetamine were drawn from the MATES cohort (N = 501). Odds ratios for within-person effects were extracted from a random intercept logistic regression model for crime during periods of methamphetamine use compared to no use. Effects were adjusted for time-varying measures of age, other substance use, and socio-economic disadvantage (income, unemployment and unstable accommodation). Involvement in crime (property crime, drug dealing, fraud, violent crime) and days of methamphetamine in the past month were assessed using the Opiate Treatment Index.

RESULTS

Crime was more likely during months when participants used methamphetamine compared to when they did not (OR 13.2 95% CI 8.5-20.6; AOR 4.7 95% CI 2.8-8.0), this reflecting more property crime (OR 10.6 95% CI 6.3-18.0; AOR 5.5 95% CI 2.8-10.8), violent crime (OR 8.2 95% CI 4.2-15.9; AOR 3.4 95% CI 1.5-8.0), fraud (OR 3.4, 95% CI 2.0-5.8; AOR 1.7 95% CI 0.8-3.3) and dealing drugs (OR 18.2 95% CI 10.2-32.5; AOR 5.9 95% CI 3.0-11.9), although the adjusted relationship for fraud was not significant. Effects were dose related.

CONCLUSIONS

The use of methamphetamine was associated with significant increases in crime beyond premorbid risk for criminality. Crime is a likely social consequence of methamphetamine use and efforts are needed to reduce this impact.

Alcohol-Related, Drug-Related, and Non-Substance-Related Aggression: 3 Facets of a Single Construct or 3 Distinct Constructs?

BACKGROUND

Aggression often occurs alongside alcohol and drug misuse. However, it is not clear whether the latent and manifest relations among alcohol-related, drug-related, and non-substance-related aggression are separate manifestations of a single construct or instead are 3 distinct constructs.

METHODS

To examine these associations, we conducted a preregistered analysis of 13,490 participants in the Collaborative Study on the Genetics of Alcoholism. In a structured interview, participants reported their lifetime perpetration of these 3 aggression phenotypes.

RESULTS

The data were better fit by a model that treated these aggression phenotypes as 3 distinct latent factors, as compared to models in which the items all loaded onto 1 ("general") or 2 ("substance-related" and "non-substance-related") aggression factors. This 3-factor model fit better for men than women. Subsequent exploratory analyses then showed that among these 3 factors, alcohol-related aggression explained the variance of overall aggression better than the other 2 factors.

CONCLUSIONS

Our findings suggest that these 3 forms of aggression are distinct phenotypes (especially among men). Yet, people's alcohol-related aggression can accurately characterize their overall aggressive tendencies across these domains. Future research will benefit from articulating the unique and shared pathways and risk factors underlying each of these facets of aggression.

Methamphetamine use and violence: Findings from a longitudinal birth cohort

AIMS

Evidence linking illicit methamphetamine use to violence perpetration and victimisation comes primarily from cross-sectional studies. These associations have not previously been studied in a longitudinal general population sample.

DESIGN

Longitudinal birth cohort.

SETTING AND PARTICIPANTS

General population sample (n = 1265) born in Christchurch, New Zealand in 1977.

MEASUREMENTS

Participants were asked at age 21, 25, 30 and 35 about their frequency of methamphetamine use, and violence perpetration or victimization since the last interview. Violence was measured both in general, and within intimate partner relationships in particular. Logistic generalised estimating equations modelled the association between methamphetamine exposure and violence outcomes within each age period, adjusting for confounding factors and time-dynamic covariate factors. The dose-response profiles were explored via associations between heaviest methamphetamine use frequency from age 18-35 and violence outcomes in that period.

FINDINGS

28 % of participants reported using methamphetamine at least once between age 18 and 35. Compared to no use, a history of any methamphetamine use in each age period was associated with an increased adjusted risk of violence perpetration (OR 1.60; 1.01-2.54), intimate partner violence perpetration (OR 1.55, 95 % CI 1.04-2.30), and violence victimization (OR 1.57, 1.00-2.47). Evidence for an association with intimate partner violence victimization was inconclusive (OR 1.09, 0.80-1.49). There was a dose response relationship whereby those who had used methamphetamine at least weekly at any time from age 18-35 had substantially elevated adjusted odds of violence involvement compared to people who used but less often, or had never used.

CONCLUSIONS

Methamphetamine use is an independent risk factor for violence perpetration and victimisation in the general population.

Risky driving behaviours among stimulant drug users and the role of aggression: findings from a national survey

BACKGROUND AND AIMS

Stimulant drug users have a greater prevalence of risky driving behaviour. This study aimed to assess how far this association remains after adjusting for aggressiveness.

DESIGN

Cross-sectional interview study assessing associations between measures of risky driving behaviours as outcomes, measures of stimulant drug use as predictors and a measure of aggressiveness as a covariate.

SETTING

United States.

PARTICIPANTS

Data were drawn from wave 3 (2012-13) of the National Epidemiological Survey on Alcohol and Related Conditions (NESARC-III) (n = 36 309 aged ≥ 18 years).

MEASUREMENTS

Stimulant drug use, past-year DSM-5 stimulant use disorder, aggression and measures of risky driving were assessed using face-to-face interviews conducted using the Alcohol Use Disorder and Associated Disabilities Interview Schedule (AUDADIS-5) and the Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5).

