Stimulant psychosis: systematic review

Gene-environment interplay in the etiology of psychosis

Schizophrenia and other types of psychosis incur suffering, high health care costs and loss of human potential, due to the combination of early onset and poor response to treatment. Our ability to prevent or cure psychosis depends on knowledge of causal mechanisms. Molecular genetic studies show that thousands of common and rare variants contribute to the genetic risk for psychosis. Epidemiological studies have identified many environmental factors associated with increased risk of psychosis. However, no single genetic or environmental factor is sufficient to cause psychosis on its own. The risk of developing psychosis increases with the accumulation of many genetic risk variants and exposures to multiple adverse environmental factors. Additionally, the impact of environmental exposures likely depends on genetic factors, through gene-environment interactions. Only a few specific gene-environment combinations that lead to increased risk of psychosis have been identified to date. An example of replicable gene-environment interaction is a common polymorphism in the AKT1 gene that makes its carriers sensitive to developing psychosis with regular cannabis use. A synthesis of results from twin studies, molecular genetics, and epidemiological research outlines the many genetic and environmental factors contributing to psychosis. The interplay between these factors needs to be considered to draw a complete picture of etiology. To reach a more complete explanation of psychosis that can inform preventive strategies, future research should focus on longitudinal assessments of multiple environmental exposures within large, genotyped cohorts beginning early in life.

Methamphetamine psychosis: insights from the past

BACKGROUND AND AIMS

To review early case reports and experimental inductions of amphetamine and methamphetamine psychosis, prior to the prohibition of these drugs, to gain a better understanding of the nature and aetiology of methamphetamine psychosis.

METHODS

Papers considered were historical case reports and case series of psychosis relating to the use and misuse of prescription amphetamine, focusing upon papers by Young & Scoville (1938), Connell (1958), and three subsequent experimental studies published in the early 1970s (Griffith 1972, Angrist & Gershon 1970 and Bell 1973), where psychosis was induced in volunteers using high-dose amphetamine and methamphetamine.

RESULTS

High-dose methamphetamine and amphetamine can result in a paranoid psychosis which remits rapidly (within days) of discontinuing use. The central feature is paranoia occurring in a clear state of consciousness. This may be accompanied by other psychotic symptoms (e.g. hallucinations). Pre-existing schizophrenia is not necessary, and the syndrome is not due to sleep deprivation.

CONCLUSIONS

Research findings from the 1930s to the 1970s suggest that paranoid psychosis should be considered a probable consequence of high-dose methamphetamine use. Individuals who experience psychotic symptoms for any substantive period after intoxication has ended should be suspected of having a functional non-organic psychosis, or a latent vulnerability thereto.

The relationship between illicit amphetamine use and psychiatric symptom profiles in schizophrenia and affective psychoses

This study examines whether illicit amphetamine use is associated with differences in the prevalence of specific psychiatric symptoms in a community sample of individuals diagnosed with schizophrenia or affective psychotic disorders. Data was drawn from the Australian Survey of High Impact Psychosis. The Diagnostic Interview for Psychosis was used to measure substance use and psychiatric symptoms. Participants had used amphetamine within their lifetime and had an ICD-10 diagnosis of schizophrenia (n = 347) or an affective psychotic disorder (n = 289). The past year prevalence of psychiatric symptoms was compared among those who had used amphetamine in the past year (past-year use, 32%) with those who had not (former use, 68%). Univariate logistic regression analysis indicated that past-year users with schizophrenia had a significantly higher past year prevalence of hallucinations, persecutory delusions, racing thoughts, dysphoria, and anhedonia relative to former amphetamine users with schizophrenia. There were no significant differences in symptoms between past-year and former users with affective psychotic disorders. The relationship between amphetamine use and specific psychiatric symptoms varies across different psychotic disorders. Amphetamine use may hinder prognosis by exacerbating symptoms of schizophrenia through dopaminergic dysfunctions or depressive vulnerabilities, however, this needs to be confirmed by prospective longitudinal research.

A systematic review of risk factors for methamphetamine-associated psychosis

OBJECTIVE

Chronic methamphetamine use is commonly associated with the development of psychotic symptoms. The predictors and correlates of methamphetamine-associated psychosis are poorly understood. We sought to systematically review factors associated with psychotic symptoms in adults using illicit amphetamine or methamphetamine.

METHODS

A systematic literature search was performed on MEDLINE (OVID), PsycINFO and EMBASE databases from inception to 8 December 2016. The search strategy combined three concept areas: methamphetamine or amphetamine, psychosis and risk factors. Included studies needed to compare adults using illicit methamphetamine or amphetamine, using a validated measure of psychosis, on a range of risk factors. Of 402 identified articles, we removed 45 duplicates, 320 articles based on abstract/title and 17 ineligible full-text articles, leaving 20 included studies that were conducted in 13 populations. Two co-authors independently extracted the following data from each study: country, setting and design; participant demographic and clinical details; sample size; measure/s used and measures of association between psychosis outcomes and risk factors. Individual study quality was assessed using a modified Newcastle-Ottawa Scale, and strength of evidence was assessed using GRADE criteria.

RESULTS

Frequency of methamphetamine use and severity of methamphetamine dependence were consistently found to be associated with psychosis, and sociodemographic factors were not. There was inconsistent evidence available for all other risk factors. Individual study quality was low-moderate for the majority of studies. Heterogeneity in study outcomes precluded quantitative synthesis of outcomes across studies.

CONCLUSION

The most consistent correlates of psychotic symptoms were increased frequency of methamphetamine use and dependence on methamphetamine. The findings of this review highlight the need for targeted assessment and treatment of methamphetamine use in individuals presenting with psychosis.

Drug-related predictors of readmission for schizophrenia among patients admitted to treatment for drug use disorders

BACKGROUND

Patients with schizophrenia and comorbid drug use disorders (DUD) have a severe course of illness. Despite strong evidence that drug use can exacerbate psychotic symptoms, we have limited knowledge of how specific drugs may increase risk of schizophrenia readmission in this group. This study aimed to assess drug-related predictors of readmission for schizophrenia among a national cohort of patients with a history of schizophrenia admitted to DUD treatment.

METHODS

A record-linkage study was used to assess drug-related factors associated with readmission to mental health treatment for schizophrenia, using a consecutive cohort of 634 patients admitted to DUD treatment between 2000 and 2006 in Danish treatment services and tracked until February 2013 or death, controlling for baseline psychiatric treatment variables.

RESULTS

The majority of patients were males (79.8%) and the mean age was 34.7years. Of all patients, 78.7% were readmitted for schizophrenia during follow-up, and 6.8% died without having been readmitted. We found a robust association between use of amphetamine at baseline and elevated risk of readmission, a less robust association between use of cannabis and elevated risk of readmission, and no association with cocaine, opioids, alcohol, benzodiazepines, and MDMA. Furthermore, one or more psychiatric inpatients visit in the year prior to DUD admission was robustly associated with elevated risk of schizophrenia readmission.

CONCLUSIONS

Use of amphetamine and cannabis are risk markers for schizophrenia readmission among patients with a history of schizophrenia and DUD. Psychiatric history is a predictor of schizophrenia readmission in this patient group.

Amphetamine-Induced Striatal Dopamine Release Measured With an Agonist Radiotracer in Schizophrenia

BACKGROUND

Receptor imaging studies have reported increased amphetamine-induced dopamine release in subjects with schizophrenia (SCH) relative to healthy control subjects (HCs). A limitation of these studies, performed with D2/3 antagonist radiotracers, is the failure to provide information about D2/3 receptors configured in a state of high affinity for the agonists (i.e., D2/3 receptors coupled to G proteins [D2/3 HIGH]). The endogenous agonist dopamine binds with preference to D2/3 HIGH receptors relative to D2/3 LOW receptors, making it critical to understand the status of D2/3 HIGH receptors in SCH.

