Cannabis use and psychosis: a review of clinical and epidemiological evidence

Multi-modal and bi-directional effects of a synthetic Δ9-Tetrahydrocannabinol (THC) analogue, Nabilone, on spatio-temporal binding windows: Evidence from the projected hand illusion

Abnormally widened spatial and temporal binding windows (SBW/TBWs; length of space/time whereby stimuli are considered part of the same percept) are observed in schizophrenia. TBW alterations have been associated with altered sense of agency (hereafter referred to as agency), and an associative relationship between embodiment (body ownership) and agency has been proposed. SBWs/TBWs are investigated separately, but no evidence exists of these being separate in mechanism, system or function. The underlying neural substrate of schizophrenia remains unclear. The literature claims either pro-psychotic or anti-psychotic effects of Δ9-Tetrahydrocannabinol (THC) in patients and healthy individuals, but major support for cannabis in the aetiology of schizophrenia is associative, not causal. To clarify if THC is pro- or anti-psychotic, this single-blind, placebo-controlled within-subjects cross-over study tested several hypotheses. 1) Competing hypotheses that a synthetic THC analogue, Nabilone (NAB, 1-2 mg), would alter measures of agency and embodiment in healthy volunteers (n = 32) similarly, or opposite, to that of in patients with schizophrenia. 2) That there would be significant associations between any NAB-induced alterations in individual agency and embodiment measures in the Projected Hand Illusion (PHI). 3) That there is a unitary spatio-temporal binding window (STBW). A large proportion of individuals did not experience the PHI. Multimodal and bi-directional effects of NAB on the PHI were observed. Evidence of a unitary spatio-temporal binding window (STBW) was observed. NAB widened the STBW in some but narrowed it in others as a function of space and delay. No associations were found between agency and embodiment.

Environmental and psychopathological predictors of clinical high-risk of psychosis in adolescence

OBJECTIVES

Clinical high-risk of psychosis (CHRp) samples can be heterogeneous, consisting essentially of people with not only psychotic-like experiences but also nonspecific symptoms that may reflect common mental disorders such as depression, anxiety, or substance abuse pathologies. Few studies have attempted to analyze and understand psychosis risk in relation to both environmental (ER) and psychopathological risk (PsR) factors. This study aimed to determine the clinical risk of psychosis in adolescents.

METHODS

A representative sample of 1824 Spanish adolescents from the general population was evaluated using different scales to thoroughly examine the possible interaction of CHRp with various ER and PsR factors. Partial correlations were calculated to assess the relationships between the variables. A series of hierarchical linear regression models were then used to obtain a CHRp predictor model.

RESULTS

The CHRp predictor model indicated that PsR was the most significant determining factor, explaining 22% of the total associated variance of CHRp. However, the ER factor also emerged as a significant predictor of high-risk psychosis (accounting for 9% of the variance).

CONCLUSIONS

A predictive model for CHRp in adolescents was found, in which common psychological problems were presented as more determinant risk factors than ER disruptors. Furthermore, certain transdiagnostic processes, such as psychological inflexibility, may play a central role in the development of mental health problems, including psychosis. Specifying the mechanisms underlying the emergence of CHRp in adolescence is the key to optimizing the focus of preventive therapeutic interventions in these early stages.

TMS for the functional evaluation of cannabis effects and for treatment of cannabis addiction: A review

The knowledge about the effects of cannabis on human cortical brain processes is increasing. In this regard, transcranial magnetic stimulation (TMS) enables the evaluation of central nervous system function, including drug effects. Moreover, repetitive TMS (rTMS) has been used therapeutically in several substance use disorders. In this scoping review, we summarize and discuss studies that have employed TMS and rTMS techniques in users of cannabis for recreational purposes. In subjects with a history of persistent cannabis use, TMS studies showed reduced short-interval cortical inhibition (SICI). This observation points more at neurobiological changes of chronic cannabis use than to a direct effect of cannabis on gamma-aminobutyric acid (GABA) A receptors. Moreover, individuals vulnerable to becoming long-term users of cannabis may also have underlying pre-existing abnormalities in SICI. Of note, the use of cannabis is associated with an increased risk of schizophrenia, and the down-regulation of GABAergic function may play a role. Less frequent cannabis use and spontaneous craving were observed following rTMS applied to the dorsolateral prefrontal cortex (DLPFC). There is emerging evidence that the posterior cingulate cortex and the precuneus are potential targets for rTMS intervention in cannabis use disorder. However, larger and randomized trials should corroborate these encouraging findings.

Are Patients with Schizophrenia Reliably Reporting their Cannabis Use? An African Cross-sectional Study

BACKGROUND

Most studies of the prevalence of cannabis use among patients with schizophrenia used a self-report as declared by the patient himself. We hypothesize that patients with schizophrenia did not tell the truth and might underreport their use for many reasons to be discussed later. Indeed, the under-report of cannabis use among these patients can affect the effectiveness of their treatment.

AIMS

To assess the degree of agreement between the prevalence values obtained from patients' reports and the results of the toxicological tests.

METHODS

A cross-sectional study was carried out on 403 patients with schizophrenia. A sociodemographic, psychiatric history and illicit drug use profile was performed for each patient. We assessed the patients with the Positive and Negative Syndrome Scale (PANSS), Calgary Depression score (CDSS), Barratt Impulsiveness Score (BIS-10) and Medication Adherence Rating Scale (MARS). The consumption of cannabis used was confirmed with MINI International Neuropsychiatric Interview (MINI-DSM IV) and using toxicological analysis.

