Clustering of methamphetamine users based on personality characteristics and self-efficacy in the west of Iran.

With the substantial increase in the use of stimulants, especially methamphetamine, in recent years, the present study aimed to cluster methamphetamine users based on personality traits and self-efficacy, and compare their mental health, sleep quality, and the risk of relapse in the identified clusters. This cross-sectional study was conducted through convenience sampling on 501 methamphetamine users in addiction treatment centers in Kermanshah, western Iran. The data were collected using the Schwarzer General Self-Efficacy Scale, Zuckerman-Kuhlman Personality Questionnaire, Goldberg and Hiller General Health Questionnaire (GHQ), Zuckerman-Kuhlman Personality Questionnaire, and Stimulant Relapse Risk Scale (SRRS). A total of 501 methamphetamine users were distinguished into three clusters with frequencies of 111 (22.2%), 298 (59.5%), and 92 (18.4%) members through hierarchical cluster analysis. The participants in the first cluster were characterized by low self-efficacy, high neuroticism, sensation seeking, and aggressiveness, along with low extroversion and activity, low positive health, high negative health, low sleep quality, and high risk of drug relapse. The participants in the second cluster reported moderate levels of self-efficacy, neuroticism, sensation seeking, activity, and aggressiveness, high extroversion, and moderate levels of mental health, sleep quality, and the risk of relapse. Moreover, the participants in the third cluster reported the highest level of self-efficacy, the lowest level of neuroticism, sensation seeking, and aggressiveness, moderate extroversion and high activity, low relapse risk, high sleep quality, as well as high positive and low negative health symptoms. The third cluster was significantly different from the other two clusters in terms of the mentioned factors. The findings of this study suggest that low self-efficacy and the presence of neuroticism, sensation seeking, and high aggressiveness contribute to reduced mental health and sleep quality, as well as an increased risk of relapse in methamphetamine users.

A case of severe opioid and methamphetamine use disorder in a 14 year old.

We present the case of a 14-year-old who established care at our primary care clinic after hospitalization for unintentional fentanyl overdose. They were diagnosed with severe opioid use disorder (OUD) and stimulant use disorder (StUD) and initiated buprenorphine while inpatient. They were then transitioned to the only known outpatient primary care clinic in her county who was actively providing medications for opioid use disorder (MOUD) in adolescents.At the first visit, they reported a history of 20 overdoses, struggling with adherence to buprenorphine and continued opioid cravings. An overdose safety plan was reviewed with them and their parent including providing them naloxone kits, fentanyl test strips, and education handout sheets. Due to their significant overdose history and adherence challenges with sublingual buprenorphine, they were started on long-acting injectable buprenorphine (LAIB) with weekly provider visits and urine toxicology screening. In collaboration with the treatment team, they initiated behavioral treatment with contingency management (CM), with incentives for appointment completion, expected urine results, and successful medication administration. Over the next 19 months, and to date, they have increasingly engaged with care and have remained abstinent. LAIB may be an appealing alternative for adolescents with OUD to improve adherence and reduce risk of recurrent use and overdose. Adjunctive treatment with CM may improve retention in MOUD and have the benefit of treating StUD. There is a need for further research to explore innovative, community-based treatment for youth with OUD.

Modulation of dlPFC function and decision-making capacity by repetitive transcranial magnetic stimulation in methamphetamine use disorder.

This study explores the impact of repetitive transcranial magnetic stimulation (rTMS) on decision-making capabilities in individuals with methamphetamine use disorder (MUD), alongside potential underlying psychological mechanisms. Employing the Iowa Gambling Task (IGT) and computational modeling techniques, we assessed the decision-making processes of 50 male MUD participants (24 underwent rTMS treatment, 26 received no treatment) and 39 healthy controls (HC). We compared pre- and post-rTMS treatment alterations in the left dorsolateral prefrontal cortex (dlPFC). Results revealed inferior performance in the IGT among the MUD group, characterized by aberrant model parameters in the Value-Plus-Perseverance (VPP) model, including heightened learning rate, outcome sensitivity, and reinforcement learning weight, alongside diminished response consistency and loss aversion. RTMS treatment demonstrated efficacy in reducing craving scores, enhancing decision-making abilities, and partially restoring normalcy to certain model parameters in the MUD cohort. Nonetheless, no linear relationship between changes in model parameters and craving was observed. These findings lend support to the somatic marker hypothesis, implicating the dlPFC in the decision-making deficits observed in MUD, with rTMS potentially ameliorating these deficits by modulating the function of these brain regions. This study not only offers novel insights and methodologies for MUD rehabilitation but also underscores the necessity for further research to corroborate and refine these findings. Trial Registration www.chictr.org.cn Identifier: No. ChiCTR17013610.

