Potential Treat-to-Target Approach for Methamphetamine Use Disorder: A Pilot Study of Adenosine 2A Receptor Antagonist With Positron Emission Tomography

Introduction: The misuse of stimulant drugs such as methamphetamine is a global public health issue. One important neurochemical mechanism of methamphetamine use disorder may be altered dopaminergic neurotransmission. For instance, previous studies using positron emission tomography (PET) have consistently shown that striatal dopamine D2-type receptor availability (quantified as binding potential; BPND) is lower in methamphetamine use disorder. Further, methamphetamine use is known to induce chronic neuroinflammation through multiple physiological pathways. Upregulation of D2-type receptor and/or attenuation of neuroinflammation may therefore provide a therapeutic effect for this disorder. In vitro studies have shown that blockage of adenosine 2A (A2A) receptors may prevent D2-receptor downregulation and neuroinflammation-related brain damage. However, no study has examined this hypothesis yet.

Methods and Analysis: Using a within-subject design, this trial will assess the effect of the selective A2A receptor antagonist, istradefylline, primarily on D2-type BPND in the striatum, and secondarily on neuroinflammation in the whole brain in individuals with methamphetamine use disorder. The research hypotheses are that istradefylline will increase striatal D2-type BPND and attenuate neuroinflammation. Twenty participants with methamphetamine use disorder, aged 20–65, will be recruited to undergo [11C]raclopride PET (for every participant) and [11C]DAA1106 PET (if applicable) once before and once after administration of 40 mg/day istradefylline for 2 weeks. Neuropsychological measurements will be performed on the same days of the PET scans.

Ifenprodil for the treatment of methamphetamine use disorder: An exploratory, randomized, double‐blind, placebo‐controlled trial

Aim

No effective pharmacological interventions have been developed for patients with methamphetamine use disorder. Ifenprodil is a blocker of G protein‐activated inwardly rectifying potassium channels, which play a key role in the mechanism of action of addictive substances. We conducted a randomized, double‑blind, exploratory, dose‐ranging, placebo‐controlled trial to examine the clinical efficacy of ifenprodil for the treatment of methamphetamine use disorder.

Methods

Participants were assigned to three groups: placebo, 60 mg/d ifenprodil, or 120 mg/d ifenprodil. The drug administration period was 84 days. The primary outcome was the use or nonuse of methamphetamine during the drug administration period in the placebo group vs 120 mg/d ifenprodil group. We also assessed drug use status, relapse risk based on the Stimulant Relapse Risk Scale (SRRS), drug craving, and methamphetamine in urine as secondary outcomes. We further evaluated drug use status and SRRS subscale scores in patients who were not taking addiction medications during the study.

Results

Ifenprodil did not affect the primary or secondary outcomes. However, the additional analyses showed that the number of days of methamphetamine use during the follow‐up period and scores on the emotionality problems subscale of the SRRS improved in the 120 mg/d ifenprodil group. The safety of ifenprodil was confirmed in patients with methamphetamine use disorder.

Conclusion

The present findings did not confirm the efficacy of ifenprodil for methamphetamine use disorder treatment based on the primary or secondary outcomes, but we found evidence of its safety and efficacy in reducing emotionality problems.

Clinical trial registration

The study was registered at the University Hospital Medical Information Network Clinical Trial Registry (no. UMIN000030849) and Japan Registry of Clinical Trials (no. jRCTs031180080). The main registration site is jRCT (https://jrct.niph.go.jp/).

We conducted an exploratory, randomized, double‐blind, placebo‐controlled trial to investigate the clinical safety and efficacy of ifenprodil for the treatment of methamphetamine use disorder in Japanese patients. Our findings confirmed the safety of ifenprodil, and ifenprodil at the highest dose exerted slight efficacy.

Does cognitive behavioral therapy for anxiety disorders assist the discontinuation of benzodiazepines among patients with anxiety disorders? A systematic review and meta-analysis

Long-term use of benzodiazepines (BZD) is not recommended for the treatment of anxiety disorders. Cognitive behavioral therapy (CBT) is an effective treatment option for discontinuation of BZD in patients with anxiety disorders. This systematic review and meta-analysis sought to clarify whether CBT is effective for discontinuing BZD anxiolytics in patients with anxiety disorders. This study was preregistered with PROSPERO (registration number: CRD42019125263). A literature search of major electronic databases was conducted in December 2018. Three randomized controlled trials were included in this review, and meta-analyses were performed. The proportion of discontinuing BZD anxiolytics was significantly higher in the CBT plus gradual tapering group than in the gradual tapering alone group, both in the short term (3 months after allocation; number needed to treat: 3.2, 95% confidence interval [CI]: 2.1 to 7.1; risk ratio: 1.96, 95%CI: 1.29 to 2.98, P = 0.002, three studies) and long term (6 to 12 months after allocation; number needed to treat: 2.8, 95%CI: 1.9 to 5.3; risk ratio: 2.16, 95%CI: 1.41 to 3.32, P = 0.0004, three studies). CBT may be effective for discontinuing BZD anxiolytics, both in the short term and in the long term after the allocation. Further studies with larger sample sizes are necessary to draw definitive conclusions regarding the efficacy and safety of CBT for discontinuing BZD anxiolytics in patients with anxiety disorders.

Risk factors for the onset of dependence and chronic psychosis due to cannabis use: Survey of patients with cannabis-related psychiatric disorders

AIM

The objective of the current study was to identify risk factors that affect the onset of dependence and chronic psychosis due to cannabis use.

METHODS

We examined clinical genetic factors, psychiatric disorders prior to cannabis use, starting age of cannabis use, duration and frequency of cannabis use, types of cannabis products used, combined use of other psychoactive substances, and the psychiatric diagnosis of 71 patients with cannabis-related psychiatric disorders who underwent treatment at nine mental health hospitals in Japan. Information was collected from cross-sectional interview surveys conducted by each patient's attending psychiatrist.