FINDINGS

Overall, 2714 (8.3%) respondents indicated life-time stimulant use, and 112 (0.3%) met criteria for past-year DSM-5 stimulant use disorder. More than 10% of ongoing stimulant users and one-third of respondents with DSM-5 stimulant use disorder reported stimulant-specific driving under the influence of drugs (DUID) in the past-year (both P < 0.0001). Adjusted for demographics and independent of aggression, life-time stimulant users reported increased likelihood of driving [adjusted odds ratio (aOR) = 3.00, 95% confidence interval (CI) = 2.63-3.42] or speeding under the influence of drugs (aOR = 3.39, 95% CI = 3.01-3.82) and licence revocation (aOR = 2.16, 95% CI = 1.87-2.50) (all P < 0.0001). Past-year DSM-5 stimulant use disorder was associated with all outcomes (aOR = 5.48, 95% CI = 2.95-10.18 and aOR = 3.87, 95% CI = 2.23-6.70, respectively, all P < 0.0001), except licence revocation (aOR = 1.72).

CONCLUSIONS

Stimulant use appears to be positively associated with risky driving behaviours after adjusting for aggressiveness.

Responding to global stimulant use: challenges and opportunities

We did a global review to synthesise data on the prevalence, harms, and interventions for stimulant use, focusing specifically on the use of cocaine and amphetamines. Modelling estimated the effect of cocaine and amphetamine use on mortality, suicidality, and blood borne virus incidence. The estimated global prevalence of cocaine use was 0·4% and amphetamine use was 0·7%, with dependence affecting 16% of people who used cocaine and 11% of those who used amphetamine. Stimulant use was associated with elevated mortality, increased incidence of HIV and hepatitis C infection, poor mental health (suicidality, psychosis, depression, and violence), and increased risk of cardiovascular events. No effective pharmacotherapies are available that reduce stimulant use, and the available psychosocial interventions (except for contingency management) had a weak overall effect. Generic approaches can address mental health and blood borne virus infection risk if better tailored to mitigate the harms associated with stimulant use. Substantial and sustained investment is needed to develop more effective interventions to reduce stimulant use.

Mental health outcomes associated with of the use of amphetamines: A systematic review and meta-analysis

BACKGROUND

The use of amphetamines is a global public health concern. We summarise global data on use of amphetamines and mental health outcomes.

METHODS

A systematic review and meta-analysis (CRD 42017081893). We searched Medline, EMBASE, PsycInfo for methamphetamine or amphetamine combined with psychosis, violence, suicidality, depression or anxiety. Included studies were human empirical cross-sectional surveys, case-control studies, cohort studies and randomised controlled trials that assessed the association between methamphetamine and one of the mental health outcomes. Random effects meta-analysis was used to pool results for any use of amphetamines and amphetamine use disorders.

FINDINGS

149 studies were eligible and 59 were included in meta-analyses. There was significant heterogeneity in effects. Evidence came mostly from cross-sectional studies. Any use of amphetamines was associated with higher odds of psychosis (odds ratio [OR] = 2.0, 95%CI 1.3-3.3), violence (OR = 2.2, 95%CI 1.2-4.1; adjusted OR [AOR] = 1.4, 95%CI 0.8-2.4), suicidality OR = 4.4, 95%CI 2.4-8.2; AOR = 1.7, 95%CI 1.0-2.9) and depression (OR = 1.6, 95%CI 1.1-2.2; AOR = 1.3, 95%CI 1.2-1.4). Having an amphetamine use disorder was associated with higher odds of psychosis (OR = 3.0, 95%CI 1.9-4.8; AOR = 2.4, 95%CI 1.6-3.5), violence (OR = 6.2, 95%CI 3.1-12.3), and suicidality (OR = 2.3, 95%CI 1.8-2.9; AOR = 1.5, 95%CI 1.3-1.8).

INTERPRETATION

Methamphetamine use is an important risk factor for poor mental health. High quality population-level studies are needed to more accurately quantify this risk. Clinical responses to methamphetamine use need to address mental health harms.

Emotion Recognition and Impulsive Choice in Relation to Methamphetamine Use and Psychosis Symptoms

Introduction: The cognitive profiles of people with methamphetamine use disorder are characterized by impulsivity and impairment in social cognition. However, previous studies have not fully accounted for the presence and impact of co-occurring mental health problems on these domains. For instance, psychotic symptoms are commonly experienced by people who use methamphetamine and may influence cognitive performance. We aimed to examine decision making and emotion recognition in individuals with methamphetamine use, compared to healthy controls, to map the nature and degree of impairments in relation to the presence of psychotic symptoms. Method: In this naturalistic study, we assessed reward-based decision-making and facial emotion recognition across three groups, methamphetamine-using individuals with (MAP, n = 29) and without psychotic symptoms (MNP, n = 70), and healthy controls (HC, n = 32). Results: In comparison to healthy controls, methamphetamine-using individuals presented with poorer performance on tasks of decision-making and emotion recognition. Emotion recognition was impaired across all methamphetamine-using individuals, with significantly poorer recognition of anger and sadness in those with psychotic symptoms. Conclusion: We found specific impairments in emotion recognition in relation to psychotic symptoms in people who use methamphetamine regularly. This builds on previous evidence on cognitive profiles in methamphetamine use disorder, highlighting the need to assess co-morbid mental health and psychotic symptoms. Our finding that methamphetamine-using individuals with psychotic symptoms present with particular difficulties recognizing anger has implications for frontline clinicians.

