Methamphetamine abuse and impairment of social functioning: a review of the underlying neurophysiological causes and behavioral implications

Chemical cousins with contrasting behavioural profiles: MDMA users and methamphetamine users differ in social-cognitive functions and aggression

Methamphetamine (METH, "Crystal Meth") and 3,4-methylenedioxymethamphetamine (MDMA, "Ecstasy") share structural-chemical similarities but have distinct psychotropic profiles due to specific neurochemical actions. Previous research has suggested that their impact on social cognitive functions and social behaviour may differ significantly, however, direct comparisons of METH and MDMA users regarding social cognition and interaction are lacking. Performances in cognitive and emotional empathy (Multifaceted Empathy Test) and emotion sensitivity (Face Morphing Task), as well as aggressive social behaviour (Competitive Reaction Time Task) were assessed in samples of n = 40 chronic METH users, n = 39 chronic MDMA users and n = 86 stimulant-naïve controls (total N = 165). Self-reports and hair samples were used to obtain subjective and objective estimates of substance use patterns. METH users displayed diminished cognitive and emotional empathy towards positive stimuli, elevated punitive social behaviour regardless of provocation, and self-reported heightened trait anger relative to controls. MDMA users diverged from the control group only by exhibiting a distinct rise in punitive behaviour when faced with provocation. Correlation analyses indicated that both higher hair concentrations of MDMA and METH may be associated with reduced cognitive empathy. Moreover, greater lifetime MDMA use correlated with increased punitive behaviour among MDMA users. Our findings confirm elevated aggression and empathy deficits in chronic METH users, while chronic MDMA users only displayed more impulsive aggression. Dose-response correlations indicate that some of these deficits might be a consequence of use. Specifically, the dopaminergic mechanism of METH might be responsible for social-cognitive deficits.

A preliminary study on the association of single nucleotide polymorphisms and methylation of dopamine system-related genes with psychotic symptoms in patients with methamphetamine use disorder

Methamphetamine use disorder (MAUD) can substantially jeopardize public security due to its high-risk social psychology and behaviour. Given that the dopamine reward system is intimately correlated with MAUD, we investigated the association of single nucleotide polymorphisms (SNPs), as well as methylation status of dopamine receptor type 4 (DRD4), catechol-O-methyltransferase (COMT) genes, and paranoid and motor-impulsive symptoms in MAUD patients. A total of 189 MAUD patients participated in our study. Peripheral blood samples were used to detect 3 SNPs and 35 CpG units of methylation in the DRD4 gene promoter region and 5 SNPs and 39 CpG units in the COMT gene. MAUD patients with the DRD4 rs1800955 C allele have a lower percentage of paranoid symptoms than those with the rs1800955 TT allele. Individuals with paranoid symptoms exhibited a reduced methylation degree at a particular DRD4 CpG2.3 unit. The interaction of the DRD4 rs1800955 C allele and the reduced DRD4CpG2.3 methylation degree were associated with a lower occurrence of paranoid symptoms. Meanwhile, those with the COMT rs4818 CC allele had lower motor-impulsivity scores in MAUD patients but greater COMT methylation levels in the promoter region and methylation degree at the COMT CpG 51.52 unit. Therefore, based only on the COMT rs4818 CC polymorphism, there was a negative correlation between COMT methylation and motor-impulsive scores. Our preliminary results provide a clue that the combination of SNP genotype and methylation status of the DRD4 and COMT genes serve as biological indicators for the prevalence of relatively high-risk psychotic symptoms in MAUD patients.

The experience of methamphetamine use disorder and the negative consequences of relapse - a qualitative study

BACKGROUND

The rate of relapse for people in recovery for substance use disorder is as high as 85% within the first 12 months of recovery, however, research on the lived experience of relapse is limited.

OBJECTIVE

The present qualitative study investigated the experience of relapse with people who have Methamphetamine use disorder and the reasons why they returned to recovery.

METHODS

The exploratory study recruited five (n = 5) adults who identified as having Methamphetamine use disorder. All participants had sought treatment for more than 12 months, they were attending an addiction support service, and had experienced a relapse within the past 15 months. Interviews were conducted in which participants were asked an open-ended question about their most recent relapse and the negative consequences associated with their drug use. Data were analyzed using thematic analysis.

RESULTS

A return to daily drug use led to negative consequences such as relationship breakdowns, poor mental health and acting in ways that went against the participant's morals and values. This study provides an insight into the types of experiences people who relapse after seeking treatment for Methamphetamine use disorder may have and how these experiences can influence their decision to return to recovery.

CONCLUSIONS

People who regularly attend a recovery program are still susceptible to relapse. Those who have maintained abstinence for a period of time prior to relapse may be able to assess the negative consequences of their drug use more easily. This prior experience of recovery might influence their decision to stop using again.

Conflict monitoring and emotional processing in 3,4-methylenedioxymethamphetamine (MDMA) and methamphetamine users - A comparative neurophysiological study

In stimulant use and addiction, conflict control processes are crucial for regulating substance use and sustaining abstinence, which can be particularly challenging in social-affective situations. Users of methamphetamine (METH, "Ice") and 3,4-methylenedioxymethamphetamine (MDMA, "Ecstasy") both experience impulse control deficits, but display different social-affective and addictive profiles. We thus aimed to compare the effects of chronic use of the substituted amphetamines METH and MDMA on conflict control processes in different social-affective contexts (i.e., anger and happiness) and investigate their underlying neurophysiological mechanisms. For this purpose, chronic but recently abstinent users of METH (n = 38) and MDMA (n = 42), as well as amphetamine-naïve healthy controls (n = 83) performed an emotional face-word Stroop paradigm, while event-related potentials (ERPs) were recorded. Instead of substance-specific differences, both MDMA and METH users showed smaller behavioral effects of cognitive-emotional conflict processing (independently of emotional valence) and selective deficits in emotional processing of anger content. Both effects were underpinned by stronger P3 ERP modulations suggesting that users of substituted amphetamines employ altered stimulus-response mapping and decision-making. Given that these processes are modulated by noradrenaline and that both MDMA and METH use may be associated with noradrenergic dysfunctions, the noradrenaline system may underlie the observed substance-related similarities. Better understanding the functional relevance of this currently still under-researched neurotransmitter and its functional changes in chronic users of substituted amphetamines is thus an important avenue for future research.

Gut microbiota-derived short-chain fatty acids ameliorate methamphetamine-induced depression- and anxiety-like behaviors in a Sigmar-1 receptor-dependent manner

Methamphetamine (Meth) abuse can cause serious mental disorders, including anxiety and depression. The gut microbiota is a crucial contributor to maintaining host mental health. Here, we aim to investigate if microbiota participate in Meth-induced mental disorders, and the potential mechanisms involved. Here, 15 mg/kg Meth resulted in anxiety- and depression-like behaviors of mice successfully and suppressed the Sigma-1 receptor (SIGMAR1)/BDNF/TRKB pathway in the hippocampus. Meanwhile, Meth impaired gut homeostasis by arousing the Toll-like receptor 4 (TLR4)-related colonic inflammation, disturbing the gut microbiome and reducing the microbiota-derived short-chain fatty acids (SCFAs). Moreover, fecal microbiota from Meth-administrated mice mediated the colonic inflammation and reproduced anxiety- and depression-like behaviors in recipients. Further, SCFAs supplementation optimized Meth-induced microbial dysbiosis, ameliorated colonic inflammation, and repressed anxiety- and depression-like behaviors. Finally, Sigmar1 knockout (Sigmar1-/-) repressed the BDNF/TRKB pathway and produced similar behavioral phenotypes with Meth exposure, and eliminated the anti-anxiety and -depression effects of SCFAs. The activation of SIGMAR1 with fluvoxamine attenuated Meth-induced anxiety- and depression-like behaviors. Our findings indicated that gut microbiota-derived SCFAs could optimize gut homeostasis, and ameliorate Meth-induced mental disorders in a SIGMAR1-dependent manner. This study confirms the crucial role of microbiota in Meth-related mental disorders and provides a potential preemptive therapy.

