A critical review of the dextroamphetamine transdermal system for the treatment of ADHD in adults and pediatric patients.

INTRODUCTION: The dextroamphetamine transdermal system (d-ATS) is a stimulant patch recently approved by the United States (U.S.) Food and Drug Administration for the treatment of attention-deficit/hyperactivity disorder (ADHD). AREAS COVERED: The composition of the d-ATS, pharmacokinetics, and metabolism are presented along with data from dermal trials evaluating the tolerability of patch application at various skin sites. Efficacy and safety data from a laboratory classroom study in children and adolescents including effect sizes are assessed. Pharmacokinetic-pharmacodynamic modeling of variable wear times is also discussed. EXPERT OPINION: Although stimulants are recommended as first-line treatment for ADHD in the U.S. some patients may have difficulty swallowing intact tablets and capsules, or dislike the taste or texture of chewable, oral disintegrating, or liquid formulations. The d-ATS fills an unmet need for those with ADHD who are unable or prefer not to take medication orally. Varying wear time of the d-ATS also gives flexibility in length of stimulant effect which may be useful for patients with changing schedules. However, dermal discomfort must be considered in addition to the usual amphetamine side effects when prescribing the d-ATS. Patient and provider experience will determine how frequent the use of d-ATS becomes.

Neural and Cognitive Predictors of Stimulant Treatment Efficacy in Medication-Naïve ADHD Adults: A Pilot Diffusion Tensor Imaging Study.

OBJECTIVE: Stimulant medications are the main treatment for Attention Deficit Hyperactivity Disorder (ADHD), but overall treatment efficacy in adults has less than a 60% response rate. This study aimed to identify neural and cognitive markers predictive of longitudinal improvement in response to stimulant treatment in drug-naïve adults with ADHD. METHOD: We used diffusion tensor imaging (DTI) and executive function measures with 36 drug-naïve adult ADHD patients in a prospective study design. RESULTS: Structural connectivity (measured by fractional anisotropy, FA) in striatal regions correlated with ADHD clinical symptom improvement following stimulant treatment (amphetamine or methylphenidate) in better medication responders. A significant positive correlation was also found between working memory performance and stimulant-related symptom improvement. Higher pre-treatment working memory scores correlated with greater response. CONCLUSION: These findings provide evidence of pre-treatment neural and behavioral markers predictive of longitudinal treatment response to stimulant medications in adults with ADHD.

A review of amphetamine extended release once-daily options for the management of attention-deficit hyperactivity disorder.

INTRODUCTION: Amphetamine preparations are one of the two categories of stimulant medications approved for the treatment of attention deficit hyperactivity disorder (ADHD). Optimal treatment of ADHD aims to reduce core symptoms for as much of the waking hours as possible, leading to longer-acting delivery formats. In addition, the pediatric population commonly has difficulty swallowing pills and manufacturers have developed a variety of options to facilitate this concern. These include chewable tablets, capsules that may be sprinkled on soft food, liquids and transdermal patches. AREAS COVERED: This article reviews the once-daily extended-release preparations currently available for amphetamine compounds, their pharmacodynamics, and common adverse effects. EXPERT OPINION: There is an extensive evidence base supporting use of amphetamine preparations in the treatment of ADHD. Rapid onset of action and a favorable side effect profile make these widely used. The availability of once-daily extended-release chewable tablets, capsules that can be opened and sprinkled, and liquid formulations provides clinicians with multiple options to meet the specific needs of patients with difficulty swallowing whole pills.

MDMA enhances positive affective responses to social feedback.

BACKGROUND: The prosocial compound ± 3,4-methylenedioxymethamphetamine (MDMA) is an amphetamine derivative that has shown promise as an adjunct to psychotherapy in the treatment of post-traumatic stress disorder. MDMA increases positive responses to social images, and it has been suggested that the ability of MDMA to positively bias social perception may underlie its therapeutic efficacy as a psychotherapy adjunct. However, the effect of the compound on affective responses to positive or negative social feedback has not been tested. AIMS: In this study, we aimed to test the effects of MDMA compared to placebo and the prototypical stimulant, methamphetamine (MA), on responses to positive and negative social feedback. METHODS: This was a double-blind, placebo-controlled, crossover trial (NCT03790618), comparing the effects of two doses of MDMA (0.75 mg/kg, 1.5 mg/kg) to both placebo and MA (20 mg) on responses to a personalized social feedback task, similar to a dating app, in healthy adult volunteers ages 18-40 (N = 36, 18 women, 18 men). RESULTS/OUTCOMES: The high dose of MDMA increased positive affective responses to social feedback. CONCLUSIONS/INTERPRETATIONS: These findings suggest one process by which MDMA may facilitate social connection. Further work is needed to understand how MDMA affects responses to more generalized types of social feedback and to understand these effects in clinical populations.