METHODS

D2/3 agonist positron emission tomography radiotracer [11C]N-propyl-norapomorphine ([11C]NPA) binding potential (BPND) was measured in 14 off-medication subjects with SCH and 14 matched HCs at baseline and after the administration of 0.5 mg kg-1 oral D-amphetamine. The amphetamine-induced change in BPND (ΔBPND) was calculated as the difference between BPND in the postamphetamine condition and BPND in the baseline condition and was expressed as a percentage of BPND at baseline.

RESULTS

A trend-level increase was observed in comparing baseline [11C]NPA BPND (repeated-measures analysis of variance, F1,26 = 3.34, p = .08) between the SCH and HC groups. Amphetamine administration significantly decreased BPND in all striatal regions across all subjects in both groups. No differences were observed in [11C]NPA ΔBPND (repeated-measures analysis of variance, F1,26 = 1.9, p = .18) between HCs and subjects with SCH. Amphetamine significantly increased positive symptoms in subjects with SCH (19.5 ± 5.3 vs. 23.7 ± 4.1, paired t test, p < .0001); however, no correlations were noted with [11C]NPA BPND or ΔBPND.

CONCLUSIONS

This study provides in vivo indication of a role for postsynaptic factors in amphetamine-induced psychosis in SCH.

Acquisition of nicotine self-administration in amphetamine and phencyclidine models of schizophrenia: A role for stress?

Nicotine use and dependence is very high in patients with schizophrenia. One possible reason is that altered dopamine or glutamate activity in schizophrenia enhances the reinforcing effectiveness of nicotine. We used animal models to test the hypothesis that a hyperdopaminergic state (induced by repeated intermittent injections of amphetamine) or altered glutamate function (subchronic injection of phencyclidine, PCP) facilitates spontaneous acquisition of nicotine self-administration in rats. In Experiment 1 animals in an amphetamine-induced sensitized state (AISS) did not differ from saline-injected controls in their acquisition and maintenance of nicotine self-administration. This effect was replicated in experiment 2, but it was also found that AISS rats and saline-injected controls showed higher rates of nicotine self-administration compared to uninjected controls. This difference was maintained across several fixed ratio and progressive ratio schedules of reinforcement. In Experiment 3 PCP treated rats and their saline-injected controls did not differ in nicotine self-administration. However, both groups showed consistently increased responding for nicotine on FR and PR schedules compared to an uninjected control group. Injection-stress appeared to influence the outcomes of these experiments in two ways. Firstly, injection stress potentially masked the impact of the AISS and PCP treatment on nicotine self-administration. Secondly, injection stress itself may have been sufficient to induce plastic changes in dopamine and glutamate systems, and these changes enhanced the acquisition and maintenance of nicotine self-administration. Further investigation is needed into the role of stress in the development of nicotine use and dependence, in the aetiology of schizophrenia and in their co-morbidity.

Distress and sleep quality in young amphetamine-type stimulant users with an affective or psychotic illness

Misuse of amphetamine-type stimulant (ATS) drugs may disrupt key neurodevelopmental processes in young people and confer protracted neurocognitive and psychopathological harm. ATS users with a co-occurring psychiatric illness are typically excluded from research, reducing generalisability of findings. Accordingly, we conducted a cross-sectional examination of key clinical, sleep, socio-occupational and neurocognitive measures in current, past and never users of ATS drugs who were accessing a youth mental health service (headspace) for affective- or psychotic-spectrum illnesses. Contrary to hypotheses, groups did not differ in psychotic symptomology, socio-occupational functioning or neurocognitive performance. Current ATS users were however significantly more distressed and reported poorer subjective sleep quality and greater subjective sleep disturbances than never users, with a trend toward greater depressive symptomology in current users. Regression analyses revealed that depressive symptoms, daily ATS use and socio-occupational functioning predicted distress, and depressive symptoms and distress predicted subjective sleep quality. Our findings suggest that distress and poor sleep quality reflect a particular pathophysiology among ATS-using patients, which may negatively impact treatment engagement. Delineating the factors that disrupt social and neurobiological development in young people (such as substance use) warrants further investigation, including longitudinal study.

The adverse consequences of mephedrone use: a case series

Aims and method

Mephedrone is a cathinone with amphetamine-like stimulant effects, and is a commonly used recreational drug. The adverse effects of mephedrone use have not been extensively studied. All individuals who self-presented between January and June 2010 to the emergency departments and acute mental health services in Edinburgh and Falkirk with adverse effects of self-reported mephedrone use were identified.

Results

Twenty cases were identified and analysed. Severe agitation was the most common presenting problem (70%), with 40% of individuals developing psychotic symptoms and a further 20% reporting low mood and suicidality. One person died by suicide.

Clinical implications

Mephedrone can produce amphetamine-like adverse psychological intoxication effects, particularly in those with a history of mental illness. Clinicians should consider advising patients on the adverse effects of mephedrone, where relevant.

Stimulant use still going strong

Amphetamines, cocaine and methylenedioxymethamphetamine (MDMA, ‘ecstasy’) have been prominent on the UK drugs scene over the past decade. Much cocaine is now in the form of ‘crack’, which produces particularly acute versions of well-known complications including paranoid psychosis, mood disorders and cardiovascular problems. Ecstasy has additional hallucinogenic properties, and the slightly different range of psychiatric effects can be long-lasting. Assessment for stimulant misuse should include drug screening more than is currently common in general settings. Management comprises psychosocial (particularly behavioural counselling) and pharmacological approaches. A wide range of dopaminergic and other medications have been studied in cocaine misuse, and specialised substitute prescribing may be appropriate for heavy amphetamine injecting. There has been recent focus on problems of dual diagnosis, with particular strategies required to address stimulant misuse by people with severe mental illnesses.

Stability of the diagnosis of first-episode drug-induced psychosis

Aims and method

To assess the stability of the diagnosis of first-episode drug-induced psychosis over a follow-up period of at least 2 years. Patients with no psychiatric history who had been discharged from in-patient care between January 2002 and April 2006 with a firm diagnosis of drug-induced psychosis were identified. Follow-up information for at least the next 2 years or until discharge from mental health services was collected retrospectively from psychiatric records.

Results

Nearly all of the patients who remained under psychiatric follow-up had a change in diagnosis, most commonly to a schizophreniform disorder. Those who were retained in follow-up had significantly longer index admissions than those discharged to primary care (P = 0.05).

Clinical implications

This study suggests that many individuals diagnosed with drug-induced psychosis are further diagnosed as having a functional psychosis, usually schizophreniform in nature. This is compatible with the suggestion that individuals diagnosed with drug-induced psychosis are experiencing either the effects of drug intoxication or an ordinary functional psychosis complicated by incidental drug use.

Latent Psychotic Symptom Profiles Amongst People Who Use Methamphetamine: What Do They Tell Us About Existing Diagnostic Categories?

