The neurobiology of methamphetamine induced psychosis

Exploring ketamine's reinforcement, cue-induced reinstatement, and nucleus accumbens cFos activation in male and female long evans rats

Ketamine (KET), a non-competitive N-methyl-d-aspartate (NMDA) receptor antagonist, has rapid onset of antidepressant effects in Treatment-Resistant Depression patients and repeated infusions are required to sustain its antidepressant properties. However, KET is an addictive drug, and so more preclinical and clinical research is needed to assess the safety of recurring treatments in both sexes. Thus, the aim of this study was to investigate the reinforcing properties of various doses of KET (0-, 0.125-, 0.25-, 0.5 mg/kg/infusion) and assess KET's cue-induced reinstatement and neuronal activation in both sexes of Long Evans rats. Neuronal activation was assessed using the protein expression of the immediate early gene cFos in the nucleus accumbens (Nac), an important brain area implicated in reward, reinforcement and reinstatement to most drug-related cues. Our findings show that KET has reinforcing effects in both male and female rats, albeit exclusively at the highest two doses (0.25 and 0.5 mg/kg/infusion). Furthermore, we noted sex differences, particularly at the highest dose of ketamine, with female rats displaying a higher rate of self-administration. Interestingly, all groups that self-administered KET reinstated to drug-cues. Following drug cue-induced reinstatement test in rats exposed to KET (0.25 mg/kg/infusion) or saline, there was higher cFos protein expression in KET-treated animals compared to saline controls, and higher cFos expression in the core compared to the shell subregions of the Nac. As for reinstatement, there were no notable sex differences reported for cFos expression in the Nac. These findings reveal some sex and dose dependent effects in KET's reinforcing properties and that KET at all doses induced similar reinstatement in both sexes. This study also demonstrated that cues associated with ketamine induce comparable neuronal activation in the Nac of both male and female rats. This work warrants further research into the potential addictive properties of KET, especially when administered at lower doses which are now being used in the clinic for treating various psychopathologies.

Positive and negative symptoms in methamphetamine-induced psychosis compared to schizophrenia: A systematic review and meta-analysis

BACKGROUND

The clinical profiles of methamphetamine-induced psychosis (MIP) and schizophrenia are largely overlapping making differentiation challenging. In this systematic review and meta-analysis, we aim to compare the positive and negative symptoms of MIP and schizophrenia to better understand the differences between them.

STUDY DESIGN

In accordance with our pre-registered protocol (CRD42021286619), we conducted a search of English-language studies up to December 16th, 2022, in PubMed, EMBASE, and PsycINFO, including stable outpatients with MIP and schizophrenia. We used the Newcastle-Ottawa Scale to measure the quality of cross-sectional, case-control, and cohort studies.

STUDY RESULTS

Of the 2052 articles retrieved, we included 12 studies (6 cross-sectional, 3 case-control, and 2 cohort studies) in our meta-analysis, involving 624 individuals with MIP and 524 individuals with schizophrenia. Our analysis found no significant difference in positive symptoms between the two groups (SMD, -0.01; 95%CI, -0.13 to +0.11; p = 1). However, individuals with MIP showed significantly less negative symptoms compared to those with schizophrenia (SMD, -0.35; 95CI%, -0.54 to -0.16; p = 0.01; I2 = 54 %). Our sensitivity analysis, which included only studies with a low risk of bias, did not change the results. However, our meta-analysis is limited by its cross-sectional approach, which limits the interpretation of causal associations. Furthermore, differences in population, inclusion criteria, methodology, and drug exposure impact our findings.

CONCLUSIONS

Negative symptoms are less prominent in individuals with MIP. While both groups do not differ regarding positive symptoms, raises the possibility of shared and partly different underlying neurobiological mechanisms related to MIP and schizophrenia.

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.

Enhanced Beta2-band Oscillations Denote Auditory Hallucination in Schizophrenia Patients and a Monkey Model of Psychosis

An electroencephalographic (EEG) signature of auditory hallucinations (AHs) is important for facilitating the diagnosis and treatment of AHs in schizophrenia. We recorded EEG from 25 schizophrenia patients with recurrent AHs. During the period of AHs, EEG recordings exhibited significantly elevated beta2-band power in the temporal region, as compared to those recorded in the absence of AHs or during stimulation with verbal sounds. We further generated methamphetamine-treated rhesus monkeys exhibiting psychosis-like behaviors, including repetitive sudden searching actions in the absence of external intrusion, suggesting the occurrence of AHs. Epidural EEG beta2-band power in the temporal region of these monkeys was enhanced immediately after methamphetamine treatment and positively correlated with the frequency of sudden searching actions. Thus, the enhancement of temporal beta2-band oscillations represents a signature for AHs in both patients and a monkey model of psychosis, and this monkey model can be used for developing closed-loop neuromodulation approaches for the treatment of refractory AHs in schizophrenia.

The role of NF-κB signaling pathway in reactive astrocytes among neurodegeneration after methamphetamine exposure by integrated bioinformatics

BACKGROUND

Methamphetamine (METH) is a highly addictive stimulant that has become one of the top five risk substances cause deaths from substance abuse. METH exposure increases the risk of neurodegenerative disease (ND), such as Parkinson's disease (PD), leading to disability and death. Activation of reactive astrocytes is an essential factor in neurodegeneration, and their complex role in METH exposure remains unclear. This study explored the role of reactive astrocyte overactivation in neurodegeneration after METH exposure.

METHODS

METH bulk RNA sequencing data (GSE107015 and GSE98793) and single-cell RNA sequencing data (GSE119861) were obtained from the GEO database. We performed immune infiltration analysis on the bulk RNA data. After cell clustering using the single-cell RNA data, astrocytes were extracted for downstream analysis. Differentially expressed genes (DEGs) were identified from the bulk and single-cell RNA sequencing datasets, and GO, KEGG, and GSEA pathway analyses were performed. The PPI network and random forest methods were performed on the overlapping genes of the DEGs to screen hub genes. To explore the common ground between METH exposure and neurodegenerative diseases, we applied a random forest algorithm to PD chip data (GSE99039 and GSE72267) to establish a diagnostic model using the hub genes in METH. New object recognition and the Morris water maze were used to examine cognitive function in mice exposed to METH for 14 days in vivo. Astrocytes were cocultured with neurons for the detection of intercellular crosstalk.

RESULTS

DEGs in the METH group significantly enriched pathways related to NDs, inflammation, and the NF-κB signaling pathway. Immune infiltration analysis revealed significantly increased infiltration of monocytes, T cells, and NK cells and decreased infiltration of neutrophils in the METH group. An intersection of 44 hub genes was screened based on the PPI network and random forest algorithm. These genes suggest that there might be similar pathogenesis between METH exposure and PD. METH exposure resulted in learning memory impairment, hippocampal astrocyte activation, and upregulation of NF-κB expression in mice. Activation of reactive astrocytes cocultured with neurons causes neural damage.

CONCLUSIONS

This study explored the crosstalk between astrocytes and neurons in METH exposure, providing a potential pathogenesis to explore the altered immune microenvironment involving reactive astrocytes after METH exposure.

Acetaldehyde-mediated increase in glutamatergic and N-acetylaspartate neurometabolite levels in the midcingulate cortex of ALDH2*1/*2 heterozygous young adults

BACKGROUND

To elucidate the neurobiology underlying alcohol's effect on the human brain, we examined the acute effects of moderate alcohol administration on levels of glutamatergic neurometabolites and N-acetylaspartate, an amino acid found in neurons, may reflect disordered neuronal integrity.