Psychometric validation of the Chinese Version of the stimulant relapse risk scale (SRRS) in patients with methamphetamine use disorder.

BACKGROUND: Evaluating the risk of relapse is a pivotal step in the treatment of patients with methamphetamine use disorder (MUD). The 30-item Stimulant Relapse Risk Scale (SRRS) was originally developed in Japan to meet the demand. This study examined the reliability, validity, and factor structure of the Chinese version of the SRRS for patients with MUD. METHODS: 247 patients with MUD self-rated the Chinese version of the SRRS. Cronbach's alpha coefficients and inter-item correlation analysis were used to assess the internal consistency reliability. Construct validity was determined through confirmatory factor analysis (CFA), and concurrent validity was examined using the visual analogue scale (VAS) for drug craving and the severity of dependence scale (SDS). We followed the participants for 1 year and assessed the predictive validity based on the correlation of the scores of the Chinese version of the SRRS with the relapse rate within 3, 6, and 12 months of follow-up. RESULTS: CFA revealed satisfactory model fit estimates for the 22-item Chinese version of the SRRS that consisted of four subscales. The four-factored 22-item Chinese version of the SRRS had adequate internal consistency with Cronbach's alphas ranging from 0.76 to 0.92. The 22-item Chinese version of the SRRS scores were significantly correlated with the VAS and SDS scores as well as the relapse rate within 3, 6, and 12 months, indicating good concurrent and predictive validity of this scale. The receiver operating characteristic curve revealed a cutoff score of 40 could discriminate between participants with (SDS score ≥ 4) and without (SDS score < 4) methamphetamine dependence (area under the curve = 0.71, p < 0.01). CONCLUSIONS: The 22-item Chinese version of the SRRS that consists of four subscales is a valid and reliable instrument to assess the relapse risk in patients with MUD.

The mediating role of trait impulsivity in the relation between cue-induced craving and functional connectivity within the salience network among abstinent patients with methamphetamine use disorder.

Given the widespread use and relapse of methamphetamine (METH), it has caused serious public health burdens globally. However, the neurobiological basis of METH addiction remains poorly understood. Therefore, this study aimed to use magnetic resonance imaging (MRI) to investigate changes in brain networks and their connection to impulsivity and drug craving in abstinent individuals with METH use disorder (MUDs). A total of 110 MUDs and 55 age- and gender-matched healthy controls (HCs) underwent resting-state functional MRI and T1-weighted imaging scans, and completed impulsivity and cue-induced craving measurements. We applied independent component analysis to construct functional brain networks and multivariate analysis of covariance to investigate group differences in network connectivity. Mediation analyses were conducted to explore the relationships among brain-network functional connectivity (FC), impulsivity, and drug craving in the patients. MUDs showed increased connectivity in the salience network (SN) and decreased connectivity in the default mode network compared to HCs. Impulsivity was positively correlated with FC within the SN and played a completely mediating role between METH craving and FC within the SN in MUDs. These findings suggest alterations in functional brain networks underlying METH dependence, with SN potentially acting as a core neural substrate for impulse control disorders.

A phase 3 randomised double-blind placebo-controlled trial of mirtazapine as a pharmacotherapy for methamphetamine use disorder: a study protocol for the Tina Trial.

BACKGROUND: There are no approved pharmacotherapies for methamphetamine use disorder. Two preliminary phase 2 randomised controlled trials have found mirtazapine, a tetracyclic antidepressant, to be effective in reducing methamphetamine use. The proposed Tina Trial is the first phase 3 placebo-controlled randomised trial to examine the effectiveness and safety of mirtazapine as an outpatient pharmacotherapy for methamphetamine use disorder. METHODS: This is a multi-site phase 3 randomised, double-blind, placebo-controlled parallel trial. Participants are randomly allocated (1:1) to receive either mirtazapine (30 mg/day for 12 weeks) or matched placebo, delivered as a take-home medication. The target population is 340 people aged 18-65 years who have moderate to severe methamphetamine use disorder. The trial is being conducted through outpatient alcohol and other drug treatment clinics in Australia. The primary outcome is measured as self-reported days of methamphetamine use in the past 4 weeks at week 12. Secondary outcomes are methamphetamine-negative oral fluid samples, depressive symptoms, sleep quality, HIV risk behaviour and quality of life. Other outcomes include safety (adverse events), tolerability, and health service use. Medication adherence is being monitored using MEMS® Smart Caps fitted to medication bottles. DISCUSSION: This trial will provide information on the safety and effectiveness of mirtazapine as a pharmacotherapy for methamphetamine use disorder when delivered as an outpatient medication in routine clinical practice. If found to be safe and effective, this trial will support an application for methamphetamine use disorder to be included as a therapeutic indication for the prescription of mirtazapine. TRIAL REGISTRATION: Australian and New Zealand Clinical Trials Registry ACTRN12622000235707. Registered on February 9, 2022.

