SLC1A2 Gene Polymorphism Influences Methamphetamine-Induced Psychosis

SLC1A2 is a gene encoded for the excitatory amino acid transporter 2 which is responsible for glutamate reuptake from the synaptic cleft in the central nervous system. Recent studies have suggested that polymorphisms on glutamate transporters can affect drug dependence, leading to the development of neurological diseases and psychiatric disorders. Our study investigated the association of rs4755404 single nucleotide polymorphism (SNP) of the SLC1A2 gene with methamphetamine (METH) dependence and METH-induced psychosis and mania in a Malaysian population. The rs4755404 gene polymorphism was genotyped in METH-dependent male subjects (n = 285) and male control subjects (n = 251). The subjects consisted of the four ethnic groups in Malaysia (Malay, Chinese, Kadazan-Dusun, and Bajau). Interestingly, there was a significant association between rs4755404 polymorphism and METH-induced psychosis in the pooled METH-dependent subjects in terms of genotype frequency (p = 0.041). However, there was no significant association between rs4755404 polymorphism and METH dependence. Also, the rs455404 polymorphism was not significantly associated with METH-induced mania for both genotype frequencies and allele frequencies in the METH-dependent subjects, regardless of stratification into the different ethnicities. Our study suggests that the SLC1A2 rs4755404 gene polymorphism confers some susceptibility to METH-induced psychosis, especially for those who carry the GG homozygous genotype.

Effects of Acute Moderate- and High-Intensity Aerobic Exercise on Oxygenation in Prefrontal Cortex of Male Methamphetamine-Dependent Patients

The aim of this study was to explore the influence of different intensities of acute aerobic exercise on brain activation in male methamphetamine (MA)-dependent patients during exercise. Twenty MA-dependent patients were divided randomly into two groups participating in 35 min of either moderate- or high-intensity aerobic exercise. Functional near-infrared spectral imaging (fNIRS) was used to detect hemodynamic changes in prefrontal cortex during the main 25-min exercise stage. The results revealed that high-intensity acute aerobic exercise aroused more cerebral oxygenation changes in the prefrontal cortex and left dorsolateral prefrontal cortex during exercise as compared with moderate-intensity exercise. Furthermore, there was a stronger positive connection observed between orbital frontal cortex and left dorsolateral prefrontal cortex in the high-intensity group than in the moderate-intensity group. Together these results suggest that for submaximal exercise intensities, high-intensity exercise may bring more benefits to male MA-dependent patients than moderate-intensity.

Altered EEG Microstates Dynamics During Cue-Induced Methamphetamine Craving in Virtual Reality Environments

BACKGROUND

Cue-induced craving is widely considered to be the most important risk factor for relapse during abstinence from methamphetamine (Meth). There is limited research regarding electroencephalography (EEG) microstates of Meth-dependent patients under exposure to drug-related cues. Our objective was to investigate whether EEG microstate temporal characteristics could capture neural correlates of cue-induced Meth craving in virtual reality (VR) environments.

METHODS

EEG recordings of 35 Meth-dependent patients and 30 healthy controls (HCs) were collected during eyes-open state and cue-induced state, respectively. Group differences and condition differences in temporal parameters of four microstate classes were compared.

RESULTS

The results demonstrated the greater presence of microstate B in both Meth-dependent patients and HCs during the cue-induced condition, compared to resting state. In addition, for Meth-dependent patients, microstate C occurred significantly less frequently, along with a tendency of increased occurrence for class D during the cue-induced condition, compared to resting state. However, the change direction of class C and class D in HCs was completely opposite to that of Meth-dependent patients. The cue-induced condition also elicited different changes in transition probability between Meth-dependent patients and HCs.

CONCLUSION

This study explored the features of EEG microstates in Meth-dependent patients during the cue-induced condition, which can improve our understanding of Meth addiction and contribute to the development of effective assessments and intervention tools.

Loneliness, Risky Beliefs and Intentions about Practicing Safer Sex among Methamphetamine Dependent Individuals

BACKGROUND

Methamphetamine use is a known predictor of riskier sexual behaviors, which can have important public health implications (e.g., HIV-transmission risk). Loneliness also is associated with riskier sexual behaviors, though the relationship between loneliness and beliefs and/or intentions to practice safer sex has not been examined among people dependent on methamphetamine.

MATERIALS AND METHODS

Individuals who met DSM-IV criteria for lifetime methamphetamine dependence and current (≤ 18-months) methamphetamine abuse or dependence (METH+ n = 56) were compared to those without severity and recency of methamphetamine use (METH- n = 59). These groups did not differ on social network size or proportion of people with HIV (∼58% HIV+). Participants completed the NIH Toolbox Loneliness Scale and the Sexual Risks Scale's "Norms" and "Intentions" subscales.

RESULTS

METH+ individuals were significantly lonelier than METH- controls (t(113) = 2.45, p = .02). Methamphetamine dependence remained significantly associated with greater loneliness, after controlling for HIV status and other relevant covariates (e.g., neurocognitive impairment, history of mood disorder, social network size; F = 3.70, Adjusted R² = 0.18, p = .0009). Loneliness, above and beyond the aforementioned covariates, was significantly associated with riskier beliefs and intentions to practice safer sex among METH+, but not METH-, individuals (β = 2.92, p = .02).