The inability to distinguish clearly between methamphetamine-related psychosis and schizophrenia has led to the suggestion that "methamphetamine psychosis" does not represent a distinct diagnostic entity but rather that the drug has triggered a vulnerability to schizophrenia. We tested this possibility by exploring the latent class structure of psychotic symptoms amongst people who use the drug and examining how these latent symptom profiles correspond to a diagnosis of schizophrenia. Latent class analysis was carried out on the lifetime psychotic symptoms of 554 current methamphetamine users, of whom 40 met the DSM-IV criteria for schizophrenia. Lifetime diagnoses of schizophrenia and individual psychotic symptoms were assessed using the Composite International Diagnostic Interview. The chosen model found 22% of participants had a high propensity to experience a wide range of psychotic symptoms (schizophrenia-like), whereas the majority (56%) more specifically experienced persecutory delusions and hallucinations (paranoid psychosis) and had a lower probability of these symptoms than the schizophrenia-like class. A third class (22%) had a low probability of all symptoms, with the exception of 34% reporting persecutory delusions. Participants in the schizophrenia-like class were more likely to meet diagnostic criteria for schizophrenia (26 vs. 3 and 1% for each of the other classes, p < 0.001) but the diagnosis failed to encompass 74% of this group. These results are consistent with there being a distinction between schizophrenia and methamphetamine-related psychotic symptoms, both in terms of the propensity to experience psychotic symptoms, as well as the symptom profile; however, this distinction may not be captured well by existing diagnostic classifications.

SYVN1, an ERAD E3 Ubiquitin Ligase, Is Involved in GABAAα1 Degradation Associated with Methamphetamine-Induced Conditioned Place Preference

Abuse of methamphetamine (METH), a powerful addictive amphetamine-type stimulants (ATS), is becoming a global public health problem. The gamma-aminobutyric acid (GABA)ergic system plays a critical role in METH use disorders. By using rat METH conditioned place preference (CPP) model, we previously demonstrated that METH-associated rewarding memory formation was associated with the reduction of GABA_Aα1 expression in the dorsal straitum (Dstr), however, the underlying mechanism was unclear. In the present study, we found that METH-induced CPP formation was accompanied by a significant increase in the expression of Synovial apoptosis inhibitor 1 (SYVN1), an endoplasmic reticulum (ER)-associated degradation (ERAD) E3 ubiquitin ligase, in the Dstr. The siRNA knockdown of SYVN1 significantly increased GABA_Aα1 protein levels in both primary cultured neurons and rodent Dstr. Inhibition of proteasomal activity by MG132 and Lactacystin significantly increased GABA_Aα1 protein levels. We further found that SYVN1 knockdown increased GABA_Aα1 in the intra-ER, but not in the extra-ER. Accordingly, endoplasmic reticulum stress (ERS)-associated Glucose-regulated protein 78 (GRP78) and C/EBP homologous protein (CHOP) increased. Thus, this study revealed that SYVN1, as the ERAD E3 ubiquitin ligase, was associated with Dstr GABA_Aα1 degradation induced by METH conditioned pairing.

The synergistic effect of dual use of amphetamine-type stimulants and ketamine on drug-induced psychotic symptoms in Chinese synthetic drug users

The use of amphetamine-type stimulants (ATS) and ketamine is of particular clinical concern because of its associated psychotic symptoms. In Chinese clinical practice, ATS and ketamine are commonly used simultaneously, but very few studies have reported the symptom profile of users who use both drugs. This study determined whether the combined use of ATS and ketamine is associated with more psychotic symptoms than either ATS or ketamine alone. According to drug use characteristics, 375 Chinese synthetic drug users were categorized into 2 pairs of comparison groups: ATS-only (n=125) vs. ATS-mainly (ATS most of the time and ketamine sometimes, n=150) and ketamine-only (n=38) vs. ketamine-mainly (ketamine most of the time and ATS sometimes, n=62). We used the Chinese Brief Psychiatric Rating Scale (BPRS) to assess these patients’ psychotic symptoms. ATS-mainly group had more anxiety/depression and anergia symptoms than ATS-only group (p<0.001), and ketamine-mainly group had more thinking-disorder, activity and hostility-suspicion symptoms than ketamine-only group (p≤0.001). These findings indicate that ATS may exacerbate the thinking-disorders, activity and hostility-suspicion symptoms of ketamine users, and ketamine may exacerbate anxiety/depression and anergia symptoms of ATS users.

Quantitative exploration of factors influencing psychotic disorder ailments in Nigeria

In this data article, records on demographic data, family problem issues, as well as results of medical tests from five major classes of psychotic disorder namely: bipolar; vascular dementia, minimal brain dysfunction; insomnia; and schizophrenia, were collected on 500 psychotic patients carefully selected from the pool of medical records of Yaba Psychiatric Hospital, Lagos, Nigeria, for the period of 5 years, between January 2010 and December 2014, were examined. X-squared Statistic was used to examine each of psychotic disorders to identify demographic (age, gender, religion, marital status, and occupation) and family issues (loss of parent, history of such ailment in the family (family status), divorce, head injury, and heredity of such ailment (genetic) factors that influence them. A clear description on each of these psychotic disorders (bipolar; vascular dementia, minimal brain dysfunction (MBD), insomnia and Schizophrenia) was considered separately using tables and bar diagrams. Data analysis results are as follows: firstly, 40.2%, of the 500 psychotic patients tested positive to bipolar, 40.6% to insomnia, 75.0% to schizophrenia, 43.6% to MBD and 69.2% to vascular dementia. Secondly, female patients were more prone to all the psychotic indicators than their male counterpart except in MBD. Thirdly, the oldest age group (> 60 years) is more prone to bipolar and insomnia ailments, while the mid age group (30 - 60 years) is prone to schizophrenia and vascular dementia, and the youngest group (< 30 years) is prone to MBD. Lastly, the factors that influence the ailments are listed: bipolar (age, occupation, marital status, divorce, and spiritual consultation); insomnia (age, occupation, marital status, divorce, and spiritual consultation); schizophrenia (age, occupation, religion, marital status, hereditary, and divorce); MBD (gender, age, occupation, and marital status); and vascular dementia (history of the ailment and spiritual consultation). Bipolar and insomnia are influenced by the same set of factors, which implies that any patient having one is most likely to be at risk of having the other.

Glutamatergic deficit and schizophrenia-like negative symptoms: new evidence from ketamine-induced mismatch negativity alterations in healthy male humans

BACKGROUND

Targeting the N-methyl-D-aspartate receptor (NMDAR) is a major translational approach for treating negative symptoms of schizophrenia. Ketamine comprehensively produces schizophrenia-like symptoms, such as positive, cognitive and negative symptoms in healthy volunteers. The amplitude of the mismatch negativity (MMN) is known to be significantly reduced not only in patients with schizophrenia, but also in healthy controls receiving ketamine. Accordingly, it was the aim of the present study to investigate whether changes of MMN amplitudes during ketamine administration are associated with the emergence of schizophrenia-like negative symptoms in healthy volunteers.

METHODS

We examined the impact of ketamine during an MMN paradigm with 64-channel electroencephalography (EEG) and assessed the psychopathological status using the Positive and Negative Syndrome Scale (PANSS) in healthy male volunteers using a single-blind, randomized, placebo-controlled crossover design. Low-resolution brain electromagnetic tomography was used for source localization.

RESULTS

Twenty-four men were included in our analysis. Significant reductions of MMN amplitudes and an increase in all PANSS scores were identified under the ketamine condition. Smaller MMN amplitudes were specifically associated with more pronounced negative symptoms. Source analysis of MMN generators indicated a significantly reduced current source density (CSD) under the ketamine condition in the primary auditory cortex, the posterior cingulate and the middle frontal gyrus.

LIMITATIONS

The sample included only men within a tight age range of 20-32 years.

CONCLUSION

The MMN might represent a biomarker for negative symptoms in schizophrenia related to an insufficient NMDAR system and could be used to identify patients with schizophrenia with negative symptoms due to NMDAR dysfunction.