Elevated C-reactive protein/albumin ratio in patients with methamphetamine use disorder

BACKGROUND

Methamphetamine use disorder causes significant crises, which have individual, familial, and social consequences. Identifying inflammatory biomarkers for methamphetamine use disorder may be useful for following the inflammatory status of patients in clinical assessment. In this study, we aimed to investigate whether neutrophil/lymphocyte ratio (NLR), platelet/lymphocyte ratio (PLR), monocyte/lymphocyte ratio (MLR), C-reactive protein/albumin ratio (CAR) and neutrophil/albumin ratio (NAR) levels can be used as inflammatory biomarkers in methamphetamine use disorder.

METHODS

The sample comprised 139 treatment-seeking participants who met the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) criteria for methamphetamine use disorder and 139 sociodemographically matched controls. Only hospitalised patients were included. An independent sample t-test, Pearson's correlation test, and binominal logistic regression analysis were performed.

RESULTS

CAR (p = 0.016) and NAR (p = 0.048) levels were significantly higher in individuals with methamphetamine use disorder when compared with healthy controls. The CAR level was found to be a significant predictor of group membership in regression analysis for methamphetamine use disorder.

CONCLUSION

CAR may be a potential inflammatory biomarker for patients with methamphetamine use disorder. CAR as a relatively easier-to-measure biomarker could be beneficial to follow the inflammatory status and treatment response of patients.

Navigating Evidence, Challenges, and Caution in the Treatment of Stimulant Use Disorders

Amidst the opioid epidemic, harm reduction-oriented approaches have gained traction, including interventions that focus on prescribing pharmaceutical-grade psychoactive substances, such as opioids, instead of illicit versions, intending to mitigate fatal overdose risks arising from the variability in potency and additives found in illicit drugs. Stimulants have increasingly been found in the victims of opioid overdoses, further prompting some to argue for the prescription of stimulant medications for individuals with stimulant use disorders. Yet, the evidence supporting this practice remains insufficient. In this communication, we critically examine the existing evidence, challenges, and cautions surrounding the treatment of stimulant use disorder.

Effect of transcranial direct current stimulation over the left dorsolateral prefrontal cortex on the aggressive behavior in methamphetamine addicts

Aggressive behavior of drug addicts threatens human security and social stability, and Methamphetamine (MA) addicts show especially aggressive behavior. Researches showed that the decreased activity of dorsolateral prefrontal cortex (DLPFC) is closely related to violence and aggression, and continuous transcranial direct current stimulation (tDCS) on DLPFC can increase the activity of this position. So, the purpose of this study was to investigate the effect of tDCS on DLPFC for the aggressive behavior of MA addicts. Ninety MA addicts were recruited and randomly divided into anodal tDCS group, cathode tDCS group and sham tDCS group (current intensity was set as 2 mA, 2 mA and 0 mA, respectively). The tDCS intervention was conducted twice a day for five consecutive days. Taylor Aggression Paradigm (TAP) was used to measure the proactive aggressiveness and reactive aggressiveness of MA addicts at different time points (Pretest, Day 1, and Day 5). At the same time, we also recruited 30 healthy adult males as healthy controls, and measured their aggressiveness through TAP for comparative analysis. The results showed that the aggressiveness of MA addicts was significantly higher than that of healthy controls. The aggressiveness of MA addicts was effectively reduced by the anode intervention of tDCS on the left DLPFC, especially when they were subjected to high-intensity provocation, the 2-way interaction between time and tDCS group was statistically significant (F_4,164 = 2.939, P = 0.022, η_p² = 0.067). This study can provide a reference for how to correct the aggressive behavior of MA addicts.

Methamphetamine: Mechanism of Action and Chinese Herbal Medicine Treatment for Its Addiction

With the proliferation of synthetic drugs, research on the mechanism of action of addictive drugs and treatment methods is of great significance. Among them, methamphetamine (METH) is the most representative amphetamine synthetic drug, and the treatment of METH addiction has become an urgent medical and social problem. In recent years, the therapeutic effects of Chinese herbal medicines on METH addiction have gained widespread attention because of their non-addictiveness, multiple targets, low side effects, low cost, and other characteristics. Previous studies have identified a variety of Chinese herbal medicines with effects on METH addiction. Based on the research on METH in recent years, this article summarizes the mechanism of action of METH as the starting point and briefly reviews the Chinese herbal medicine-based treatment of METH.

Exploring psilocybin-assisted psychotherapy in the treatment of methamphetamine use disorder

Methamphetamine use disorder is a chronic relapsing condition associated with substantial mental, physical, and social harms and increasing rates of mortality. Contingency management and psychotherapy interventions are the mainstays of treatment but are modestly effective with high relapse rates, while pharmacological treatments have shown little to no efficacy. Psilocybin-assisted psychotherapy is emerging as a promising treatment for a range of difficult-to-treat conditions, including substance use disorders; however, no studies have yet been published looking at psilocybin-assisted psychotherapy in the treatment of methamphetamine use disorder. Here we review the rationale for psilocybin-assisted psychotherapy as a potential treatment for this indication, and describe practical considerations based on our early experience designing and implementing four separate clinical trials of psilocybin-assisted psychotherapy for methamphetamine use disorder.

Effect of Aerobic Exercise on Intestinal Microbiota with Amino Acids and Short-Chain Fatty Acids in Methamphetamine-Induced Mice

This study aimed to investigate the changes in intestinal homeostasis and metabolism in mice after methamphetamine (MA) administration and exercise intervention. In this study, male C57BL/B6J mice were selected to establish a model of methamphetamine-induced addiction, and the gut microbiota composition, short-chain fatty acids (SCFAs), and amino acid levels were assessed by 16S rRNA, liquid chromatography–tandem mass spectrometry, and gas chromatography–tandem mass spectrometry, respectively. The results showed that 23 dominant microbiota, 12 amino acids, and 1 SCFA were remarkably higher and 9 amino acids and 6 SCFAs were remarkably lower in the exercise model group than in the control group. Among the top 10 markers with opposite trends between the exercise intervention group and model group, the differential microbiomes included Oscillibacter, Alloprevotella, Colidextribacter, Faecalibaculum, Uncultured, Muribaculaceae, and Negativibacillus; amino acids included proline; and SCFAs included isovaleric acid and pentanoic acid. Proline was negatively correlated with Negativibacillus and positively correlated with pentanoic acid. The results suggested that moderate-intensity aerobic exercise may modulate changes in the composition of the gut microbiota and the levels of amino acids and SCFAs induced by MA administration.

Methamphetamine-induced locomotor sensitization in mice is not associated with deficits in a range of cognitive, affective and social behaviours: interaction with brain-derived neurotrophic factor Val66Met genotype

Chronic methamphetamine (Meth) abuse may induce psychosis similar to that observed in schizophrenia. Brain-derived neurotrophic factor (BDNF) has been implicated in the development of psychosis. We have previously shown long-term protein expression changes in mice treated chronically with Meth depending on BDNF Val66Met genotype. The aim of this study was to investigate if these protein expression changes were associated with differential changes in a range of behavioural paradigms for cognition, anxiety, social and other behaviours. Male and female Val/Val, Val/Met and Met/Met mice were treated with an escalating Meth dose protocol from 6 to 9 weeks of age, with controls receiving saline injections. Several overlapping cohorts were tested in the Y-maze for short-term spatial memory, novel-object recognition test, context and cued fear conditioning, sociability and social preference, elevated plus maze for anxiety-like behaviour and prepulse inhibition (PPI) of acoustic startle. Finally, the animals were assessed for spontaneous exploratory locomotor activity and acute Meth-induced locomotor hyperactivity. Acute Meth caused significantly greater locomotor hyperactivity in mice previously treated with the drug than in saline-pretreated controls. Meth-pretreated female mice showed a mild increase in spontaneous locomotor activity. There were no Meth-induced deficits in any of the other behavioural tests. Val/Met mice showed higher overall social investigation time and lower PPI compared with the Val/Val genotype independent of pretreatment. These results show limited long-term effects of chronic Meth on a range of cognitive, affective and social behaviours despite marked drug-induced locomotor sensitization in mice. There was no interaction with BDNF Val66Met genotype.