A Single-Blind, Placebo Controlled Trial of Triple Beaded Mixed Amphetamine Salts in DSM-5 Adults With ADHD Assessing Effects Throughout the Day.

OBJECTIVE: To examine the effects of triple beaded mixed amphetamine salts (TB MAS) on ADHD and executive dysfunction symptoms throughout the day in adults with DSM-5 ADHD. METHOD: This was a 6 week, single-blind, placebo-lead in trial of TB MAS (12.5-37.5 mg/day); all participants received 2 weeks of single-blind placebo); one individual was a placebo responder and was discontinued. One of these 18 dropped after 1 week on 12.5 mg/day, while all others completed the trial and received 37.5 mg/day TB MAS. RESULTS: There were significant effects of TB MAS on all clinical measures, including investigator overall symptoms (AISRS); self-report overall (ASRS), time-sensitive ADHD (TASS) scores throughout the day, impairment (CGI) and executive function scores (BRIEF-A). TB MAS was generally well tolerated. CONCLUSIONS: This study extends prior findings of TB MAS to adults with DSM-5 ADHD; it further re-validates findings of efficacy of TB MAS throughout the day.

Viloxazine extended-release capsules for the treatment of attention-deficit/ hyperactivity disorder in adult patients.

INTRODUCTION: Attention-deficit/hyperactivity disorder (ADHD) is a common neurobehavioral disorder with symptoms that may persist in up to 90% of adults diagnosed during childhood and continue to cause significant impairment throughout the lifespan. In the United States (US), amphetamine and methylphenidate formulations have been available to treat ADHD for several decades. Only one nonstimulant, atomoxetine, was available for the treatment of ADHD in adults until recently. In April 2022, a second nonstimulant, viloxazine extended-release (VLX-ER), became available in the US for the treatment of adult ADHD. Efficacy was previously established in placebo-controlled trials in children and adolescents. AREAS COVERED: VLX-ER is a norepinephrine reuptake inhibitor with serotonin activity. The efficacy in adults, adverse event profile, pharmacokinetics, drug-drug interactions, and metabolism of VLX-ER are reviewed. EXPERT OPINION: Despite the availability of effective pharmacological treatments for ADHD, many patients discontinue treatment in less than 1 year. Stimulants are effective in more than 80% of patients; however, some may have difficulty tolerating them. Although there were no head-to-head studies, the effect size of VLX-ER in an adult efficacy trial was lower than has been shown for stimulants. Nevertheless, the approval of VLX-ER adds another effective ADHD treatment option for adults.

Medical Cannabis Legalization: No Contribution to Rising Stimulant Rates in the USA.

INTRODUCTION: There has been a pronounced increase in the use of Schedule II stimulants to treat attention-deficit hyperactivity disorder (ADHD) in the United States over the last two decades. Interestingly, chronic medical cannabis (MC) use can present with cognitive impairments that resemble ADHD symptoms. This study aimed to determine if MC legalization increased prescription stimulant distribution. METHODS: Information on the distribution of methylphenidate, amphetamine, and lisdexamfetamine for 2006 to 2021 was extracted from the Drug Enforcement Administration's comprehensive database and the three-year population-corrected slopes of stimulant distribution before and after MC program implementation were compared. RESULTS: We found a significant main effect of time (p<0.001); however, contrary to the hypothesis, the sales status of states' MC, did not influence slopes of distribution (p=0.391). There was a significantly large interaction effect of time and MC sales status on slopes of distribution (p<0.001). Slopes of distribution rates of stimulants were significantly lower in states that proceeded to legalize MC prior to MC program implementation than those states that did not (p=0.022). After MC program implementation, however, the distribution rates of the Schedule II stimulants were not significantly different when comparing states with MC sales to those without (p=0.355). DISCUSSION: These findings suggest that MC program legalization did not contribute to certain states having rapid increases in Schedule II stimulant distribution rates over time. Other factors, including the liberalization of the adult ADHD diagnostic criteria in the DSM-5 and the introduction of Binge Eating Disorder, also likely contributed to elevations in stimulant distribution.