Association between alcohol, cannabis, and other illicit substance abuse and risk of developing schizophrenia: a nationwide population based register study

BACKGROUND

Several studies have examined whether use of substances can cause schizophrenia. However, due to methodological limitations in the existing literature (e.g. selection bias and lack of adjustment of co-abuse) uncertainties still remain. We aimed to investigate whether substance abuse increases the risk of developing schizophrenia, addressing some of these limitations.

METHOD

The longitudinal, nationwide Danish registers were linked to establish a cohort of 3 133 968 individuals (105 178 673 person-years at risk), identifying 204 505 individuals diagnosed with substance abuse and 21 305 diagnosed with schizophrenia. Information regarding substance abuse was extracted from several registers and did not include psychotic symptoms caused by substance abuse in the definition. This resulted in a large, generalizable sample of exposed individuals. The data was analysed using Cox regression analyses, and adjusted for calendar year, gender, urbanicity, co-abuse, other psychiatric diagnosis, parental substance abuse, psychiatric history, immigration and socioeconomic status.

RESULTS

A diagnosis of substance abuse increased the overall risk of developing schizophrenia [hazard ratio (HR) 6.04, 95% confidence interval (CI) 5.84-6.26]. Cannabis (HR 5.20, 95% CI 4.86-5.57) and alcohol (HR 3.38, 95% CI 3.24-3.53) presented the strongest associations. Abuse of hallucinogens (HR 1.86, 95% CI 1.43-2.41), sedatives (HR 1.68, 95% CI 1.49-1.90), and other substances (HR 2.85, 95% CI 2.58-3.15) also increased the risk significantly. The risk was found to be significant even 10-15 years subsequent to a diagnosis of substance abuse.

CONCLUSION

Our results illustrate robust associations between almost any type of substance abuse and an increased risk of developing schizophrenia later in life.

Classics in Chemical Neuroscience: Aripiprazole

Aripiprazole was the first antipsychotic developed to possess agonist properties at dopamine D₂ autoreceptors, a groundbreaking strategy that presented a new vista for schizophrenia drug discovery. The dopamine D₂ receptor is the crucial target of all extant antipsychotics, and all developed prior to aripiprazole were D₂ receptor antagonists. Extensive blockade of these receptors, however, typically produces extrapyramidal (movement) side effects, which plagued first-generation antipsychotics, such as haloperidol. Second-generation antipsychotics, such as clozapine, with unique polypharmacology and D₂ receptor binding kinetics, have significantly lower risk of movement side effects but can cause myriad additional ones, such as severe weight gain and metabolic dysfunction. Aripiprazole's polypharmacology, characterized by its unique agonist activity at dopamine D₂ and D₃ and serotonin 5-HT_1A receptors, as well as antagonist activity at serotonin 5-HT_2A receptors, translates to successful reduction of positive, negative, and cognitive symptoms of schizophrenia, while also mitigating risk of weight gain and movement side effects. New observations, however, link aripiprazole to compulsive behaviors in a small group of patients, an unusual side effect for antipsychotics. In this review, we discuss the chemical synthesis, pharmacology, pharmacogenomics, drug metabolism, and adverse events of aripiprazole, and we present a current understanding of aripiprazole's neurotherapeutic mechanisms, as well as the history and importance of aripiprazole to neuroscience.

[Nosospecific anxiety and a spectrum of anxiolytic activity of psychotropic drugs]

The article discusses the pathogenetic mechanisms of anxiety in different psychiatric disorders. The influence of anxiety on the course, pharmacotherapeutic treatment with respect to the pathogenesis and the possible neurochemical imbalance in the definite type of anxiety are discussed. An anti-anxiety effect in the action of psychotropic drugs is described. It is proposed that neurochemical disturbances are not the same with the various types of anxiety, which requires using drugs from various groups to achieve treatment of the symptom on the pathogenetic level. The various roles of anxiety in the course of different mental disorders is suggested.

Association Between Substance Use Diagnoses and Psychiatric Disorders in an Adolescent and Young Adult Clinic-Based Population

PURPOSE

Adolescents with substance use disorders are more likely to have a current psychiatric disorder. However, when compared with the adult literature, there is relatively limited information regarding the specific co-occurrence of certain mental health diagnoses and substance use disorders in adolescents. The objectives of this study were to build on the previous literature regarding mental health diagnoses and different types of substance use disorders in adolescents, as well as explore the differences, if any, between groupings of mental health diagnosis and type of substance used.

METHODS

Data were extracted from the clinical records of 483 individuals aged 11-24 years referred for an evaluation at the Adolescent Substance Abuse Program at Boston Children's Hospital. According to DSM-IV-Text Revision criteria, individuals received diagnoses of substance abuse or dependence and any additional psychiatric disorders. Problematic use was included within the sample for greater power analysis. A multivariable logistic regression model estimated the association between psychiatric diagnosis and substance use while adjusting for covariates including age and gender.

RESULTS

Multiple significant associations were found, including having any anxiety-related diagnosis and opioid use (odds ratio [OR] = 2.23, p < .001), generalized anxiety disorder and opioids (OR = 3.42, p = .008), cocaine and post-traumatic stress disorder (OR = 3.61, p = .01), and marijuana and externalizing behavior disorders (OR = 2.10, p = .024).

CONCLUSIONS

Our study found multiple significant associations between specific substances and certain co-occurring psychiatric disorders. The use of office screening systems to efficiently identify these youths should be a part of routine medical and psychiatric care.

Differences in the symptom profile of methamphetamine-related psychosis and primary psychotic disorders

We examined the lifetime experience of hallucinations and delusions associated with transient methamphetamine-related psychosis (MAP), persistent MAP and primary psychosis among a cohort of dependent methamphetamine users. Participants were classified as having (a) no current psychotic symptoms, (n=110); (b) psychotic symptoms only when using methamphetamine (transient MAP, n=85); (c) psychotic symptoms both when using methamphetamine and when abstaining from methamphetamine (persistent MAP, n=37), or (d) meeting DSM-IV criteria for lifetime schizophrenia or mania (primary psychosis, n=52). Current psychotic symptoms were classified as a score of 4 or more on any of the Brief Psychiatric Rating Scale items of suspiciousness, hallucinations or unusual thought content in the past month. Lifetime psychotic diagnoses and symptoms were assessed using the Composite International Diagnostic Interview. Transient MAP was associated with persecutory delusions and tactile hallucinations (compared to the no symptom group). Persistent MAP was additionally associated with delusions of reference, thought interference and complex auditory, visual, olfactory and tactile hallucinations, while primary psychosis was also associated with delusions of thought projection, erotomania and passivity. The presence of non-persecutory delusions and hallucinations across various modalities is a marker for persistent MAP or primary psychosis in people who use methamphetamine.

Additive Effects of Former Methylenedioxymethamphetamine and Cannabis Use on Subclinical Psychotic Symptoms

INTRODUCTION

Methylenedioxymethamphetamine (MDMA) is an amphetamine-derived psychostimulant, usually known as "ecstasy." The long-term neuropsychological effects of MDMA are examined in several studies with conflicting results. The most common findings reported are depression, anxiety, and memory and attention deficits. In addition to acute psychotic reactions observed after MDMA use, serotonergic and dopaminergic toxicities may increase the psychosis risk in the long-term. Cannabis usage among MDMA users is very high. The aim of this study was, therefore, to examine the additive effects of cannabis and MDMA on subclinical psychotic symptoms (SPS).