METHODS

Eighteen healthy Japanese participants (7 males/11 females) aged 20-30 years who were heterozygous for an inactive allele of acetaldehyde dehydrogenase-2 (ALDH/*1/*2) were included. Participants underwent an intravenous alcohol infusion using the clamp method at a target blood alcohol concentration (BAC) of 0.50 mg/mL for 90 min within a range of ±0.05 mg/mL. We examined glutamate + glutamine (Glx) and N-acetylaspartate N-acetylaspartylglutamate (NAA) levels in the midcingulate cortex (MCC) using 3 T 1 H-MRS PRESS at baseline, 90 min, and 180 min (i.e., 90 min after alcohol infusion was finished). A two-way repeated-measures analysis of variance was used to assess longitudinal changes in Glx and NAA levels, with time and sex as within- and between-subject factors, respectively. Pearson's correlation coefficients were calculated among neurometabolite levels and BAC or blood acetaldehyde concentration (BAAC).

RESULTS

Both Glx (F(2,32) = 8.15, p = 0.004, η2  = 0.15) and NAA (F(2,32) = 5.01, p = 0.04, η2  = 0.07) levels were increased after alcohol injection. There were no sex or time × sex interaction effects observed. NAA levels were positively correlated with BAAC at 90 min (r(13) = 0.77, p = 0.01). There were no associations between neurometabolite levels and BAC.

CONCLUSIONS

Both Glx and NAA levels in the MCC increased in response to the administration of moderate concentrations of alcohol. Given positive associations between NAA levels and BAAC and the hypothetical glutamate release via dopamine pathways, the effects of drinking on the MCC in the acute phase may be ascribed to acetaldehyde metabolized from alcohol.

Drug-induced change in transmitter identity is a shared mechanism generating cognitive deficits

Cognitive deficits are a long-lasting consequence of drug use, yet the convergent mechanism by which classes of drugs with different pharmacological properties cause similar deficits is unclear. We find that both phencyclidine and methamphetamine, despite differing in their targets in the brain, cause the same glutamatergic neurons in the medial prefrontal cortex to gain a GABAergic phenotype and decrease their expression of the vesicular glutamate transporter. Suppressing the drug-induced gain of GABA with RNA-interference prevents the appearance of memory deficits. Stimulation of dopaminergic neurons in the ventral tegmental area is necessary and sufficient to produce this gain of GABA. Drug-induced prefrontal hyperactivity drives this change in transmitter identity. Returning prefrontal activity to baseline, chemogenetically or with clozapine, reverses the change in transmitter phenotype and rescues the associated memory deficits. The results reveal a shared and reversible mechanism that regulates the appearance of cognitive deficits upon exposure to different drugs.

Melatonin enhances the restoration of neurological impairments and cognitive deficits during drug withdrawal in methamphetamine-induced toxicity and endoplasmic reticulum stress in rats

Methamphetamine (METH) is a psychostimulant with a very high addiction rate. Prolonged use of METH has been observed as one of the root causes of neurotoxicity. Melatonin (Mel) has been found to have a significant role in METH-induced neurotoxicity. This study aimed to investigate the restorative effect of Mel on behavioral flexibility in METH-induced cognitive deficits. Male Sprague-Dawley rats were randomly assigned to be intraperitoneally injected with saline (control) or Meth at 5 mg/kg for 7 consecutive days. Then, METH injection was withdrawn and rats in each group were subcutaneously injected with saline or Mel at 10 mg/kg for 14 consecutive days. The stereotypic behavioral test and attentional set-shifting task (ASST) were used to evaluate neurological functions and cognitive flexibility, respectively. Rats developed abnormal features of stereotyped behaviors and deficits in cognitive flexibility after 7 days of METH administration. However, post-treatment with Mel for 14 days after METH withdrawal dramatically ameliorated the neurological and cognitive deficits in METH-treated rats. Blood biomarkers indicated METH-induced systemic low-grade inflammation. Moreover, METH-induced endoplasmic reticulum (ER) stress in the prefrontal cortex was diminished by melatonin supplementation. These findings might reveal the therapeutic potential of Mel in METH toxicity-induced neurological and cognitive deficits.

Association of clozapine treatment and rate of methamphetamine or amphetamine relapses and abstinence among individuals with concurrent schizophrenia spectrum and amphetamine use disorder: A retrospective cohort study

BACKGROUND

Preliminary evidence suggest clozapine is associated with more favorable impact on concurrent substance use disorder related outcomes in patients with concurrent schizophrenia spectrum disorders (SSD). At the same time, there is a dearth of evidence with regards to clozapine outcomes in the context of concurrent methamphetamine or amphetamine use disorder (MAUD).

AIMS

To examine whether clozapine use decreases rate of methamphetamine or amphetamine (MA) relapses and increases the likelihood of maintaining abstinence from any MA use.

METHODS

A descriptive-analytic retrospective cohort study was conducted on individuals with SSD-MAUD in an inpatient provincial treatment and rehabilitation center for concurrent disorders. Antipsychotic exposure was categorized as "on clozapine" or "on other antipsychotic(s)." Data were collected using electronic health records. Logistic regression was used to examine association of clozapine treatment with likelihood of complete abstinence from MA use for the duration of antipsychotic exposure. Negative binomial regression was used to examine association of clozapine treatment with rate of MA relapses for the duration of antipsychotic exposure.

RESULTS

The majority of the 87 included patients were male. Ethnicity was diverse, with the largest groups self-identifying as Indigenous and European. Clozapine use was both associated with increased likelihood of maintaining abstinence from MA use (adjusted odds ratio (aOR) = 3.05, 95% confidence intervals (CI) = 1.15-8.1, p = 0.025), and decreased rate of MA relapses (aRR = 0.45, 95% CI = 0.25-0.82, p = 0.009) for the duration of antipsychotic exposure. Co-prescription of psychostimulants was associated with increased rate of MA relapses (aRR = 2.43, 95% CI = 1.16-5.10, p = 0.019).

CONCLUSION(S)

In this study, clozapine use compared with other antipsychotics in SSD was associated with improved outcomes related to severe concurrent MAUD. Co-prescription of psychostimulant medications was associated with a poor outcome.

Corpus-Based Discourse Analysis of a Reddit Community of Users of Crystal Methamphetamine: Mixed Methods Study

BACKGROUND

Methamphetamine is a highly addictive stimulant that affects the central nervous system. Crystal methamphetamine is a form of the drug resembling glass fragments or shiny bluish-white rocks that can be taken through smoking, swallowing, snorting, or injecting the powder once it has been dissolved in water or alcohol.

OBJECTIVE

The objective of this study is to examine how identities are socially (discursively) constructed by people who use methamphetamine within a subreddit for people who regularly use crystal meth.

METHODS

Using a mixed methods approach, we analyzed 1000 threads (318,422 words) from a subreddit for regular crystal meth users. The qualitative component of the analysis used concordancing and corpus-based discourse analysis to identify discursive themes informed by assemblage theory. The quantitative portion of the analysis used corpus linguistic techniques including keyword analysis to identify words occurring with statistically marked frequency in the corpus and collocation analysis to analyze their discursive context.

RESULTS

Our findings reveal that the subreddit contributors use a rich and varied lexicon to describe crystal meth and other substances, ranging from a neuroscientific register (eg, methamphetamine and dopamine) to informal vernacular (eg, meth, dope, and fent) and commercial appellations (eg, Adderall and Seroquel). They also use linguistic resources to construct symbolic boundaries between different types of methamphetamine users, differentiating between the esteemed category of "functional addicts" and relegating others to the stigmatized category of "tweakers." In addition, contributors contest the dominant view that methamphetamine use inevitably leads to psychosis, arguing instead for a more nuanced understanding that considers the interplay of factors such as sleep deprivation, poor nutrition, and neglected hygiene.

CONCLUSIONS

The subreddit contributors' discourse offers a "set and setting" perspective, which provides a fresh viewpoint on drug-induced psychosis and can guide future harm reduction strategies and research. In contrast to this view, many previous studies overlook the real-world complexities of methamphetamine use, perhaps due to the use of controlled experimental settings. Actual drug use, intoxication, and addiction are complex, multifaceted, and elusive phenomena that defy straightforward characterization.