Neural Correlates of Impaired Cognitive Control in Individuals with Methamphetamine Dependence: An fMRI Study

Impaired cognitive and behavioral control has often been observed in people who use methamphetamine (MA). However, a comprehensive understanding of the neural substrates underlying these impairments is still lacking. The goal of the present study was to study the neural correlates of impaired cognitive control in individuals with MA dependence according to DSM-IV criteria. Eighteen individuals with MA dependence and 21 healthy controls were investigated using Stroop task, fMRI, and an impulsivity questionnaire. Overall, patients were found to have significantly poorer accuracy on the Stroop task and higher self-rated impulsivity. Comparing brain activations during the task, decreased activation in the dorsolateral prefrontal cortex (DLPFC), anterior midcingulate cortex (aMCC), and dorsal striatum was observed in individuals with MA dependence, compared to healthy controls. Altered fMRI signal in DLPFC and aMCC significantly correlated with impaired behavioral task performance in individuals with MA dependence. Furthermore, significantly lower and pronounced brain activations in the MA group were additionally detected in several sensory cortical regions, i.e., in the visual, auditory, and somatosensory cortices. The results of the current study provide evidence for the negative impact of chronic crystal meth consumption on the proper functioning of the fronto-cingulate and striatal brain regions, presumably underlying the often-observed deficits in executive functions in individuals with MA use disorder. As a new finding, we also revealed abnormal activation in several sensory brain regions, suggesting the negative effect of MA use on the proper neural activity of these regions. This blunted activation could be the cause of the observed deficits in executive functions and the associated altered brain activation in higher-level brain networks.

The predictive role of impulsivity and perceived social support in psychiatric symptoms of women with methamphetamine use disorder

Background

Currently, few studies have examined the mental states of Women methamphetamine patients, and the influence of impulsivity and perceived social support on substance misuse-induced mental disorders is unclear. We want to examine the mental state of women with methamphetamine use disorder and compare it to the Chinese norm value of healthy women. Investigate the connection between impulsivity, perceived social support and mental state of women with methamphetamine use disorder.

Method

Two hundred thirty women subjects with a history of methamphetamine usage were recruited. The Chinese version of the SCL-90-R, (SCL-90) was used to evaluate psychological health problems, while the Multidimensional Scale of Perceived Social Support (MSPSS) and Barratt Impulsiveness Seale-11 (BIS-11) were utilized to evaluate perceived social support and impulsivity, respectively. The t-test, Pearson correlation analysis, multivariable linear regression, stepwise regression models, moderating effect analysis were used to analyze the statistics.

Results

There was a noticeable difference between the Chinese norm and all participants' SCL-90 ratings, especially for Somatization (t = 24.34, p < 0.001), Anxiety (t = 22.23, p < 0.001), Phobic anxiety (t = 26.47, p < 0.001), and Psychoticism (t = 24.27, p < 0.001). In addition, perceived social support levels and impulsivity levels are independently predictive of SCL-90 scores. Lastly, the impact of Impulsivity on SCL-90 can be modulated by perceived social support.

Conclusion

According to this study, women with methamphetamine use disorder have worse mental health conditions compared to healthy subjects. Furthermore, certain psychological symptoms associated with methamphetamine use in women can be aggravated by impulsivity, while perceived social support acts as a protective factor for methamphetamine-related psychiatric symptoms. Specifically, perceived social support weakens the impact of impulsivity on psychiatric symptoms in women with methamphetamine use disorder.

Nanowired Delivery of Curcumin Attenuates Methamphetamine Neurotoxicity and Elevates Levels of Dopamine and Brain-Derived Neurotrophic Factor

Curcumin is a well-known antioxidant used as traditional medicine in China and India since ages to treat variety of inflammatory ailments as a food supplement. Curcumin has antitumor properties with neuroprotective effects in Alzheimer's disease. Curcumin elevates brain-derived neurotrophic factor (BDNF) and dopamine (DA) levels in the brain indicating its role in substance abuse. Methamphetamine (METH) is one of the most abused substances in the world that induces profound neurotoxicity by inducing breakdown of the blood-brain barrier (BBB), vasogenic edema and cellular injuries. However, influence of curcumin on METH-induced neurotoxicity is still not well investigated. In this investigation, METH neurotoxicity and neuroprotective effects of curcumin nanodelivery were examined in a rat model. METH (20 mg/kg, i.p.) neurotoxicity is evident 4 h after its administration exhibiting breakdown of BBB to Evans blue albumin in the cerebral cortex, hippocampus, cerebellum, thalamus and hypothalamus associated with vasogenic brain edema as seen measured using water content in all these regions. Nissl attaining exhibited profound neuronal injuries in the regions of BBB damage. Normal curcumin (50 mg/kg, i.v.) 30 min after METH administration was able to reduce BBB breakdown and brain edema partially in some of the above brain regions. However, TiO₂ nanowired delivery of curcumin (25 mg/kg, i.v.) significantly attenuated brain edema, neuronal injuries and the BBB leakage in all the brain areas. BDNF level showed a significant higher level in METH-treated rats as compared to saline-treated METH group. Significantly enhanced DA levels in METH-treated rats were also observed with nanowired delivery of curcumin. Normal curcumin was able to slightly elevate DA and BDNF levels in the selected brain regions. Taken together, our observations are the first to show that nanodelivery of curcumin induces superior neuroprotection in METH neurotoxicity probable by enhancing BDNF and DA levels in the brain, not reported earlier.

Evaluation of Adenosine A2A receptor gene polymorphisms as risk factors of methamphetamine use disorder susceptibility and predictors of craving degree

The adenosine A2A receptor (ADORA2A) is highly expressed in the central nervous system and plays vital roles in drug addiction. In this study, we aimed to explore the susceptibility of ADORA2A to methamphetamine use disorder (MUD) and the craving degree based on a two-stage association analysis. A total of 3,542 (1,216 patients with MUD and 2,326 controls) and 1,740 participants (580 patients with MUD and 1,160 controls) were recruited in discovery and replication stage, respectively. Significant SNPs identified in the discovery stage were genotyped in the replication samples. Serum levels of ADORA2A were measured using enzyme-linked immunosorbent assay kits. The genetic association signal of each SNP was examined using Plink. A linear model was fitted to investigate the relationship between craving scores and genotypes of significant SNPs. SNP rs5751876 was significantly associated with MUD in the discovery samples and this association signal was then further replicated in the replication samples. Significant associations were also identified between serum levels of ADORA2A and the genotypes of rs5751876 (P = 0.0002). The craving scores in patients with MUD were strongly correlated with rs5751876 genotypes. Our results suggest that polymorphisms of the ADORA2A gene could affect the susceptibility to MUD and its craving degree.

Decoding Emotion in Drug Abusers: Evidence for Face and Body Emotion Recognition and for Disgust Emotion

Background: Different drugs damage the frontal cortices, particularly the prefrontal areas involved in both emotional and cognitive functions, with a consequence of decoding emotion deficits for people with substance abuse. The present study aimed to explore the cognitive impairments in drug abusers through facial, body and disgust emotion recognition, expanding the investigation of emotions processing, measuring accuracy and response velocity. Methods: We enrolled 13 addicted to cocaine and 12 alcohol patients attending treatment services in Italy, comparing them with 33 matched controls. Facial emotion and body posture recognition tasks, a disgust rating task and the Barrat Impulsivity Scale were included in the experimental assessment. Results: We found that emotional processes are differently influenced by cocaine and alcohol, suggesting that these substances impact diverse cerebral systems. Conclusions: Drug abusers seem to be less accurate on elaboration of facial, body and disgust emotions. Considering that the participants were not cognitively impaired, our data support the hypothesis that emotional impairments emerge independently from the damage of cognitive functions.

Associations between psychosocial risk factors, and changes in substance dependence and psychosocial functioning, during engagement with digital cognitive behavioral therapy for methamphetamine use: use of 'Breaking Free from Substance Abuse' by incarcerated people during the COVID-19 pandemic

BACKGROUND

Methamphetamine use can be associated with involvement with correctional services and incarceration. Traditionally, treatments for methamphetamine use have been delivered in-person - however, lockdowns initiated during the COVID-19 pandemic significantly reduced access to such in-person support in prisons. Therefore, in May 2020 a digital cognitive-behavioral therapy (CBT) program for substance use disorders - 'Breaking Free from Substance Abuse' - was made available across prisons in Ohio in order to meet this treatment gap. This represents the first time this digital CBT intervention has been made widely available to incarcerated people residing in prisons or jails in the United States (US). This was a within-subjects study using data from 2187 Ohio prison residents who engaged with this digital CBT program to address their methamphetamine use.