CONCLUSIONS

Loneliness is prevalent among individuals dependent on methamphetamine, and is uniquely associated with riskier beliefs and intentions regarding practicing safer sex. Findings may aid in identifying individuals at-risk of engaging in riskier sexual behaviors and guide risk prevention strategies.

The Vulnerability to Methamphetamine Dependence and Genetics: A Case-Control Study Focusing on Genetic Polymorphisms at Chromosomal Region 5q31.3

OBJECTIVES

Methamphetamine (METH) is a central nervous psychostimulant and one of the most frequently used illicit drugs. Numerous genetic loci that influence complex traits, including alcohol abuse, have been discovered; however, genetic analyses for METH dependence remain limited. An increased histone deacetylase 3 (HDAC3) expression has been detected in Fos-positive neurons in the dorsomedial striatum following withdrawal after METH self-administration. Herein, we aimed to systematically investigate the contribution of HDAC3 to the vulnerability to METH dependence in a Han Chinese population.

METHODS

In total, we recruited 1,221 patients with METH dependence and 2,328 age- and gender-matched controls. For genotyping, we selected 14 single nucleotide polymorphisms (SNPs) located within ± 3 kb regions of HDAC3. The associations between genotyped genetic polymorphisms and the vulnerability to METH dependence were examined by single marker- and haplotype-based methods using PLINK. The effects of expression quantitative trait loci (eQTLs) on targeted gene expressions were investigated using the Genotype-Tissue Expression (GTEx) database.

RESULTS

The SNP rs14251 was identified as a significant association signal (χ² = 9.84, P = 0.0017). An increased risk of METH dependence was associated with the A allele (minor allele) of rs14251 [odds ratio (95% CI) = 1.25 (1.09-1.43)]. The results of in silico analyses suggested that SNP rs14251 could be a potential eQTL signal for FCHSD1, PCDHGB6, and RELL2, but not for HDAC3, in various human tissues.

CONCLUSION

We demonstrated that genetic polymorphism rs14251 located at 5q31.3 was significantly associated with the vulnerability to METH dependence in Han Chinese population.

Prior Methamphetamine Use Disorder History Does Not Impair Interoceptive Processing of Soft Touch in HIV Infection

Introduction: Interoception, defined as the sense of the internal state of one’s body, helps motivate goal-directed behavior. Prior work has shown that methamphetamine (METH) use disorder is associated with altered interoception, and that this may contribute to risky behavior. As people with HIV (PWH) may also experience disrupted bodily sensations (e.g., neuropathy), an important question is whether PWH with a history of METH use disorder might exhibit greater impairment of interoceptive processing. Methods: Eighty-three participants stratified by HIV infection and a past history of methamphetamine use disorder experienced a soft touch paradigm that included slow brush strokes on the left forearm and palm during blood-oxygen level-dependent functional MRI acquisition. To assess differences in interoception and reward, voxelwise analyses were constrained to the insula, a hub for the evaluation of interoceptive cues, and the striatum, which is engaged in reward processing. Results: Overall, individuals with a history of METH use disorder had an attenuated neural response to pleasant touch in both the insula and striatum. Longer abstinence was associated with greater neural response to touch in the insula, suggesting some improvement in responsivity. However, only PWH with no METH use disorder history had lower brain activation in the insula relative to non-using seronegative controls. Conclusions: Our findings suggest that while METH use disorder history and HIV infection independently disrupt the neural processes associated with interoception, PWH with METH use disorder histories do not show significant differences relative to non-using seronegative controls. These findings suggest that the effects of HIV infection and past methamphetamine use might not be additive with respect to interoceptive processing impairment.

Association of NQO1 levels and its genetic polymorphism with susceptibility to methamphetamine dependence

BACKGROUND

The quinone oxidoreductase 1 (NQO1) gene was involved in the pathophysiological process of illicit drugs abuse, and its polymorphisms might be associated with methamphetamine (METH) dependence susceptibility. The purpose of this study was to examine the NQO1 mRNA and protein levels and to analyze the 609C/T polymorphism (rs1800566) between METH-dependent patients and controls.

METHODS

A total of 392 METH-dependent patients (cases) and 669 healthy controls (controls) were enrolled in the study. The quantitative real-time polymerase chain reaction (RT-qPCR) and enzyme-linked immunosorbent assay (ELISA) were used to detect the relative expressions of NQO1 mRNA in PBMCs and protein levels in plasma, respectively. PCR-restriction fragment length polymorphism (RFLP-PCR) and direct-sequencing genotyping were used to detect the alleles and genotypes of NQO1 609C/T polymorphism.

RESULTS

The levels of NQO1 mRNA in cases (3.2650 ± 2.2943) was significantly higher than in controls (1.0125 ± 0.7959) (p < 0.001), the plasma protein in cases (0.2368 ± 0.1486) was significantly lower than in controls (0.5844 ± 0.1742) (p < 0.001). The T allele of the 609C/T polymorphism significantly increased the risk of METH dependence (p = 0.032, OR = 1.214, 95%CI = 1.017-1.450). The TC and TC/TT genotypes of 609C/T were observed significantly more frequently in cases than in controls, respectively (TC vs CC: p = 0.012, OR = 1.457, 95% CI = 1.087-1.952; TC/TT vs CC: p = 0.008, OR = 1.460, 95% CI = 1.102-1.935). Similar results were obtained after adjusting for age and sex. We failed to find that any genotype of 609C/T polymorphism affected the mRNA or plasma protein levels in controls, respectively (p > 0.05).