Gegen-Qinlian decoction-A traditional Chinese medicine formula-Alleviates methamphetamine withdrawal induced anxiety by targeting GABAergic interneuron-pyramidal neuron pathway in mPFC

Methamphetamine (Meth) withdrawal elicits anxiety, which is a public health concern with limited therapeutic options. Previous studies implied a strong correlation between mPFC and Meth withdrawal. Here, we examined the role of Gegen-Qinlian decoction (GQD) in Meth withdrawal anxiety and explored potential therapeutic targets in mPFC. We found that intra-gastric administration of GQD during the withdrawal period efficiently alleviated anxiety-like behaviours in Meth-withdrawn mice. Further, GQD could restore Meth withdrawal-triggered pathway of GABAergic interneurons (GABA IN)-pyramidal neurons (PN) in the mPFC of Meth-withdrawn mice, especially the prelimbic cortex (PrL) sub-region and PV-positive GABA IN. While, GQD had no obvious effects on the glial cells in the mPFC of Meth-withdrawn mice. By transcriptomic analysis and validation of several gene candidates, we found that genes in the MAPK signalling pathway, especially those related to heat shock proteins, including Hspa1a, Hspa1b and Hspb1, might be GQD-targeting genes in mPFC to treat Meth withdrawal anxiety, as indicated that these genes were up-regulated by Meth withdrawal but rescued by GQD in mPFC. Collectively, our findings identified for the first time that GQD could efficiently alleviate Meth withdrawal anxiety, partially through regulating the local GABA IN-PN pathway and transcriptomic profile of mPFC. The present study confirms that TCM, such as GQD, will be a desirable therapeutic approach in the treatment of drug addiction and related emotional deficits.

Neural basis of the attention bias during addiction stroop task in methamphetamine-dependent patients with and without a history of psychosis: an ERP study

Background

Attentional bias plays an important role in sustaining various types of drug addiction. No prior studies examined methamphetamine (MA)-associated psychosis (MAP) relationships between ERP time course and performance on an addiction Stroop task in MA abusers. The aim of the present study was to determine whether MA abusers with (MAP+) or without (MAP-) psychosis exhibit alterations of the ERP during the addiction Stroop task.

Methods

Thirty-one healthy controls (CTRL), 14 MAP-, and 24 MAP+ participants were recruited and completed the addiction Stroop task during EEG recording using 32 electrodes. Group variations were compared on measures of behavioral task performance and event-related potentials (ERP) of performance monitoring (N200, P300, N450). The Barratt impulsiveness scores were analyzed to investigate correlations with ERP changes.

Results

MA-related word stimulus elicited a more negative N200 amplitude over left-anterior electrodes in MAP- abusers; furthermore, a positive association between the N200 amplitude and Barratt attentional scores and non-planning scores was observed, while no such differences were found in MAP+ abusers. There were no significant differences in reaction time (RT) and error rate between each group.

Conclusion

This is the first study to examine psychosis relationships between ERP time course and performance on an addiction Stroop task in MA abusers with or without psychosis. These findings support the association between attentional bias measured by the MA addiction Stroop task and N200 component as well as indicate the possibility of using this cognitive task in combination with ERP technology to detect psychosis factors among abstinent MA abusers.

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.

Association of GABA receptor delta subunit gene variations with increased risk of methamphetamine dependence

OBJECTIVE

Evidence reveals that γ-aminobutyric acid (GABA) receptors are involved in the development of methamphetamine (METH) dependence. The GABA receptor delta subunit gene (GABRD) might be a good candidate gene for METH dependence. In a case-control study, we investigated the association between the single nucleotide polymorphisms (SNPs) in GABRD and METH dependence in a Chinese Han population.

METHODS

A total of 300 METH dependent patients and 300 age and sex matched normal control subjects were recruited. Four SNPs (rs13303344, rs4481796, rs2376805, and rs2229110) in GABRD were determined with the TaqMan genotyping assay. The association of the SNPs with METH dependence was assessed.

RESULTS

Only the allele frequency of rs2376805 significantly differed between the patients and controls (P = 0.030). The G allele frequency of rs2376805 was higher in the METH dependent group than in the controls (odds ratio = 1.332, 95 % CI: 1.028-1.724). This association was found in females but not in males. In females, the frequencies of genotype and allele at rs2376805 significantly differed between the patients and controls (P = 0.025, 0.022, respectively); the rs2376805 G allele may also be a risk factor for METH dependence (odds ratio = 1.548, 95 % CI: 1.063-2.257). The haplotype ACGT frequency significantly differed between the patients and controls in total subjects (P = 0.008, odds ratio = 1.815, 95 % CI: 1.183-2.782), as well as in females (P = 0.005, odds ratio = 2.702, 95 % CI: 1.313-5.562). In females only, the METH craving score was significantly lower in patients harboring the G allele at rs2376805 than in those harboring the homozygous AA genotype (P = 0.044).

CONCLUSION

The preliminary results indicate that GABRD rs2376805 is associated with METH dependence, especially in females.

Chronic methamphetamine exposure exerts few effects on the iTat mouse model of HIV, but blocks Tat expression-induced slowed reward retrieval

Human immunodeficiency virus (HIV) continues to infect millions worldwide, negatively impacting neurobehavioral function. Further understanding of the combined effects of HIV and methamphetamine use is crucial, as methamphetamine use is prevalent in people with HIV. The HIV-associated protein Tat may contribute to cognitive dysfunction, modeled preclinically in mice using doxycycline (DOX)-inducible Tat expression (iTat). Tat may exert its effects on cognitive function via disruption of the dopamine transporter, similar to the action of methamphetamine. Additionally, Tat and methamphetamine both decrease interneuron populations, including those expressing calbindin. It is important to understand the combined effects of Tat and methamphetamine in preclinical models of HIV infection. Here, we used iTat transgenic mice and a chronic binge regimen of methamphetamine exposure to determine their combined impact on reward learning and motivation. We also measured calbindin expression in behavior-relevant brain regions. Before induction with DOX, iTat mice exhibited no differences in behavior. Chronic methamphetamine exposure before Tat induction impaired initial reward learning but did not affect motivation. Furthermore, DOX-induced Tat expression did not alter behavior, but slowed latencies to retrieve rewards. This effect of Tat, however, was not observed in methamphetamine-treated mice, indicative of a potential protective effect. Finally, Tat expression was associated with an increase in calbindin-expressing cells in the VTA, while methamphetamine exposure did not alter calbindin numbers. These findings may indicate a protective role of methamphetamine in HIV neuropathology, which in turn may help in our understanding of why people with HIV use methamphetamine at disproportionately higher rates.

Differential expression profiling of tRNA-Derived small RNAs and their potential roles in methamphetamine self-administered rats

Transfer RNA-derived small RNAs (tsRNAs) are a novel class of short, non-coding RNAs that are closely associated with the pathogenesis of various diseases. Accumulating evidence has demonstrated their critical functional roles as regulatory factors in gene expression regulation, protein translation regulation, regulation of various cellular activities, immune mediation, and response to stress. However, the underlying mechanisms by which tRFs & tiRNAs affect methamphetamine-induced pathophysiological processes are largely unknown. In this study, we used a combination of small RNA sequencing, quantitative reverse transcription-polymerase chain reaction (qRT‒PCR), bioinformatics, and luciferase reporter assays to screen the expression profiles and identify the functional roles of tRFs and tiRNAs in the nucleus accumbens (NAc) of methamphetamine self-administration rat models. A total of 461 tRFs & tiRNAs were identified in the NAc of rats after 14 days of methamphetamine self-administration training. Of those, 132 tRFs & tiRNAs were significantly differentially expressed: 59 were significantly upregulated, whereas 73 were significantly downregulated in the rats with methamphetamine self-administration. Decreased expression levels of tiRNA-1-34-Lys-CTT-1 and tRF-1-32-Gly-GCC-2-M2, as well as increased expression levels of tRF-1-16-Ala-TGC-4 in the METH group compared with the saline control were validated by using RT‒PCR. Then, bioinformatic analysis was performed to analyse the possible biological functions of tRFs & tiRNAs in methamphetamine-induced pathogenesis. Furthermore, tRF-1-32-Gly-GCC-2-M2 was identified to target BDNF using the luciferase reporter assay. An altered tsRNA expression pattern was proven, and tRF-1-32-Gly-GCC-2-M2 was shown to be involved in methamphetamine-induced pathophysiologic processes by targeting BDNF. The current study provides new insights for future investigations to explore the mechanisms and therapeutic methods for methamphetamine addiction.