Switching patterns of immediate-release forms of generic mixed amphetamine salts products among privately and publicly insured individuals aged 15-64 years in the United States, 2013-2019.

PURPOSE: Immediate-release forms of generic mixed amphetamine salts (MAS) have been the subject of passive surveillance reports signaling lack of effectiveness. We examined switching patterns that might suggest whether long-term users of specific MAS are more likely to switch away or switch back after use of the MAS of interest in the FDA's Sentinel Distributed Database. METHODS: We required at least 60-day continuous supply of selected MAS grouped by Abbreviated New Drug Application (ANDA) to describe patterns of switching away from and to generics approved under the ANDAs of interest among individuals ages 15-64 years with attention deficit hyperactivity disorder or narcolepsy during 2013-2019. RESULTS: We observed the greatest number of treatment episodes for ANDA 040422 (n = 525 771), followed by ANDA 202424 (n = 181 693), ANDA 040439 (n = 62 363), ANDA 040440 (n = 21 143), and ANDA 040480 (n = 8792). Of those with switches away from their original ANDA, episodes initiated on generic products under ANDA 040422 (48.6%) and ANDA 202424 (43.0%) were most likely to switch back, while those initiated on generic product under ANDA 040480 were least likely (24.1%). Of those episodes with switches to a generic under an ANDA of interest, about one-third (range 27.1% to 37.0%) switched back to the same product. These switches back had a median time to switch of about 30 days. CONCLUSIONS: These descriptive analyses, although subject to limitations, did not suggest increased switching away or switching back after use of the generics of interest. Continued post-marketing surveillance is warranted.

Different pharmacokinetics of lithium orotate inform why it is more potent, effective, and less toxic than lithium carbonate in a mouse model of mania.

Lithium carbonate (LiCO) is a mainstay therapeutic for the prevention of mood-episode recurrences in bipolar disorder (BD). Unfortunately, its narrow therapeutic index is associated with complications that may lead to treatment non-compliance. Intriguingly, lithium orotate (LiOr) is suggested to possess unique uptake characteristics that would allow for reduced dosing and mitigation of toxicity concerns. We hypothesized that due to differences in pharmacokinetics, LiOr is more potent with reduced adverse effects. Dose responses were established for LiOr and LiCO in male and female mice using an amphetamine-induced hyperlocomotion (AIH) model; AIH captures manic elements of BD and is sensitive to a dose-dependent lithium blockade. LiCO induced a partial block of AIH at doses of 15 mg/kg in males and 20 mg/kg in females. In contrast, LiOr elicited a near complete blockade at concentrations of just 1.5 mg/kg in both sexes, indicating improved efficacy and potency. Prior application of organic anion transport inhibitors, or inhibition of orotate uptake into the pentose pathway, completely blocked the effects of LiOr on AIH while sparing LiCO effects, confirming differences in transport and compartmentalization between the two compounds. Next, the relative toxicities of LiOr and LiCO were contrasted after 14 consecutive daily administrations. LiCO, but not LiOr, elicited polydipsia in both sexes, elevated serum creatinine levels in males, and increased serum TSH expression in females. LiOr demonstrates superior efficacy, potency, and tolerability to LiCO in both male and female mice because of select transport-mediated uptake and pentose pathway incorporation.

Risk of Major Malformations in Infants After First-Trimester Exposure to Stimulants: Results From the Massachusetts General Hospital National Pregnancy Registry for Psychiatric Medications.