CONCLUSION

The findings suggested that NQO1 might play an important role in the pathophysiological process of METH dependence, and the 609C/T polymorphism might contribute to the susceptibility to METH dependence in a Chinese Han population.

Treatment Response Prediction and Individualized Identification of Short-Term Abstinence Methamphetamine Dependence Using Brain Graph Metrics

Background: The abuse of methamphetamine (MA) worldwide has gained international attention as the most rapidly growing illicit drug problem. The classification and treatment response prediction of MA addicts are thereby paramount, in order for effective treatments to be more targeted to individuals. However, there has been limited progress. Methods: In the present study, 43 MA-dependent participants and 38 age- and gender-matched healthy controls were enrolled, and their resting-state functional magnetic resonance imaging data were collected. MA-dependent participants who showed 50% reduction in craving were defined as responders to treatment. The present study used the machine learning method, which is a support vector machine (SVM), to detect the most relevant features for discriminating and predicting the treatment response for MA-dependent participants based on the features extracted from the functional graph metrics. Results: A classifier was able to differentiate MA-dependent subjects from normal controls, with a cross-validated prediction accuracy, sensitivity, and specificity of 73.2% [95% confidence interval (CI) = 71.23-74.17%), 66.05% (95% CI = 63.06-69.04%), and 80.35% (95% CI = 77.77-82.93%), respectively, at the individual level. The most accurate combination of classifier features included the nodal efficiency in the right middle temporal gyrus and the community index in the left precentral gyrus and cuneus. Between these two, the community index in the left precentral gyrus had the highest importance. In addition, the classification performance of the other classifier used to predict the treatment response of MA-dependent subjects had an accuracy, sensitivity, and specificity of 71.2% (95% CI = 69.28-73.12%), 86.75% (95% CI = 84.48-88.92%), and 55.65% (95% CI = 52.61-58.79%), respectively, at the individual level. Furthermore, the most accurate combination of classifier features included the nodal clustering coefficient in the right orbital part of the superior frontal gyrus, the nodal local efficiency in the right orbital part of the superior frontal gyrus, and the right triangular part of the inferior frontal gyrus and right temporal pole of middle temporal gyrus. Among these, the nodal local efficiency in the right temporal pole of the middle temporal gyrus had the highest feature importance. Conclusion: The present study identified the most relevant features of MA addiction and treatment based on SVMs and the features extracted from the graph metrics and provided possible biomarkers to differentiate and predict the treatment response for MA-dependent patients. The brain regions involved in the best combinations should be given close attention during the treatment of MA.

Neurofunctional Differences Related to Methamphetamine and Sexual Cues in Men With Shorter and Longer Term Abstinence Methamphetamine Dependence

BACKGROUND

Stimulant use and sexual behaviors have been linked in behavioral and epidemiological studies. Although methamphetamine-related neurofunctional differences have been investigated, few studies have examined neural responses to drug and sexual cues with respect to shorter or longer term methamphetamine abstinence in individuals with methamphetamine dependence.

METHODS

Forty-nine men with shorter term methamphetamine abstinence, 50 men with longer term methamphetamine abstinence, and 47 non-drug-using healthy comparison men completed a functional magnetic resonance imaging cue-reactivity task consisting of methamphetamine, sexual, and neutral visual cues.

RESULTS

Region-of-interest analyses revealed greater methamphetamine cue-related activation in shorter term methamphetamine abstinence and longer term methamphetamine abstinence individuals relative to healthy comparison men in the ventromedial prefrontal cortex. A significant interaction of group and condition in the anterior insula was found. Relative to healthy comparison participants, both shorter term methamphetamine abstinence and longer term methamphetamine abstinence groups displayed greater sexual cue-related anterior insula activation relative to methamphetamine cues and neutral cues, but there were no differences between shorter term methamphetamine abstinence and longer term methamphetamine abstinence groups in anterior insula responses. Subsequent whole-brain analyses indicated a group-by-condition interaction with longer term methamphetamine abstinence participants showing greater sexual-related activation in the left superior frontal cortex relative to healthy comparison men. Shorter term methamphetamine abstinence participants showed greater superior frontal cortex activation to sexual relative to neutral cues, and longer term methamphetamine abstinence participants showed greater superior frontal cortex activation to sexual relative to neutral and methamphetamine cues.

CONCLUSIONS

The findings suggest that abstinence from methamphetamine may alter how individuals respond to drug and sexual cues and thus may influence drug use and sexual behaviors. Given the use of methamphetamine for sexual purposes and responses to natural vs drug rewards for addiction recovery, the findings may have particular clinical relevance.

Study of effects of ifenprodil in patients with methamphetamine dependence: Protocol for an exploratory, randomized, double-blind, placebo-controlled trial

Aims

Pharmacotherapy for methamphetamine dependence has not yet been developed in Japan or elsewhere in the world. Ifenprodil is a blocker of G protein‐activated inwardly rectifying potassium channels that play a key role in the mechanism of action of addictive substances. Our aim is to examine the safety, efficacy, and outcomes of ifenprodil for the treatment of methamphetamine dependence in a randomized, double‐blind, placebo‐controlled trial.