Transcranial magnetic stimulation for methamphetamine use disorder: A scoping review within the neurocircuitry model of addiction.

The use of methamphetamine in the United States is increasing, contributing now to the "fourth wave" in the national opioid epidemic crisis. People who suffer from methamphetamine use disorder (MUD) have a higher risk of death. No pharmacological interventions are approved by the FDA and psychosocial interventions are only moderately effective. Transcranial Magnetic Stimulation (TMS) is a relatively novel FDA-cleared intervention for the treatment of Major Depressive Disorder (MDD) and other neuropsychiatric conditions. Several lines of research suggest that TMS could be useful for the treatment of addictive disorders, including MUD. We will review those published clinical trials that show potential effects on craving reduction of TMS when applied over the dorsolateral prefrontal cortex (DLPFC) also highlighting some limitations that affect their generalizability and applicability. We propose the use of the Koob and Volkow's neurocircuitry model of addiction as a frame to explain the brain effects of TMS in patients with MUD. We will finally discuss new venues that could lead to a more individualized and effective treatment of this complex disorder including the use of neuroimaging, the exploration of different areas of the brain such as the frontopolar cortex or the salience network and the use of biomarkers.

Neurofunctional changes related to methamphetamine and sexual cues in methamphetamine dependence from short- to long-term abstinence.

AIMS: Abuse of methamphetamine has aroused concern worldwide. Stimulant use and sexual behaviours have been linked in behavioural and epidemiological studies. Although methamphetamine-related neurofunctional differences are reported in previous studies, only few studies have examined neurofunctional changes related to methamphetamine and sexual cues in methamphetamine dependence from short- to long-term abstinence. METHODS: Neurofunctional changes were measured using a cue-reactivity task involving methamphetamine, sexual, and neutral cues in 20 methamphetamine abusers who were evaluated after a short- (1 week to 3 months) and long-term (10-15 months) abstinence. RESULTS: Five brain regions mainly involved in the occipital lobe and the parietal lobe were found with the group-by-condition interaction. Region-of-interest analyses found higher sexual-cue-related activation than other two activations in all five brain regions in the long-term methamphetamine abstinence group while no group differences were found. Negative relationships between motor impulsivity and methamphetamine- or sexual-cue-related activations in the left middle occipital gyrus, the superior parietal gyrus and the right angular gyrus were found. CONCLUSIONS: The findings suggested that methamphetamine abstinence may change the neural response of methamphetamine abusers to methamphetamine and sexual cues, and the neurofunction of the five brain regions reported in this study may partly recover with long-term methamphetamine abstinence. Given the use and relapse of methamphetamine for sexual purposes, the findings of this study may have particular clinical relevance.

Effects of electroacupuncture combined with paliperidone palmitate long-acting injection on withdrawal symptoms and neurotransmitters in methamphetamine addicts.

OBJECTIVE: To investigate the effects of electroacupuncture combined with paliperidone palmitate long-acting injection (PP-LAI) on withdrawal symptoms and neurotransmitters in methamphetamine (MA) addicts. MATERIALS AND METHODS: A total of 109 methamphetamine addicts, who were treated in the hospital from October 2021 to October 2022, were selected. According to the random number table, the patients were divided into the study group (n=54) and the control group (n=55), in which the control group was treated with PP-LAI and the study group was treated with electroacupuncture on the basis of the control group; the methamphetamine withdrawal symptom score scale was used to assess the therapeutic effect before treatment and within 12 months after treatment; the changes of brain neurotransmitters dopamine, γ-aminobutyric acid, serotonin, acetylcholine values were compared between the two groups. RESULTS: 1) There was no statistical difference in MA withdrawal symptom scores between the two groups before treatment (p>0.05); 2) MA withdrawal symptom scores have a statistically significant difference between the study group and the control group after 3 and 6 months of treatment; 3) dopamine levels in the study group were significantly higher than those in the control group after 6 months of completion of treatment, and γ-aminobutyric acid values and 5- serotonin values in the study group were significantly lower than those in the control group (p<0.05). CONCLUSIONS: Electroacupuncture combined with PP-LAI can partially improve the withdrawal symptoms and anxiety of methamphetamine addicts. This is a potential treatment for preventing relapse of withdrawal symptoms.