Oxytocin and opioid addiction revisited: old drug, new applications

Opioid addiction has devastating health and socio-economic consequences, and current pharmacotherapy is limited and often accompanied by side effects, thus novel treatment is warranted. Traditionally, the neurohypophyseal peptide oxytocin (OT) is known for its effects on mediating reward, social affiliation and bonding, stress and learning and memory. There is now strong evidence that OT is a possible candidate for the treatment of drug addiction and depression-addiction co-morbidities. This review summarizes and critically discusses the preclinical evidence surrounding the consequences of pharmacological manipulation of the oxytocinergic system on opioid addiction-related processes, as well as the effects of opioids on the OT system at different stages of the addiction cycle. The mechanisms underlying the effects of OT on opioid addiction, including OT' interaction with the monoaminergic, glutamatergic, opioidergic systems and its effect on the amygdala, the hypothalamic-pituitary-adrenal axis and on memory consolidation of traumatic memories, are also reviewed. We also review clinical evidence on the effects of intranasal OT administration on opioid-dependent individuals and discuss the therapeutic potential along with the limitations that accompany OT-based pharmacotherapies. Review of these studies clearly indicates that the OT system is profoundly affected by opioid use and abstinence and points towards the OT system as an important target for developing pharmacotherapies for the treatment of opioid addiction and co-existing affective disorders, thereby preventing relapse. Therefore, there is a clear need for clinical studies assessing the efficacy of OT-based pharmacotherapies in opioid addiction.

LINKED ARTICLES

This article is part of a themed section on Emerging Areas of Opioid Pharmacology. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.14/issuetoc.

Disrupted Executive Function and Aggression in Individuals With a History of Adverse Childhood Experiences: An Event-Related Potential Study

Here, we explored the functional and neural mechanisms underlying aggression related to adverse childhood experiences. We assessed behavioral performance and event-related potentials during a go/no-go and N-back paradigm. The participants were 15 individuals with adverse childhood experiences and high aggression (ACE + HA), 13 individuals with high aggression (HA), and 14 individuals with low aggression and no adverse childhood experiences (control group). The P2 latency (initial perceptual processing) was longer in the ACE + HA group for the go trials. The HA group had a larger N2 (response inhibition) than controls for the no-go trials. Error-related negativity (error processing) in the ACE + HA and HA groups was smaller than that of controls for false alarm go trials. Lastly, the ACE + HA group had shorter error-related negativity latencies than controls for false alarm trials. Overall, our results reveal the neural correlates of executive function in aggressive individuals with ACEs.

Impairment of opiate-mediated behaviors by the selective TRPV1 antagonist SB366791

Transient receptor potential vanilloid type 1 (TRPV1), the archetypal member of the vanilloid TRP family, was initially identified as the receptor for capsaicin, the pungent ingredient in hot chili peppers. We previously demonstrated that TRPV1 in the dorsal striatum significantly contributes to morphine reward by using the conditioned place preference paradigm in mice; however, it is unknown whether TRPV1 has the same effect in other reward models. In this study, we investigated the role of TRPV1 in morphine reward by using a self-administration paradigm in rats. We found that treatment with a selective TRPV1 antagonist, SB366791, significantly decreased morphine self-administration on a fixed-ratio 1 schedule or a progressive ratio schedule of reinforcement. In addition, treatment with another selective TRPV1 antagonist, AMG9810, not only significantly prevented morphine self-administration but also prevented morphine-induced c-fos expression in the nucleus accumbens. Furthermore, administration of SB366791 decreased an anxiolytic-like effect during the morphine abstinence period. Moreover, treatment with SB366791 significantly decreased morphine-priming reinstatement. Taken together, our findings suggest that blockade of TRPV1 receptors could provide an approach to limiting morphine addiction.

Phosphorylation of the Amino Terminus of the Dopamine Transporter: Regulatory Mechanisms and Implications for Amphetamine Action

Amphetamines (AMPHs) are potent psychostimulants that are widely used and abused, with profound medical and societal impact. Their actions at dopaminergic neurons are thought to mediate their therapeutic efficacy as well as their liability for abuse and dependence. AMPHs target the dopamine transporter (DAT), the plasmalemmal membrane protein that mediates the inactivation of released dopamine (DA) through its reuptake. AMPHs act as substrates for DAT and are known to cause mobilization of dopamine (DA) to the cell exterior via DAT-mediated reverse transport (efflux). It has become increasingly evident that the mechanisms that regulate AMPH-induced DA efflux are distinct from those that regulate DA uptake. Central to these mechanisms is the phosphorylation of the DAT amino (N)-terminus, which has been repeatedly demonstrated to facilitate DAT-mediated DA efflux, without impacting other aspects of DAT physiology. This review aims to summarize the current status of knowledge regarding DAT N-terminal phosphorylation and its regulation by protein modulators and the membrane microenvironment. A better understanding of these mechanisms may lead to the identification of novel therapeutic approaches that interfere selectively with the pharmacological effects of AMPHs without altering the physiological function of DAT.

Aggressive behaviour among drug-using women from Cape Town, South Africa: ethnicity, heavy alcohol use, methamphetamine and intimate partner violence

Background

Women have generally been found to be the victims of violence, but scant attention has been paid to the characteristics of women who perpetrate aggression and violence. In South Africa, violence is a prevalent societal issue, especially in the Western Cape.

Method

This study aimed at identifying factors that were associated with aggression among a sample of 720 substance-using women. We conducted multivariate logistic regression to identify factors that are significantly associated with these behaviours.

Results

Ethnicity (Wald Χ² = 17.07(2), p < 0.01) and heavy drinking (Wald Χ² = 6.60 (2), p = 0.01) were significantly related to verbal aggression, methamphetamine use was significantly related to physical (Wald Χ² = 2.73 (2), p = 0.01) and weapon aggression (Wald Χ² = 7.94 (2), p < 0.01) and intimate partner violence was significantly related to verbal (Wald Χ² = 12.43 (2), p < 0.01) and physical aggression (Wald Χ² = 25.92 (2), p < 0.01).