Methods

The recruitment of outpatients with methamphetamine dependence began in January 2018. The patients will be randomized into three arms: placebo, 60 mg/d ifenprodil, or 120 mg/d ifenprodil. Placebo or ifenprodil will be taken for 84 days. We will use Cerocral fine granule 4%^® (ifenprodil tartrate). Follow‐up assessments will be conducted for 84 d after the drug administration period. All of the patients will be assessed by self‐administered questionnaires and urine tests. The primary outcome will be the presence or absence of methamphetamine use during the 84‐day administration period in the 120 mg/d ifenprodil and placebo groups. Secondary outcomes will include the number of days and percentage of days of abstinence from methamphetamine use, positive urine for methamphetamine, relapse risk, and drug craving.

Discussion

This study is the first clinical trial of ifenprodil treatment for methamphetamine dependence and is designed as an intervention test with off‐label drug use. The present study is expected to provide evidence of the effects of ifenprodil treatment on methamphetamine dependence.

Trial registry

This trial was registered in the UMIN clinical trial registry (UMIN000030849; date of registration: January 17, 2018).

This study is the first clinical trial of ifenprodil treatment for methamphetamine dependence and is designed as an intervention test with off‐label drug use. The present study is expected to provide evidence of the effects of ifenprodil treatment on methamphetamine dependence.

Impulsivity predicts poorer improvement in quality of life during early treatment for people with methamphetamine dependence

BACKGROUND AND AIMS

Methamphetamine dependence is associated with heightened impulsivity and diminished quality of life, but the link between impulsivity and changes in quality of life during treatment has not been examined. We aimed to investigate how different elements of impulsivity predict change in quality of life in the 6 weeks after engaging in treatment.

DESIGN

Longitudinal, observational cohort study.

SETTING

Public and private detoxification and rehabilitation facilities in metropolitan Melbourne, Australia.

PARTICIPANTS

One hundred and eight individuals with methamphetamine dependence (81 male) tested within 3 weeks of commencing treatment; 80 (74%) were followed-up at 6 weeks.

MEASUREMENTS

The Continuous Performance Test-2 measured impulsive action (cognitive and motor impulsivity); the Delay Discounting Task measured impulsive choice. Quality of life was measured with the World Health Organization Quality of Life Scale-Brief, which includes social, psychological, physical and environment domains. Control variables included age, gender, estimated IQ, depression severity score, methamphetamine dependence severity score, cannabis dependence severity score and treatment modality.

FINDINGS

We found that all three forms of impulsivity were significant predictors of change in the social domain: motor impulsivity (β = -0.54, P = 0.013), cognitive impulsivity (β = -0.46, P = 0.029) and impulsive choice (β = -0.26, P = 0.019). Change in the psychological domain was predicted significantly by motor impulsivity (β = -0.45, P = 0.046). Control variables of age and depression were associated significantly with changes in the physical domain.

CONCLUSIONS

In Australian methamphetamine-dependent individuals, elevated impulsivity predicts lower improvement of social and psychological quality of life in the first 6-9 weeks of treatment.

Identification of Novel Signal Transduction, Immune Function, and Oxidative Stress Genes and Pathways by Topiramate for Treatment of Methamphetamine Dependence Based on Secondary Outcomes

BACKGROUND

Topiramate (TPM) is suggested to be a promising medication for treatment of methamphetamine (METH) dependence, but the molecular basis remains to be elucidated.

METHODS

Among 140 METH-dependent participants randomly assigned to receive either TPM (N = 69) or placebo (N = 71) in a previously conducted randomized controlled trial, 50 TPM- and 49 placebo-treated participants had a total 212 RNA samples available at baseline, week 8, and week 12 time points. Following our primary analysis of gene expression data, we reanalyzed the microarray expression data based on a latent class analysis of binary secondary outcomes during weeks 1-12 that provided a classification of 21 responders and 31 non-responders with consistent responses at both time points.

RESULTS

Based on secondary outcomes, 1,381, 576, 905, and 711 differentially expressed genes at nominal P values < 0.05 were identified in responders versus non-responders for week 8 TPM, week 8 placebo, week 12 TPM, and week 12 placebo groups, respectively. Among 1,381 genes identified in week 8 TPM responders, 359 genes were identified in both week 8 and week 12 TPM groups, of which 300 genes were exclusively detected in TPM responders. Of them, 32 genes had nominal P values < 5 × 10^-3 at either week 8 or week 12 and false discovery rates < 0.15 at both time points with consistent directions of gene expression changes, which include GABARAPL1, GPR155, and IL15RA in GABA receptor signaling that represent direct targets for TPM. Analyses of these 300 genes revealed 7 enriched pathways belonging to neuronal function/synaptic plasticity, signal transduction, inflammation/immune function, and oxidative stress response categories. No pathways were enriched for 72 genes exclusively detected in both week 8 and week 12 placebo groups.

CONCLUSION

This secondary analysis study of gene expression data from a TPM clinical trial not only yielded consistent results with those of primary analysis but also identified additional new genes and pathways on TPM response to METH addiction.