RESULTS

Among the 403 patients who consented to give their urine samples, 49.1% (198/403) tested positive for cannabis, and 41.41% (82/198) underreported their use. The sensitivity and specificity of the questionnaire were 0.58 and 0.74. Based on the comparison between sociodemographic and psychiatric history data of patients who self-report and underreport their cannabis use, no significant difference was observed except for the duration of cannabis use and the score on the medication adherence scale. Moreover, it was found that impulsivity, PANSS score, CDSS score, and the type of schizophrenia are not involved in predicting the underreporting of cannabis use.

CONCLUSION

The rate of patients who under-report cannabis use is important. Therefore, toxicological analysis is becoming relevant for identifying drug use among schizophrenic patients and in the addictive comorbidity research field.

Impact of cannabis use on outcomes of patients admitted to an involuntary psychiatric unit: A retrospective cohort study

INTRODUCTION

Cannabis is associated with an increased risk of mental disorders, including the onset or adverse evolution of schizophrenia, bipolar disorder and depression. The aim of our study was to examine how cannabis use influences length of stay and readmissions in a unit of involuntary care.

METHOD

All patients admitted to one secure adult psychiatry unit in France in 2016 were included (n = 370). Patients were assigned to one of two groups according to detection of urinary tetrahydrocannabinol (THC + or -). Clinical outcomes, such as length of stay and readmissions, were compared between the groups in multivariate analyses.

RESULTS

We identified 130 THC + patients and 240 THC- patients. THC + patients were often young men. In adjusted analyses, THC + status was significantly associated with one-year readmissions (OR = 2.29, p = .0082) and more prescriptions of benzodiazepines (OR = 1.93, p = .02), but not antipsychotics, at discharge.

CONCLUSIONS

Cannabis users seem to have a particular profile in secure units, and are associated with specific diagnoses and treatments, and a higher risk of readmissions. Adapted management strategies might be warranted for these patients.

Psychotic disorders hospitalizations associated with cannabis abuse or dependence: A nationwide big data analysis

OBJECTIVES

We aimed to describe and correlate the hospital panorama of psychotic disorders (PD) with cannabis use (CU) trends in all Portuguese public hospitals.

METHODS

We conducted a retrospective observational study that analysed all hospitalizations that occurred in Portuguese public hospitals from 2000 to 2015. Hospitalizations with a primary diagnosis of PD or schizophrenia were selected based on Clinical Classification Software diagnostic single-level 659. Episodes associated with CU were identified by the International Classification of Diseases Version 9, Clinical Modification code 304.3/305.2 that correspond to cannabis dependence/cannabis abuse.

RESULTS

The number of hospitalizations with a primary diagnosis of PD and schizophrenia associated with CU rose 29.4 times during the study period, from 20 to 588 hospitalizations yearly (2000 and 2015, respectively) with a total of 3,233 hospitalizations and an average episode cost of €3,500. Male patients represented 89.8% of all episodes, and the mean/median age at discharge were 30.66/29.00 years, respectively. From all hospitalizations with a primary diagnosis of PD or schizophrenia, the ones with a secondary diagnosis of CU rose from 0.87% in 2000 to 10.60% in 2015.

CONCLUSIONS

The increase on secondary diagnosis coding and the change on cannabis patterns of consumption in Portuguese population with an increasing frequency of moderate/high dosage cannabis consumers may explain the rise on PD hospitalizations.

Adolescent stress contributes to aberrant dopamine signaling in a heritable rodent model of susceptibility

Evidence suggests that both genetic and environmental factors contribute to the development of schizophrenia. Rodent models of the disorder have been developed that model either genetic or environment factors to recapitulate various aspects of the disease; however, the examination of gene by environment interactions requires a model of susceptibility. We have previously demonstrated that a proportion of the F2 generation of MAM-treated rats display a schizophrenia-like phenotype, defined as an increase in ventral tegmental area (VTA) dopamine neuron population activity. Here we use this model to examine the consequence of adolescent stress (AS), a known risk factor for psychiatric disease, on dopamine neuron activity in the VTA. Specifically, F2 MAM rats were exposed to predator odor, a stressor of high ethological relevance, intermittently over 10 days throughout the adolescent period and VTA dopamine neuron activity was evaluated in adulthood. Both saline and MAM F2 rats exposed to AS displayed significant increases in population activity; however, the proportion of F2 MAM rats exhibiting this increase was significantly greater (approximately 70%) compared to their respective controls. Given that we have previously demonstrated that the augmented dopamine neuron activity in rodent models of psychosis is directly attributable to aberrant activity in the ventral hippocampus (vHipp), we examined whether AS altered activity within the vHipp. Indeed, there was a positive correlation between dopamine neuron activity and hippocampal firing rates, such that those rats that displayed increases in population activity also had increases in the firing rates of vHipp putative pyramidal neurons. Taken together, these data further demonstrate a role for AS as a risk factor for psychosis, particularly in those with a heritable predisposition.

[Cannabis use in subjects at ultra high risk for psychosis]

Cannabis use is widespread among people at ultra-high risk (UHR) for psychosis. The causal link as well as the temporal link between cannabis use and further occurrence of psychosis in UHR people remain inconclusive. Current science data supported an increased risk of transition to psychosis in cannabis users who are genetically predisposed to psychosis. This risk would be even greater in the presence of a family history of psychosis, in case of a strong use and an early onset use. Several models have been cited to explain the link between cannabis use and the subsequent onset of psychosis or prepsychotic states: cannabis-induced modifications of some brain structures, a dysregulation of the hypothalamic-pituitary axis and an alteration of normal neurological development via the endocannabinoid system. Cannabis represents a modifiable risk for psychosis. Current interventions aim to reduce or stop the cannabis use in order to reduce the risk of transition to psychosis.