Conclusions

The findings show high levels of aggression among this sample, and highlight the need for interventions that address methamphetamine, heavy drinking and intimate partner violence among vulnerable substance-using women.

Quality of Caregiving in Mothers With Illicit Substance Use: A Systematic Review and Meta-analysis

Background:

The quality of caregiving in mothers with substance abuse problems appears to be compromised. However, divergent findings, methodological variability, and sample characteristics point to the need for research synthesis.

Methods:

A comprehensive systematic search was undertaken. Studies were eligible if they (1) compared substance-misusing mothers with non–substance-misusing mothers, (2) involved children from birth to 3 years, and (3) maternal sensitivity and child responsiveness were measured using observational methodology.

Results:

A global meta-analysis for maternal sensitivity (n = 24 studies) and child responsiveness (n = 16 studies) on 3433 mother-infant dyads yielded significant population effect sizes and significant heterogeneity. Subgroup analyses found reduced heterogeneity when the meta-analysis was conducted on studies where groups were matched on key demographic characteristics; although the effect size was small, it was still significant for maternal sensitivity but not child responsiveness.

Conclusions:

Compromised quality of caregiving is found in high-risk, substance-misusing mothers, emphasising the importance of early intervention that draws from attachment-based interventions.

Violent offences of methamphetamine users and dilemmas of forensic psychiatric assessment

Methamphetamine (MA), an extremely addictive synthetic stimulant, has quickly spread to become the most frequently used illicit drug in China. People with a history of chronic and heavy MA use have a high possibility of exhibiting schizophrenia-like psychotic symptoms, mainly delusions of reference, auditory hallucinations and cognitive deficits. These emerging findings suggest MA use increases aggression and violence and that there is a correlation between MA use and violence. However, it is unclear how to assess the capacity of criminal responsibility in "MA-induced" psychosis and how to set clear boundaries between schizophrenia and MA-induced psychosis when only limited and inconsistent evidence is available. Furthermore, a final persuasive differential diagnostic method based on improved understanding of schizophrenia and MA-induced psychotic disorders has yet to be developed. This paper will evaluate the epidemiology, social harm, and forensic psychiatric assessment of MA users, propose a future direction for the differential diagnosis between MA-induced psychotic disorders and schizophrenia, and put forward some practical solutions to assess the capacity of criminal responsibility of defendants with drug-induced psychotic disorder.

Neurobehavioral Sequelae of Psychostimulant Abuse

Psychostimulants are a heterogeneous group of drugs known not only for its arousal and motor activity enhancing effects but also for its high risk of abuse. In susceptible individuals, chronic use can cause addiction leading to devastating physical, psychological, and social health consequences. This chapter will focus on the neurobehavioral consequences of psychostimulant abuse. Different models and theories of addiction and possible underlying mechanisms as well as changed in decision making on neuropsychological tasks have been discussed. Prevention and early behavioral intervention are of paramount importance given the lack of approved drug therapies for these patients.

White matter microstructure and impulsivity in methamphetamine dependence with and without a history of psychosis

BACKGROUND

Methamphetamine (MA) use may lead to white matter injury and to a range of behavioral problems and psychiatric disorders, including psychosis. The present study sought to assess white matter microstructural impairment as well as impulsive behavior in MA dependence and MA-associated psychosis (MAP).

METHODS

Thirty patients with a history of MAP, 39 participants with MA dependence and 40 healthy controls underwent diffusion tensor imaging (DTI). Participants also completed the UPPS-P impulsive behavior questionnaire. We applied tract-based spatial statistics (TBSS) to investigate group differences in mean diffusivity (MD), fractional anisotropy (FA), axial (λ‖ ) and radial diffusivity (λ⊥ ), and their association with impulsivity scores and psychotic symptoms.

RESULTS

The MAP group displayed widespread higher MD, λ‖ and λ⊥ levels compared to both controls and the MA group, and lower FA in extensive white matter areas relative to controls. MD levels correlated positively with negative psychotic symptoms in MAP. No significant DTI group differences were found between the MA group and controls. Both clinical groups showed high levels of impulsivity, and this dysfunction was associated with DTI measures in frontal white matter tracts.

CONCLUSIONS

MAP patients show distinct patterns of impaired white matter integrity of global nature relative to controls and the MA group. Future work to investigate the precise nature and timing of alterations in MAP is needed. The results are further suggestive of frontal white matter pathology playing a role in impulsivity in MA dependence and MAP. Hum Brain Mapp 37:2055-2067, 2016. © 2016 Wiley Periodicals, Inc.

The effects of the dopamine stabilizer (-)-OSU6162 on aggressive and sexual behavior in rodents

The dopamine stabilizer (-)-OSU61612 dampens locomotion in rodents rendered hyperactive by exposure to a novel environment or treatment with amphetamine, but stimulates locomotion in habituated animals displaying low motor activity, tentatively exerting this profile by selectively blocking extrasynaptic D2 receptors. The major aim of the present study was to explore the possible usefulness of (-)-OSU61612 as an anti-aggressive drug. To this end, the effect of (-)-OSU61612 on isolation-induced aggression in male mice and estrous cycle-dependent aggression in female rats were studied using the resident intruder test; in addition, the possible influence of (-)-OSU61612 on sexual behavior in male mice and on elevated plus maze (EPM) performance in male rats were assessed. (-)-OSU61612 at doses influencing neither locomotion nor sexual activity reduced aggression in male mice. The effect was observed also in serotonin-depleted animals and is hence probably not caused by the antagonism of serotonin receptors displayed by the drug; refuting the possibility that it is due to 5-HT1B activation, it was also not counteracted by isamoltane. (-)-OSU61612 did not display the profile of an anxiogenic or anxiolytic drug in the EPM but caused a general reduction in activity that is well in line with the previous finding that it reduces exploratory behavior of non-habituated animals. In line with the observations in males, (-)-OSU61612 reduced estrus cycle-related aggression in female Wistar rats, a tentative animal model of premenstrual dysphoria. By stabilizing dopaminergic transmission, (-)-OSU61612 may prove useful as a well-tolerated treatment of various forms of aggression and irritability.