RESULTS

For the diagnosis of dependence syndrome due to the use of cannabis, we found associations with the number of years of cannabis use and the use of cannabis products with a high Δ9-tetrahydrocannabinol (THC) content. However, we found no association between diagnosis of residual and late-onset psychotic disorders and clinical genetic factors, presence of preceding psychiatric disorders, duration and frequency of cannabis use, starting age of cannabis use, or combined use of other psychoactive substances; an association was found only for the absence of use of cannabis products other than dried cannabis.

CONCLUSION

The onset of cannabis dependence was related to long-term cannabis use and the use of cannabis products with a high THC content. However, chronic psychosis was not associated with total THC intake or psychiatric vulnerability. Thus, unknown factors appear to be involved in the onset of chronic psychosis.

Changes of clinical symptoms in patients with new psychoactive substance (NPS)-related disorders from fiscal year 2012 to 2014: A study in hospitals specializing in the treatment of addiction

Aims

The use of new psychoactive substances (NPS) has become increasingly widespread over the last decade, in Japan and internationally. NPS are associated with a range of increasingly serious clinical, public, and social issues. Political measures to ameliorate the effects of NPS in Japan have focused on tightening regulation rather than establishing treatment methods. The current study sought to compare the neuropsychiatric symptoms of patients with NPS‐related disorders across several years. We examined patients who attended specialized hospitals for treating addiction, to elucidate the impacts of legal measures to control NPS.

Methods

Subjects (n = 864) were patients with NPS‐related disorders who received medical treatment at eight specialized hospitals for treating addiction in Japan between April 2012 and March 2015. Clinical information was collected retrospectively from medical records.

Results

Among psychiatric symptoms, the ratio of hallucinations/delusions decreased over time across 3 years of study (first year vs second year vs third year: 40.1% vs 30.9% vs 31.7%, P = 0.037). Among neurological symptoms, the ratio of coma/syncope increased over the 3‐year period (7.8% vs 11.0% vs 17.0%, P = 0.002), as did the ratio of convulsions (2.8% vs 4.3% vs 9.7%, P = 0.001).

Conclusion

The symptoms associated with NPS were primarily psychiatric in the first year, while the prevalence of neurological symptoms increased each year. The risk of death and the severity of symptoms were greater in the third year compared with the first year, as regulation of NPS increased.

We collected information retrospectively based on medical records and compared with psychiatric and neurological symptoms of NPS users observed in the fiscal year of their first medical examination. We found that adverse health effects resulting from the use of NPS were changed from mainly psychiatric symptoms to neurological symptoms. These findings suggest the possibility that contained more dangerous and toxic compounds after drug‐related regulations had been tightened.

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.

The influence of tightening regulations on patients with new psychoactive substance-related disorders in Japan

Aims

This study aimed to investigate the influence of tightened regulations on new psychoactive substances in patients with disorders related to these drugs in Japan.

Methods

We used a biennial nationwide survey on drug‐related psychiatric disorders to examine why individuals who had previously used new psychoactive substances as their primary drug (the drug that had the greatest impact on their psychiatric symptoms) had switched to other drugs, how they had used drugs in the last 12 months and what type of drugs they were now using. We compared the clinical features of these individuals with patients who mainly used new psychoactive substances and had used these drugs at least once in the last 12 months.

Results

A total of 2262 people were included, and 399 had used new psychoactive substances. Of those, 71 people had switched to another drug as primary drug, mostly stimulant drugs (35.2%), hypnotics and anxiolytics (15.5%), and cannabis (14.1%) and used these drugs during the previous 12 months. The majority, 53.3%, had switched “because new psychoactive substances were no longer available.” In total, 25 people mainly used new psychoactive substances. The group that had changed drugs had more experience of using methamphetamine and were more likely to have abused other drugs before using new psychoactive substances. They had often switched to illegal or prescription drugs after regulations had been tightened.

Conclusion

The number of patients abusing new psychoactive substances decreased after drug regulations were tightened, but new psychoactive substances‐related problems still exist. It is therefore not enough to tighten regulations. Drug dependence treatment and recovery support are also needed.

We investigate the influence of tightened regulations on new psychoactive substances in patients with disorders related to these drugs in Japan. Tightening regulations were not enough. Drug dependence treatment and recovery support are also needed.

Recent changes in the clinical features of patients with new psychoactive-substances-related disorders in Japan: Comparison of the Nationwide Mental Hospital Surveys on Drug-related Psychiatric Disorders undertaken in 2012 and 2014

AIM

The aim of this study was to examine changes in the psychosocial backgrounds and clinical features of patients with psychiatric disorders associated with new psychoactive substances (NPS) between 2012 and 2014 in Japan.

METHODS

Clinical features of patients with NPS-related disorders were compared using data from the Nationwide Mental Hospital Surveys on Drug-related Psychiatric Disorders undertaken in 2012 and 2014. NPS patients were compared with a control group comprising patients with methamphetamine-related disorders, using data from the same period.

RESULTS

In NPS patients, changes were observed in the following three areas between 2012 and 2014: (i) a decrease in the number of employed patients; (ii) an increase in the ratio of patients diagnosed with dependence syndrome; and (iii) a decrease in the ratio of patients diagnosed with psychotic disorder. In methamphetamine patients, only one change was observed: protective custody or arrest record relating to the Pharmaceutical Affairs Act.

CONCLUSION

This study suggests that the number of patients dependent upon NPS, and those exhibiting social dysfunction, increased between 2012 and 2014. There is a need to focus future measures against NPS dependence: not only on stopping the supply of drugs, but also on reducing the demand for them.