Cannabis consumption and psychosis or schizophrenia development

OBJECTIVE:

Cannabis consumption produces psychopathology, in some cases psychotic episodes, which are of our interest in this work. However, the relationship between cannabis use and psychosis has not been fully elucidated. The objectives of this work are to (1) review the current state of knowledge on the association of cannabis use with the risk of the development of psychosis or psychotic symptoms in people without schizophrenia and (2) assess the consistency of the hypothesis that cannabis use is associated with increased risk of psychosis in people without schizophrenia.

METHOD:

This work included research done in humans until May 2018 with the keywords 'cannabis' and 'psychosis', published in English and Spanish, in the PubMed database.

RESULTS:

In all, 66 papers were analyzed, of which 23 were cohort trials and 43 were reviews.

CONCLUSION:

Cannabis use doubles the risk of developing psychosis in vulnerable people. There even exists a relationship regarding the dose used and the age of first use. Gene-environment interactions that modulate the association between cannabis use and the presence of psychosis have also been described.

Towards a comprehensive routine outcome monitoring program for people with psychotic disorders: The Pharmacotherapy Monitoring and Outcome Survey (PHAMOUS)

BACKGROUND

Patients with psychotic disorders are at risk of developing mental health and social problems, and physical disorders. To monitor and treat these problems when indicated, an annual routine outcome monitoring program, Pharmacotherapy Monitoring and Outcome Survey (PHAMOUS), was developed. This paper presents the background and content of PHAMOUS, implementation of PHAMOUS, characteristics of the patients screened in 2015, and the outcome of patients with three annual screenings between 2011 and 2015.

METHODS

PHAMOUS was implemented in four mental health institutions in the Northern Netherlands in 2006. During the PHAMOUS screening, patients are assessed on socio-demographics, psychiatric symptoms, medication, physical parameters, lifestyle, (psycho)social functioning and quality of life, using internationally validated instruments.

RESULTS

In 2015, 1955 patients with psychotic disorders were enrolled in the PHAMOUS screening. The majority (72%) was receiving mental healthcare for ten years or longer. A small group was hospitalized (10%) in the past year. Half of the patients were in symptomatic remission. Less than 10% had a paid job. More than half of the patients fulfilled the criteria for metabolic syndrome (54%). The subsample with three annual screenings from 2011 to 2015 (N = 1230) was stable, except the increasing prevalence of high glucose levels and satisfaction with social relationships (Cochran's Q = 16.33, p = .001 resp. Q = 14.79, p = .001).

CONCLUSION

The annual PHAMOUS screening enables to follow the mental, physical and social health problems of patients, which offers a good basis for shared-decision making with regard to updating the annual treatment plan, next to a wealth of data for scientific research.

Long-Acting Injectable Second-Generation Antipsychotics Improve Negative Symptoms and Suicidal Ideation in Recent Diagnosed Schizophrenia Patients: A 1-Year Follow-up Pilot Study

Long-acting injectable second-generation antipsychotics (LAI-SGA) are typically used to maintain treatment adherence in patients with chronic schizophrenia. Recent research suggests that they may also provide an effective treatment strategy for patients with early-phase disease. The aim of this study is to evaluate clinical and psychosocial outcomes among recent and long-term diagnosed schizophrenia outpatients treated with LAI-SGA during a follow-up period of 12 months. Stable schizophrenia patients receiving LAI-SGA with 5 or less years of illness duration (n = 10) were compared to those with more than 5 years of illness duration (n = 15). Clinical data was assessed through the Positive and Negative Syndrome Scale (PANSS), the Global Assessment of Functioning (GAF), the Columbia Suicide Severity Rating Scale (C-SSRS), the Recovery Style Questionnaire (RSQ), and the Mayer-Salovey-Caruso Emotional Intelligence Test (MSCEIT) Managing Emotion branch. Recently diagnosed patients showed greater improvement versus patients diagnosed for more than 5 years in adjusted mean GAF score, in PANSS factor score for negative and depressive symptoms, and in severity and intensity of suicidal ideation. Our preliminary findings support the hypothesis that LAI-SGA may influence the course of the illness if administered at the early phase of the illness. However, replicate studies are needed, possibly with larger samples.

Co-Occurrence of Substance use Disorders with other Psychiatric Disorders: Implications for Treatment Services

Introduction

This paper critically evaluates the literature on the co-occurrence of substance-use disorders (SUDs) with other psychiatric conditions. Our review considers the variety of different associations between the two, and suggests the implications of the literature for the design of treatment services that address both types of disorders. Methods: A narrative review of research and theory was conducted, covering epidemiology of co-occurring psychiatric disorders worldwide, mechanisms underlying co-occurrence, and treatment models. Results: Epidemiological research has documented a high prevalence of co-occurring disorders in both clinical samples and the general population, although the literature is based primarily on studies in high-income countries and some of the overlap might be due to the co-occurrence of milder forms of both types of disorders. Consistent with what has been reported in other reviews, we conclude that clients with co-occurring disorders tend to have a more severe course of illness, more severe health and social consequences, more difficulties in treatment, and worse treatment outcomes than clients with a single disorder; we address the implications of these findings for the design of treatment services. Conclusions: Much of the evidence shows that separately, treatments for both SUD and other psychiatric disorders are effective in reducing substance use and in improving behavioral, familial, and psychosocial outcomes. The evidence further suggests that these outcomes might be improved when treatment modalities are offered in combination within an integrated treatment plan that simultaneously addresses substance abuse and psychiatric problems. It is concluded that there is potentially more to be gained from taking a public health perspective and working on efforts to implement existing evidence-based practices at the systems level, than from the current tendency to look for ever more powerful individual-level interventions at the clinical level.