PURPOSE/BACKGROUND: The prevalence of attention-deficit/hyperactivity disorder in adult females is 3% to 4%. Attention-deficit/hyperactivity disorder is highly comorbid with other psychiatric disorders such as mood, anxiety, and substance use disorders. For reproductive-aged women, the treatment of attention-deficit/hyperactivity disorder with stimulant medications may be considered during pregnancy or breastfeeding, although historically, data are lacking to inform these decisions. The aim of this investigation was to determine the risk of major malformations in infants after first-trimester prescription stimulant exposure in a small but rigorously characterized sample. METHODS/PROCEDURES: The Massachusetts General Hospital National Pregnancy Registry for Psychiatric Medications systematically ascertains information from pregnant females including demographic information, medical and psychiatric history, use of prescription medications, and other information relevant to fetal outcomes. Participants provide verbal informed consent and are interviewed twice during gestation and again at approximately 3 months postpartum. The primary outcome of interest is the presence of a major malformation identified within 6 months after birth. Redacted cases of major malformations are reviewed by a dysmorphologist blinded to medication exposure. FINDINGS/RESULTS: A total of N = 1988 women were eligible for this analysis, including the following exposures: n = 173 to mixed amphetamine salts; n = 40 to lisdexamfetamine; n = 45 to methylphenidate; n = 3 to dexmethylphenidate; and n = 1755 controls. The odds ratio of a major malformation among infants after first-trimester exposure to any stimulant was 0.39 (95% confidence interval, 0.09-1.61) compared with controls. There were no major malformations observed in infants exposed to lisdexamfetamine, methylphenidate, or dexmethylphenidate. IMPLICATIONS/CONCLUSIONS: Although preliminary, this analysis from an ongoing pregnancy registry provides reassurance that these stimulants do not appear to have major teratogenic effects. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT01246765 .

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.

Polyunsaturated fatty acids (PUFA) for attention deficit hyperactivity disorder (ADHD) in children and adolescents.

BACKGROUND: Attention deficit hyperactivity disorder (ADHD) is a major problem in children and adolescents, characterised by age-inappropriate levels of inattention, hyperactivity, and impulsivity, and is associated with long-term social, academic, and mental health problems. The stimulant medications methylphenidate and amphetamine are the most frequently used treatments for ADHD, but these are not always effective and can be associated with side effects. Clinical and biochemical evidence suggests that deficiencies of polyunsaturated fatty acids (PUFA) could be related to ADHD. Research has shown that children and adolescents with ADHD have significantly lower plasma and blood concentrations of PUFA and, in particular, lower levels of omega-3 PUFA. These findings suggest that PUFA supplementation may reduce the attention and behaviour problems associated with ADHD. This review is an update of a previously published Cochrane Review. Overall, there was little evidence that PUFA supplementation improved symptoms of ADHD in children and adolescents. OBJECTIVES: To compare the efficacy of PUFA to other forms of treatment or placebo in treating the symptoms of ADHD in children and adolescents. SEARCH METHODS: We searched 13 databases and two trials registers up to October 2021. We also checked the reference lists of relevant studies and reviews for additional references. SELECTION CRITERIA: We included randomised and quasi-randomised controlled trials that compared PUFA with placebo or PUFA plus alternative therapy (medication, behavioural therapy, or psychotherapy) with the same alternative therapy alone in children and adolescents (aged 18 years and under) diagnosed with ADHD. DATA COLLECTION AND ANALYSIS: We used standard Cochrane methods. Our primary outcome was severity or improvement of ADHD symptoms. Our secondary outcomes were severity or incidence of behavioural problems; quality of life; severity or incidence of depressive symptoms; severity or incidence of anxiety symptoms; side effects; loss to follow-up; and cost. We used GRADE to assess the certainty of evidence for each outcome. MAIN RESULTS: We included 37 trials with more than 2374 participants, of which 24 trials were new to this update. Five trials (seven reports) used a cross-over design, while the remaining 32 trials (52 reports) used a parallel design. Seven trials were conducted in Iran, four each in the USA and Israel, and two each in Australia, Canada, New Zealand, Sweden, and the UK. Single studies were conducted in Brazil, France, Germany, India, Italy, Japan, Mexico, the Netherlands, Singapore, Spain, Sri Lanka, and Taiwan. Of the 36 trials that compared a PUFA to placebo, 19 used an omega-3 PUFA, six used a combined omega-3/omega-6 supplement, and two used an omega-6 PUFA. The nine remaining trials were included in the comparison of PUFA to placebo, but also had the same co-intervention in the PUFA and placebo groups. Of these, four trials compared a combination of omega-3 PUFA plus methylphenidate to methylphenidate. One trial each compared omega-3 PUFA plus atomoxetine to atomoxetine; omega-3 PUFA plus physical training to physical training; and an omega-3 or omega-6 supplement plus methylphenidate to methylphenidate; and two trials compared omega-3 PUFA plus dietary supplement to dietary supplement. Supplements were given for a period of between two weeks and six months. Although we found low-certainty evidence that PUFA compared to placebo may improve ADHD symptoms in the medium term (risk ratio (RR) 1.95, 95% confidence interval (CI) 1.47 to 2.60; 3 studies, 191 participants), there was high-certainty evidence that PUFA had no effect on parent-rated total ADHD symptoms compared to placebo in the medium term (standardised mean difference (SMD) -0.08, 95% CI -0.24 to 0.07; 16 studies, 1166 participants). There was also high-certainty evidence that parent-rated inattention (medium-term: SMD -0.01, 95% CI -0.20 to 0.17; 12 studies, 960 participants) and hyperactivity/impulsivity (medium-term: SMD 0.09, 95% CI -0.04 to 0.23; 10 studies, 869 participants) scores were no different compared to placebo. There was moderate-certainty evidence that overall side effects likely did not differ between PUFA and placebo groups (RR 1.02, 95% CI 0.69 to 1.52; 8 studies, 591 participants). There was also moderate-certainty evidence that medium-term loss to follow-up was likely similar between groups (RR 1.03, 95% CI 0.77 to 1.37; 13 studies, 1121 participants). AUTHORS' CONCLUSIONS: Although we found low-certainty evidence that children and adolescents receiving PUFA may be more likely to improve compared to those receiving placebo, there was high-certainty evidence that PUFA had no effect on total parent-rated ADHD symptoms. There was also high-certainty evidence that inattention and hyperactivity/impulsivity did not differ between PUFA and placebo groups. We found moderate-certainty evidence that overall side effects likely did not differ between PUFA and placebo groups. There was also moderate-certainty evidence that follow-up was similar between groups. It is important that future research addresses the current weaknesses in this area, which include small sample sizes, variability of selection criteria, variability of the type and dosage of supplementation, and short follow-up times.