RESULTS

Participants reported multiple psychosocial risk factors, including moderate to severe substance dependence, depression and anxiety; interpersonal conflict; aggressive behavior; paranoia; and difficulties with work, education and accommodation. Significant reductions in substance dependence, depression/anxiety and biopsychosocial impairment, and improvements in quality of life, were identified in the sample. Risk factors were associated with less positive outcomes, specifically interpersonal conflict and poor mental health. Completion of specific components of the program were associated with more positive outcomes - a dose response was also identified.

CONCLUSIONS

Digital CBT can be delivered in secure US correctional settings and may help to fill unmet needs for in-person treatment. Specifically, this digital CBT program may support incarcerated individuals to address methamphetamine use, with outcomes being associated with psychosocial risk factors and program engagement.

Repeated methamphetamine administration produces cognitive deficits through augmentation of GABAergic synaptic transmission in the prefrontal cortex

Methamphetamine (METH) abuse is associated with the emergence of cognitive deficits and hypofrontality, a pathophysiological marker of many neuropsychiatric disorders that is produced by altered balance of local excitatory and inhibitory synaptic transmission. However, there is a dearth of information regarding the cellular and synaptic mechanisms underlying METH-induced cognitive deficits and associated hypofrontal states. Using PV-Cre transgenic rats that went through a METH sensitization regime or saline (SAL) followed by 7-10 days of home cage abstinence combined with cognitive tests, chemogenetic experiments, and whole-cell patch recordings on the prelimbic prefrontal cortex (PFC), we investigated the cellular and synaptic mechanisms underlying METH-induce hypofrontality. We report here that repeated METH administration in rats produces deficits in working memory and increases in inhibitory synaptic transmission onto pyramidal neurons in the PFC. The increased PFC inhibition is detected by an increase in spontaneous and evoked inhibitory postsynaptic synaptic currents (IPSCs), an increase in GABAergic presynaptic function, and a shift in the excitatory-inhibitory balance onto PFC deep-layer pyramidal neurons. We find that pharmacological blockade of D1 dopamine receptor function reduces the METH-induced augmentation of IPSCs, suggesting a critical role for D1 dopamine signaling in METH-induced hypofrontality. In addition, repeated METH administration increases the intrinsic excitability of parvalbumin-positive fast spiking interneurons (PV + FSIs), a key local interneuron population in PFC that contributes to the control of inhibitory tone. Using a cell type-specific chemogenetic approach, we show that increasing PV + FSIs activity in the PFC is necessary and sufficient to cause deficits in temporal order memory similar to those induced by METH. Conversely, reducing PV + FSIs activity in the PFC of METH-exposed rats rescues METH-induced temporal order memory deficits. Together, our findings reveal that repeated METH exposure increases PFC inhibitory tone through a D1 dopamine signaling-dependent potentiation of inhibitory synaptic transmission, and that reduction of PV + FSIs activity can rescue METH-induced cognitive deficits, suggesting a potential therapeutic approach to treating cognitive symptoms in patients suffering from METH use disorder.

In- and Out-Group Effects on Social Perception and Empathy in Cocaine Use Disorder

Earlier research revealed that cocaine users display impairments in emotional but not necessarily in cognitive empathy. However, no study to date has tested whether empathy is generally altered or whether impairments are restricted to specific social targets. The current investigation addresses this open question. In addition, we examined whether attributions of warmth and competence as well as personal future expectancies differed between cocaine users and substance-naïve controls. Twenty-two chronic cocaine users and 40 stimulant-naïve controls specified their perceived warmth and competence for four social targets [in-group member, opposite consumption out-group member (cocaine user for controls and non-user for cocaine user), opposite consumption out-group member of opposite gender, and elderly person]. They also specified their cognitive and emotional empathy for these four targets facing eight desirable and eight undesirable events. Finally, they rated the likelihood of these scenarios happening to themselves. Both cocaine users and controls attributed lower warmth to cocaine-using than non-using targets. Comparably, no in-group preference was observed in cocaine user's emotional empathy ratings, and greater denigration of the in-group was associated with higher frequency and doses of cocaine consumption. In addition, cocaine users rated both desirable and undesirable events as more likely to happen to themselves than did controls. Results show that substance-naïve individuals stigmatize cocaine users. They further point to compromised self-esteem in cocaine users resulting from such stigmatization. Interventions should address stigmatization processes to break the vicious circle of mutual social distancing and stronger dedication to the drug.

Quercetin Mitigates Methamphetamine-Induced Anxiety-Like Behavior Through Ameliorating Mitochondrial Dysfunction and Neuroinflammation

Methamphetamine (MA) abuse results in neurotoxic outcomes, including increased anxiety and depression. Studies have reported an association between MA exposure and anxiety, nonetheless, the underlying mechanism remains elusive. In the present study, we developed a mouse model of anxiety-like behavior induced by MA administration. RNA-seq was then performed to profile the gene expression patterns of hippocampus (HIPP), and the differentially expressed genes (DEGs) were significantly enriched in signaling pathways related to psychiatric disorders and mitochondrial function. Based on these, mitochondria was hypothesized to be involved in MA-induced anxiety. Quercetin, as a mitochondrial protector, was used to investigate whether to be a potential treatment for MA-induced anxiety; accordingly, it alleviated anxiety-like behavior and improved mitochondrial impairment in vivo. Further experiments in vitro suggested that quercetin alleviated the dysfunction and morphological abnormalities of mitochondria induced by MA, via decreasing the levels of reactive oxygen species (ROS), mitochondrial membrane potential (MMP), and increasing the oxygen consumption rate (OCR) and ATP production. Moreover, the study examined the effect of quercetin on astrocytes activation and neuroinflammation, and the results indicated that it significantly attenuated the activation of astrocytes and reduced the levels of IL-1β, TNFα but not IL-6. In light of these findings, quantitative evidence is presented in the study supporting the view that MA can evoke anxiety-like behavior via the induction of mitochondrial dysfunction. Quercetin exerted antipsychotic activity through modulation of mitochondrial function and neuroinflammation, suggesting its potential for further therapeutic development in MA-induced anxiety.

Natural Products in Modulating Methamphetamine-Induced Neuronal Apoptosis

Methamphetamine (METH), an amphetamine-type psychostimulant, is highly abused worldwide. Chronic abuse of METH causes neurodegenerative changes in central dopaminergic neurons with numerous neuropsychiatric consequences. Neuronal apoptosis plays a critical role in METH-induced neurotoxicity and may provide promising pharmacological targets for preventing and treating METH addiction. In recent years, accumulating evidence has revealed that natural products may possess significant potentials to inhibit METH-evoked neuronal apoptosis. In this review, we summarized and analyzed the improvement effect of natural products on METH-induced neuronal apoptosis and their potential molecular mechanisms on modulating dopamine release, oxidative stress, mitochondrial-dependent apoptotic pathway, endoplasmic reticulum stress-mediated apoptotic pathway, and neuroinflammation. Hopefully, this review may highlight the potential value of natural products in modulating METH-caused neuronal apoptosis and provide useful information for future research and developments of novel and efficacious pharmacotherapies in this field.

Correlates of Aggression in Men With Methamphetamine Use Disorder: Childhood Trauma and Methamphetamine-Use Characteristics

BACKGROUND

Aggression is common among individuals with methamphetamine use disorder (MAUD) and constitutes a serious public health issue. The current study aimed to examine associations of methamphetamine-use characteristics and childhood trauma with aggression in men with MAUD.

METHODS

This cross-sectional study was conducted from December 2017 to August 2018. MAUD patients recruited from a compulsory drug rehabilitation center (n = 360) and healthy comparison subjects (n = 604) completed a survey that measured aggression and childhood trauma, using the Chinese version of Buss-Perry Aggressive Questionnaire (AQ-CV), and the short form of Childhood Trauma Questionnaire (CTQ-SF), respectively. MAUD patients also provided information on methamphetamine-use characteristics such as the age of MAUD onset, MAUD severity, and co-occurring alcohol use disorder (AUD) and tobacco use disorder (TUD) using standard or self-designed questionnaires. Chi-square tests and t-tests were used to compare childhood trauma and aggression between the MAUD and comparison groups. Multiple linear regressions were conducted to determine correlates of overall aggression and its five sub-scales among the MAUD group.