Cannabis use related to early psychotic onset: Role of premorbid function

The present cross-sectional study investigates the relation between Cannabis and the development of a psychotic disorder. The main objective is to explore the relations between Cannabis use and psychosis onset, premorbid adjustment cognitive impairment and familiarity. Forty-three patients with a diagnosis of Psychotic Disorder were recruited and divided in two groups based on Cannabis use before onset: Cannabis-using patients (PCU, N=21) and Cannabis-free patients (PCF, N=22). Cognitive functioning was evaluated by Trail Making Test A and B (TMT), Rey-Osterrieth Complex Figure Test (ROCF), and the Rey Auditory-Verbal Learning Test (RAVLT). Premorbid functioning was assessed retrospectively through the Premorbid Adjustment Scale (PAS). PCU group showed earlier onset of the psychotic disorder compared to PCF (p=0.008). This finding was not influenced by age or positive family history for psychiatric illness. PCU subjects showed a worse premorbid functioning respect to PCF and this difference was found to impact on the early onset in the PCU group. In conclusion the present study suggests the hypothesis of an interactive role of Cannabis and poor premorbid school adjustment in the development of psychotic disorders.

Association Between Cannabis and Psychosis: Epidemiologic Evidence

Associations between cannabis use and psychotic outcomes are consistently reported, but establishing causality from observational designs can be problematic. We review the evidence from longitudinal studies that have examined this relationship and discuss the epidemiologic evidence for and against interpreting the findings as causal. We also review the evidence identifying groups at particularly high risk of developing psychosis from using cannabis. Overall, evidence from epidemiologic studies provides strong enough evidence to warrant a public health message that cannabis use can increase the risk of psychotic disorders. However, further studies are required to determine the magnitude of this effect, to determine the effect of different strains of cannabis on risk, and to identify high-risk groups particularly susceptible to the effects of cannabis on psychosis. We also discuss complementary epidemiologic methods that can help address these questions.

Cannabis use and transition to psychosis in individuals at ultra-high risk: review and meta-analysis

BACKGROUND

Previous research has established the relationship between cannabis use and psychotic disorders. Whether cannabis use is related to transition to psychosis in patients at ultra-high risk (UHR) for psychosis remains unclear. The present study aimed to review the existing evidence on the association between cannabis use and transition to psychosis in UHR samples.

METHOD

A search of PsychInfo, Embase and Medline was conducted from 1996 to August 2015. The search yielded 5559 potentially relevant articles that were selected on title and abstract. Subsequently 36 articles were screened on full text for eligibility. Two random-effects meta-analyses were performed. First, we compared transition rates to psychosis of UHR individuals with lifetime cannabis use with non-cannabis-using UHR individuals. Second, we compared transition rates of UHR individuals with a current DSM-IV cannabis abuse or dependence diagnosis with lifetime users and non-using UHR individuals.

RESULTS

We found seven prospective studies reporting on lifetime cannabis use in UHR subjects (n = 1171). Of these studies, five also examined current cannabis abuse or dependence. Lifetime cannabis use was not significantly associated with transition to psychosis [odds ratio (OR) 1.14, 95% confidence interval (CI) 0.856-1.524, p = 0.37]. A second meta-analysis yielded an OR of 1.75 (95% CI 1.135-2.710, p = 0.01), indicating a significant association between current cannabis abuse or dependence and transition to psychosis.

CONCLUSIONS

Our results show that cannabis use was only predictive of transition to psychosis in those who met criteria for cannabis abuse or dependence, tentatively suggesting a dose-response relationship between current cannabis use and transition to psychosis.

Chronic adolescent marijuana use as a risk factor for physical and mental health problems in young adult men

Some evidence suggests that youth who use marijuana heavily during adolescence may be particularly prone to health problems in later adulthood (e.g., respiratory illnesses, psychotic symptoms). However, relatively few longitudinal studies have prospectively examined the long-term physical and mental health consequences associated with chronic adolescent marijuana use. The present study used data from a longitudinal sample of Black and White young men to determine whether different developmental patterns of marijuana use, assessed annually from early adolescence to the mid-20s, were associated with adverse physical (e.g., asthma, high blood pressure) and mental (e.g., psychosis, anxiety disorders) health outcomes in the mid-30s. Analyses also examined whether chronic marijuana use was more strongly associated with later health problems in Black men relative to White men. Findings from latent class growth curve analysis identified 4 distinct subgroups of marijuana users: early onset chronic users, late increasing users, adolescence-limited users, and low/nonusers. Results indicated that the 4 marijuana use trajectory groups were not significantly different in terms of their physical and mental health problems assessed in the mid-30s. The associations between marijuana group membership and later health problems did not vary significantly by race. Findings are discussed in the context of a larger body of work investigating the potential long-term health consequences of early onset chronic marijuana use, as well as the complications inherent in studying the possible link between marijuana use and health effects.

Mismatch negativity in tobacco-naïve cannabis users and its alteration with acute nicotine administration

Chronic cannabis use may interact with factors, such as age of onset of cannabis use, family history, and genetic factors, to elicit schizophrenia (SZ)-like symptoms, including sensory and cognitive deficits. However, evidence of a relationship between cannabis use and cognitive impairment is confounded by concomitant use of tobacco. The objective of this study was to compare tobacco-naïve cannabis users with individuals without a history of tobacco/cannabis use on the auditory mismatch negativity (MMN) event-related potential (ERP), a neural measure of auditory deviance detection which is diminished in SZ. An exploratory arm of the study, conducted within a randomized, double-blind, placebo controlled design, examined the acute effects of nicotine gum (6mg) on MMN in cannabis users. MMN was recorded in response to 5 deviant stimuli within an optimal MMN paradigm in 44 healthy, non-tobacco smoking volunteers aged 18-26. Cannabis users (n=21) started smoking cannabis prior to age 17, at least 1 joint per month. To examine the effects of chronicity, users were grouped into relatively heavy long-term (HLT; n=11) users and light short-term (LST; n=10) users. Impaired deviance detection was shown in cannabis users vs. nonusers as reflected by a smaller MMN to duration deviants. Chronicity of use was also associated with MMN alterations, as HLTs displayed a reduced duration and gap MMN vs. LSTs. Compared with placebo, nicotine treatment enhanced select MMN deviants in cannabis user subgroups. As deficits associated with early and persistent cannabis use are similar to those seen in SZ, these dose-dependant disturbances in early sensory processing with cannabis use may be one cognitive pathway which mediates an increased risk for SZ in vulnerable youth, and be influenced by concurrent cigarette smoking behavior.