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.

Increased Lipid Peroxidation and Lowered Antioxidant Defenses Predict Methamphetamine Induced Psychosis

BACKGROUND

a significant percentage of methamphetamine (MA) dependent patients develop psychosis. The associations between oxidative pathways and MA-induced psychosis (MIP) are not well delineated.

OBJECTIVE

the aim of this study is to delineate whether acute MA intoxication in MA dependent patients is accompanied by increased nitro-oxidative stress and whether the latter is associated with MIP.

METHOD

we recruited 30 healthy younger males and 60 acutely intoxicated males with MA dependence and assessed severity of MA use and dependence and psychotic symptoms during intoxication, and serum oxidative toxicity (OSTOX) biomarkers including oxidized high (oxHDL) and low (oxLDL)-density lipoprotein, myeloperoxidase (MPO), malondialdehyde (MDA), and nitric oxide (NO), and antioxidant defenses (ANTIOX) including HDL-cholesterol, zinc, glutathione peroxidase (GPx), total antioxidant capacity (TAC), and catalase-1.

RESULTS

a large part (50%, n = 30) of patients with MA dependence could be allocated to a cluster characterized by high psychosis ratings including delusions, suspiciousness, conceptual disorganization and difficulties abstract thinking and an increased OSTOX/ANTIOX ratio. Partial Least Squares analysis showed that 29.9% of the variance in MIP severity (a first factor extracted from psychosis, hostility, excitation, mannerism, and formal thought disorder scores) was explained by HDL, TAC and zinc (all inversely) and oxLDL (positively). MA dependence and dosing explained together 44.7% of the variance in the OSTOX/ANTIOX ratio.

CONCLUSIONS

MA dependence and intoxication are associated with increased oxidative stress and lowered antioxidant defenses, both of which increase risk of MIP during acute intoxication. MA dependence is accompanied by increased atherogenicity due to lowered HDL and increased oxLDL and oxHDL.

Common gray matter loss in the frontal cortex in patients with methamphetamine-associated psychosis and schizophrenia

BACKGROUND AND HYPOTHESIS

Methamphetamine (MA)-associated psychosis has become a public concern. However, its mechanism is not clear. Investigating similarities and differences between MA-associated psychosis and schizophrenia in brain alterations would be informative for neuropathology.

STUDY DESIGN

This study compared gray matter volumes of the brain across four participant groups: healthy controls (HC, n = 53), MA users without psychosis (MA, n = 22), patients with MA-associated psychosis (MAP, n = 34) and patients with schizophrenia (SCZ, n = 33). Clinical predictors of brain alterations, as well as association of brain alterations with psychotic symptoms and attention impairment were further investigated.

STUDY RESULTS

Compared with the HC, the MAP and the SCZ showed similar gray matter reductions in the frontal cortex, particularly in prefrontal areas. Moreover, a stepwise extension of gray matter reductions was exhibited across the MA - MAP - SCZ. Duration of abstinence was associated with regional volumetric recovery in the MAP, while this amendment in brain morphometry was not accompanied with symptom's remission. Illness duration of psychosis was among the predictive factors of regional gray matter reductions in both psychotic groups. Volume reductions were found to be associated with attention impairment in the SCZ, while this association was reversed in the MAP in frontal cortex.

CONCLUSIONS

This study suggested MA-associated psychosis and schizophrenia had common neuropathology in cognitive-related frontal cortices. A continuum of neuropathology between MA use and schizophrenia was tentatively implicated. Illness progressions and glial repairments could both play roles in neuropathological changes in MA-associated psychosis.

Risk of psychosis in illicit amphetamine users: a 10 year retrospective cohort study

QUESTION

Amphetamine use is a risk factor for psychosis, which imposes a substantial burden on society. We aimed to investigate the incidence of psychosis associated with illicit amphetamine use and whether rehabilitation treatments could influence the psychosis risk.

STUDY SELECTION AND ANALYSIS

A retrospective cohort study was conducted using the population based Taiwan Illicit Drug Issue Database (TIDID) and the National Health Insurance Research Database (NHIRD), from 2007 to 2016. We identified 74 601 illicit amphetamine users as the amphetamine cohort and 2 98 404 subjects as the non-amphetamine cohort. The incidence rate of newly diagnosed psychosis was the main outcome. Cox proportional hazards models were applied to assess the effects of amphetamine, and the Kaplan-Meier method was used to estimate the cumulative psychosis incidence curves.

FINDINGS

Illicit amphetamine users were 5.28 times more likely to experience psychosis than those without illicit drug use records. The risk was higher for subjects with multiple arrests for amphetamine use. A greater hazard ratio (HR) magnitude was observed in female patients. We also observed a significant decrease in the risk of psychosis in patients receiving rehabilitation treatments during deferred prosecution (adjusted HR 0.74, 95% CI 0.61 to 0.89).

CONCLUSIONS

Illicit amphetamine use was associated with an increased incidence of psychosis. The risk was identified across all age groups, particularly in women and in those arrested multiple times, and was inversely correlated with rehabilitation treatments for amphetamine misuse.

Comparing Cognitive Functions in Patients with Schizophrenia and Methamphetamine-Induced Psychosis with Healthy Controls

BACKGROUND

There are similar findings about the similarities and differences of cognitive dysfunctions in patients with schizophrenia and methamphetamine-induced psychosis (MIP). This study aimed to compare cognitive functioning in schizophrenia and MIP patients, using a performance-based cognitive assessment battery and an interview-based assessment of cognition.

METHODS

Three groups participated in this study including, (a) 30 patients with MIP, (b) 30 patients with schizophrenia, and (c) 30 healthy individuals. All participants received the Brief Assessment of Cognition in Schizophrenia (BACS), a standardized performance-based cognitive battery, the Schizophrenia Cognition Rating Scale (SCoRS), and the interview-based assessment of cognition.

FINDINGS

Both groups of patients with schizophrenia and MIP performed poorly on all the BACS cognitive domains compared with the healthy controls. The two patient groups were significantly different on the three BACS subscales including verbal fluency, verbal memory, and speed of information processing. Schizophrenia patients performed worse than the MIP group concerning these three subscales. However, the two patient groups were similar in executive function, working memory, and motor speed. Moreover, the SCoRS-informant, SCoRS-global, and PANSS-negative significantly differed between schizophrenia and MIP patients.

CONCLUSION

Although cognitive dysfunctions are mostly similar in patients with MIP and schizophrenia, there are some differences especially in the functions related to prefrontal and temporal lobes.