RESULTS

The MAUD group had higher childhood trauma and aggression scores than the comparison group. Within the MAUD group, age of MAUD onset, having severe MAUD, co-occurring AUD, co-occurring TUD, and childhood trauma were associated with overall aggression, with slightly different correlates found for its five sub-scales.

CONCLUSIONS

Our study shows a high level of childhood trauma and aggression in the MAUD group. Both methamphetamine-use characteristics (age of MAUD onset, severe MAUD, co-occurring AUD/TUD) and childhood trauma were associated with aggression in MAUD. Our findings provide useful information on potential risk factors for aggression and inform future longitudinal research to establish causal relationships between these factors and aggression to guide further prevention and treatment programs.

Genome-wide association study detected novel susceptibility genes for social cognition impairment in people with schizophrenia

OBJECTIVES

People with schizophrenia (SCZ) present serious and generalised deficits in social cognition (SC), which affect negatively patients' functioning and treatment outcomes. The genetic background of SC has been investigated in disorders other than SCZ providing weak and sparse results. Thus, our aim was to explore possible genetic correlates of SC dysfunctions in SCZ patients with a genome-wide study (GWAS) approach.

METHODS

We performed a GWAS meta-analysis of data coming from two cohorts made of 242 and 160 SCZ patients, respectively. SC was assessed with different tools in order to cover its different domains.

RESULTS

We found GWAS significant association between the TMEM74 gene and the patients' ability in social inference as assessed by The Awareness of Social Inference Test; this association was confirmed by both SNP-based analysis (lead SNP rs3019332 p-value = 5.24 × 10^-9) and gene-based analysis (p-value = 1.09 × 10^-7). Moreover, suggestive associations of other genes with different dimensions of SC were also found.

CONCLUSIONS

Our study shows for the first time GWAS significant or suggestive associations of some gene variants with SC domains in people with SCZ. These findings should stimulate further studies to characterise the genetic underpinning of SC dysfunctions in SCZ.

Effects of moderate-intensity exercise on social health and physical and mental health of methamphetamine-dependent individuals: A randomized controlled trial

OBJECTIVE

Methamphetamine (MA)-dependent individuals' health problems are widespread and need to be solved urgently. Exercise is considered a potential treatment for MA dependents. The study aimed to determine the effects of a 12-week aerobic exercise on the social, physical, and mental health of MA-dependent individuals.

MATERIALS AND METHODS

Sixty MA-dependent individuals were randomly assigned into two groups. Subjects in the exercise group (n = 30) received an exercise intervention five days a week for 60 min each for 12 weeks. Subjects in the control group (n = 30) received regular corrective rehabilitation without exercise in the same setting. Outcome measures, including questionnaires [quality of life scale for drug addiction (QOL-DA), self-rating anxiety scale (SAS), self-rating depression scale (SDS), and Pittsburgh sleep quality index (PSQI)] and physical fitness, were arranged the day before the start of the intervention and the day after the end of the intervention. Two-factor repeated measures ANOVA was used to compare the treatment differences between the two groups.

RESULTS

After 12 weeks of the intervention period, social health was significantly improved in the exercise group (P < 0.01), and there was a statistically significant difference in mental health scores between exercise group and control group, with a greater impact in exercise group.(Psychology: P < 0.01; SAS: P < 0.01; SDS: P < 0.01; PSQI: P < 0.01), physical health improved in the exercise group, physiology (P < 0.01), symptom (P < 0.01), heart rate (P < 0.01), systolic blood pressure (P < 0.01), systolic blood pressure (P < 0.01), vital capacity (P < 0.05), grip (P < 0.01), vertical jump (P < 0.001), sit and reach (P < 0.01), 50-meter run (P < 0.01), and reaction time (P < 0.01).

CONCLUSION

Aerobic exercise intervention is an effective treatment for MA-dependent individuals, and the 12-week intervention improved the social, physical, and mental health of MA-dependent individuals. We recommend that future studies focus more on drug-dependent individuals' overall health status rather than just relapse.Clinical trial registration: [https://www.chictr.org.cn/hvshowproject.aspx?id=131048], identifier [ChiCTR2200055348].

Associations of executive function and age of first use of methamphetamine with methamphetamine relapse

BACKGROUND AND AIMS

Methamphetamine (MA) is a psychostimulant associated with a high relapse rate among patients with MA use disorder (MUD). Long-term use of MA is associated with mental disorders, executive dysfunction, aggressive behaviors, and impulsivity among patients with MUD. However, identifying which factors may be more closely associated with relapse has not been investigated. Thus, we aimed to investigate the psychological factors and the history of MA use that may influence MA relapse.

METHODS

This cross-sectional study included 168 male MUD patients (MUD group) and 65 healthy male residents (control group). Each patient was evaluated with self-report measures of executive dysfunction, psychopathological symptoms, impulsiveness, aggressiveness, and history of MA use. Data were analyzed with t-tests, analyses of variance, and correlation and regression analyses.

RESULTS

The MUD group reported greater executive dysfunction, psychopathological symptoms, impulsivity, and aggression than the control group. Lower age of first MA use was associated both with having relapsed one or more times and with having relapsed two or more times; greater executive dysfunction was associated only with having relapsed two or more times.

CONCLUSION

Patients with MUD reported worse executive function and mental health. Current results also suggest that lower age of first MA use may influence relapse rate in general, while executive dysfunction may influence repeated relapse in particular. The present results add to the literature concerning factors that may increase the risk of relapse in individuals with MUD.

Impact of adolescent methamphetamine use on social cognition: A human-mice reverse translation study

BACKGROUND

Methamphetamine dependence is associated with social cognition deficits that may underpin negative social outcomes. However, there are considerable inter-individual differences in social cognition within people with methamphetamine dependence, with age of onset of methamphetamine use being a potential contributing factor.

MATERIALS AND METHODS

We conducted two sequential studies examining the link between age of onset of methamphetamine use (adolescence versus young adulthood) and performance in social cognition tests: (1) a human cross-sectional study in 95 participants with methamphetamine dependence varying in age of onset (38 with adolescent onset and 57 with adult onset) and 49 drug-naïve controls; (2) a mice study in which we tested the effects of methamphetamine exposure during adolescence versus young adulthood on social interaction and aggression, and their potential neurochemical substrates in the striatal dopaminergic system.

RESULTS

We initially showed that people with methamphetamine dependence who started use in adolescence had higher antisocial beliefs (p = 0.046, Cohen's d=0.42) and worse emotion recognition (p = 0.031, Cohen's d=0.44) than those who started use during adulthood. We reasoned that this could be due to either social cognition deficits leading to earlier onset of methamphetamine use, or methamphetamine-induced neuroadaptive effects specific to adolescence. Mice experiments showed that methamphetamine exposure during adolescence specifically decreased social investigation during social interaction and upregulated striatal tyrosine hydroxylase (p < 0.05, Bonferroni corrected). There was no evidence of adolescent-specific methamphetamine effects on aggression or other measures of dopaminergic function.

CONCLUSION

Together, translational findings demonstrate heightened sensitivity to methamphetamine effects on social cognition during adolescence.

Training and transfer effects of working memory updating training in male abstinent long-term methamphetamine users

Methamphetamine use is associated with cognitive impairments, including executive functioning. These impairments might be cause and/or effect of the drug (re-)use and have, therefore, motivated interventions to improve cognitive functioning. Until now, only very few studies have examined the effect of training working memory updating (WMU), one of the core executive functions, in this population. In the present study, 32 long-term male abstinent methamphetamine inpatients received either a multiple-session WMU training or an active control treatment. All participants performed a number of tasks assessing WMU, inhibition, and task-switching ability- before and after treatment. The WMU-trained patients improved their performance on the trained task and on a non-trained WMU task, reflecting near transfer. However, there was no beneficial training-induced effect for the other tasks, indicating the absence of far transfer. Possible treatment implications of these findings were discussed.