Do ADHD Treatments Improve Executive Behavior Beyond Core ADHD Symptoms in Adults? Evidence From Systematic Analysis of Clinical Trials.

We sought to understand the effect of current treatments for attention deficit hyperactivity disorder (ADHD) on executive functioning deficits, which are often comorbid with ADHD, via a systematic analysis of adult ADHD treatment studies evaluating change in behavioral measures beyond the core symptoms of Diagnostic and Statistical Manual of Mental Disorders ADHD. The standardized mean difference for behavioral measures of executive functioning was determined from controlled trials of adults with ADHD and compared with effects on core ADHD symptoms. Several studies of atomoxetine revealed small to large standardized mean differences. Nonreplicated studies revealed small to medium effects for triple-bead mixed amphetamine salts, lisdexamfetamine, and forms of cognitive behavioral therapy. Proportional effect versus core ADHD symptoms ranged from 0.78 to 1.16 for atomoxetine, and from 0.65 to 1.44 across all the studies. ADHD treatments have effects on executive functioning behavior beyond core ADHD symptoms in adults. Clinicians can measure and treat this morbidity using available clinical tools.

The rising threat of illicit amphetamine-type stimulant use among methadone maintenance treatment patients in East Coast Malaysia: a retrospective observational study.

Background: In recent years, amphetamine-type-stimulants (ATS) have been extensively misused in South-East Asia, inducing major problems among methadone-maintenance-treatment (MMT) patients.Objective: We examine ATS-misuse prevalence and its determinants among MMT patients in East-Coast-Malaysia.Methods: A retrospective-observational study was conducted on government-subsidized medication for opioid-use-disorder (MOUD) treatment clinics involving 292 MMT-patients (98% males) who were selected using a multilevel-proportional-stratified random sampling technique. Information obtained during the mandatory monitoring procedure from January 1 to December 31 2019, was utilized to determine ATS misuse prevalence from consecutive random urine drug screening. The determinants associated with its use, namely sociodemographics, social networks, comorbidities, and pharmacological assessments were analyzed via a logistic model.Results: Overall, 52.2% of the MMT-patients (95% CI: 0.42-0.54) had misused ATS at least once during their methadone treatment. These misusing patients were active smokers, hepatitis B and C seronegative, concurrently misused opioids, and had received suboptimum prescribed doses of methadone. Multiple logistic regression analysis demonstrated that the odds of misusing ATS during methadone treatment were 37 times higher among those who concurrently misused opioids (AOR: 37.60, 95% CI: 14.03-100.74) and 12 times higher among those who received suboptimal methadone doses (<60 mg/day) (AOR: 12.24, 95% CI: 5.58-25.43).Conclusion: This study demonstrated the significant prevalence of ATS misuse among MMT-patients in East-Coast-Malaysia, especially among patients who were prescribed suboptimal doses of methadone and/or demonstrated concomitant opioid-misuse. Stringent urine-monitoring is crucial to prevent diversion to ATS misuse. Nonetheless, to avoid negligence and improve physician engagement, the relevant authorities should immediately plan a comprehensive national-standard training module comprising support activities for professional methadone-prescribers.