The quantitative analysis of EEG during resting and cognitive states related to neurological dysfunctions and cognitive impairments in methamphetamine abusers

Several lines of evidence demonstrated the deleterious effect of methamphetamine (MA) on neurological and psychological functions. However, recent evidence on the neurological dysfunctions related to cognitive performance and psychosis in MA abusers needs to be elucidated. Therefore, the present study aimed to investigate the neurological functions using EEG measurement during cognitive tests in MA abusers with (MWP) or without (MWOP) psychosis compared to age-matched normal participants. The quantitative EEG (qEEG) was used to reveal the absolute power in 4 brain-wave frequencies including delta, theta, alpha, and beta waves. The results demonstrated poor attention in both groups of MA abusers. The deficit in mental flexibility was observed in MWP. The deficit in inhibition control and working memory were observed in MWOP. The greater delta, alpha and beta brain waves in multiple brain areas were observed in MWP during the resting (eyes-open) state. The greater alpha wave in multiple brain areas of MWP correlated with poor attention. The greater delta wave and lesser beta wave in the frontal brain correlated with poor inhibition and working memory in MWOP respectively. These findings demonstrated the applicability of EEG to determine neurological dysfunction related to cognitive impairments in MA abusers.

Exercise Regulates the Metabolic Homeostasis of Methamphetamine Dependence

Physical exercise is effective in enhancing cognitive function, reducing anxiety and depressive symptoms, reducing cravings, and improving quality of life in methamphetamine (METH) addiction. However, little is known about the effect of exercise on metabolic profiles. We performed LC/MS-based targeted metabolic profiling on serum samples to investigate the metabolic characteristics of METH dependence and find the differences between METH-dependent individuals and nonusers and evaluated the metabolomic profiles of individuals with METH dependence following aerobic exercise training. We identified a total of 201 metabolites, among which 115 were differentially expressed under METH use. Among the differentially regulated metabolites, 72 were selected as potential biomarkers. Further analysis identified 19 pathways, among which glyoxylate and dicarboxylate metabolism; alanine, aspartate, and glutamate metabolism; and citrate cycle were most significantly affected by METH. The aerobic exercise intervention differentially regulated 55 metabolites, of which 51 were selected as potential biomarkers and were mainly enriched in 10 pathways. Interestingly, alanine, aspartate, and glutamate metabolism and nitrogen metabolism were the remarkably affected pathways. Furthermore, METH increased the serum levels of glutamate and decreased GABA, whereas exercise decreased the serum levels of glutamate and increased GABA. Results suggested that METH dependency disturbed normal metabolic homeostasis, whereas exercise restored metabolism.

A review of basic to clinical studies of the association between hyperammonemia, methamphetamine

Methamphetamine (METH), an addictive psychostimulant drug, is the second most widely used type of drug all around the world. METH abusers are more likely to develop a psycho-neurological complication. Hyperammonemia (HAM) causes neuropsychiatric illnesses such as mental state changes and episodes of acute encephalopathy. Recently, there are some shreds of evidence about the relationship between METH complication and HAM. Both METH intoxication and HAM could induce psychosis, agitation, memory impairment, and psycho-neuronal disorders. They also have similar mechanisms of neuronal damages, such as excitotoxicity, oxidative stress, mitochondrial impairments, and inflammation responses, which can subsequently increase the glutamate level of the brain. Hence, the basic to clinical studies of the association between HAM and METH are reviewed by monitoring six case studies and a good body of animal studies literature. All instances of METH-associated HAM had changes in mental state and some level of confusion that were improved when the ammonia serum level returned to the normal level. Furthermore, most of them had typical vital signs. Several studies suggested some sources for METH-associated HAM, including METH-induced liver and renal damages, muscular hyperactivity, gut bacterial overgrowth, co-abuse of other substances, and using some forms of NH3 in METH cooking. In conclusion, it seems that mental status changes in METH abusers may be related to ammonia intoxication or HAM; therefore, it is important to assess the serum level of ammonia in METH intoxicated patients and resolve it.

Difference in topological organization of white matter structural connectome between methamphetamine and heroin use disorder

The psychological symptoms caused by heroin and methamphetamine are significantly different in people with substance use disorders. The topological organization of structural connections that may underlie these differences remains unknown. The study sample consisted of 23 males with methamphetamine use disorder (MAUD), 20 males with heroin use disorder (HUD), and 21 male healthy controls (HCs) who were demographically matched. Diffusion tensor imaging and probabilistic tractography were used for white matter network construction. Psychological symptoms were evaluated by the Symptom Checklist-90. Using graph theoretical analysis, we examined the difference in graph-level and nodal-level properties among the groups. The network Hubs distribution and the relationship between the network alterations and psychological symptoms were identified. The MAUD group demonstrated significantly higher scores on anxiety, hostility, and symptoms of schizophrenia than the HUD and HCs groups. The HUD group showed significantly higher global efficiency and network strength than the HCs group, and higher network strength than the MAUD group. Compared with the HUD group, the MAUD group showed significantly lower Nodal Strength and efficiency, distributed mainly in the temporal, parietal, and occipital regions. We also found the network Hubs were decreased in the MAUD group, but increased in the HUD group. The Nodal Strength in the right superior temporal gyrus was significantly correlated with psychological symptoms in the MAUD group. These findings reflect the significant differences in topological structural connection between HUD and MAUD. This evidence helps shed some light on the neurobiological mechanisms of the psychological differences between HUD and MAUD, and extend our understanding of the structural disruption underlying MAUD-related psychological symptoms.

Medial prefrontal cortex Notch1 signalling mediates methamphetamine-induced psychosis via Hes1-dependent suppression of GABAB1 receptor expression

Methamphetamine (METH), a widely abused stimulant drug, induces psychosis in approximately half of abusers; this effect is becoming a major concern for society. Although the Notch1 signalling pathway has been shown to play a part in the pathogenesis of some psychiatric disorders, its role in METH-induced psychosis (MIP) is still unknown. Here, the METH-induced locomotor sensitization model in rodents is considered to represent the underlying neurochemical changes driving psychoses. We found that the Notch1 signalling was downregulated in the medial prefrontal cortex (mPFC) in sensitized mice. Direct genetic and pharmacological manipulations of Notch1 signalling bidirectionally altered METH-induced locomotor sensitization and other MIP-related behaviours through governing neuronal activity in the mPFC. Moreover, Notch1 signalling negatively regulated GABA_B1 receptor expression in the mPFC of METH-sensitized mice through Hes1, a transcriptional repressor in Notch1 signalling. Further, we show that Hes1 can directly bind to the GABA_B1 receptor promoter. Notably, pharmacological regulation of the GABA_B receptor in the mPFC reversed the changes in METH-induced locomotor sensitization caused by the dysfunction of Notch1 signalling. Together, our findings uncover a previously unrecognised Notch1-Hes1-GABA_B1 receptor-dependent mechanism involved in regulating mPFC neuronal activity and behavioural phenotypes in MIP. Our work provides mechanistic insight into the aetiology and pathophysiology of MIP.

Methamphetamine, Neurotransmitters and Neurodevelopment

Methamphetamine (MA), as massively abused psychoactive stimulant, has been associated with many neurological diseases. It has various potent and neurotoxic properties. There are many mechanisms of action that contribute to its neurotoxic and degenerative effects, including excessive neurotransmitter (NEU) release, blockage of NEU uptake transporters, degeneration of NEU receptors, process of oxidative stress etc. MA intoxication is caused by blood-brain barrier disruption resulted from MA-induced oxidation stress. In our laboratory we constantly work on animal research of MA. Our current interest is to investigate processes of MA-induced alteration in neurotransmission, especially during development of laboratory rat. This review will describe current understanding in role of NEUs, which are affected by MA-induced neurotoxicity caused by altering the action of NEUs in the central nervous system (CNS). It also briefly brings information about NEUs development in critical periods of development.