METHODS

Here, 131 healthy controls (hC), 54 former cannabis and MDMA users (C&M), and 46 former cannabis users (C) were evaluated for SPS. The definition of former user was based on the Munich Composite International Diagnostic Interview. The SPS scores were assessed by using the Schizotypal Personality Questionnaire (SPQ). The relationship between substance-free periods and total MDMA exposure with SPS was also examined.

RESULTS

The C&M group had higher levels of SPS than both C and hC groups. This is true not only for the total SPQ scores but both positive and negative schizotypy scores as well as cognitive-perceptual, disorganized, and interpersonal schizotypy scores aligned hierarchically in the 3 study groups (C&M>C>hC). The total MDMA exposure was positively correlated and MDMA-free period was negatively correlated with the SPS score.

CONCLUSION

We found that the former use of cannabis and MDMA is associated with marked elevation in SPS. Moreover, the exposure amount of MDMA and MDMA-free periods are important determinants of SPS. The longer the cannabis and ecstasy free periods, the larger is the waning of SPS.

Stimulants for impulsive violence in schizophrenia spectrum disordered women: a case series and brief review

High violence prevalence is a common concern for forensic psychiatric settings. Categorizing underlying drivers of violence has helped to direct treatment and management efforts toward psychotic, predatory, and impulsively violent psychopathology. This article describes a series of cases in which clozapine provided adequate control of psychosis in women suffering schizophrenia-spectrum disorders. Nevertheless, impulsive violence remained problematic. Add-on methylphenidate was found to be safe and effective in curbing impulsive violent behavior in this select group of patients.

Polysubstance-induced relapse of schizoaffective disorder refractory to high-dose antipsychotic medications: a case report

BACKGROUND

The high prevalence of comorbid illicit drug use in persons with chronic psychotic illness represents a strong determinant of psychotic relapse and rehospitalization. Epidemiological studies indicate changing patterns of illicit drug use in Australia, which are concerning because of increased use of crystal methamphetamine, also known as "ice." An important complication of habitual use of crystal methamphetamine is the development of a dose-dependent acute psychotic reaction. We report a case of an acute psychotic relapse in response to polydrug use most notable for multiple recent binges of crystal methamphetamine. Unlike previously described case reports, our patient's acute psychosis was refractory to ultra-high doses of multiple antipsychotic medications. This presented safety challenges due to the risk of serious side effects with high-dose antipsychotic medications.

CASE PRESENTATION

A 30-year-old white man with a past history of schizoaffective disorder was brought to our emergency department by the police in a state of extreme agitation, combativeness, and paranoia after use of cannabis and crystal methamphetamine. Despite existing compliance with zuclopenthixol decanoate depot medication, he required multiple emergency injections of zuclopenthixol acetate, and regular high-dose droperidol, chlorpromazine, and lorazepam. However, he remained severely agitated and psychotic with continuous threats of harm to others. A test of antipsychotic drug metabolism by cytochrome P450 enzymes did not reveal a pharmacogenetic cause for the poor therapeutic efficacy of antipsychotic medications. His psychosis did not appear to be modified by psychoactive medications but was instead self-limited to the presence of endogenous methamphetamine within his system. He fully recovered 96 to 120 hours post-presentation and was discharged home with out-patient clinic follow-up.

CONCLUSIONS

The current case highlights the challenging nature of a severe psychotic relapse precipitated by illicit substances that is resistant to medical management. High doses of multiple antipsychotic medications may be required to manage dangerous behaviors associated with these acute psychotic relapses. These patients require close monitoring for adverse effects with adjustment of dosing to ensure the optimal balance of risk versus benefit while the patient is acutely psychotic. The results are of relevance for the management of psychiatric emergencies in emergency departments and acute mental health settings.

Methamphetamine-Associated Psychosis and Treatment With Haloperidol and Risperidone: A Pilot Study

BACKGROUND

Different studies have suggested that antipsychotic medications of the first generation have better effectiveness for the treatment of psychotic symptoms compared with antipsychotic medications of the second generation.

OBJECTIVES

The current study was the first pilot study in Iran that compared Haloperidol with Risperidone in the treatment of positive symptoms of psychosis among a group of methamphetamine-dependent patients.

MATERIALS AND METHODS

This randomized clinical trial was designed and conducted in 2012. Overall, 44 patients who met the diagnostic and statistical manual of mental disorders, fourth edition-text revised (DSM.IV-TR) criteria for methamphetamine-associated psychosis (MAP) and were hospitalized at Razi psychiatric hospital in Tehran were selected. Patients (1: 1) were randomly divided to two groups. Overall, 22 subjects received Haloperidol (5 - 20 mg) and 22 subjects received Risperidone (2 - 8 mg). All subjects were assessed at baseline, during three consecutive weeks of treatment and one week after treatment (i.e., follow-up). Scale of assessment of positive symptoms (SAPS) was completed for each subject.

RESULTS

The study findings indicated that both Haloperidol (< 0.05) and Risperidone (< 0.05) were similarly applicable in the treatment of MAP but no differential effectiveness was found between the two medications. The treatment effects of both medications increased in the first two weeks of treatment and remained stable in the second two weeks.

CONCLUSIONS

Risperidone and Haloperidol are two effective antipsychotic medications for the treatment of positive symptoms of MAP but other aspects of these two neuroleptic medications such as the long-term treatment effects should be studied. Further studies with more samples and longer follow-ups are suggested.

Decreased Expression of Plasma MicroRNA in Patients with Methamphetamine (MA) Use Disorder

Recent research have revealed that circulating miRNAs may offer noninvasive biomarkers for human disease, offering the prospect for earlier diagnosis, and improved precision of diagnoses. The diagnoses of drug use disorders is still mainly based on subjective report and no objective biomarkers available. Many animal and cell studies found that miRNAs were involved in substance use disorders, including alcohol, morphine, cocaine and amphetamine use disorders. However, no study on circulating miRNAs for drug use disorders so far. We investigated the differential expression of plasma miRNAs in 124 patients with methamphetamine (MA) use disorders. Based on the preliminary results from microarray screen, plasma expression of 6 candidate miRNAs were measured by Quantitative real-time RT-PCR. We found that the expression of miR181a, miR15b, miR- let-7e, miR- let-7d in plasma were decreased compared to normal controls. The expression of the altered miRNAs were negative correlated with drug use frequencies in past months. Our findings suggested that miR-181a, miR-15b, miR-let-7e and miR-let-7d may play a potential role in the pathology of MA use disorder, and could serve as a potential peripheral biomarker for MA use disorder when confirmed by future studies. Further study are needed to elucidate the molecular mechanism modulated by miRNAs and explore potential novel intervention targets.

Reduced Prefrontal Cortex Hemodynamic Response in Adults with Methamphetamine Induced Psychosis: Relevance for Impulsivity

Patients with methamphetamine abuse/dependence often exhibit high levels of impulsivity, which may be associated with the structural abnormalities and functional hypoactivities observed in the frontal cortex of these subjects. Although near-infrared spectroscopy (NIRS) is a simple and non-invasive method for characterizing the clinical features of various psychiatric illnesses, few studies have used NIRS to directly investigate the association between prefrontal cortical activity and inhibitory control in patients with methamphetamine-induced psychosis (MAP). Using a 24-channel NIRS system, we compared hemodynamic responses during the Stroop color-word task in 14 patients with MAP and 21 healthy controls matched for age, sex and premorbid IQ. In addition, we used the Barrett Impulsivity Scale-11 (BIS-11) to assess impulsivity between subject groups. The MAP group exhibited significantly less activation in the anterior and frontopolar prefrontal cortex accompanied by lower Stroop color-word task performance, compared with controls. Moreover, BIS-11 scores were significantly higher in the MAP group, and were negatively correlated with the hemodynamic responses in prefrontal cortex. Our data suggest that reduced hemodynamic responses in the prefrontal cortex might reflect higher levels of impulsivity in patients with MAP, providing new insights into disrupted inhibitory control observed in MAP.