Long-term consequences of adolescent cannabinoid exposure in adult psychopathology

Marijuana is the most widely used illicit drug among adolescents and young adults. Unique cognitive, emotional, and social changes occur during this critical period of development from childhood into adulthood. The adolescent brain is in a state of transition and differs from the adult brain with respect to both anatomy (e.g., neuronal connections and morphology) and neurochemistry (e.g., dopamine, GABA, and glutamate). These changes are thought to support the emergence of adult cerebral processes and behaviors. The endocannabinoid system plays an important role in development by acting on synaptic plasticity, neuronal cell proliferation, migration, and differentiation. Delta-9-tetrahydrocanabinol (THC), the principal psychoactive component in marijuana, acts as a partial agonist of the cannabinoid type 1 receptor (CB1R). Thus, over-activation of the endocannabinoid system by chronic exposure to CB1R agonists (e.g., THC, CP-55,940, and WIN55,212-2) during adolescence can dramatically alter brain maturation and cause long-lasting neurobiological changes that ultimately affect the function and behavior of the adult brain. Indeed, emerging evidence from both human and animal studies demonstrates that early-onset marijuana use has long-lasting consequences on cognition; moreover, in humans, this use is associated with a two-fold increase in the risk of developing a psychotic disorder. Here, we review the relationship between cannabinoid exposure during adolescence and the increased risk of neuropsychiatric disorders, focusing on both clinical and animal studies.

Stimulant and other substance use disorders in schizophrenia: prevalence, correlates and impacts in a population sample

OBJECTIVES

Stimulants may worsen psychotic symptoms but there is limited evidence about the impact of stimulant abuse in people with schizophrenia. This study examined the prevalence and correlates of stimulant and other drug disorders in a population-based sample of people with schizophrenia, examining associations with frequent service use, physical health comorbidities and accommodation instability.

METHODS

New South Wales (NSW) hospital, community mental health and emergency department data were used to examine health service contact over 5 years in 13,624 people with a diagnosis of schizophrenia. Associations of stimulant disorders were examined with multinomial logistic regression, comparing people with no substance disorders to those with cannabis disorders, stimulant disorders or both.

RESULTS

Of people with schizophrenia, 51% had substance disorders, including 14% with stimulant disorders. Stimulant disorders were more common in young adults and in urban areas, less common in migrants, and unrelated to initial social disadvantage. More than 80% of those with stimulant disorders also had cannabis disorders. Service use and harms were most common in this group, including frequent mental health admissions (59%), frequent emergency department presentations (52%), admissions with injury or self-harm (44%), infectious disease diagnoses (22%), multiple changes of residence (61%), movement to more disadvantaged locations (42%) and periods of homelessness (18%). People with stimulant disorders alone had higher rates of self-harm, infectious disease and non-mental health admissions than people with cannabis disorders alone.

CONCLUSIONS

Stimulant disorders occur in people with schizophrenia and in first-episode psychosis at rates more than 10 times that of the broader population. Stimulant disorders are likely to worsen the burden of psychosis, and strategies are needed to engage and support the highly disadvantaged group of people with schizophrenia who have cannabis and stimulant disorders.

Cannabis use and transition to psychosis in people at ultra-high risk

BACKGROUND

Cannabis use is associated with an increased risk of developing a psychotic disorder but the temporal relationship between cannabis use and onset of illness is unclear. The objective of this study was to assess prospectively the influence of cannabis use on transition to psychosis in people at ultra-high risk (UHR) for the disorder.

METHOD

Lifetime and continued cannabis use was assessed in a consecutively ascertained sample of 182 people (104 male, 78 female) at UHR for psychosis. Individuals were then followed clinically for 2 years to determine their clinical outcomes.

RESULTS

Lifetime cannabis use was reported by 134 individuals (73.6%). However, most of these individuals had stopped using cannabis before clinical presentation (n=98, 73.1%), usually because of adverse effects. Among lifetime users, frequent use, early-onset use and continued use after presentation were all associated with an increase in transition to psychosis. Transition to psychosis was highest among those who started using cannabis before the age of 15 years and went on to use frequently (frequent early-onset use: 25%; infrequent or late-onset use: 5%; χ(2)1=10.971, p=0.001). However, within the whole sample, cannabis users were no more likely to develop psychosis than those who had never used cannabis (cannabis use: 12.7%; no use: 18.8%; χ(2)1=1.061, p=0.303).

CONCLUSIONS

In people at UHR for psychosis, lifetime cannabis use was common but not related to outcome. Among cannabis users, frequent use, early-onset use and continued use after clinical presentation were associated with transition to psychosis.

Risk and protective factors for relapse among individuals with schizophrenia: a qualitative study in Dar es Salaam, Tanzania

BACKGROUND

Relapse in people with schizophrenia is a major challenge for mental health service providers in Tanzania and other countries. Approximately 10% of people with schizophrenia are re-admitted due to relapse at Muhimbili National Hospital (MNH) Psychiatric Unit each month. Relapse brings about negative effects and it results in a huge burden to patients, their families, the mental health sector and the country's economy. So far no study has been done to address relapse in Tanzania. The purpose of the study was to explore perspectives on risk and protective factors influencing relapse of people with schizophrenia and their caregivers attending Muhimbili National Hospital Psychiatric Out-patient Department, Dar es Salaam, Tanzania.