Substance-Induced Psychoses: An Updated Literature Review

Background: On the current psychopharmacological panorama, the variety of substances able to provoke an episode of acute psychosis is rapidly increasing. Such psychotic episodes are classified according to the major category of symptoms: positive, negative, or cognitive psychotic episodes. On one hand, the abuse of methamphetamines, cannabis, and cocaine plays a big role in increasing the incidence of episodes resembling a psychotic disorder. On the other hand, the progress in terms of pharmacodynamics knowledge has led to the synthesis of new drugs, such as cannabinoids and cathinone's, which have rapidly entered into the common pool of abusers' habits. Regarding these newly synthesized substances of abuse, further clinical studies are needed to understand their psychogenic properties. The topic of this review is complicated due to the frequent abuse of psychotomimetic drugs by patients affected by psychotic disorders, a fact that makes it extremely difficult to distinguish between an induced psychosis and a re-exacerbation of a previously diagnosed disorder. Methods: The present narrative review summarizes results from clinical studies, thus investigating the psychotogenic properties of abused substances and the psychotic symptoms they can give rise to. It also discusses the association between substance abuse and psychosis, especially with regards to the differential diagnosis between a primary vs. a substance-induced psychotic disorder. Findings: Our findings support the theory that psychosis due to substance abuse is commonly observed in clinical practice. The propensity to develop psychosis seems to be a function of the severity of use and addiction. Of note, from a phenomenological point of view, it is possible to identify some elements that may help clinicians involved in differential diagnoses between primary and substance-induced psychoses. There remains a striking paucity of information on the outcomes, treatments, and best practices of substance-induced psychotic episodes.

Brain dysfunction of methamphetamine-associated psychosis in resting state: Approaching schizophrenia and critical role of right superior temporal deficit

Methamphetamine (MA)-associated psychosis (MAP) is highly debilitating and common among individuals who use the drug, yet the underlying neural mechanism is not clear. This study compared brain functions between patients with MAP and those with schizophrenia during resting state and investigated the effect of brain alteration on the association between MA use and psychosis in patients with MAP. Three groups, including 24 patients with MAP, 17 with schizophrenia in first-episode (SCZ) and 31 healthy controls (HCs), were included after receiving a resting-state functional MRI scan. The severity of psychosis was assessed with Positive and Negative Syndrome Scale (PANSS). Imaging data were analysed using regional homogeneity (ReHo) to measure individual's brain function. Compared with the HC subjects, the MAP and SCZ groups had significantly lower ReHo in the cortical regions including left postcentral cortex, right superior temporal gyrus and right rolandic operculum, while had higher ReHo in the left putamen, with brain dysfunctions being more pronounced in the SCZ group. Among the MAP subjects, a mediating effect of ReHo in the right superior temporal gyrus was found on the association between MA use frequency and PANSS positive score. MAP and schizophrenia had a common trend of brain alteration, with the dysfunction being more pronounced in schizophrenia. This finding implicated that MAP might be a condition with neuropathology approaching schizophrenia. The observed critical role of right superior temporal deficit between MA use and psychosis proposed a potential target for interventions.

Functional and structural alternations in the choroid plexus upon methamphetamine exposure

Choroid plexus (CP) is the principal source of cerebrospinal fluid. CP can produce and release a wide range of materials including growth factors, neurotrophic factors, etc. all of which play an important role in the maintenance and proper functioning of the brain. Methamphetamine (METH) is a CNS neurostimulant that causes brain dysfunction. Herein, we investigated the potential effects of METH exposure on CP structure and function. Stereological analysis revealed a significant alteration in CP volume, epithelial cells and capillary number upon METH treatment. Electron microscopy exhibited changes in ultrastructure. Moreover, the upregulation of neurotrophic factors such as BDNF and VEGF as well as autophagy and apoptosis gene following METH administration were observed. We also identified several signaling cascades related to autophagy. In conclusion, gene expression changes coupled with structural alterations of the CP in response to METH suggested METH-induced autophagy in CP.

The neuroprotective role of melatonin against methamphetamine toxicity-induced neurotransmission dysregulation and cognitive deficits in rats

Methamphetamine (MA) is a psychostimulant and addictive substance. Long-term uses and toxic high doses of MA can induce neurotoxicity. The present study aimed to investigate the protective role of melatonin against MA toxicity-induced dysregulation of the neurotransmission related to cognitive function in rats. The adult male Sprague Dawley rats were intraperitoneally injected with 5 mg/kg MA for 7 consecutive days with or without subcutaneously injected with 10 mg/kg melatonin before MA injection. Some rats were injected with saline solution (control) or 10 mg/kg melatonin. MA administration induced reduction in total weight gain, neurotoxic features of stereotyped behaviors, deficits in cognitive flexibility, and significantly increased lipid peroxidation in the brain which diminished in melatonin pretreatment. The neurotoxic effect of MA on glutamate, dopamine and GABA transmitters was represented by the alteration of the GluR1, DARPP-32 and parvalbumin (PV) levels, respectively. A significant decrease in the GluR1 was observed in the prefrontal cortex of MA administration in rats. MA administration significantly increased the DARPP-32 but decreased PV in the striatum. Pretreatment of melatonin can abolish the neurotoxic effect of MA on neurotransmission dysregulation. These findings might reveal the antioxidative role of melatonin to restore neurotransmission dysregulation related to cognitive deficits in MA-induced neurotoxicity.

Distinct dose-dependent effects of methamphetamine on real-time dopamine transmission in the rat nucleus accumbens and behaviors

Methamphetamine (METH) is a potent psychostimulant that exerts many of its physiological and psychomotor effects by increasing extracellular dopamine (DA) concentrations in limbic brain regions. While several studies have focused on how potent, neurotoxic doses of METH augment or attenuate DA transmission, the acute effects of lower and behaviorally activating doses of METH on modulating DA regulation (release and clearance) through DA D2 autoreceptors and transporters remain to be elucidated. In this study, we investigated how systemic administration of escalating, subneurotoxic doses of METH (0.5-5 mg/kg, IP) alter extracellular DA regulation in the nucleus accumbens (NAc), in both anesthetized and awake-behaving rats through the use of in vivo fast-scan cyclic voltammetry. Pharmacological, electrochemical, and behavioral evidence show that lower doses (≤2.0 mg/kg, IP) of METH enhance extracellular phasic DA concentrations and locomotion as well as stereotypies. In contrast, higher doses (≥5.0 mg/kg) further increase both phasic and baseline DA concentrations and stereotypies but decrease horizontal locomotion. Importantly, our results suggest that acute METH-induced enhancement of extracellular DA concentrations dose dependently activates D2 autoreceptors. Therefore, these different METH dose-dependent effects on mesolimbic DA transmission may distinctly impact METH-induced behavioral changes. This study provides valuable insights regarding how low METH doses alter DA transmission and paves the way for future clinical studies on the reinforcing effects of METH.

Neurotoxicity of methamphetamine: Main effects and mechanisms

Methamphetamine (METH) is an illicit psychostimulant that is abused throughout the world. METH addiction is also a major public health concern and the abuse of large doses of the drug is often associated with serious neuropsychiatric consequences that may include agitation, anxiety, hallucinations, paranoia, and psychosis. Some human methamphetamine users can also suffer from attention, memory, and executive deficits. METH-associated neurological and psychiatric complications might be related, in part, to METH-induced neurotoxic effects. Those include altered dopaminergic and serotonergic functions, neuronal apoptosis, astrocytosis, and microgliosis. Here we have endeavored to discuss some of the main effects of the drug and have presented the evidence supporting certain of the molecular and cellular bases of METH neurotoxicity. The accumulated evidence suggests the involvement of transcription factors, activation of dealth pathways that emanate from mitochondria and endoplasmic reticulum (ER), and a role for neuroinflammatory mechanisms. Understanding the molecular processes involved in METH induced neurotoxicity should help in developing better therapeutic approaches that might also serve to attenuate or block the biological consequences of use of large doses of the drug by some humans who meet criteria for METH use disorder.

Recommendations for the medical work-up of first episode psychosis, including specific relevance to Indigenous Australians: A narrative review

AIMS

To collate existing literature for busy practicing psychiatrists about the medical work-up for first-episode psychosis (FEP). Therefore, (a) to review current guidelines for the medical work-up of first episode psychosis. (b) To examine whether any specific recommendations for Indigenous Australians exist. (c) To produce an easy reference table of evidence based investigations.