Mixed Amphetamine Salts Without a Mood Stabilizer for Treating Comorbid Attention-Deficit Hyperactivity Disorder and Bipolar Disorder: Two Case Reports.

Attention-deficit hyperactivity disorder (ADHD) and bipolar disorder (BD) are often comorbid in patients and can have significant overlap in symptoms. Because of this common comorbidity and often overlapping symptoms, accurate diagnoses can be difficult. The standard treatment for these comorbid disorders is a mood stabilizer with the possibility of adding a psychostimulant. However, research suggesting treatment for comorbid disorders with a psychostimulant without a mood stabilizer is lacking. Here, we present two cases where mixed amphetamine salts, which are traditionally avoided in those with BD, were effectively used without a mood stabilizer to treat comorbid BD and ADHD in both patients. The outcome of this case series serves to motivate future investigations which are needed to validate treatment with a psychostimulant without a mood stabilizer for the treatment of comorbid BD and ADHD.

Characteristics of Amphetamine Psychosis with Respect to the Length of Drug Exposure.

BACKGROUND: Over the past decade, the number of individuals requiring medical care for amphetamine-related psychosis has increased. OBJECTIVE: This study aims to examine the psychological characteristics of amphetamine psychosis in drug-addicted patients depending on the length of drug exposure and compared to patients diagnosed with paranoid schizophrenia. METHODS: The study was carried out in psychiatric clinic No. 1 in Kyiv (Ukraine) in 2019, involving 107 patients. Of all the participants, 50 were included in Group 1 (methamphetamine psychosis) and 57 - in Group 2 (paranoid schizophrenia). All patients were treated with medication to relieve exacerbating symptoms. They underwent extensive testing to determine the impairment severity of cognitive function, attention, and task performance during remission. RESULTS: In Group 1, the timing of onset for paranoid symptoms depends on the length of amphetamine exposure (Spearman correlation coefficient = 0.89). The efficacy and dynamics of drug treatment in Group 2 were similar to patients in Group 1. However, the effect of reduction in Group 2 was achieved only in 4 months. Delusions, emotional disturbances, hallucinations in patients of Group 1 occurred 2.3 times more frequently than in Group 2 (p ≤ 0.05). The patients of Group 1 are characterized by the presence of disorders related to the affective and behavioral components. CONCLUSION: All reported exacerbations are related to amphetamine use. Patients in Group 1 learned a smaller number of words compared to those in Group 2. Besides, a large number of errors and difficulties with shifting focus were recorded.

The effect of selective nigrostriatal dopamine excess on behaviors linked to the cognitive and negative symptoms of schizophrenia.

Excess dopamine release in the dorsal striatum (DS) is linked to psychosis. Antipsychotics are thought to work by blocking striatal D2 dopamine receptors, but they lack efficacy for the negative and cognitive symptoms of schizophrenia. These observations and the fact that increasing brain-wide dopamine improves cognition have fueled the dogma that excess dopamine is not involved in negative and cognitive symptoms. However, this idea has never been explicitly tested with DS-pathway specificity. To determine if excess DS dopamine is involved in cognitive and negative symptoms, we selectively re-expressed excitatory TRPV1 receptors in DS-projecting dopamine neurons of Trpv1 knockout mice. We treated these mice with capsaicin (TRPV1 agonist) to selectively activate these neurons, validated this approach with fiber photometry, and assessed its effects on social interaction and working memory, behavioral constructs related to negative and cognitive symptoms. We combined this manipulation with antipsychotic treatment (haloperidol) and compared it to brain-wide dopamine release via amphetamine treatment. We found that selectively activating DS-projecting dopamine neurons increased DS (but not cortical) dopamine release and increased locomotor activity. Surprisingly, this manipulation also impaired social interaction and working memory. Haloperidol normalized locomotion, but only partially rescued working memory and had no effect on social interaction. By contrast, amphetamine increased locomotion but did not impair social interaction or working memory. These results suggest that excess dopamine release, when restricted to the DS, causes behavioral deficits linked to negative and cognitive symptoms. Future therapies should address this disregarded role for excess striatal dopamine in the treatment-resistant symptoms of psychosis.