Comparison of striatal dopamine transporter levels in chronic heroin-dependent and methamphetamine-dependent subjects

To compare the effects of heroin and methamphetamine (METH) addiction on dopamine transporters (DATs) in the same dose and duration, we assessed DAT levels in the striatum by ^99m Tc-TRODAT-1 single-photon emission computed tomography (SPECT) brain images in people with heroin and METH dependence. We recruited 21 healthy human controls, 23 heroin-dependent subjects and 25 METH abusers. The heroin- and METH-dependent subjects exhibited negative urine toxicology after undergoing physiological detoxification. All subjects underwent SPECT brain imaging, and specific tracer uptake ratios (SURs) were assessed bilaterally in the regions of interest. A significant SUR reduction in heroin-dependent subjects and METH-dependent subjects compared with healthy controls was found in the left striatum, right striatum, left caudate nucleus, right caudate nucleus, left putamen and right putamen. There were no significant differences in the heroin group and METH group for the left striatum, right striatum, left caudate nucleus, right caudate nucleus, left putamen and right putamen. The scores of craving, HAMA (Hamilton Anxiety Rating Scale), in heroin abusers were lower than in the METH abusers. Our results show that people with heroin and METH dependence who are currently abstinent had lower DAT levels in the striatum than healthy controls. There were no differences in striatal DAT in heroin and METH users. These results suggest that chronic heroin and METH abuse appears to produce similar effects in striatal DAT in humans. METH users may have more serious craving and anxiety symptoms than heroin users with prolonged abstinence.

Topiramate for the management of methamphetamine dependence: a pilot randomized, double-blind, placebo-controlled trial

To date, no medication has been approved as an effective treatment for methamphetamine dependence. Topiramate has attracted considerable attention as a treatment for the dependence on alcohol and stimulants. Therefore, this study aimed to evaluate the effect of topiramate for methamphetamine dependence. This study was a double-blind, randomized, placebo-controlled trial. In the present investigation, 62 methamphetamine-dependent adults were enrolled and randomized into two groups, and received topiramate or a placebo for 10 weeks in escalating doses from 50 mg/day to the target maintenance dose of 200 mg/day. Addiction severity index (ASI) and craving scores were registered every week. The Beck questionnaire was also given to each participant at baseline and every 2 weeks during the treatment. Urine samples were collected at baseline and every 2 weeks during the treatment. Fifty-seven patients completed 10 weeks of the trial. There was no significant difference between both groups in the mean percentage of prescribed capsules taken by the participants. At week six, the topiramate group showed a significantly lower proportion of methamphetamine-positive urine tests in comparison with the placebo group (P = 0.01). In addition, there were significantly lower scores in the topiramate group in comparison with the placebo group in two domains of ASI: drug use severity (P < 0.001) and drug need (P < 0.001). Furthermore, the craving score (duration) significantly declined in the topiramate patients compared to those receiving the placebo. In conclusion, the results of this trial suggest that topiramate may be beneficial for the treatment of methamphetamine dependence.

BDNF (Val66Met) genetic polymorphism is associated with vulnerability for methamphetamine dependence

AIM

Association of the brain-derived neurotrophic factor (BDNF) genetic polymorphism rs6265 (Val66Met) with methamphetamine (METH) dependence and METH-induced psychosis was investigated in the Thai population.

MATERIALS & METHODS

The rs6265 genotype was determined in 100 male METH-dependent subjects and 102 controls using a real-time PCR high-resolution melt (RT-PCR-HRM) assay.

RESULTS

The rs6265 genotype demonstrated significant differences in distribution between METH-dependent subjects and controls in which the frequency of GG genotype versus A-allele carriers was associated with METH dependence. Moreover, a significant effect of genotype on the occurrence of psychosis was found, with a lower frequency of GG genotype associated with METH-induced psychosis.

CONCLUSION

The present findings indicate that rs6265 is associated with METH dependence in the Thai population, with the GG genotype greater in METH-dependent subjects but reducing the emergence of METH-dependent psychosis.

Predictors of Attrition in a Cohort Study of HIV Infection and Methamphetamine Dependence

Longitudinal cohort studies of HIV and substance use disorders play an important role in understanding these conditions, but high rates of attrition can threaten their integrity and generalizability. This study aimed to identify factors associated with attrition in a 5-year observational cohort study of 469 individuals with and without HIV infection and methamphetamine (MA) dependence. Rates of attrition in our four study groups were approximately 24% in HIV-MA-, 15% in HIV+MA-, 56% in HIV-MA+, and 47% in HIV+MA+ individuals. Predictors of attrition in the overall cohort included history of MA, alcohol, and other substance dependence, learning impairment, reduced cognitive reserve, and independence in activities of daily living (all ps < .05), but varied somewhat by clinical group. Of particular note, enrollment in a neuroimaging substudy was associated with significantly boosted rates of retention in the MA groups. Results from this investigation highlight the complexity of the clinical factors that influence retention in cohort studies of HIV-infected MA users and might guide the development and implementation of targeted retention efforts.