Monoamine-sensitive developmental periods impacting adult emotional and cognitive behaviors

Development passes through sensitive periods, during which plasticity allows for genetic and environmental factors to exert indelible influence on the maturation of the organism. In the context of central nervous system development, such sensitive periods shape the formation of neurocircuits that mediate, regulate, and control behavior. This general mechanism allows for development to be guided by both the genetic blueprint as well as the environmental context. While allowing for adaptation, such sensitive periods are also vulnerability windows during which external and internal factors can confer risk to disorders by derailing otherwise resilient developmental programs. Here we review developmental periods that are sensitive to monoamine signaling and impact adult behaviors of relevance to psychiatry. Specifically, we review (1) a serotonin-sensitive period that impacts sensory system development, (2) a serotonin-sensitive period that impacts cognition, anxiety- and depression-related behaviors, and (3) a dopamine- and serotonin-sensitive period affecting aggression, impulsivity and behavioral response to psychostimulants. We discuss preclinical data to provide mechanistic insight, as well as epidemiological and clinical data to point out translational relevance. The field of translational developmental neuroscience has progressed exponentially providing solid conceptual advances and unprecedented mechanistic insight. With such knowledge at hand and important methodological innovation ongoing, the field is poised for breakthroughs elucidating the developmental origins of neuropsychiatric disorders, and thus understanding pathophysiology. Such knowledge of sensitive periods that determine the developmental trajectory of complex behaviors is a necessary step towards improving prevention and treatment approaches for neuropsychiatric disorders.

Anabolic androgenic steroids and violent offending: confounding by polysubstance abuse among 10,365 general population men

BACKGROUND AND AIMS

Anabolic androgenic steroid (AAS) use is associated with aggressive and violent behaviour, but it remains uncertain if this relationship is causal in humans. We examined the link between AAS use and violent crime while controlling for polysubstance abuse and additional suggested risk factors for violence.

DESIGN

Cross-sectional study of a population-based sample.

SETTING

In 2005, all Swedish-born male twins aged 20-47 years were invited to participate in the Swedish Twin Adults: Genes and Environment (STAGE) survey of the Swedish Twin Register (response rate = 60%).

PARTICIPANTS

A total of 10,365 male survey participants with information on AAS use.

MEASUREMENT

Data on self-reported use of AAS, alcohol and other substances, attention deficit hyperactivity disorder (ADHD) and personality disorder symptoms were linked to nation-wide, longitudinal register information on criminal convictions, IQ, psychological functioning and childhood socio-economic status (SES) covariates.

FINDINGS

Any life-time use of AAS was associated strongly with conviction for a violent crime [2.7 versus 0.6% in convicted and non-convicted men, respectively; odds ratio (OR) = 5.0, 95% confidence interval (CI) = 2.7-9.3]. However, this link was substantially reduced and no longer significant when controlling for other substance abuse (OR = 1.6, 95% CI = 0.8-3.3). Controlling for IQ, psychological functioning, ADHD, personality disorder symptoms and childhood SES did not reduce the risk further.

CONCLUSION

In the general population, co-occurring polysubstance abuse, but not IQ, other neuropsychological risks or socio-economic status, explains most of the relatively strong association between any anabolic androgenic steroid use and conviction for a violent crime.

Posttraumatic stress disorder symptoms, emotion dysregulation, and aggressive behavior among incarcerated methamphetamine users

OBJECTIVE

Methamphetamine use remains a prevalent problem in the United States and is linked to numerous deleterious outcomes, including aggressive behavior, criminal activity, and incarceration. Given these associations, a greater understanding of factors that contribute to aggression among users of methamphetamine is needed, particularly within criminal justice settings, where users of this drug are overrepresented.

METHODS

The present study examined the relationships between posttraumatic stress disorder (PTSD) symptoms and emotion dysregulation and in-prison physical aggression among incarcerated males who identified as methamphetamine users (N = 60).

RESULTS

Participants' average age was 34.4 years (SD = 7.9), and they were predominantly European American (n = 48, 80%), had spent an average of 6.53 years incarcerated (SD = 4.64), and perpetrated about 1.54 acts of aggression (SD = 6.74) during the past three months. Bivariate correlations found that greater PTSD symptoms (p < .001), greater impulse control difficulties (p < .001), and limited access to emotion regulation strategies (p < .05) were associated with aggression perpetrated in prison. However, results from multiple regression analyses indicated that only PTSD symptoms (p <.001) and nonacceptance of emotional responses (p < .03) were predictive of aggression. Regression analyses also suggested that impulse control difficulties (p < .001), limited access to emotion regulation strategies (p < .04), and nonacceptance of emotional responses (p < .001) interacted with PTSD symptoms to predict increased aggressive behavior. The first interaction ran counter to study hypotheses: At greater levels of PTSD symptoms, those with greater acceptance of emotional responses reported greater aggression perpetration than those with lesser acceptance of emotional responses. The other two interactions were in line with hypotheses, showing that at greater levels of PTSD symptoms, those with greater impulse control difficulties (or lesser access to emotion regulation strategies) reported more aggressive behaviors.