Unmet needs and harm reduction preferences of syringe services program participants: differences by co-use of illicit opioids and methamphetamine.

BACKGROUND: The current fourth wave of the United States opioid overdose epidemic is characterized by the co-use of opioids and stimulants, including illicit opioids and methamphetamine. The co-use of these two drugs, known as "goofballing," is associated with higher risk for several adverse outcomes, including more frequent injections, greater health risks, and higher morbidity. Considering these differences, this unique subpopulation of people who inject drugs (PWID) may also have unique unmet needs and harm reduction preferences. METHODS: We collected self-reported data from participants (N = 50) of a syringe services program (SSP), including basic needs and harm reduction preferences. Using bivariate analyses, we examined differences between SSP participants who do and do not co-use illicit opioids and methamphetamine. Co-use was defined as reporting the use of both drugs, which may or may not have been used simultaneously. RESULTS: In the overall sample, the mean level of need was highest for bus passes or other transportation, a person who can help you get the services you need, medication for opioid use disorder, and a job or job training. Additionally, all participants reported being either interested or very interested in fentanyl test strips, safe consumption sites, delivery of syringe service supplies, and delivery of naloxone. Those who endorsed co-use had a greater need for food, healthcare, substance use disorder treatment, a support person to help them access needed services, and bus passes or transportation. CONCLUSIONS: Unmet needs were prevalent, and the desire for more harm reduction services was high among these PWID. Results also suggest people who co-use illicit opioids and methamphetamine may have the greatest unmet needs and desire for additional harm reduction services.

Changes in injecting versus smoking heroin, fentanyl, and methamphetamine among people who inject drugs in San Diego, California, 2020-2023.

BACKGROUND: Amidst an increasingly toxic drug supply in North America, people who inject drugs may be transitioning to smoking them. We aimed to assess changes in injecting and smoking opioids and methamphetamine among a cohort of people who inject drugs from San Diego, California. METHODS: Over five six-month periods spanning October 2020-April 2023, we assessed prevalence of injecting and smoking opioids or methamphetamine and whether participants used these drugs more frequently by smoking than injecting. Multivariable Poisson regression via generalized estimating equations was used to examine time trends. RESULTS: Of 362 participants, median age was 40 years; a minority were female (29%), Hispanic/Latinx/Mexican (45%), and housed (33%). Among this cohort, of whom 100% injected (and 84% injected and smoked) in period one (October 2020-April 2021), by period five (November 2022-April 2023), 34% only smoked, 59% injected and smoked, and 7% only injected. By period five, the adjusted relative risk (aRR) of injecting opioids was 0.41 (95% Confidence Interval [CI]: 0.33, 0.51) and the aRR for injecting methamphetamine was 0.50 (95% CI: 0.39, 0.63) compared to period one. Risks for smoking fentanyl rose significantly during period three (aRR=1.44, 95% CI: 1.06, 1.94), four (aRR=1.65, 95% CI: 1.24, 2.20) and five (aRR=1.90, 95% CI: 1.43, 2.53) compared to period one. Risks for smoking heroin and methamphetamine more frequently than injecting these drugs increased across all periods. CONCLUSIONS: Opioid and methamphetamine injection declined precipitously, with notable increases in smoking these drugs. Research is needed to understand the health consequences of these trends.

Proteomic Landscape Associated with Cognitive Impairment in Individuals with Long-term Methamphetamine Dependence.