Creatine as a Novel Treatment for Depression in Females Using Methamphetamine: A Pilot Study

OBJECTIVE

Depression among methamphetamine users is more prevalent in females than males, but gender-specific treatment options for this comorbidity have not been described. Reduced brain phosphocreatine levels have been shown to be lower in female methamphetamine users compared to males, and, of relevance, studies have demonstrated an association between treatment-resistant depression and reduced brain phosphocreatine concentrations. The nutritional supplement creatine monohydrate has been reported to reduce symptoms of depression in female adolescents and adults taking antidepressants, as well as to increase brain phosphocreatine in healthy volunteers. Therefore, the purpose of this pilot study was to investigate creatine monohydrate as a treatment for depression in female methamphetamine users.

METHODS

Fourteen females with depression and comorbid methamphetamine dependence were enrolled in an 8-week open label trial of 5 g of daily creatine monohydrate and of these 14, 11 females completed the study. Depression was measured using the Hamilton Depression Rating Scale (HAMD) and brain phosphocreatine levels were measured using phosphorus magnetic resonance spectroscopy pre- and post-creatine treatment. Secondary outcome measures included anxiety symptoms, measured with the Beck Anxiety Inventory (BAI), as well as methamphetamine use, monitored by twice weekly urine drug screens and self-reported use.

RESULTS

The results of a linear mixed effects repeated measures model showed significantly reduced HAMD and BAI scores as early as week 2 when compared to baseline scores. This improvement was maintained through study completion. Brain phosphocreatine concentrations were higher at the second phosphorus magnetic resonance spectroscopy scan compared to the baseline scan; Mbaseline = 0.223 (SD = 0.013) vs. Mpost-treatment = 0.233 (SD = 0.009), t (9) = 2.905, p <.01, suggesting that creatine increased phosphocreatine levels. Also, a reduction in methamphetamine positive urine drug screens of greater than 50% was observed by week 6. Finally, creatine was well tolerated and adverse events that were related to gastrointestinal symptoms and muscle cramping were determined as possibly related to creatine.

CONCLUSIONS

The current study suggests that creatine treatment may be a promising therapeutic approach for females with depression and comorbid methamphetamine dependence. This study is registered on clinicaltrials.gov (NCT01514630).

Placebo-group responders in methamphetamine pharmacotherapy trials: the role of immediate establishment of abstinence

Treatment responses of placebo groups in addiction medicine trials have important implications for research methodology and clinical practice, however studies examining placebo group responses in addiction medicine are scarce. Extant data suggest the importance of early treatment responsiveness for long-term outcomes. Among methamphetamine-(MA) dependent individuals randomized to placebo pill plus behavioral support conditions in pharmacotherapy development trials, we hypothesized that immediate abstinence would be a necessary but insufficient predictor for end-of-trial (EOT) abstinence. The study is a secondary analysis of participants (n = 184; 36% female) in the placebo condition of three randomized, placebo-controlled methamphetamine dependence pharmacotherapy trials. Receiver operating characteristic (ROC) curve analyses assessed the predictive power of initial abstinence, assessed by thrice weekly urine samples, for EOT abstinence. Sixty percent of individuals with complete abstinence in the first two weeks of treatment were abstinent at EOT, while 18% of people who failed to meet this standard were abstinent at EOT. Early response was related to retention at EOT and 12-month follow-up. Findings suggest that the inability to achieve at least three MA negative screenings in the first two weeks is associated with greater than 90% likelihood of treatment failure. A third week of screening added minimally to the prediction of EOT outcomes. The prediction of treatment failure was more precise than the prediction of treatment success. The absence of a clinical response in the first two weeks of treatment among participants in the placebo group signals high risk of treatment failure. The majority of information regarding response in the placebo group from a 12-week trial is obtained early in the trial.

A retrospective analysis of two randomized trials of bupropion for methamphetamine dependence: suggested guidelines for treatment discontinuation/augmentation

BACKGROUND

Two clinical trials have shown efficacy for bupropion in treating methamphetamine (MA) dependence among those with moderate baseline MA use. However, treatment response is highly variable and it is unclear what duration of treatment is necessary to determine if maintaining the treatment course is indicated or if discontinuation or augmentation is appropriate. The present study assessed the relationship among early bupropion treatment response for moderate MA users and end-of-treatment (EOT) abstinence. These data provide estimates of the duration of treatment and the degree of responsiveness required to persist in bupropion treatment.

METHODS

Participants with moderate baseline MA use in the bupropion condition of two randomized double-blind placebo controlled trials were included. The relationship between early treatment response and EOT outcomes was assessed with Receiver Operating Characteristic (ROC) curves.

RESULTS

With thrice weekly urine drug testing, excellent predictive power was established in the first two weeks of treatment. The inability to achieve at least three MA negative samples in the first two weeks is associated with greater than 90% likelihood of treatment failure. More closely approximating clinical settings, once-weekly testing featured reliable predictive power within three weeks, suggesting that the failure to produce at least two clean samples in the first three weekly visits confers high risk of treatment failure.

DISCUSSION

The findings provide preliminary evidence to guide clinical decisions for moderate MA users receiving bupropion. The results are consistent with data from the smoking cessation literature and may highlight the importance of early response in addiction treatment.