METHODS

A qualitative study was conducted, involving in-depth interviews of seven people with schizophrenia who are out-patients and their seven family caregivers at MNH. Purposive sampling procedure was used to select participants for the study. Audio recorded in-depth interviews in Swahili language were conducted with all study participants. The recorded information was transcribed and analyzed using NVivo 9 computer assisted qualitative data analysis software.

RESULTS

Personal risk and protective factors for relapse, environmental risk and protective factors for relapse and suggestions to reduce relapse were the main themes that emerged from this study. People with schizophrenia and their caregivers (all of whom were relatives) perceived non adherence to antipsychotic medication as a leading risk factor of relapse; other risks included poor family support, stressful life events and substance use. Family support, adherence to antipsychotic medication, employment and religion were viewed as protective factors. Participants suggested strengthening mental health psycho-education sessions and community home visits conducted by mental health nurses to help reduce relapse. Other suggestions included strengthening the nurse-patient therapeutic relationship in provision of mental health care.

CONCLUSIONS

This study calls for improvement in mental health care service delivery to individuals with schizophrenia. Establishing a curricular in mental health nursing that aims to produce competent mental health nurse force would improve nursing practice in mental health care service delivery.

Anxiety mediates the association between cannabis use and attenuated positive psychotic symptoms

Cannabis use has been associated with a continuum of psychotic experiences. However, it is unclear whether mood and anxiety symptoms account for increases in attenuated positive psychotic symptoms (APPS) among cannabis users. We predicted that depression and anxiety symptoms would mediate the relation between cannabis use and APPS, and between cannabis use and endorsement of eight or more distressing APPS (D-APPS), a potentially more clinically meaningful group. Young adults (n=674) completed the Prodromal Questionnaire (PQ); Drug Use Frequency measure; Center for Epidemiologic Studies Depression Scale; State-Trait Anxiety Inventory, Trait Form, Anxiety Subscale; and Social Phobia Scale. Results indicated that symptoms of trait anxiety, but not symptoms of depression or social anxiety, mediated the relationship between cannabis use and APPS, as well as the relationship between cannabis use and D-APPS. Results indicate that symptoms of trait anxiety may play a role in the relation between cannabis use and APPS. Findings underscore the importance of considering clinical characteristics co-occurring with psychotic symptoms, such as affective symptoms, when examining the association between cannabis use and psychotic symptoms.

Systematic meta-analysis of outcomes associated with psychosis and co-morbid substance use

OBJECTIVE

To compare the symptoms and social function of patients with psychosis and current substance use to those with psychosis and no history of substance use.

METHOD

The databases EMBASE, MEDLINE and PsycINFO were searched for peer-reviewed publications in English that reported the characteristics of patients with psychotic illness who were current substance users and those who had never used substances. The searches yielded 22 articles that met the inclusion criteria. Meta-analysis was used to compare four key outcome variables: positive symptoms, negative symptoms, depression and social function - and three secondary outcomes: violence, self-harm and hospital admissions.

RESULTS

Current substance-using patients were significantly younger than non-substance-using patients and were more likely to be male, but did not differ in age at onset of psychosis or in their level of education. Current substance users had higher ratings of positive symptoms and were more likely to have a history of violence. Older studies reported a stronger association between current substance use and positive symptoms than more recently published studies. Current substance users did not differ from non-users on measurements of negative symptoms, depressive symptoms, social function, self-harm, or the number of hospital admissions.

CONCLUSION

Current substance users with psychosis may have more severe positive symptoms than patients who have never used substances, but this result should be interpreted with caution because of demographic differences between substance users and non-substance users.

Medical consequences of marijuana use: a review of current literature

With the advent of legalization of marijuana for medicinal and recreational purposes, and the increase use of marijuana, healthcare providers will be increasingly confronted with marijuana users as patients in clinical environments. While there is vast literature regarding the societal and mental health harms associated with marijuana use, there is a paucity of reviews of the potential consequences of marijuana use on physical health or medical conditions. We examine the recent literature on the physical harms associated with illicit and legal marijuana administration. We surveyed the peer-reviewed medical literature from 1998 to 2013 of studies assessing the association of marijuana use and physical diseases. We conclude that healthcare providers should be cognizant that the existing literature suggests that marijuana use can cause physical harm. However, evidence is needed, and further research should be considered, to prove causal associations of marijuana with many physical health conditions.

Pathways from cannabis to psychosis: a review of the evidence

The nature of the relationship between cannabis use (CU) and psychosis is complex and remains unclear. Researchers and clinicians remain divided regarding key issues such as whether or not cannabis is an independent cause of psychosis and schizophrenia. This paper reviews the field in detail, examining questions of causality, the neurobiological basis for such causality and for differential inter-individual risk, the clinical and cognitive features of psychosis in cannabis users, and patterns of course and outcome of psychosis in the context of CU. The author proposes two major pathways from cannabis to psychosis based on a differentiation between early-initiated lifelong CU and a scenario where vulnerable individuals without a lifelong pattern of use consume cannabis over a relatively brief period of time just prior to psychosis onset. Additional key factors determining the clinical and neurobiological manifestation of psychosis as well as course and outcome in cannabis users include: underlying genetic and developmental vulnerability to schizophrenia-spectrum disorders; and whether or not CU ceases or continues after the onset of psychosis. Finally, methodological guidelines are presented for future research aimed at both elucidating the pathways that lead from cannabis to psychosis and clarifying the long-term outcome of the disorder in those who have a history of using cannabis.