A Zebrafish Model of Neurotoxicity by Binge-Like Methamphetamine Exposure

Hyperthermia is a common confounding factor for assessing the neurotoxic effects of methamphetamine (METH) in mammalian models. The development of new models of methamphetamine neurotoxicity using vertebrate poikilothermic animals should allow to overcome this problem. The aim of the present study was to develop a zebrafish model of neurotoxicity by binge-like methamphetamine exposure. After an initial testing at 20 and 40 mg/L for 48 h, the later METH concentration was selected for developing the model and the effects on the brain monoaminergic profile, locomotor, anxiety-like and social behaviors as well as on the expression of key genes of the catecholaminergic system were determined. A concentration- and time-dependent decrease in the brain levels of dopamine (DA), norepinephrine (NE) and serotonin (5-HT) was found in METH-exposed fish. A significant hyperactivity was found during the first hour of exposure, followed 3 h after by a positive geotaxis and negative scototaxis in the novel tank and in the light/dark paradigm, respectively. Moreover, the behavioral phenotype in the treated fish was consistent with social isolation. At transcriptional level, th1 and slc18a2 (vmat2) exhibited a significant increase after 3 h of exposure, whereas the expression of gfap, a marker of astroglial response to neuronal injury, was strongly increased after 48 h exposure. However, no evidences of oxidative stress were found in the brain of the treated fish. Altogether, this study demonstrates the suitability of the adult zebrafish as a model of METH-induced neurotoxicity and provides more information about the biochemical and behavioral consequences of METH abuse.

Effects of Taijiquan and Qigong exercises on depression and anxiety levels in patients with substance use disorders: A systematic review and meta-analysis

Previous studies have shown that Taijiquan and Qigong exercise can effectively reduce depression and anxiety in healthy and clinical populations. At present, only a few reviews have elaborated on the premise of different types of interventions, and there is still a lack of studies that systematically summarize the clinical evidence of patients with substance use disorders. The purpose of this meta-analysis was to assess the impact of the Taijiquan and Qigong exercise on the mood of individuals with substance use disorders (SUD); Articles were searched in Pubmed, Embase, Cochrane Library, Web of Science, and CNKI from their inception to the May 24, 2021. All randomized controlled trials (RCT) using Taijiquan and Qigong intervention were included. With the Review Manager software to determine the effect (standardized mean difference, SMD), subgroup analysis was conducted to intervention type, exercise time, and exercise duration. Nine studies totaling 823 participants were included in the study. Overall results indicated that Taijiquan and Qigong exercise had significant benefits in reducing depression (SMD = −0.35, 95% CI: −0.53 to −0.18, Z = 4.00, p < 0.01) and anxiety (SMD = −0.31, 95% CI: −0.50 to −0.11, Z = 3.06, p < 0.01) symptoms in SUD. When depression and anxiety were examined separately, subgroup analysis demonstrated that Taijiquan intervention (SMD = −0.45, 95% CI: −0.71 to −0.19, Z = 3.39, p < 0.01) and Qigong intervention (SMD = −0.28, 95% CI −0.51 to −0.04, Z = 2.33, p = 0.02),30–60 min exercise time (SMD = −0.41, 95% CI: −0.61 to −0.20, Z = 3.82, p < 0.01) and duration of 9–12 weeks (SMD = −0.57, 95% CI: −1.10 to −0.04, Z = 2.10, p = 0.04) more than 12 weeks (SMD = −0.28, 95% CI: −0.50 to −0.07, Z = 2.59, p = 0.01) could effectively alleviate the symptoms of depression. Meanwhile, Qigong intervention (SMD = −0.31, 95% CI: −0.52 to −0.10, Z = 2.85, p < 0.01), 30–60 min exercise time (SMD = −0.29, 95% CI: −0.53 to −0.04, Z = 2.28, p = 0.02), more than 60 min exercise time (SMD = −0.54, 95% CI: −1.06 to −0.02, Z = 2.05, p = 0.04), and duration of less than 9 weeks (SMD = −0.35, 95% CI: −0.68 to −0.02, Z = 2.07, p = 0.04) had positive effects on alleviating anxiety symptoms with SUD. Taijiquan and Qigong exercise could reduce levels of anxiety and depression in those with SUD. Considering the small number of included studies, more reliable RCTs are needed on this topic.

Oxytocin increases physiological linkage during group therapy for methamphetamine use disorder: a randomized clinical trial

Patients and psychotherapists often exhibit behavioral, psychological, and physiological similarity. Here, we test whether oxytocin—a neuropeptide that can enhance expressivity and social perception—influences time-lagged “linkage” of autonomic nervous system responses among participants and facilitators during group therapy. Physiological linkage estimates (n = 949) were created from ten cohorts, each with two facilitators (n = 5) and four to six participants (n = 48), over six weekly sessions of group therapy for methamphetamine use disorder. All participants of a cohort received oxytocin or placebo intranasally in a randomized double-blind procedure before each session. Cardiac interbeat intervals (IBI) were measured continuously during sessions to estimate physiological linkage, operationalized as one cohort-mate’s IBI reactivity during one minute predicting another cohort-mate’s IBI reactivity during the following minute. In oxytocin cohorts, participants and facilitators experienced significant physiological linkage to their cohort-mates (i.e., their physiological responses were predicted by the prior responses of their cohort-mates) and significantly more linkage than people in placebo cohorts. Both effects occurred during the first and second sessions but not later sessions. Results suggest that oxytocin may enhance psychosocial processes often associated with linkage—such as social engagement—in groups and highlight oxytocin’s potential to improve group cohesion during group therapy.

Clinical Trials Registration: NCT02881177, First published on 26/08/2016.

The impact of methamphetamine/amphetamine use on receipt and outcomes of medications for opioid use disorder: a systematic review

Background

Methamphetamine/amphetamine use has sharply increased among people with opioid use disorder (OUD). It is therefore important to understand whether and how use of these substances may impact receipt of, and outcomes associated with, medications for OUD (MOUD). This systematic review identified studies that examined associations between methamphetamine/amphetamine use or use disorder and 3 classes of outcomes: (1) receipt of MOUD, (2) retention in MOUD, and (3) opioid abstinence during MOUD.

Methods

We searched 3 databases (PubMed/MEDLINE, PsycINFO, CINAHL Complete) from 1/1/2000 to 7/28/2020 using key words and subject headings, and hand-searched reference lists of included articles. English-language studies of people with documented OUD/opioid use that reported a quantitative association between methamphetamine/amphetamine use or use disorder and an outcome of interest were included. Study data were extracted using a standardized template, and risk of bias was assessed for each study. Screening, inclusion, data extraction and bias assessment were conducted independently by 2 authors. Study characteristics and findings were summarized for each class of outcomes.

Results

Thirty-nine studies met inclusion criteria. Studies generally found that methamphetamine/amphetamine use or use disorder was negatively associated with receiving methadone and buprenorphine; 2 studies suggested positive associations with receiving naltrexone. Studies generally found negative associations with retention; most studies finding no association had small samples, and these studies tended to examine shorter retention timeframes and describe provision of adjunctive services to address substance use. Studies generally found negative associations with opioid abstinence during treatment among patients receiving methadone or sustained-release naltrexone implants, though observed associations may have been confounded by other polysubstance use. Most studies examining opioid abstinence during other types of MOUD treatment had small samples.

Conclusions

Overall, existing research suggests people who use methamphetamine/amphetamines may have lower receipt of MOUD, retention in MOUD, and opioid abstinence during MOUD. Future research should examine how specific policies and treatment models impact MOUD outcomes for these patients, and seek to understand the perspectives of MOUD providers and people who use both opioids and methamphetamine/amphetamines. Efforts to improve MOUD care and overdose prevention strategies are needed for this population.

Cocaine Increases Sensorimotor Gating and is Related to Psychopathy

OBJECTIVE

Prepulse inhibition regulates sensorimotor gating and is a marker of vulnerability to certain disorders. We compared prepulse inhibition, psychopathy, and sensitivity to punishment and reward in patients with cocaine-related disorder without psychiatric comorbidities and a control group.

METHODS

This was an observational study of a sample of 22 male cases with cocaine-related disorder and 22 healthy male controls. We used the Psychiatric Research Interview for Substance and Mental Disorders and Mini International Neuropsychiatric Interview; the Sensitivity to Punishment and Sensitivity to Reward Questionnaire; and the Levenson Self-Report Psychopathy Scale and Hare Psychopathy Checklist-Revised. Prepulse inhibition was evaluated at 30, 60, and 120 ms.

RESULTS

Cocaine-related disorder group had a higher overall score (t = 12.556, p = .001) and primary psychopathy score (t = 3.750, p = .001) on Levenson Self-Report Psychopathy Scale, a higher score on both Hare Psychopathy Checklist-Revised factors, sensitivity to rewards (t = 3.076, p = .005) and prepulse inhibition at 30 ms (t = 2.859, p = .008).