BACKGROUND: Methamphetamine (METH) is a highly addictive drug that directly affects the central nervous system. METH use not only harms the user's health but also poses risks and costs to society. Prolonged METH dependence has been shown to impair cognition, which may be the primary factor in impulsive drug-seeking behaviors and high relapse rates. However, the molecular mechanisms underlying METH addiction and METH-induced cognitive decline remain poorly understood. METHODS: To illuminate the potential molecular mechanisms underpinning METH addiction, we compared serum protein expression levels between 12 long-term METH users and 12 healthy controls using label-free quantitative proteomics. Bioinformatic analyses were conducted to determine functional networks and protein-protein interactions. RESULTS: In total, 23 differentially expressed proteins were identified between the two groups. The differentially expressed proteins were related to cognitive dysfunction, neuroinflammation, immune impairment, metabolic disturbances, and calcium binding and regulation. CONCLUSIONS: These 23 proteins may underpin the multi-system damage induced by chronic METH exposure. Our findings provide novel insights into the molecular basis of METH addiction and inform potential prevention and treatment strategies for individuals with METH dependence.

Safety strategies and harm reduction for methamphetamine users in the era of fentanyl contamination: A qualitative analysis.

INTRODUCTION: In the United States, methamphetamine use is increasing and the context of its use has changed, with reports of illicitly manufactured fentanyl being mixed with methamphetamine (either deliberately or inadvertently). We explore risk-mitigating actions taken by people who use drugs to protect their health when using methamphetamine in that context. METHODS: We conducted qualitative interviews with 48 adults (18+) who used methamphetamine in the past three months at two sites in Nevada, USA and two sites in New Mexico, USA. Interviews were recorded, transcribed, and analyzed using thematic analysis. RESULTS: Respondents described two rationales for employing harm reduction strategies. First, to prevent harm from methamphetamine containing illicit fentanyl, and second, to maintain their general wellbeing while using methamphetamine. Regarding methamphetamine containing illicit fentanyl, our findings highlight how respondents employ primary strategies like buying from trusted sources and secondary strategies such as spotting and selective use of harm reduction tools (i.e., fentanyl test strips) to reduce risks. To maintain their general wellbeing, participants reduced their use of methamphetamine as reasonably as possible, and used other substances like marijuana and alcohol alongside methamphetamine to counter the unwanted side effects of methamphetamine (i.e., hallucinations and paranoia). Use of these harm reduction strategies varied within situational and social contexts, and respondents usually developed these strategies based on their lived experiences. CONCLUSION: Our findings uniquely demonstrate that people who use methamphetamine prioritize community driven, trust-based strategies within their social networks to mitigate risks in a fentanyl-contaminated drug environment. Additionally, our results indicate that harm reduction behaviors are influenced by multilevel risk environments, which include social, physical, economic, and political factors. Overall, these results highlight the potential for targeted interventions at the network level, which are responsive to complexities and shifts in drug market dynamics- such as illicit fentanyl in methamphetamine.

The Association Between Rumination and Craving in Chinese Methamphetamine-Dependent Patients: The Masking Effect of Depression.

BACKGROUND: Craving is a core feature of addiction. Rumination and depression play a crucial role in the process of methamphetamine addiction. The aim of this study was to examine the relationship between rumination, depression and craving in methamphetamine patients, which has not been explored yet. METHODS: A total of 778 patients with methamphetamine user disorder (MUD) at the Xinhua Drug Rehabilitation Center, located in Mianyang City, Sichuan Province, China. We used a set of self-administered questionnaires that included socio-demographic, detailed drug use history, rumination, depression and craving information. The Rumination Response Scale (RRS) was used to measure rumination, the Beck Depression Inventory (BDI) to measure depression and the Visual Analogue Scale (VAS) to measure craving. RESULTS: There was a significant positive correlation between rumination and craving, or depression, and between depression and craving. Furthermore, depression mediated between rumination and craving, with a mediation effect of 160%. CONCLUSIONS: Our findings suggest that there is a close interrelationship between rumination, craving and depression in MUD patients, and that depression may play a mediating role between rumination and craving.

This is the first study to investigate the relationship between rumination and craving during withdrawal in methamphetamine dependent patients and the mediating role of depression.Among methamphetamine patients, it was found that reflection was positively correlated with rumination and depression, depression and craving, rumination and craving, and depression plays the mediating role between rumination and craving.These findings suggest that interventions to reduce depression and rumination may also be effective for withdrawal and relapse reduction in methamphetamine patients, providing further rationale for the treatment of methamphetamine patients.

The reflections of health service providers on implementing contingency management for methamphetamine use disorder in Australia.