Towards diagnostic markers for the psychoses

Psychotic disorders are currently grouped under broad phenomenological diagnostic rubrics. Researchers hope that progress in identifying aetiological mechanisms will ultimately enable more precise division of heterogeneous diagnoses into specific and valid subgroups. This goal has been an aim of psychiatry since the 19th century, when patients with general paresis were thought to have "insanity" similar to dementia praecox and manic depressive illness. Nowadays, the constructs of organic-induced and substance-induced psychotic disorder show that our diagnostic classification system already reflects, in part, aetiological factors. Most recently, gene copy number variation and autoimmunity have been associated with schizophrenia. We suggest how, on the basis of recent scientific advances, we can progress the identification of further putative subgroups and make the most of currently available interventions. Prompt diagnosis and treatment, and a more routine search for causes, could preserve function and improve outcome, and therefore be more acceptable to patients and carers.

Why young people's substance use matters for global health

During puberty, when young people are completing their education, transitioning into employment, and forming longer-term intimate relationships, a shift in emotional regulation and an increase in risky behaviour, including substance use, is seen. This Series paper considers the potential effects of alcohol, tobacco, and illicit drug use during this period on: social, psychological, and health outcomes in adolescence and young adulthood; role transitions, and later health and social outcomes of regular substance use initiated in adolescence; and the offspring of young people who use substances. We sourced consistent support for causal relations between substance use and outcomes and evidence of biological plausibility from different but complementary research designs. Many adverse health and social outcomes have been associated with different types of substance use. The major challenge lies in deciding which are causal. Furthermore, qualitatively different harms are associated with different substances, differences in life stage when these harms occur, and the quality of evidence for different substances and health outcomes varies substantially. The preponderance of evidence comes from a few high-income countries, thus whether the same social and health outcomes would occur in other countries and cultures is unclear. Nonetheless, the number of harms that are causally related to substance use in young people warrant high-quality research design interventions to prevent or ameliorate these harms.

Involvement of dorsal striatal α1-containing GABAA receptors in methamphetamine-associated rewarding memories

Rewarding memories induced by addictive drugs may contribute to persistent drug-seeking behaviors, which is an important contributing factor to drug addiction. However, the biological mechanisms underlying drug-associated rewarding memories have not yet been fully understood, especially the new synthetic drugs, such as amphetamine-type stimulants (ATS). In this study, using the rat-conditioned place preference (CPP) model, a classic animal model for the reward-associated effects of addictive drugs, we found that the expression level of GABAA α1 subunits was significantly decreased in the dorsal striatum (Dstr) after conditioned methamphetamine (METH) pairing, and no significant differences were observed in the other four rewarding memory-associated areas (medial prefrontal cortex (mPFC), nucleus accumbens (NAc), amygdala (Amy), and dorsal hippocampus (DH)). Intra-Dstr injection of either the GABAA receptor agonist muscimol or the specific α1GABAA receptor-preferring benzodiazepine (BDZ) agonist zolpidem significantly abolished METH CPP formation. Thus, this study extends previous findings by showing that GABAA receptors, particularly the α1-containing GABAA receptors, may be strongly implicated in METH-associated rewarding memories. This work provides us with a new perspective on the goal of treating ATS addiction.

Stimulant Medication and Psychotic Symptoms in Offspring of Parents With Mental Illness

BACKGROUND

Stimulants, such as methylphenidate, are among the most commonly used medications in children and adolescents. Psychotic symptoms have been reported as rare adverse reactions to stimulants but have not been systematically inquired about in most previous studies. Family history of mental illness may increase the vulnerability to drug-induced psychotic symptoms. We examined the association between stimulant use and psychotic symptoms in sons and daughters of parents with major mood and psychotic disorders.

METHODS

We assessed psychotic symptoms, psychotic-like experiences, and basic symptoms in 141 children and youth (mean ± SD age: 11.8 ± 4.0 years; range: 6-21 years), who had 1 or both parents with major depressive disorder, bipolar disorder, or schizophrenia, and of whom 24 (17.0%) had taken stimulant medication.

RESULTS

Psychotic symptoms were present in 62.5% of youth who had taken stimulants compared with 27.4% of participants who had never taken stimulants. The association between stimulant use and psychotic experiences remained significant after adjustment for potential confounders (odds ratio: 4.41; 95% confidence interval: 1.82-10.69; P = .001) and was driven by hallucinations occurring during the use of stimulant medication. A temporal relationship between use of stimulants and psychotic symptoms was supported by an association between current stimulant use and current psychotic symptoms and co-occurrence in cases that were assessed on and off stimulants.

CONCLUSIONS

Psychotic symptoms should be monitored during the use of stimulants in children and adolescents. Family history of mood and psychotic disorders may need to be taken into account when considering the prescription of stimulants.

Opioid abuse and hospitalization rates in patients with schizophrenia

BACKGROUND

Substance abuse worsens the course of schizophrenia, but it is not known whether or not there are differences between specific substances concerning their association with the hospitalizations of patients with schizophrenia.

AIMS

The primary aims of this study were to examine the possible associations between amphetamine, cannabis, and opioid abuse, and the risk of hospitalizations among patients with schizophrenia.

METHODS

The study population consisted of 146 patients with ICD-defined schizophrenia from two different geographical sites in Finland, and it included both inpatients and outpatients. Data were collected retrospectively from the patients' medical files. Substance abuse was defined as either harmful use or dependence according to ICD-10.

RESULTS

The cumulative prevalence of substance abuse was 10.9% (16/146) for cannabis, 8.9% (13/146) for amphetamine, and 4.1% (6/146) for opioids. Among patients with schizophrenia and abuse of any substance, the number of hospitalizations was about 1.5-fold when compared to those without substance abuse. The incidence rate ratio for hospitalizations was 2.9 (95% CI 2.47-3.63) for opioids, 2.0 (1.71-2.41) for amphetamine, and 1.6 (1.33-1.84) for cannabis, when compared with no abuse of each substance. The risk of hospitalizations was significantly higher for opioids when compared with amphetamine (p < 0.001) or cannabis (p < 0.001).

CONCLUSIONS

Harmful use or dependence of opioids among patients with schizophrenia is associated with significantly higher risk of hospitalizations than either harmful use or dependence of amphetamine or cannabis.

Prescription stimulant use is associated with earlier onset of psychosis

A childhood history of attention deficit hyperactivity disorder (ADHD) is common in psychotic disorders, yet prescription stimulants may interact adversely with the physiology of these disorders. Specifically, exposure to stimulants leads to long-term increases in dopamine release. We therefore hypothesized that individuals with psychotic disorders previously exposed to prescription stimulants will have an earlier onset of psychosis. Age of onset of psychosis (AOP) was compared in individuals with and without prior exposure to prescription stimulants while controlling for potential confounding factors. In a sample of 205 patients recruited from an inpatient psychiatric unit, 40% (n = 82) reported use of stimulants prior to the onset of psychosis. Most participants were prescribed stimulants during childhood or adolescence for a diagnosis of ADHD. AOP was significantly earlier in those exposed to stimulants (20.5 vs. 24.6 years stimulants vs. no stimulants, p < 0.001). After controlling for gender, IQ, educational attainment, lifetime history of a cannabis use disorder or other drugs of abuse, and family history of a first-degree relative with psychosis, the association between stimulant exposure and earlier AOP remained significant. There was a significant gender × stimulant interaction with a greater reduction in AOP for females, whereas the smaller effect of stimulant use on AOP in males did not reach statistical significance. In conclusion, individuals with psychotic disorders exposed to prescription stimulants had an earlier onset of psychosis, and this relationship did not appear to be mediated by IQ or cannabis.