CONCLUSIONS

Consistent with theories of aggression, study findings suggest that PTSD symptoms bolster the risk of aggression via various forms emotion dysregulation. Results shed light on potential mechanisms that promote in-prison aggression and violent recidivism among this population.

Dopamine and serotonin signaling during two sensitive developmental periods differentially impact adult aggressive and affective behaviors in mice

Pharmacologic blockade of monoamine oxidase A (MAOA) or serotonin transporter (5-HTT) has antidepressant and anxiolytic efficacy in adulthood. Yet, genetically conferred MAOA or 5-HTT hypoactivity is associated with altered aggression and increased anxiety/depression. Here we test the hypothesis that increased monoamine signaling during development causes these paradoxical aggressive and affective phenotypes. We find that pharmacologic MAOA blockade during early postnatal development (P2-P21) but not during peri-adolescence (P22-41) increases anxiety- and depression-like behavior in adult (>P90) mice, mimicking the effect of P2-21 5-HTT inhibition. Moreover, MAOA blockade during peri-adolescence, but not P2-21 or P182-201, increases adult aggressive behavior, and 5-HTT blockade from P22-P41 reduced adult aggression. Blockade of the dopamine transporter, but not the norepinephrine transporter, during P22-41 also increases adult aggressive behavior. Thus, P2-21 is a sensitive period during which 5-HT modulates adult anxiety/depression-like behavior, and P22-41 is a sensitive period during which DA and 5-HT bi-directionally modulate adult aggression. Permanently altered DAergic function as a consequence of increased P22-P41 monoamine signaling might underlie altered aggression. In support of this hypothesis, we find altered aggression correlating positively with locomotor response to amphetamine challenge in adulthood. Proving that altered DA function and aggression are causally linked, we demonstrate that optogenetic activation of VTA DAergic neurons increases aggression. It therefore appears that genetic and pharmacologic factors impacting dopamine and serotonin signaling during sensitive developmental periods can modulate adult monoaminergic function and thereby alter risk for aggressive and emotional dysfunction.

Does methamphetamine use increase violent behaviour? Evidence from a prospective longitudinal study

AIMS

To determine whether violent behaviour increases during periods of methamphetamine use and whether this is due to methamphetamine-induced psychotic symptoms.

DESIGN

A fixed-effects (within-subject) analysis of four non-contiguous 1-month observation periods from a longitudinal prospective cohort study.

SETTING

Sydney and Brisbane, Australia.

PARTICIPANTS

A total of 278 participants aged 16 years or older who met DSM-IV criteria for methamphetamine dependence on entry to the study but who did not meet DSM-IV criteria for life-time schizophrenia or mania.

MEASUREMENTS

Violent behaviour was defined as severe hostility in the past month on the Brief Psychiatric Rating Scale (BPRS) (corresponding to assault/damage to property). Days of methamphetamine and other substance use in the past month were assessed using the Opiate Treatment Index. Positive psychotic symptoms in the past month were identified using the BPRS.

FINDINGS

There was a dose-related increase in violent behaviour when an individual was using methamphetamine compared with when they were not after adjusting for other substance use and socio-demographics [cf. no use in the past month: 1-15 days of use odds ratio (OR) = 2.8, 95% confidence interval (CI) =1.6-4.9; 16+ days of use OR = 9.5, 95% CI = 4.8-19.1]. The odds of violent behaviour were further increased by psychotic symptoms (OR = 2.0, 95% CI = 1.1-3.6), which accounted for 22-30% of violent behaviour related to methamphetamine use. Heavy alcohol consumption also increased the risk of violent behaviour (OR = 3.1, 95% CI = 1.4-7.0) and accounted for 12-18% of the violence risk related to methamphetamine use.

CONCLUSIONS

There is a dose-related increase in violent behaviour during periods of methamphetamine use that is largely independent of the violence risk associated with psychotic symptoms.

The oxytocin analogue carbetocin prevents emotional impairment and stress-induced reinstatement of opioid-seeking in morphine-abstinent mice

The main challenge in treating opioid addicts is to maintain abstinence due to the affective consequences associated with withdrawal which may trigger relapse. Emerging evidence suggests a role of the neurohypophysial peptide oxytocin (OT) in the modulation of mood disorders as well as drug addiction. However, its involvement in the emotional consequences of drug abstinence remains unclear. We investigated the effect of 7-day opioid abstinence on the oxytocinergic system and assessed the effect of the OT analogue carbetocin (CBT) on the emotional consequences of opioid abstinence, as well as relapse. Male C57BL/6J mice were treated with a chronic escalating-dose morphine regimen (20-100 mg/kg/day, i.p.). Seven days withdrawal from this administration paradigm induced a decrease of hypothalamic OT levels and a concomitant increase of oxytocin receptor (OTR) binding in the lateral septum and amygdala. Although no physical withdrawal symptoms or alterations in the plasma corticosterone levels were observed after 7 days of abstinence, mice exhibited increased anxiety-like and depressive-like behaviors and impaired sociability. CBT (6.4 mg/kg, i.p.) attenuated the observed negative emotional consequences of opioid withdrawal. Furthermore, in the conditioned place preference paradigm with 10 mg/kg morphine conditioning, CBT (6.4 mg/kg, i.p.) was able to prevent the stress-induced reinstatement to morphine-seeking following extinction. Overall, our results suggest that alterations of the oxytocinergic system contribute to the mechanisms underlying anxiety, depression, and social deficits observed during opioid abstinence. This study also highlights the oxytocinergic system as a target for developing pharmacotherapy for the treatment of emotional impairment associated with abstinence and thereby prevention of relapse.