METHOD

A multi-part narrative review process was undertaken. Step 1 "Source identification and summary": identified key existing national and international guidelines and expert opinions related to the medical work-up of FEP and summarised these suggestions. Step 2 "Exploration of each investigation": examined each of the identified investigations for its importance. Step 3 "Relevance to Indigenous Australians": reviewed any particular relevance to the Indigenous Australian population. Step 4 "Clinician guide": involved presenting recommended investigations in a simple table.

RESULTS

Multiple guidelines were identified. There was clear consensus for many aspects. However, there were also differences in the approach for some investigations. Clinical reasoning for the proposed investigations was commonly absent. There were limited specific recommendations for Indigenous Australians. Evidence and importance was explored for each investigation and auseful table for the practicing psychiatrist was constructed. Investigations were stratified into those considered to be "universal," "low yield," or "unecessary."

CONCLUSION

A narrative review of multiple guidelines relating to the medical work-up of FEP identified many similarities and some differences to their approach. Little additional information exists for the Indigenous Australian context. A clinician friendly worksheet for everyday use may be helpful to busy clinicians.

Changes of BDNF exon IV DNA methylation are associated with methamphetamine dependence

Aim: We investigated DNA methylation of BDNF in methamphetamine (METH) dependence in humans and an animal model. Materials & methods: BDNF methylation at exon IV was determined by pyrosequencing of blood DNA from METH-dependent and control subjects, and from rat brain following an escalating dose of METH or vehicle. Bdnf expression was determined in rat brain. Results: BDNF methylation was increased in human METH dependence, greatest in subjects with psychosis and in prefrontal cortex of METH-administered rats; rat hippocampus showed reduced Bdnf methylation and increased gene expression. Conclusion: BDNF methylation is abnormal in human METH dependence, especially METH-dependent psychosis, and in METH-administered rats. This may influence BDNF expression and contribute to the neurotoxic effects of METH exposure.

A latent class analysis of psychiatric symptom profiles associated with past-month methamphetamine use

We explored latent psychiatric symptom profiles associated with methamphetamine use, and examined how these corresponded to diagnoses of schizophrenia (SZ) and methamphetamine-associated psychosis (MAP). We assessed psychiatric symptoms among 160 people who had used methamphetamine in the past month. Psychiatric symptoms were defined as a score of 4+ on Brief Psychiatric Rating Scale (BPRS) items. Diagnoses were made using the Composite International Diagnostic Interview (CIDI). Participants were defined as having MAP if they met symptom criteria for SZ, but symptoms were considered to be always the result of substance use. Latent class analysis identified three classes. Class one (44% of participants) had a low probability of most BPRS symptoms; 4% met criteria for SZ, 51% for MAP. Class two (31% of participants) had a higher probability hallucinations and suspiciousness (37-46%); 72% met criteria for MAP, and 7% for SZ. Class three (25% of participants) had the highest probability for all positive psychotic symptoms (hallucinations, suspiciousness, grandiosity, unusual thought content; 32-82%), and reported activation, conceptual disorganisation, and tension (35% met criteria for SZ and 17% for MAP). We found three distinct classes of psychiatric symptom profiles, two of which showed partial alignment with diagnostic constructs of SZ and MAP.

Extensive tissue necrosis of the tongue in a methamphetamine user: A case report

AIMS

Methamphetamine (meth) is a powerful, highly addictive stimulant that affects the central nervous system, and its side effects may result in severe self-mutilation. This report describes a case of a meth user with severe oral injury that demonstrates the necessity for prompt treatment when severe tongue biting occurs.

METHODS AND RESULTS

A 43-year-old meth-using man with severe tongue biting was left untreated for more than 24 hours, resulting in extensive ischemic changes in the tongue and eventual extensive tissue necrosis. After debridement and deep suture repair in several layers, the wound healed. However, tongue dysfunction and a speech disorder remained because of tongue shortening.

CONCLUSION

Meth may induce or aggravate severe oral self-mutilation. Tongue biting with severe tissue damage may occur as oral self-mutilation in meth users; however, among self-mutilation behaviors, tongue biting is especially difficult to prevent. A withdrawal from meth and a behavioral approach may be necessary for fundamental prevention, but it is often difficult in high dependence users. When severe tongue biting occurs, prompt suture reconstruction must be performed before ischemic change occurs to prevent tissue necrosis.

Treatment Response Distinguishes Persistent Type of Methamphetamine Psychosis From Schizophrenia Spectrum Disorder Among Inmates at Japanese Medical Prison

Introduction: Persistent methamphetamine-associated psychosis (pMAP) is a disorder similar to schizophrenia, so much so that the differences in clinical symptoms and treatment response between the two remain unknown. In this study, we compared the features of pMAP with those of schizophrenia spectrum disorders (SSD). Materials and Methods: This was a retrospective quasi-experimental case-control study of inmates in a medical prison. The behavioral problems, clinical symptoms, and chlorpromazine (CP)-equivalent doses of 24 patients with pMAP and 27 with SSD were compared. Results: Patients in the pMAP group were hospitalized for fewer days than those in the SSD group (281.5 vs. 509.5; p = 0.012), but there were no other significant group differences in behavioral problems or clinical symptoms. The pMAP group received fewer antipsychotics in CP-equivalent doses than the SSD group at 4, 8, and 12 weeks after admission and at the time of discharge (p = 0.018, 0.001, 0.007, and 0.023, respectively). The number of CP-equivalent doses in the SSD group tended to increase after admission, but not in the pMAP group. Discussion: These findings suggest that differentiation between pMAP and SSD based on behavior and symptoms alone may be difficult, and that patients with pMAP may respond better to treatment with a lower dose of antipsychotic medication than those with SSD. Further confirmatory studies are warranted.

Glial cell diversity and methamphetamine-induced neuroinflammation in human cerebral organoids

Methamphetamine (METH) is a potent stimulant that induces a euphoric state but also causes cognitive impairment, neurotoxicity and neurodevelopmental deficits. Yet, the molecular mechanisms by which METH causes neurodevelopmental defects have remained elusive. Here we utilized human cerebral organoids and single-cell RNA sequencing (scRNA-seq) to study the effects of prenatal METH exposure on fetal brain development. We analyzed 20,758 cells from eight untreated and six METH-treated cerebral organoids and found that the organoids developed from embryonic stem cells contained a diverse array of glial and neuronal cell types. We further identified transcriptionally distinct populations of astrocytes and oligodendrocytes within cerebral organoids. Treatment of organoids with METH-induced marked changes in transcription in multiple cell types, including astrocytes and neural progenitor cells. METH also elicited novel astrocyte-specific gene expression networks regulating responses to cytokines, and inflammasome. Moreover, upregulation of immediate early genes, complement factors, apoptosis, and immune response genes suggests a neuroinflammatory program induced by METH regulating neural stem cell proliferation, differentiation, and cell death. Finally, we observed marked METH-induced changes in neuroinflammatory and cytokine gene expression at the RNA and protein levels. Our data suggest that human cerebral organoids represent a model system to study drug-induced neuroinflammation at single-cell resolution.

Features of Psychotic Symptoms in Methamphetamine Use Disorder Patients and Ketamine Use Disorder Patients: A Cross-Sectional Study

BACKGROUND

Methamphetamine and ketamine are commonly used club drugs. Both of them have been reported to mimic psychotic symptoms of schizophrenia. However, the prevalence and detailed features of psychotic symptoms among methamphetamine use disorder (MUD) and ketamine use disorder (KUD) patients are largely unknown. This study aimed to measure psychotic symptoms among patients with MUD and KUD.

METHODS

A total sample of 842 patients from voluntary drug rehabilitation centers, including 462 MUD patients and 380 KUD patients, were invited to this study. The Positive and Negative Syndrome Scale (PANSS) was applied to assess psychotic symptoms in these two groups of patients.