INTRODUCTION: Contingency management (CM) is the most effective treatment for reducing methamphetamine use. We sought to understand why CM has not been taken up to manage methamphetamine use disorder in Australia. METHODS: Six focus groups (4-8 participants per group) were conducted with health workers from agencies in Australia that provided drug-related health care to people who use methamphetamine. These agencies had no previous experience delivering CM for substance use. The potential acceptability and feasibility of implementing CM in their services were discussed. RESULTS: Participants felt that it would be beneficial to have an evidence-based treatment for methamphetamine use disorder. This sentiment was offset by concerns that CM conflicted with a client-centred harm-reduction approach and that it dictated the goal of treatment as abstinence. It was also perceived as potentially coercive and seen to reify the power imbalance in the therapeutic relationship and therefore potentially reinforce stigma. There was also concern about the public's perception and the political acceptability of CM, who would fund CM, and the inequity of providing incentives only to clients with a methamphetamine use disorder. Some concerns could be ameliorated if the goals and structure of CM could be tailored to a client's needs. DISCUSSION AND CONCLUSIONS: Many healthcare workers were keen to offer CM as an effective treatment option for people with methamphetamine use disorder, but CM would need to be sufficiently flexible to allow it to be tailored to client needs and implemented in a way that did not adversely impact the therapeutic relationship.

Geographic and Racial/Ethnic Differences in Access to Methamphetamine Detoxification Services, United States, 2021.

INTRODUCTION: Methamphetamine detoxification before entering formal and longer term treatment may have a positive impact on treatment retention and success. Understanding geographic distribution of methamphetamine specialty detox services and differential access by race/ethnicity is critical for establishing policies that ensure equitable access across populations. METHODS: We used the Mental health and Addiction Treatment Tracking Repository to identify treatment facilities that offered any substance use detoxification in 2021 (N=2346) as well as the census block group in which they were located. We sourced data from the US Census Bureau to identify the percentage of a census block group that was White, Black, and Hispanic. We used logistic regression to model the availability of methamphetamine-specific detox, predicted by the percentage of a block group that was Black and Hispanic. We adjusted for relevant covariates and defined state as a random effect. We calculated model-based predicted probabilities. RESULTS: Over half (60%) of detox facilities offered additional detox services specifically for methamphetamine. Sixteen states had <10 methamphetamine-specific detox facilities. The predicted probability of methamphetamine-specific detox availability was 60% in census block groups with 0%-9% Black residents versus only 46% in census block groups with 90%-100% Black residents, and was 61% in census block groups with 0%-9% Hispanic residents versus 30% in census block groups with 90%-100% Hispanic residents. CONCLUSIONS: During an unprecedented national methamphetamine crisis, access to a critical health care service was disproportionately lower in communities that were predominately Black and Hispanic. We orient our findings around a discussion of health disparities, residential segregation, and the upstream causes of the systematic exclusion of minoritized communities from health care.

Trait anger as a predictor of dangerous driving behaviour amongst people who use methamphetamine.

INTRODUCTION: Despite increased prevalence of methamphetamine in road trauma, it remains unclear how its use translates to an increased risk of traffic-related harm. Exploration of psychosocial factors may thus help identify relevant predictors of dangerous driving behaviour among people who regularly consume methamphetamine. METHODS: Licenced individuals who report predominant and sustained methamphetamine use (at least 1-time/month for 6 months at heaviest use) were recruited from the Australian community and via targeted campaign (Eastern Health). Psychosocial, substance use and driving behaviour data (Dula Dangerous Driving Index, DDDI) were collected via a secure anonymous online forced-entry survey platform (Qualtrics). RESULTS: Seventy-seven individuals (65.5 % male) aged between 20-50 years [mean = 29.7, ± Standard Deviation (SD) 6.1] were included. Most (90 %) respondents met criteria for problematic methamphetamine use [Severity of Dependency Scale (SDS) score ≥ 5], and 75 % were high-risk alcohol consumers [Alcohol Use Disorders Identification Test (AUDIT-C) score ≥ 4 for men and ≥ 3 for women]. On average, age of first methamphetamine use occurred at 23.3 years (±5.2). A best-possible subset's regression selection method with dangerous driving behaviour as the dependent variable determined the model with three predictors (alcohol use, substance dependence severity and trait anger) as most parsimonious. After controlling for substance use, trait anger strongly and positively predicted dangerous driving behaviour as measured by the DDDI ([F(3,74) = 26.06, p < .001, adjusted R2 = 0.50, Cohens f2 = 0.42). DISCUSSION AND CONCLUSIONS: Trait anger is a strong predictor of risky driving among road users who use methamphetamine. Interactions between stable negative-emotional and situational traffic and driving-related factors may increase risk of harm through greater engagement in risk-taking behaviour.