Amphetamine-induced psychosis: Transition to schizophrenia and mortality in a small prospective sample

BACKGROUND AND OBJECTIVES

We investigated transition from amphetamine-induced psychosis (AIP) to schizophrenia.

METHODS

A sample of 28 individuals was identified while hospitalized for AIP. We reviewed their hospital records after six years.

RESULTS

During follow-up, seven individuals (25%) died and nine (32%) had moved from the area. Of the remaining 12, four individuals (25%) were diagnosed with schizophrenia. These individuals were, at baseline, characterized by fewer hallucinatory symptoms and more homelessness.

CONCLUSION AND SCIENTIFIC SIGNIFICANCE

Hospitalization for AIP was a relatively specific risk factor for schizophrenia and the mortality rate in AIP was high.

Using Intermediate Cognitive Endpoints to Facilitate Translational Research in Psychosis

Recent advances in the understanding of psychosis have uncovered potential for a paradigm shift in related drug discovery efforts. The study of psychosis is evolving from its origins in serendipity and empiricism to more formal, hypothesis driven accounts of the cognitive substrates underlying hallucinations and delusions. Recent evidence suggests that misattribution of salience and abnormal prediction error might underlie some forms of psychosis. If substantiated, such intermediate constructs could significantly facilitate translational research for drug discovery. Aberrant salience and prediction error can be assayed with simple tests of associative learning in both species, and a convincing back translation of effects, when combined with measures of neurotransmitter release and brain activity could for the first time allow robust, causal connections to be made between molecular mechanisms in rodents and symptoms in patients.

Striatal and extrastriatal dopamine release in the common marmoset brain measured by positron emission tomography and [(18)F]fallypride

Previous studies have demonstrated that patients with schizophrenia show greater sensitivity to psychostimulants than healthy subjects. Sensitization to psychostimulants and resultant alteration of dopaminergic neurotransmission in rodents has been suggested as a useful model of schizophrenia. This study sought to examine the use of methylphenidate as a psychostimulant to induce dopamine release and that of [(18)F]fallypride as a radioligand to quantify the release in a primate model of schizophrenia. Four common marmosets were scanned by positron emission tomography twice, before and after methylphenidate challenge, to evaluate dopamine release. Four other marmosets were sensitized by repeated methamphetamine (MAP) administration. Then, they were scanned twice, before and after methylphenidate challenge, to evaluate whether MAP-sensitization induced greater sensitivity to methylphenidate. We revealed a main effect of the methylphenidate challenge but not the MAP pretreatment on the striatal binding potential. These results suggest that methylphenidate-induced striatal dopamine release in the common marmoset could be evaluated by [(18)F]fallypride.

Differential patterns of blood oxygenation in the prefrontal cortex between patients with methamphetamine-induced psychosis and schizophrenia

Despite some slight differences in symptomatology, differential diagnosis of methamphetamine-induced psychosis (MAP) versus schizophrenia can be challenging because both disorders present a large overlap in their clinical symptoms. However, a recent study has shown that near-infrared spectroscopy (NIRS) performed during a cognitive task can be a powerful tool to differentiate between these two disorders. Here, we evaluated verbal fluency task performance during NIRS in 15 patients diagnosed with MAP and 19 with schizophrenia matched for age and sex. We used prefrontal probes and a 24-channel NIRS machine to measure the relative concentrations of oxyhaemoglobin every 0.1 s during the task. For each patient, the neurocognitive function and clinical psychopathology were evaluated using the Positive and Negative Symptom Scale (PANSS), and the Brief Assessment of Cognition in Schizophrenia (BACS). Oxyhaemoglobin changes in the prefrontal cortex were significantly higher in the MAP group compared to those in the schizophrenia group, particularly in the right dorsolateral prefrontal cortex. In contrast, we found no significant difference in PANSS and BACS scores. Our findings suggest that NIRS measurement could be applied to differentiate patients with MAP from those with schizophrenia, even in cases where clinical symptoms are similar.

The role of the GABA system in amphetamine-type stimulant use disorders

Abuse of amphetamine-type stimulants (ATS) has become a global public health problem. ATS causes severe neurotoxicity, which could lead to addiction and could induce psychotic disorders or cognitive dysfunctions. However, until now, there has been a lack of effective medicines for treating ATS-related problems. Findings from recent studies indicate that in addition to the traditional dopamine-ergic system, the GABA (gamma-aminobutyric acid)-ergic system plays an important role in ATS abuse. However, the exact mechanisms of the GABA-ergic system in amphetamine-type stimulant use disorders are not fully understood. This review discusses the role of the GABA-ergic system in ATS use disorders, including ATS induced psychotic disorders and cognitive dysfunctions. We conclude that the GABA-ergic system are importantly involved in the development of ATS use disorders through multiple pathways, and that therapies or medicines that target specific members of the GABA-ergic system may be novel effective interventions for the treatment of ATS use disorders.

Methamphetamine-sensitized rats show augmented dopamine release to methylphenidate stimulation: a positron emission tomography using [18F]fallypride

Previous studies demonstrated that patients with schizophrenia show greater sensitivity to psychostimulants than healthy subjects. Sensitization to psychostimulants and resultant alteration of dopaminergic neurotransmission in rodents have been suggested as a useful model of schizophrenia. This study was aimed to examine the use of methylphenidate as a psychostimulant to induce dopamine release and that of [18F]fallypride as a radioligand to estimate the release in a rat model of schizophrenia. Six rats were scanned by positron emission tomography (PET) twice before and after methylphenidate challenge to evaluate dopamine release. After the scans, these rats were sensitized by using repeated methamphetamine (MAP) administration. Then, they were re-scanned twice again before and after methylphenidate challenge to evaluate whether MAP-sensitized rats show greater sensitivity to methylphenidate. We revealed a main effect of MAP-pretreatment and that of metylphenidate challenge. We found that % change of distribution volume ratio after repeated administration of MAP was greater than that before sensitization. These results suggest that methylphenidate-induced striatal dopamine release increased after sensitization to MAP. PET scan using [18F]fallypride at methylphenidate-challenge may provide a biological marker for schizophrenia and be useful to diagnose schizophrenia.

Raising attention to attention deficit hyperactivity disorder in schizophrenia

Schizophrenia and attention deficit hyperactivity disorder (ADHD) are two psychiatric disorders with a negative impact on quality of life of individuals affected. Although they are classified into distinct disorders categories, attentional dysfunction is considered as a core feature in both conditions, either at the clinical then pathophysiological level. Beyond the obvious clinical overlap between these disorders, the Research Domain Criteria approach might offer an interesting perspective for disentangling common circuits underpinning both disorders. Hence, we review evidences regarding the overlap between schizophrenia and ADHD, at the clinical level, and at the level of underlying brain mechanisms. The evidence regarding the influence of environmental risk factors in the emergence of both disorders, and their developmental trajectories is also reviewed. Among these, we will try to elucidate the complex relationship between stimulants use and psychotic symptoms, discussing the potential role of ADHD medication in inducing psychosis or in exacerbating it. We aim that, taken together, these findings may promote further investigation with important implications both for clinicians and research. In fact, considering the amounting evidence on the overlap between schizophrenia and ADHD, the delineation of their boundaries might help in the decision for diagnosis and treatment. Moreover, it may help to promote interventions focused on the prevention of both schizophrenia and ADHD, by the reduction of recognized environmental risk factors.