CONCLUSIONS

Cocaine use in patients without psychiatric comorbidities seems to increase sensorimotor gating. Therefore, these patients likely have an increased sensitivity to rewards, causing them to focus more on cocaine-boosting stimuli, thus explaining the psychopathic traits of these individuals.

Development of the Risk of Relapse Assessment Scale for methamphetamine abusers in China

BACKGROUND

Relapse to Methamphetamine (MA) use is among the public concerns nowadays, which result in adverse outcomes associated with physical and mental health problems. This study aimed to develop the Risk of Relapse Assessment Scale (RRAS) for Chinese MA abusers.

METHOD

A sample of 438 MA abusers aged between 17 and 58 years (M ± SD age = 34.08 ± 8.61 years) in compulsory detoxification institutes were randomly divided into sub-sample 1 (n = 223) and sub-sample 2 (n = 215) for conducting exploratory factor analysis and confirmatory factor analysis respectively.

RESULTS

Compared four-factor model with 19 items and three-factor model with 16 items using principal axis factoring, the three-factor solution showed better model fit. Three factors were identified in RRAS: Craving for MA, Social Recognition, and Attitude towards MA which accounted for 50.06 % of the variance in total. The results of confirmation factor analysis demonstrated good model fits (CFI = 0.95; TLI = 0.94; RMSEA = 0.050; GFI = 0.92). The internal consistency analysis indicated that the three-factor model had satisfactory reliability with Cronbach alphas ranging from 0.71 to 0.88 for different factors. Overall, the results showed that the RRAS had good construct validity and satisfactory reliability, suggesting that it was a good instrument for measuring the relapse of MA.

CONCLUSIONS

The RRAS with good psychometric properties provides a promising future for developing effective relapse prevention programs for MA abusers in China.

Methamphetamine exacerbates pathophysiology of traumatic brain injury at high altitude. Neuroprotective effects of nanodelivery of a potent antioxidant compound H-290/51

Military personnel are often exposed to high altitude (HA, ca. 4500-5000m) for combat operations associated with neurological dysfunctions. HA is a severe stressful situation and people frequently use methamphetamine (METH) or other psychostimulants to cope stress. Since military personnel are prone to different kinds of traumatic brain injury (TBI), in this review we discuss possible effects of METH on concussive head injury (CHI) at HA based on our own observations. METH exposure at HA exacerbates pathophysiology of CHI as compared to normobaric laboratory environment comparable to sea level. Increased blood-brain barrier (BBB) breakdown, edema formation and reductions in the cerebral blood flow (CBF) following CHI were exacerbated by METH intoxication at HA. Damage to cerebral microvasculature and expression of beta catenin was also exacerbated following CHI in METH treated group at HA. TiO2-nanowired delivery of H-290/51 (150mg/kg, i.p.), a potent chain-breaking antioxidant significantly enhanced CBF and reduced BBB breakdown, edema formation, beta catenin expression and brain pathology in METH exposed rats after CHI at HA. These observations are the first to point out that METH exposure in CHI exacerbated brain pathology at HA and this appears to be related with greater production of oxidative stress induced brain pathology, not reported earlier.

Gut and brain profiles that resemble pre-motor and early-stage Parkinson's disease in methamphetamine self-administering rats

INTRODUCTION

Methamphetamine is a potent psychomotor stimulant, and methamphetamine abusers are up to three times more likely to develop Parkinson's disease (PD) later in life. Prodromal PD may involve gut inflammation and the accumulation of toxic proteins that are transported from the enteric nervous system to the central nervous system to mediate, in part, the degeneration of dopaminergic projections. We hypothesized that self-administration of methamphetamine in rats produces a gut and brain profile that mirrors pre-motor and early-stage PD.

METHODS

Rats self-administered methamphetamine in daily 3 h sessions for two weeks. Motor function was assessed before self-administration, during self-administration and throughout the 56 days of forced abstinence. Assays for pathogenic markers (tyrosine hydroxylase, glial fibrillary acidic protein (GFAP), α-synuclein) were conducted on brain and gut tissue collected at one or 56 days after cessation of methamphetamine self-administration.

RESULTS

Motor deficits emerged by day 14 of forced abstinence and progressively worsened up to 56 days of forced abstinence. In the pre-motor stage, we observed increased immunoreactivity for GFAP and α-synuclein within the ganglia of the myenteric plexus in the distal colon. Increased α-synuclein was also observed in the substantia nigra pars compacta. At 56 days, GFAP and α-synuclein normalized in the gut, but the accumulation of nigral α-synuclein persisted, and the dorsolateral striatum exhibited a significant loss of tyrosine hydroxylase.

CONCLUSION

The pre-motor profile is consistent with gut inflammation and gut/brain α-synuclein accumulation associated with prodromal PD and the eventual development of the neurological disease.

Effective connectivity predicts cognitive empathy in cocaine addiction: a spectral dynamic causal modeling study

Social cognition plays a crucial role in the development and treatment of cocaine dependence. However, studies investigating social cognition, such as empathy and its underlying neural basis, are lacking. To explore the neural interactions among reward and memory circuits, we applied effective connectivity analysis on resting-state fMRI data collected from cocaine-dependent subjects. The relationship between effective connectivity within these two important circuits and empathy ability - evaluated with the Interpersonal Reactivity Index (IRI) - was assessed by machine learning algorithm using multivariate regression analysis. In accordance with the neurocircuitry disruptions of cocaine addiction, the results showed that cocaine-dependent subjects relative to healthy controls had altered resting state effective connectivity between parts of the memory and reward systems. Furthermore, effective connectivity between the memory and reward system could predict the fantasy empathy (FE) subscale scores in cocaine dependence. Overall, our findings provide further evidence for the neural substrates of social cognition in cocaine-dependent patients. These new insights could be useful for the development of new treatment programs for this substance dependency disorder.

The Chronic Oral Administration of Clobenzorex or Amphetamine Decreases Motor Behavior and Induces Glial Activation in the Striatum Without Dopaminergic Degeneration

Described as amphetamine-like due to their structural and stimulant similarities, clobenzorex is one of the five most-commonly used drugs in Mexico for the treatment of obesity. Various studies have shown that amphetamines induce dopaminergic neurotoxicity and neuroinflammation in the striatum, symptoms which are associated with motor damage. For this reason, the present study aimed to evaluate the effect of chronic clobenzorex administration on motor behaviors, TH immunoreactivity, gliosis, and the neurodegenerative process in the striatum and substantia nigra pars compacta (SNpc). The present research was conducted on three experimental groups of male Wistar rats: the vehicle group, the amphetamine group (2 mg/kg), and the clobenzorex group (30 mg/kg). All groups were subject to oral administration every 24 h for 31 days. Motor activity and motor coordination were evaluated in the open field test and the beam walking test, respectively. The animals were euthanized after the last day of treatment to enable the extraction of their brains for the evaluation of tyrosine hydroxylase (TH) levels, the immunoreactivity of the glial cells, and the neurodegeneration of both the striatum and SNpc via amino-cupric-silver stain. The results obtained show that amphetamine and clobenzorex administration decrease motor activity and motor coordination in the beam walking test and cause increased gliosis in the striatum, while no significant changes were observed in terms of immunoreactivity to TH and neurodegeneration in both the striatum and SNpc. These results suggest that the chronic administration of clobenzorex may decrease motor function in a manner similar to amphetamine, via the neuroadaptive and non-neurotoxic changes caused to the striatum under this administration scheme.

Prosocialness in young males with substance and behavioral addictions

BACKGROUND AND AIMS

Social determinants are closely related to addiction, both as a cause and a consequence of substance use and other addictive behaviors. The present paper examines prosocialness (i.e. the tendency to help, empathize, and care for others) among a population of young males. We compared prosocialness across different types of addiction and examined whether prosocialness varied according to the presence of multiple addictions.

METHODS

A sample of 5,675 young males, aged 19-29 years old (Mean = 21.4; Median = 21), completed a questionnaire that included screening tools to identify addictive behaviors with regards to alcohol, nicotine, cannabis, gambling, and gaming. The questionnaire also included a scale to measure prosocialness.