Craving for cannabis in patients with psychotic disorder, their non-affected siblings and healthy controls: psychometric analysis of the obsessive compulsive drug use scale

Cannabis use is more common in individuals with non-affective psychotic disorder and their siblings compared to healthy controls. As cannabis use is associated with a greater risk to develop psychotic disorder and an adverse outcome in those who already developed psychosis, it is important to know the role of craving in continued cannabis use and relapse in these vulnerable subjects. Therefore, we examined the validity of the Obsessive Compulsive Drug Use Scale for cannabis (OCDUS-CAN) in patients with non-affective psychotic disorder, their siblings, and healthy controls who all used cannabis in the past year. Simultaneous component analysis (SCA) was used to determine component weights that optimally explained the (co)variance of the OCDUS-CAN variables in these different populations simultaneously. A three-component SCA solution explained 74.2 % of the total variance, and consisted of well-interpretable subscales that could be best described as craving/urge, resistance, and impact. Reliability of the subscales was good. The three subscales significantly discriminated between frequent and infrequent cannabis users. Patients scored higher on the craving/urge and impact scale than siblings and controls, which could be related to primary and secondary symptoms of their disorder. The OCDUS-CAN is well suitable for people with or without vulnerability for psychotic disorder.

Mapping brain regions in which deep brain stimulation affects schizophrenia-like behavior in two rat models of schizophrenia

BACKGROUND AND OBJECTIVES

The development of more efficient treatment remains a major unmet need in the realm of schizophrenia disease. Using the maternal immune stimulation and the pubertal cannabinoid administration rat model of schizophrenia, the present study aimed at testing the hypothesis that deep brain stimulation (DBS) serves as a novel therapeutic technique for this disorder.

METHODS

Adult offspring of dams, treated with the immune activating agent poly I:C (4 mg/kg, n = 50) or saline (n = 50), underwent bilateral stereotactic electrode implantation into one of the following brain regions: subthalamic nucleus (STN, n = 12/10), entopeduncularis nucleus (EP, n = 10/11), globus pallidus (GP, n = 10/10), medial prefrontal cortex (mPFC, n = 8/8), or dorsomedial thalamus (DM, n = 10/11). Adult rats treated with the CB1 receptor agonist WIN 55,212-2 (WIN, n = 16) or saline (n = 12) during puberty were bilaterally implanted with electrodes into either the mPFC (n = 8/6) or the DM (n = 8/6). After a post-operative recovery period of one week, all rats were tested on a well-established cross-species phenomenon that is disrupted in schizophrenia, the pre-pulse inhibition (PPI) of the acoustic startle reflex (ASR) under different DBS conditions.

RESULTS

Poly I:C induced deficits in PPI of the ASR were normalized upon DBS. DBS effects depended on both stimulation target and stimulation parameters. Most prominent effects were found under DBS at high frequencies in the mPFC and DM. These effects were replicated in the pubertal WIN administration rat model of schizophrenia.

CONCLUSIONS

Brain regions, in which DBS normalized PPI deficits, might be of therapeutic relevance to the treatment of schizophrenia. Results imply that DBS could be considered a plausible therapeutic technique in the realm of schizophrenia disease.

Prevalence and correlates of psychotic symptoms among Asian males

PURPOSE

Psychotic symptoms have been reported at varying rates in the general population in the West. We studied the association of psychotic symptoms with educational attainment and other psychiatric disorders in 23,248 male pre-enlistees for National Service in Singapore.

METHODS

In a 2-stage assessment, these enlistees were first screened with the Self-Reporting Questionnaire (SRQ-24) and the CRAFFT. Those screened positive were then assessed by the Composite International Diagnostic Interview (CIDI) to establish the presence of psychiatric disorders based on the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV).

RESULTS

The rate of psychotic symptoms (after excluding those with psychotic disorders) was 8.2% (n = 1,909). A multinomial logistic regression using the controls as the reference group revealed that younger age, lower PSLE scores, and mood and anxiety disorder remained significantly associated with both the diagnoses of psychotic disorders and the presence of psychotic symptoms.

CONCLUSIONS

A combination of categorical and dimensional representation of psychopathology for the diagnosis of psychotic disorders would better inform treatment and prognosis as there is a considerable overlap in the presentation of psychotic symptoms and psychotic disorders.

Cannabis use and psychosis: re-visiting the role of childhood trauma

BACKGROUND

Cannabis consumption continues to be identified as a causal agent in the onset and development of psychosis. However, recent findings have shown that the effect of cannabis on psychosis may be moderated by childhood traumatic experiences.

METHOD

Using hierarchical multivariate logistic analyses the current study examined both the independent effect of cannabis consumption on psychosis diagnosis and the combined effect of cannabis consumption and childhood sexual abuse on psychosis diagnosis using data from the Adult Psychiatric Morbidity Survey 2007 (n=7403).

RESULTS

Findings suggested that cannabis consumption was predictive of psychosis diagnosis in a bivariate model; however, when estimated within a multivariate model that included childhood sexual abuse, the effect of cannabis use was attenuated and was not statistically significant. The multivariate analysis revealed that those who had experienced non-consensual sex in childhood were over six times [odds ratio (OR) 6.10] more likely to have had a diagnosis of psychosis compared with those who had not experienced this trauma. There was also a significant interaction. Individuals with a history of non-consensual sexual experience and cannabis consumption were over seven times more likely (OR 7.84) to have been diagnosed with psychosis compared with those without these experiences; however, this finding must be interpreted with caution as it emerged within an overall analytical step which was non-significant.

CONCLUSIONS

Future studies examining the effect of cannabis consumption on psychosis should adjust analyses for childhood trauma. Childhood trauma may advance existing gene-environment conceptualisations of the cannabis-psychosis link.