Improper activation of D1 and D2 receptors leads to excess noise in prefrontal cortex

The dopaminergic system has been shown to control the amount of noise in the prefrontal cortex (PFC) and likely plays an important role in working memory and the pathophysiology of schizophrenia. We developed a model that takes into account the known receptor distributions of D1 and D2 receptors, the changes these receptors have on neuron response properties, as well as identified circuitry involved in working memory. Our model suggests that D1 receptor under-stimulation in supragranular layers gates internal noise into the PFC leading to cognitive symptoms as has been proposed in attention disorders, while D2 over-stimulation gates noise into the PFC by over-activation of cortico-striatal projecting neurons in infragranular layers. We apply this model in the context of a memory-guided saccade paradigm and show deficits similar to those observed in schizophrenic patients. We also show set-shifting impairments similar to those observed in rodents with D1 and D2 receptor manipulations. We discuss how the introduction of noise through changes in D1 and D2 receptor activation may account for many of the symptoms of schizophrenia depending on where this dysfunction occurs in the PFC.

Psychedelic symptoms of cannabis and cocaine use as a function of trait impulsivity

Trait impulsivity has been linked to addiction in humans. It has been suggested that drug users with high trait impulsivity levels are more sensitive to subjective drug intoxication. This study assessed whether subjective response to drugs differs between drug users with normal or high levels of trait impulsivity. Regular drug users (N = 122) received doses of cocaine HCl, cannabis, and placebo in a three-way crossover study. Their mood, dissociative state, and psychedelic symptoms were measured with subjective rating scales (CADDS, Bowdle, POMS). Trait impulsivity was assessed with the Barratt Impulsiveness Scale. Cannabis increased dissociation and psychedelic state, as well as fatigue, confusion, depression and anxiety, and decreased arousal, positive mood, vigor, friendliness, and elation. Cocaine increased dissociation, psychedelic state, vigor, friendliness, elation, positive mood, anxiety and arousal, while decreasing fatigue. Only a few subjective items revealed a drug × trait impulsivity interaction, suggesting that psychedelic symptoms were most intense in high impulsivity subjects. Trait impulsiveness ratings were negatively correlated with ratings of vigor (r = -.197) and positively correlated with ratings of loss of thought control (r = .237) during cannabis intoxication. It is concluded that a broad association between trait impulsivity and psychedelic subjective drug experience appears to be absent.

Stimulant use disorders in people with psychosis: a meta-analysis of rate and factors affecting variation

OBJECTIVE

Stimulant abuse and dependence often complicate the care of people with psychotic disorders. This study systematically reviews the prevalence estimates reported for stimulant abuse and dependence in people with psychotic disorders, and examines personal, clinical, regional and methodological factors which explain variation in these rates.

METHODS

PsychINFO, EMBASE and MEDLINE (1946-2013) were searched systematically for studies reporting on stimulant drug use disorders in representative samples of people with psychotic disorders. Random effects models estimated the pooled rate of a stimulant use disorder, defined to include stimulant abuse and stimulant dependence. Study characteristics associated with heterogeneity in rates of stimulant use disorder were examined by subgroup analyses for categorical variables, by meta-regression for continuous independent variables and by multiple meta-regression.

RESULTS

Sixty-four studies provided 68 estimates of lifetime or recent stimulant use disorders in 22,500 people with psychosis. The pooled rate of stimulant use disorder was 8.9% (95% CI 7.4%, 10.5%). Higher rates of stimulant use disorders were reported in studies of affective psychosis, studies from inpatient settings, studies from the USA and Australia, and studies with higher rates of cannabis disorder; in multiple meta-regression analysis these factors explained 68% of between-study variance. Rates of stimulant use disorder were stable over time, and unrelated to age, sex, stage of psychosis, type of stimulant drug or study methodology factors.

CONCLUSIONS

Reported rates of stimulant use disorder in people with psychosis are much higher than in the general population but vary widely and are associated with regional, service setting and clinical differences between studies. It is likely that stimulants contribute to the overall burden of psychosis, and that social and environmental factors combine with drug and illness-related factors to influence stimulant use in psychosis.

Cognitive changes in patients with acute phase psychosis--effects of illicit drug use

Illicit drug use may influence cognition in non-affective psychosis. Previous studies have shown better cognition in psychosis with illicit drug use as compared to psychosis only. Possibly, illicit drug using patients have more transient drug-related cognitive deficits. Thus, the aim of the present study was to examine cognitive change the first weeks after admission to a psychiatric emergency ward, expecting more cognitive improvement at follow-up in the illicit drug group as compared to psychosis only. Patients with acute non-affective psychosis with (26%) and without illicit drug use were examined at baseline (n=123) and follow-up (n=67), with alternative forms of the Repeatable Battery for the Assessment of Neuropsychological Status. Latent Growth Curve models, controlling for cognition at baseline and age differences between the groups, were used to analyze cognitive change. The illicit drug using patients showed the largest improvement in cognition, especially among the youngest patients. Younger patients with non-affective psychosis and illicit drug use showed more cognitive improvement the first weeks after acute psychosis as compared to psychosis only. This suggests that the illicit drug users constitute a sub-group with less stable cognitive deficits and less cognitive vulnerability.

Safety and pharmacokinetics of lisdexamfetamine dimesylate in adults with clinically stable schizophrenia: a randomized, double-blind, placebo-controlled trial of ascending multiple doses

To assess the safety and pharmacokinetics of lisdexamfetamine dimesylate (LDX), a d-amphetamine prodrug, this double-blind study enrolled adults with clinically stable schizophrenia who were adherent (≥12 weeks) to antipsychotic pharmacotherapy. The participants received placebo or ascending LDX doses (50, 70, 100, 150, 200, and 250 mg) daily for 5 days at each dose (dose periods, 1-6; days, 1-5). Of the 31 enrolled participants, 27 completed the study (placebo, n = 6; LDX, n = 21). Treatment-emergent adverse events (AEs) were reported by 4 participants receiving placebo and by 23 participants receiving LDX (all doses) with no serious AEs while on active treatment. For all periods, the mean postdose change on day 5 (up to 12 hours postdose) in systolic and diastolic blood pressure and pulse, respectively, ranged from -4.62 to 8.05 mm Hg, -3.67 to 4.43 mm Hg, and -3.57 to 14.43 beats per minute for placebo and -3.83 to 11.25 mm Hg, -1.55 to 5.80 mm Hg, and -0.36 to 21.26 beats per minute for LDX. With ascending LDX dose, the mean (SD) maximum plasma concentration for LDX-derived d-amphetamine ranged from 51.68 (10.28) to 266.27 (56.55) ng/mL. The area under the plasma concentration-time curve for 24 hours ranged from 801.8 (170.2) to 4397.9 (1085.9) ng[BULLET OPERATOR]h/mL. The d-amphetamine maximum plasma concentration and area under the plasma concentration-time curve increased linearly with ascending LDX dose. Antipsychotic agents did not markedly affect d-amphetamine pharmacokinetics. Over a wide range of ascending doses, LDX safety profile in adults with schizophrenia was consistent with previous findings with no unexpected treatment-emergent AEs. Pulse tended to increase with LDX dose; overall, blood pressure did not increase with LDX dose. Consistent with previous studies, pharmacokinetic parameters increased linearly with increasing LDX dose.