RESULTS

Compared to a no-addiction control group, the subgroups of young men suffering from behavioral addictions (i.e., gambling and gaming) reported the lowest levels of prosocialness. Respondents with an alcohol addiction also showed lower prosocialness compared to no-addiction controls. By contrast, no significant differences in prosocialness were found between respondents with nicotine disorder or cannabis disorder and the no-addiction controls. Furthermore, the number of addictions had no clear, observable effects on prosocialness. Significant differences were found between the no-addiction control group and the groups reporting one or more addictions, but not between the separate groups reporting one, two, and three or more addictions.

DISCUSSION AND CONCLUSIONS

A better understanding of the social dimension affecting young males with addiction, particularly gambling and gaming addictions, may be useful for their prevention and treatment.

Autophagy as a gateway for the effects of methamphetamine: From neurotransmitter release and synaptic plasticity to psychiatric and neurodegenerative disorders

As a major eukaryotic cell clearing machinery, autophagy grants cell proteostasis, which is key for neurotransmitter release, synaptic plasticity, and neuronal survival. In line with this, besides neuropathological events, autophagy dysfunctions are bound to synaptic alterations that occur in mental disorders, and early on, in neurodegenerative diseases. This is also the case of methamphetamine (METH) abuse, which leads to psychiatric disturbances and neurotoxicity. While consistently altering the autophagy machinery, METH produces behavioral and neurotoxic effects through molecular and biochemical events that can be recapitulated by autophagy blockade. These consist of altered physiological dopamine (DA) release, abnormal stimulation of DA and glutamate receptors, as well as oxidative, excitotoxic, and neuroinflammatory events. Recent molecular insights suggest that METH early impairs the autophagy machinery, though its functional significance remains to be investigated. Here we discuss evidence suggesting that alterations of DA transmission and autophagy are intermingled within a chain of events underlying behavioral alterations and neurodegenerative phenomena produced by METH. Understanding how METH alters the autophagy machinery is expected to provide novel insights into the neurobiology of METH addiction sharing some features with psychiatric disorders and parkinsonism.

Methamphetamine in Orthopaedics: Considerations of an At-Risk Population

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Methamphetamine use by orthopaedic trauma patients has risen to epidemic proportions.

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Perioperative methamphetamine use by orthopaedic trauma patients requires physicians to consider both medical and psychosocial factors during treatment.

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Behavioral and psychosocial effects of methamphetamine use present barriers to care.

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Patients who use methamphetamine face elevated rates of complications.

Methamphetamine facilitates pulmonary and splenic tissue injury and reduces T cell infiltration in C57BL/6 mice after antigenic challenge

Methamphetamine (METH) is a strong addictive central nervous system stimulant. METH abuse can alter biological processes and immune functions necessary for host defense. The acquisition and transmission of HIV, hepatitis, and other communicable diseases are possible serious infectious consequences of METH use. METH also accumulates extensively in major organs. Despite METH being a major public health and safety problem globally, there are limited studies addressing the impact of this popular recreational psychostimulant on tissue adaptive immune responses after exposure to T cell dependent [ovalbumin (OVA)] and independent [lipopolysaccharide (LPS)] antigens. We hypothesized that METH administration causes pulmonary and splenic tissue alterations and reduces T cell responses to OVA and LPS in vivo, suggesting the increased susceptibility of users to infection. Using a murine model of METH administration, we showed that METH causes tissue injury, apoptosis, and alters helper and cytotoxic T cell recruitment in antigen challenged mice. METH also reduces the expression and distribution of CD3 and CD28 molecules on the surface of human Jurkat T cells. In addition, METH decreases the production of IL-2 in these T-like cells, suggesting a negative impact on T lymphocyte activation and proliferation. Our findings demonstrate the pleotropic effects of METH on cell-mediated immunity. These alterations have notable implications on tissue homeostasis and the capacity of the host to respond to infection.

Methamphetamine Compromises the Adaptive B Cell-Mediated Immunity to Antigenic Challenge in C57BL/6 Mice

Methamphetamine (METH) is a substance of abuse that causes dysregulation of the innate and adaptive immunity in users. B cells are involved in the humoral component of the adaptive immunity by producing and secreting antibodies (Abs). METH modifies Ab production, although limited information on the impact of this psychostimulant on antigen (Ag)-specific humoral immune responses is available. Since T cell-dependent and T cell-independent Ags are involved in the activation of B lymphocytes, we explored the role of METH on humoral immunity to ovalbumin (OVA; T cell-dependent) and bacterial lipopolysaccharide (LPS; T cell-independent) in C57BL/6 mice. We demonstrated that METH extends the infiltration of B cells into pulmonary and splenic tissues 7 days post-Ag challenge. METH impairs Ab responses in the blood of animals challenged with OVA and LPS. Furthermore, METH diminishes the expression and distribution of IgM on B cell surface, suggesting a possible detrimental impact on users' humoral immunity to infection or autoimmunity.

Understanding the Basis of METH Mouth Using a Rodent Model of Methamphetamine Injection, Sugar Consumption, and Streptococcus mutans Infection

“METH mouth” is characterized by severe tooth decay and gum disease, which often causes teeth to break or fall out. METH users are also prone to colonization by cariogenic bacteria such as Streptococcus mutans.

“METH mouth” is a common consequence of chronic methamphetamine (METH) use, resulting in tooth decay and painful oral tissue inflammation that can progress to complete tooth loss. METH reduces the amount of saliva in the mouth, promoting bacterial growth, tooth decay, and oral tissue damage. This oral condition is worsened by METH users’ compulsive behavior, including high rates of consumption of sugary drinks, recurrent tooth grinding, and a lack of frequent oral hygiene. Streptococcus mutans is a Gram-positive bacterium found in the oral cavity and associated with caries in humans. Hence, we developed a murine model of METH administration, sugar intake, and S. mutans infection to mimic METH mouth in humans and to investigate the impact of this drug on tooth colonization. We demonstrated that the combination of METH and sucrose stimulates S. mutans tooth adhesion, growth, and biofilm formation in vivo. METH and sucrose increased the expression of S. mutans glycosyltransferases and lactic acid production. Moreover, METH contributes to the low environmental pH and S. mutans sucrose metabolism, providing a plausible mechanism for bacterium-mediated tooth decay. Daily oral rinse treatment with chlorhexidine significantly reduces tooth colonization in METH- and sucrose-treated mice. Furthermore, human saliva inhibits S. mutans colonization and biofilm formation after exposure to either sucrose or the combination of METH and sucrose. These findings suggest that METH might increase the risk of microbial dental disease in users, information that may help in the development of effective public health strategies to deal with this scourge in our society.

The Impact of Neonatal Methamphetamine on Spatial Learning and Memory in Adult Female Rats

The present study was aimed at evaluating cognitive changes following neonatal methamphetamine exposure in combination with repeated treatment in adulthood of female Wistar rats. Pregnant dams and their pups were used in this study. One half of the offspring were treated indirectly via the breast milk of injected mothers, and the other half of pups were treated directly by methamphetamine injection. In the group with indirect exposure, mothers received methamphetamine (5 mg/ml/kg) or saline (1 ml/kg) between postnatal days (PD) 1-11. In the group with direct exposure, none of the mothers were treated. Instead, progeny were either: (1) treated with injected methamphetamine (5 mg/ml/kg); or (2) served as controls and received sham injections (no saline, just a needle stick) on PD 1-11. Learning ability and memory consolidation were tested on PD 70-90 in the Morris Water Maze (MWM) using three tests: Place Navigation Test, Probe Test, and Memory Recall Test. Adult female progeny were injected daily, after completion of the last trial of MWM tests, with saline or methamphetamine (1 mg/ml/kg). The effects of indirect/direct neonatal methamphetamine exposure combined with acute adult methamphetamine treatment on cognitive functions in female rats were compared. Statistical analyses showed that neonatal drug exposure worsened spatial learning and the ability to remember the position of a hidden platform. The study also demonstrated that direct methamphetamine exposure has a more significant impact on learning and memory than indirect exposure. The acute dose of the drug did not produce any changes in cognitive ability. Analyses of search strategies (thigmotaxis, scanning) used by females during the Place Navigation Test and Memory Recall Test confirmed all these results. Results from the present study suggested extensive deficits in learning skills and memory of female rats that may be linked to the negative impact of neonatal methamphetamine exposure.