Methamphetamine Use and Violent Behavior: User Perceptions and Predictors

This study describes the extent to which methamphetamine users perceive that their methamphetamine use has resulted in violent behavior, and describes the level of self-reported prevalence of specific violent criminal behaviors irrespective of methamphetamine use. Predictors of these two violence-related indicators, in terms of potential correlates from substance use history, criminal history, and health risk domains are examined. Data are from extensive interviews of 350 methamphetamine users who received substance use treatment in a large California county. A majority (56%) perceived that their methamphetamine use resulted in violent behavior; 59% reported specific violent criminal behaviors. For more than half of those reporting violent criminal behavior, this behavior pattern began before methamphetamine initiation. Thus, for a subsample of methamphetamine users, violence may be related to factors other than methamphetamine use. Users' perceptions that their methamphetamine use resulted in violence appears strongest for those with the most severe methamphetamine-related problems, particularly paranoia.

Chronic methamphetamine treatment induces oxytocin receptor up-regulation in the amygdala and hypothalamus via an adenosine A2A receptor-independent mechanism

There is mounting evidence that the neuropeptide oxytocin is a possible candidate for the treatment of drug addiction. Oxytocin was shown to reduce methamphetamine self-administration, conditioned place-preference, hyperactivity and reinstatement in rodents, highlighting its potential for the management of methamphetamine addiction. Thus, we hypothesised that the central endogenous oxytocinergic system is dysregulated following chronic methamphetamine administration. We tested this hypothesis by examining the effect of chronic methamphetamine administration on oxytocin receptor density in mice brains with the use of quantitative receptor autoradiographic binding. Saline (4ml/kg/day, i.p.) or methamphetamine (1mg/kg/day, i.p.) was administered daily for 10 days to male, CD1 mice. Quantitative autoradiographic mapping of oxytocin receptors was carried out with the use of [(125)I]-vasotocin in brain sections of these animals. Chronic methamphetamine administration induced a region specific upregulation of oxytocin receptor density in the amygdala and hypothalamus, but not in the nucleus accumbens and caudate putamen. As there is evidence suggesting an involvement of central adenosine A2A receptors on central endogenous oxytocinergic function, we investigated whether these methamphetamine-induced oxytocinergic neuroadaptations are mediated via an A2A receptor-dependent mechanism. To test this hypothesis, autoradiographic oxytocin receptor binding was carried out in brain sections of male CD1 mice lacking A2A receptors which were chronically treated with methamphetamine (1mg/kg/day, i.p. for 10 days) or saline. Similar to wild-type animals, chronic methamphetamine administration induced a region-specific upregulation of oxytocin receptor binding in the amygdala and hypothalamus of A2A receptor knockout mice and no genotype effect was observed. These results indicate that chronic methamphetamine use can induce profound neuroadaptations of the oxytocinergic receptor system in brain regions associated with stress, emotionality and social bonding and that these neuroadaptations are independent on the presence of A2A receptors. These results may at least partly explain some of the behavioural consequences of chronic methamphetamine use.

The triggering effect of alcohol and illicit drugs on violent crime in a remand prison population: a case crossover study

BACKGROUND

The association between substance abuse, particularly alcohol abuse, and violence has been well established. However, since substance abuse co-occurs with several other risk factors for violence, the causal link between substance abuse and violence and the extent to which the acute influence of alcohol, illicit drugs, benzodiazepines, and anabolic androgenic steroids have a triggering effect on violent behavior are more uncertain.

METHODS

Case-crossover design was used based on data from structured face to face interviews with remand prisoners (n=194; 172 men, 22 women) suspected of violent crimes.

MAIN OUTCOME MEASURE

odds ratio (OR 95% CI) for a violent crime, 24h after exposure to different substances, compared to periods of no exposure was calculated using conditional logistic regression and a Mantel-Haenszel estimator with confidence intervals for sparse data.

RESULTS

Intake of alcohol (OR 6.41 CI 4.24-9.67) and large doses of benzodiazepines (OR 36.32 CI 7.14-183.65) triggered interpersonal violence. Stratified analyses of possible effect modifiers were sex, conduct/behavioral problems, trauma experiences; psychiatric vulnerability did not reveal any substantial differences.

CONCLUSION

Influences of alcohol and unusually high doses of benzodiazepines are proximal risk factors for violent crime. Improved knowledge of short-term (and dose-related) risk factors may contribute to treatment planning and risk assessment of violence.

Amphetamine as a social drug: effects of d-amphetamine on social processing and behavior

RATIONALE

Drug users often report using drugs to enhance social situations, and empirical studies support the idea that drugs increase both social behavior and the value of social interactions. One way that drugs may affect social behavior is by altering social processing, for example by decreasing perceptions of negative emotion in others.

OBJECTIVES

We examined effects of d-amphetamine on processing of emotional facial expressions and on the social behavior of talking. We predicted amphetamine would enhance attention, identification, and responsivity to positive expressions, and that this in turn would predict increased talkativeness.

METHODS

Over three sessions, 36 healthy normal adults received placebo, 10, and 20 mg d-amphetamine under counterbalanced double-blind conditions. At each session, we measured processing of happy, fearful, sad, and angry expressions using an attentional visual probe task, a dynamic emotion identification task, and measures of facial muscle activity. We also measured talking.

RESULTS

Amphetamine decreased the threshold for identifying all emotions, increased negative facial responses to sad expressions, and increased talkativeness. Contrary to our hypotheses, amphetamine did not alter attention to, identification of, or facial responses to positive emotions specifically. Interestingly, the drug decreased the threshold to identify all emotions, and this effect was uniquely related to increased talkativeness, even after controlling for overall sensitivity to amphetamine.