Methamphetamine: Mechanism of Action and Chinese Herbal Medicine Treatment for Its Addiction / 中国结合医学杂志

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.

Acute Hyperkinetic Movement Disorders as a Multifactorial Pharmacodynamic Drug Interaction Between Methylphenidate and Risperidone in Children and Adolescents.

PURPOSE/BACKGROUND: Acute hyperkinetic movement disorders have been reported with the concomitant use of attention-deficit/hyperactivity disorder (ADHD) stimulants and antipsychotics in children and adolescents. We analyzed postmarketing reports of suspected acute hyperkinetic movement disorder associated with concomitant use of ADHD stimulants and antipsychotics. METHODS/PROCEDURES: We searched for postmarketing reports of acute hyperkinetic movement disorders associated with concomitant use of ADHD stimulants-antipsychotics in the US Food and Drug Administration Adverse Event Reporting System through December 6, 2019. PubMed and EMBASE were also searched for acute hyperkinetic movement reports with the concomitant use of ADHD stimulants-antipsychotics through January 13, 2020. FINDINGS/RESULTS: We identified 36 cases resulting in acute hyperkinetic movement disorder associated with the concomitant use of ADHD stimulants-antipsychotics, 19 of which were also identified in the medical literature. From an ADHD stimulant perspective, methylphenidate products accounted for the largest number of cases (n = 23 [64%]), followed by amphetamine products (n = 9 [25%]) and atomoxetine (n = 4 [11%]). From an antipsychotic perspective, all 36 cases were reported with second-generation antipsychotics, particularly risperidone (n = 20 [56%]). Most of the cases were reported in boys (n = 31 [86%]) aged 6 to 12 years (n = 27 [75%]). Approximately 53% of the cases reported a time to onset within 24 hours of the drug change. Acute dystonic reactions (n = 27 [75%]) were the most frequently reported movement disorder. IMPLICATIONS/CONCLUSIONS: As outlined in changes to the US prescribing information for all methylphenidate and risperidone products, health care professionals should be aware that changes to this combination may be associated with a pharmacodynamic drug-drug interaction resulting in acute hyperkinetic movement disorder.

Amphetamine-induced dopamine release and impulsivity in Parkinson's disease.

Impulsive-compulsive behaviours manifest in a substantial proportion of subjects with Parkinson's disease. Reduced ventral striatum dopamine receptor availability, and increased dopamine release is noted in patients with these symptoms. Prior studies of impulsivity suggest that midbrain D2 autoreceptors regulate striatal dopamine release in a feedback inhibitory manner, and in healthy populations, greater impulsivity is linked to poor proficiency of this inhibition. This has not been assessed in a Parkinson's disease population. Here, we applied 18F-fallypride PET studies to assess striatal and extrastriatal D2-like receptor uptake in a placebo-controlled oral dextroamphetamine sequence. We hypothesized that Parkinson's disease patients with impulsive-compulsive behaviours would have greater ventral striatal dopaminergic response to dextroamphetamine, and that an inability to attenuate ventral striatal dopamine release via midbrain D2 autoreceptors would underlie this response. Twenty patients with Parkinson's disease (mean age = 64.1 ± 5.8 years) both with (n = 10) and without (n = 10) impulsive-compulsive behaviours, participated in a single-blind dextroamphetamine challenge (oral; 0.43 mg/kg) in an OFF dopamine state. All completed PET imaging with 18F-fallypride, a high-affinity D2-like receptor ligand, in the placebo and dextroamphetamine state. Both voxelwise and region of interest analyses revealed dextroamphetamine-induced endogenous dopamine release localized to the ventral striatum, and the caudal-medial orbitofrontal cortex. The endogenous dopamine release observed in the ventral striatum correlated positively with patient-reported participation in reward-based behaviours, as quantified by the self-reported Questionnaire for Impulsivity in Parkinson's disease Rating Scale. In participants without impulsive-compulsive behaviours, baseline midbrain D2 receptor availability negatively correlated with ventral striatal dopamine release; however, this relationship was absent in those with impulsive-compulsive behaviours. These findings emphasize that reward-based behaviours in Parkinson's disease are regulated by ventral striatal dopamine release, and suggest that loss of inhibitory feedback from midbrain autoreceptors may underlie the manifestation of impulsive-compulsive behaviours.