RESULTS

The prevalence of psychotic symptoms was significantly higher among MUD patients than KUD patients (75.1 vs. 50.5%, 95% CI: 3.532 - 11.858, p < 0.001). Compared with KUD patients, MUD patients were more likely to experience positive symptoms (PANSS positive scores: 11.5 ± 6.07 vs. 15.1 ± 8.22, P < 0.001) and negative symptoms (PANSS negative scores: 12.4 ± 6.60 vs. 14.5 ± 8.63, P < 0.001), but not general symptoms (PANSS general scores: 31.2 ± 13.90 vs. 32.2 ± 15.13, P < 0.001).

CONCLUSIONS

The current study found that more than half of MUD and KUD patients experienced psychotic symptoms, and that patients with MUD are more likely to experience positive and negative symptoms than patients with KUD. The findings provide a new perspective for exploring the neuropathological mechanism of psychotic symptoms of schizophrenia.

Comparisons of Voxel-Based Morphometric Brain Volumes of Individuals with Methamphetamine-Induced Psychotic Disorder and Schizophrenia Spectrum Disorder and Healthy Controls

BACKGROUND

Several psychological and neurological pathways are described to explain the emergence and maintenance of psychiatric disorders, and changes in brain volumes and brain activity are observed as correlates of psychiatric disorders. In the present study, we investigated if and to what extent specific voxel-based morphometric brain volume differences could be observed among individuals with methamphetamine-induced psychosis (MAIP) and schizophrenia spectrum disorder (SSD) compared to healthy controls.

METHODS

A total of 69 individuals took part in the present study. Of those, 26 were diagnosed with MAIP, 23 with SSD, and 20 were healthy controls. After a thorough psychiatric assessment, participants underwent brain volume measurement.

RESULTS

Compared to healthy controls, participants with MAIP had smaller volumes for left caudate and left and right parahippocampal gyrus. Compared to healthy controls, participants with SSD had smaller volumes for the gray and white matter, left amygdala, left hippocampus, left parahippocampal gyrus, left putamen, and the total volume. Compared to individuals with MAIP, individuals with SSD had a lower white matter brain volume.

CONCLUSIONS

The pattern of results suggests that individuals with MAIP and SSD showed specific and regional brain atrophies on the left hemisphere, always compared to healthy controls. Given the cross-sectional design, it remains undisclosed if specific and regional brain atrophies were the cause or the consequence of the psychiatric issues.

Beyond the tip of the iceberg: A narrative review to identify research gaps on comorbid psychiatric disorders in adolescents with methamphetamine use disorder or chronic methamphetamine use

BACKGROUND

Methamphetamine use disorder (MUD) frequently begins in adolescence, often accompanied by other psychiatric or mental disorders. Up to now, no comprehensive review about MUD and comorbid disorders in adolescents is available. We thus aimed to review the literature on comorbid mental disorders and MUD in adolescents in order to identify future research topics. Method: A PubMed search was conducted in July 2019. Relevant comorbidities were defined as attention-deficit disorder with/without hyperactivity, anxiety disorders, depression, eating disorders, post-traumatic stress disorder, psychosis, borderline personality disorder, conduct disorder and antisocial personality disorder, as well as other substance use disorders. For each comorbidity, we summarized prevalence rates, findings on comorbidity mechanisms, and recommended treatment options, if applicable. Results: Few articles focused on MUD in adolescents. Prevalence rates differed largely between comorbid disorders, with tobacco use disorder, conduct disorder, post-traumatic stress disorder, anxiety disorders, and attention-deficit disorders being the most prevalent comorbidities while eating disorders were rare. Examined onset patterns and comorbidity mechanisms indicated three groups of comorbidities: preexisting disorders self-medicated with methamphetamine, disorders induced by chronic methamphetamine use, and disorders arising due to risk factors shared with MUD. Reviewed comorbidities were frequently associated with worse treatment outcomes. Conclusions: The limited evidence is in stark contrast to the presumably high prevalence and relevance of comorbid mental disorders in adolescents with MUD. Suggestions for future research topics, informed by adult findings, include genetic vulnerabilities, biological changes, and consequences of different use patterns. Surprisingly few MUD treatment programs explicitly integrate comorbid mental disorder modules.

Differences in the amplitude of low-frequency fluctuation between methamphetamine and heroin use disorder individuals: A resting-state fMRI study

INTRODUCTION

Methamphetamine has surpassed heroin as the most popular abused drug in China. Although the use of both heroin and methamphetamine leads to use disorders through dysfunction of the dopamine pathway, the incidence of psychiatric disorder caused by methamphetamine abuse is higher than the incidence of psychiatric disorder caused by heroin abuse. The difference in resting-state function between heroin use disorder (HUD) and methamphetamine use disorder (MAUD) and the relationship between resting-state function and psychiatric disorder related to MAUD are unknown.

METHODS

In the present study, 21 male individuals with MAUD, 21 demographically matched individuals with HUD, and 21 normal controls (NC) were recruited. The amplitude of low-frequency fluctuation (ALFF) during resting-state brain function was measured by magnetic resonance imaging. Psychiatric status was evaluated by the Symptom Checklist-90 (SCL90).

RESULTS

Individuals with MAUD had increased SCL90 scores compared to those of the NC for anxiety, paranoia, and additional items, and the hostility score was significantly increased compared to that of individuals with HUD. There is no significant difference between HUD and NC individuals. Individuals with MAUD had increased ALFF compared to those of the NC for thalamus, right postcentral, and right inferior temporal gyri, but a decreased ALFF in the cerebellum. Individuals with HUD had significantly increased ALFF compared to those of the NC for left middle frontal gyrus but a decreased ALFF in the left postcentral gyrus. Individuals with MAUD had significantly increased ALFF compared to those of the HUD for thalamus, the right inferior temporal, and bilateral postcentral gyri, and the ALFF of cerebellum and left middle frontal was significantly increased.

CONCLUSIONS

Methamphetamine can induce more serious psychiatric disorders than heroin. The resting-state function involved in mood adjustment, the auditory, and memory-related brain regions may affect psychotic symptoms related to MAUD.

Methamphetamine-associated psychosis: links to drug use characteristics and similarity to primary psychosis

Objectives: Despite the prevalence of methamphetamine-associated psychosis, how characteristics of drug use affect the severity and clinical course, and its optimal treatments have not been established. We addressed these questions, assessing clinical features of methamphetamine-associated psychosis, and compared it with primary psychosis.Methods: Hospitalised patients with methamphetamine-associated (n = 70) or primary schizophrenic psychosis (n = 70) were matched on sex, age and duration of psychosis. Association of drug use variables (age at initiation, duration of methamphetamine use) with the Brief Psychiatric Rating Scale (BPRS) scores and psychosis duration were examined for patients with methamphetamine-associated psychosis, and the groups were compared on the BPRS scores.Results: Methamphetamine use initiation age correlated negatively with the BPRS total score and the Activation subscale score; methamphetamine use duration correlated positively with psychosis duration. Methamphetamine-associated psychosis group scored lower on the Hostility-Suspiciousness and Anergia subscales of the BPRS (adjusted p values < .05).Conclusions: Association of early initiation of methamphetamine with psychosis severity may suggest a lasting effect on brain development. Correlation of drug use and psychosis durations may suggest a cumulative effect of methamphetamine exposure. Less severe paranoia and negative symptoms in the methamphetamine-using group could implicate better social functioning of these patients. Further mechanistic studies are warranted.Key pointsEarly initiation of methamphetamine use is associated with psychosis severity.Methamphetamine use duration associates with psychosis duration.Methamphetamine-associated and primary schizophrenic psychoses were similar in symptoms.Methamphetamine psychosis patients were less severe in paranoia and negative symptoms.