CONCLUSIONS

The results suggest that amphetamine may encourage sociability by increasing sensitivity to subtle emotional expressions. These findings suggest novel social mechanisms that may contribute to the rewarding effects of amphetamine.

Breaking the loop: oxytocin as a potential treatment for drug addiction

Drug use typically occurs within a social context, and social factors play an important role in the initiation, maintenance and recovery from addictions. There is now accumulating evidence of an interaction between the neural substrates of affiliative behavior and those of drug reward, with a role for brain oxytocin systems in modulating acute and long-term drug effects. Early research in this field indicated that exogenous oxytocin administration can prevent development of tolerance to ethanol and opiates, the induction of stereotyped, hyperactive behavior by stimulants, and the withdrawal symptoms associated with sudden abstinence from drugs and alcohol. Additionally, stimulation of endogenous oxytocin systems is a key neurochemical substrate underlying the prosocial and empathogenic effects of party drugs such as MDMA (Ecstasy) and GHB (Fantasy). Brain oxytocin systems exhibit profound neuroplasticity and undergo major neuroadaptations as a result of drug exposure. Many drugs, including cocaine, opiates, alcohol, cannabis, MDMA and GHB cause long-term changes in markers of oxytocin function and this may be linked to enduring deficits in social behavior that are commonly observed in laboratory animals repeatedly exposed to these drugs. Very recent preclinical studies have illustrated a remarkable ability of exogenously delivered oxytocin to inhibit stimulant and alcohol self-administration, to alter associated drug-induced changes in dopamine, glutamate and Fos expression in cortical and basal ganglia sites, and to prevent stress and priming-induced relapse to drug seeking. Oxytocin therefore has fascinating potential to reverse the corrosive effects of long-term drugs abuse on social behavior and to perhaps inoculate against future vulnerability to addictive disorders. The results of clinical studies examining intranasal oxytocin effects in humans with drug use disorders are eagerly awaited. This article is part of a Special Issue entitled Oxytocin, Vasopressin, and Social Behavior.

Asymmetrical frontal resting-state beta oscillations predict trait aggressive tendencies and behavioral inhibition

Asymmetrical patterns of frontal cortical activity have been implicated in the development and expression of aggressive behavior. Along with individual motivational tendencies, the ability to restrain one's impulses might be a factor in aggressive behavior. Recently, a role for the inhibitory cortical beta rhythm was suggested. The present study investigated whether individual differences in resting state asymmetries in the beta frequency band were associated with trait aggression and behavioral inhibition. In addition, the selective contributions of the prefrontal and motor cortex areas to these associations were examined. Results showed that relative dominant right frontal beta frequency activity was associated with both heightened trait aggression, especially hostility, and reduced response inhibition. Moreover, asymmetries over the anterior electrode locations proved to be related most closely to trait aggression, while asymmetries over the central electrode locations were associated with response inhibition. Together these findings show that right-dominant frontal beta activity is positively associated with aggressive tendencies and reduced behavioral inhibition.

Violence perpetrated by women who use methamphetamine

Methamphetamine (meth) is widely recognized as being associated with violence and aggression. This association is found among women and men, with rates of meth-related violence among women possibly being equal to or even exceeding rates among men. This study examined female-perpetrated violence from the phenomenological point of view of 30 women (aged 18-45 years; mean age of 28.5 years) in residential treatment for meth dependence. Of the 30 participants, 80% (n = 24) reported experiencing violence in their lifetimes: 67% (n = 20) had violence perpetrated against them, and 57% (n = 17) had perpetrated violence. Most participants described perpetrating violence when they were 'coming down' off of meth (i.e. withdrawing). Five women (29%) attributed their violent behaviors to meth and said they would not have been violent had they not been using meth. In contrast, 10 women (59%) described pre-existing 'anger issues' that were 'enhanced' by meth. This article describes the timing of meth-related violence, bi-directional violence, men's responses to female-perpetrated violence, aggression in the context of sexual activities, and violence perpetrated against non-partners. A biopsychosocial theoretical framework is useful to interpret the complex explanations that women provide for their perpetration of violence under the influence of chronic meth use.

Methamphetamine use, aggressive behavior and other mental health issues among high-school students in Cape Town, South Africa

OBJECTIVE

Methamphetamine use has become a growing problem in a number of countries over the past two decades, but has only recently emerged in South Africa. This study investigated the prevalence of methamphetamine use among high-school students in Cape Town and whether students reporting methamphetamine use were more likely to be at risk for mental health and aggressive behavior problems.

METHODS

A cross-sectional survey of 15 randomly selected high schools in Cape Town, of 1561 males and females grade 8-10 students (mean age 14.9), was conducted using the Problem Oriented Screening Instrument for Teenagers (POSIT) and the Beck Depression Inventory (BDI).

RESULTS

Findings indicated that 9% of the students had tried methamphetamine at least once. Ordinal logistic regression analyses showed that methamphetamine use in the past year was significantly associated with higher aggressive behavior scores (OR=1.81, 95% CI: 1.04-3.15, p<0.05), mental health risk scores (OR=2.04, 95% CI: 1.26-3.31, p<0.01) and depression scores (OR=2.65, 95% CI: 1.64-4.28, p<0.001).

CONCLUSIONS

Methamphetamine use has become a serious problem in Cape Town, particularly among adolescents. Screening adolescents in school settings for methamphetamine use and behavior problems may be useful in identifying youth at risk for substance misuse, providing an opportunity for early intervention. These findings have implications for other parts of the world where methamphetamine use may be occurring at younger ages and highlight the importance of looking at co-morbid issues related to methamphetamine use.