Lack of association between prokineticin 2 gene and Japanese methamphetamine dependence

Disruption of circadian rhythms may be involved in the pathophysiology of psychiatric disorders, including drug addiction. Recently, we detected the significant association between prokineticin 2 receptor gene (PROKR2) and Japanese methamphetamine dependence patients. Also, prokineticin 2 (PK2) gene deficient mice showed reduced physiological and behavioral parameters, including circadian locomotor activity, circulating glucocorticoid, glucose levels and the expression of peripheral clock genes compared with WT mice. These evidences indicate that PK2 gene (PROK2) is a good candidate gene for the pathogenesis of methamphetamine dependence. To evaluate the association between PROK2 and methamphetamine dependence, we conducted a case-control study of Japanese samples (215 methamphetamine dependence and 232 controls) with four tagging SNPs selected by HapMap database. The age and sex of the control subjects did not differ from those of the methamphetamine dependence patients. Written informed consent was obtained from each subject. This study was approved by the ethics committees at Fujita Health University, Nagoya University Graduate School of Medicine and each participating member of the Institute of the Japanese Genetics Initiative for Drug Abuse (JGIDA). We did not detect an association between PROK2 and Japanese methamphetamine dependence patients in allele/genotype-wise analysis, or the haplotype analysis. Our findings suggest that PROK2 does not play a major role in the pathophysiology of methamphetamine dependence in the Japanese population.

Association Analysis of Nuclear Receptor Rev-erb Alpha Gene (NR1D1) and Japanese Methamphetamine Dependence

Several investigations suggested abnormalities in circadian rhythms are related to the pathophysiology of psychiatric disorders, including drug addiction. Recently, orphan nuclear receptor rev-erb alpha and glycogen synthase kinase-3 β (GSK-3β) were shown to be important circadian components. In addition, the orphan nuclear receptor rev-erb alpha is a key negative feedback regulator of the circadian clock. These evidences indicate that rev-erb alpha gene (NR1D1) is a good candidate gene for the pathogenesis of methamphetamine dependence. To evaluate the association between NR1D1 and methamphetamine dependence, we conducted a case-control study of Japanese samples (215 methamphetamine dependence and 232 controls) with three tagging SNPs selected by HapMap database. Written informed consent was obtained from each subject. This study was approved by the ethics committees at Fujita Health University, Nagoya University Graduate School of Medicine and each participating member of the Institute of the Japanese Genetics Initiative for Drug Abuse (JGIDA). We did not detect an association between NR1D1 and Japanese methamphetamine dependence patients in allele/genotype-wise analysis, or the haplotype analysis. Our findings suggest that NR1D1 does not play a major role in the pathophysiology of methamphetamine dependence in the Japanese population.

Family dysfunction differentially affects alcohol and methamphetamine dependence: a view from the Addiction Severity Index in Japan

We investigated the differential influence of family dysfunction on alcohol and methamphetamine dependence in Japan using the Addiction Severity Index (ASI), a useful instrument that multilaterally measures the severity of substance dependence. The participants in this study were 321 male patients with alcohol dependence and 68 male patients with methamphetamine dependence. We conducted semi-structured interviews with each patient using the ASI, which is designed to assess problem severity in seven functional domains: Medical, Employment/Support, Alcohol use, Drug use, Legal, Family/Social relationships, and Psychiatric. In patients with alcohol dependence, bad relationships with parents, brothers and sisters, and friends in their lives were related to current severe psychiatric problems. Bad relationships with brothers and sisters and partners in their lives were related to current severe employment/support problems, and bad relationships with partners in their lives were related to current severe family/social problems. The current severity of psychiatric problems was related to the current severity of drug use and family/social problems in patients with alcohol dependence. Patients with methamphetamine dependence had difficulty developing good relationships with their father. Furthermore, the current severity of psychiatric problems was related to the current severity of medical, employment/support, and family/social problems in patients with methamphetamine dependence. The results of this study suggest that family dysfunction differentially affects alcohol and methamphetamine dependence. Additionally, family relationships may be particularly related to psychiatric problems in these patients, although the ASI was developed to independently evaluate each of seven problem areas.

Advantages of Joint Modeling of Component HIV Risk Behaviors and Non-Response: Application to Randomized Trials in Cocaine-Dependent and Methamphetamine-Dependent Populations

The HIV risk-taking behavior scale (HRBS) is an 11-item instrument designed to assess the risks of HIV infection due to self-reported injection-drug use and sexual behavior. A retrospective analysis was performed on HRBS data collected from approximately 1,000 participants pooled across seven clinical trials of pharmacotherapies for either the treatment of cocaine dependence or methamphetamine dependence. Analysis faced three important challenges. The sample contained a high proportion of missing assessments after randomization. Also, the HRBS scale consists of two distinct behavioral components which may or may not coincide in response patterns. In addition, distributions of responses on the subscales were highly concentrated at just a few values (e.g., 0, 6). To address these challenges, a single probit regression model was fit to three outcomes variables simultaneously - the two subscale totals plus an indicator variable for assessments not obtained (non-response). This joint-outcome regression model was able to identify that those who left assessment early had higher self-reported risk of injection-drug use and lower self-reported risky sexual behavior because the model was able to draw on information on associations among the three outcomes collectively. These findings were not identified in analyses performed on each outcome separately. No evidence for an effect of pharmacotherapies was observed, except to reduce missing assessments. Univariate-outcome modeling is not recommended for the HRBS.

Neurochemical alterations in methamphetamine-dependent patients treated with cytidine-5'-diphosphate choline: a longitudinal proton magnetic resonance spectroscopy study

Cytidine-5'-diphosphate choline (CDP-choline), as an important intermediate for major membrane phospholipids, may exert neuroprotective effects in various neurodegenerative disorders. This longitudinal proton magnetic resonance spectroscopy ((1)H-MRS) study aimed to examine whether a 4-week CDP-choline treatment could alter neurometabolite levels in patients with methamphetamine (MA) dependence and to investigate whether changes in neurometabolite levels would be associated with MA use. We hypothesized that the prefrontal levels of N-acetyl-aspartate (NAA), a neuronal marker, and choline-containing compound (Cho), which are related to membrane turnover, would increase with CDP-choline treatment in MA-dependent patients. We further hypothesized that this increase would correlate with the total number of negative urine results. Thirty-one treatment seekers with MA dependence were randomly assigned to receive CDP-choline (n=16) or placebo (n=15) for 4 weeks. Prefrontal NAA and Cho levels were examined using (1)H-MRS before medication, and at 2 and 4 weeks after treatment. Generalized estimating equation regression analyses showed that the rate of change in prefrontal NAA (p=0.005) and Cho (p=0.03) levels were greater with CDP-choline treatment than with placebo. In the CDP-choline-treated patients, changes in prefrontal NAA levels were positively associated with the total number of negative urine results (p=0.03). Changes in the prefrontal Cho levels, however, were not associated with the total number of negative urine results. These preliminary findings suggest that CDP-choline treatment may exert potential neuroprotective effects directly or indirectly because of reductions in drug use by the MA-dependent patients. Further studies with a larger sample size of MA-dependent patients are warranted to confirm a long-term efficacy of CDP-choline in neuroprotection and abstinence.

Depression among methamphetamine users: association with outcomes from the Methamphetamine Treatment Project at 3-year follow-up

Although depression is highly comorbid with substance use disorders, little is known about the clinical course and outcomes of methamphetamine (MA) users with depressive symptoms and syndromes. In this study of MA-dependent individuals entering psychosocial treatment, we predicted that (1) depressive symptoms would decline during treatment, an effect that would vary as a function of MA use and (2) depression diagnoses post-treatment would be associated with poorer outcomes. Participants (N = 526) were assessed for depression, substance use, and psychosocial outcomes at baseline, treatment discharge, and 3-year follow-up. Depressive symptoms declined significantly during treatment, an effect that was greatest among those who abstained from MA. Major depression at follow-up was associated with poorer MA use outcomes and impairment across multiple domains of functioning. The findings highlight the relationship of depressive symptoms and diagnoses to treatment outcomes, and suggest a need for further studies of depression in populations using MA.

Randomized, placebo-controlled trial of bupropion for the treatment of methamphetamine dependence

OBJECTIVE

To compare bupropion to placebo for reducing methamphetamine (MA) use, increasing retention, and reducing the severity of depressive symptoms and MA-cravings. A secondary objective compared bupropion to placebo for reducing cigarette smoking among MA dependent participants.

METHODS

Following a 2-week, non-medication baseline screening period, 73 treatment-seeking MA dependent participants were randomly assigned to bupropion sustained release (150 mg twice daily; N=36) or placebo (twice daily; N=37) for 12-weeks under double-blind conditions. Participants attended clinic thrice weekly to provide urine samples analyzed for MA-metabolite, to complete research measures and assessments, and to receive contingency management and weekly cognitive behavioral therapy sessions.

RESULTS

There were no statistically significant effects for bupropion relative to placebo on MA use verified by urine drug screens, for reducing the severity of depressive symptoms or MA-cravings, or on study retention. In a post hoc analysis, there was a statistically significant effect of bupropion treatment on MA use among participants with lighter (0-2 MA-positive urines), but not heavier (3-6 MA-positive urines) MA use during baseline (OR=2.81, 95% CI=1.61-4.93, p<0.001 for MA-free week with bupropion among light users). Bupropion treatment was also associated with significantly reduced cigarette smoking, by almost five cigarettes per day (p=0.0002).

CONCLUSION

Bupropion was no more effective than placebo in reducing MA use in planned analyses, though bupropion did reduce cigarette smoking. Post hoc findings of an effect for bupropion among baseline light, but not heavy, MA users suggests further evaluation of bupropion for light-MA users is warranted.

The orbitofrontal cortex in methamphetamine addiction: involvement in fear

We used Tellegen's Multidimensional Personality Questionnaire (MPQ) harm avoidance (fear) scale and the constraint superfactor as personality measures of inhibitory control and examined their association with glucose metabolism in the orbitofrontal gyrus at rest in 14 recently abstinent methamphetamine-dependent subjects and 22 comparison subjects. Higher MPQ scores were associated with higher relative orbitofrontal gyrus metabolism in the methamphetamine-dependent subjects. There was a tendency towards a negative association for the comparison subjects (test of coincidence of regression lines for the two subject groups: F = 3.3, df = 2,32; = 0.051). These results suggest that the role of the orbitofrontal cortex in inhibitory control can be manifested in stable personality predispositions and further implicate this region in the core characteristics of drug addiction.