Marijuana use among older adults in the U.S.A.: user characteristics, patterns of use, and implications for intervention

BACKGROUND

Epidemiological studies show that the number of older adults using marijuana is increasing. This study aimed to determine the correlates and patterns of marijuana use among older adults that might help health and social service providers better assist this group.

METHODS

Data are from the 2008 National Survey on Drug Use and Health conducted by the Substance Abuse and Mental Health Services Administration in the U.S.A. The sample consisted of 5,325 adults aged 50 years and older.

RESULTS

Of the sample, 2.8% were past-year marijuana users. Of them, 23% had used marijuana on at least half the days of the year. Past-year users were more likely to be younger (50-64 years old), black, and not married, and they had significantly higher psychological distress scores, but they did not rate their health as poorer than others in the sample, nor did they attribute many problems, including psychological problems, as being related to their marijuana use. Nevertheless, past-year users present a high-risk profile because, in addition to frequent marijuana use, they also are more likely to smoke cigarettes, engage in binge drinking, and use other illicit drugs.

CONCLUSIONS

Health and social service providers should be alert to the small number of routine marijuana users among the younger members of the older adult population, especially those suffering significant psychological distress, so that these individuals can be encouraged to utilize services that will help alleviate this distress and promote a healthier lifestyle and increase general well being.

Caffeine and clinical change in a patient with schizophrenia on a long-stay ward

We report a case of a 33-year-old male patient with schizophrenia, who showed significant and persistent changes in psychotic and mood symptoms relating to his caffeine intake.

Cannabis involvement in individuals with bipolar disorder

In a study of 471 bipolar disorder (BD) cases and 1761 controls, individuals with BD were 6.8 times more likely to report a lifetime history of cannabis use. Rates of DSM-IV cannabis use disorders in those with BD were 29.4% and were independently and significantly associated with increased suicide attempts, greater likelihood of mixed episodes and greater disability attributable to BD.

Chronic pubertal cannabinoid treatment as a behavioural model for aspects of schizophrenia: effects of the atypical antipsychotic quetiapine

Chronic pubertal cannabinoid treatment in rats has been suggested for modelling aspects of schizophrenia since it results in long-lasting behavioural alterations reflecting certain characteristics of schizophrenia symptomatology. Lasting deficits in sensorimotor gating, impaired short-term mnemonic processing, reduced motivation as well as inappropriate and deficient social behaviour have been reported after chronic cannabinod treatment during pubertal development. In addition, sensorimotor gating deficits were able to be restored by acute injections of the typical antipsychotic haloperidol. The aim of this study was to examine possible acute as well as lasting beneficial effects of the atypical antipsychotic drug quetiapine in adult animals undergoing chronic treatment of the synthetic cannabinoid receptor agonist WIN 55,212-2 (WIN) (1.2 mg/kg) during puberty. Therefore, animals were tested repeatedly for their performance in social interaction and social recognition after acute and chronic quetiapine treatment. Chronic pubertal WIN treatment induced persistent deficits in social recognition and impaired social interaction. Acute quetiapine treatment was able to completely restore those deficits in social behaviour and social memory. Social recognition memory was affected again 1 wk after cessation of chronic quetapine treatment; however, in social interaction persistent improvements could be detected. In conclusion, the results indicate that the atypical antipsychotic drug quetiapine is able to acutely restore deficits in social behaviour induced by developmental cannabinoid exposure and even exert some persistent beneficial effects. Furthermore, the present data give further support and validity for the suitability of chronic pubertal cannabinoid administration as an animal model for aspects of schizophrenia.

Understanding the genesis of psychotic disorder: Issues in the prediction and prophylaxis of those at ultra-high risk

PURPOSE

Recent research is starting to identify individuals at an increased risk of developing a psychotic disorder. This review seeks to identify the 'state of the art' with respect to the clinical identification and treatment of individuals at 'ultra-high risk'.

METHOD

The research and clinical literature are reviewed with respect to a wide range of predictors relevant across development.

RESULTS

The review draws on evidence from childhood and adolescence to suggest that a range of biological, cognitive, personality, and social features are predictive of, but often not specific to, psychosis within the context of the diathesis-stress model. Much evidence supports the view that environmental stressors act in combination with vulnerability factors to increase risk of transition, often during late adolescence and early adulthood.

CONCLUSIONS

Recent clinical research has used both retrospective and prospective means of identifying individuals at ultra-high risk and has made substantial gains in predicting transition. The clinical implications of their identification are discussed in the context of current pharmacological and psychosocial treatment studies. However, significant unresolved clinical and ethical issues remain with both types of study.

A comparison of psychosocial and cognitive functioning between depressed and non-depressed patients with cannabis dependence

Cannabis use and depressive disorders are thought to impair cognitive performance and psychosocial functioning. Both disorders co-occurring may compound the negative effects of these diagnoses. In this study, the authors used the California Computerized Assessment Package as the cognitive performance measure and the Addiction Severity Index as the psychosocial functioning measure to compare individuals who were cannabis dependent and either depressed or not depressed (N= 108: 54 cannabis dependent only, 54 cannabis dependent and depressed or dysthymic). As predicted, cannabis dependent individuals with comorbid depression showed more psychosocial impairment than individuals with cannabis dependence alone. However, contrary to the authors' hypothesis, individuals who were cannabis dependent with comorbid depression showed less cognitive impairment in some California Computerized Assessment Package modules than individuals with cannabis dependence alone. Based on the authors' results, they concluded that the additive effects of cannabis dependency and depression may only be limited to psychosocial domains and may not extend to cognitive functioning.

Auditory mismatch negativity deficits in long-term heavy cannabis users

Mismatch negativity (MMN) is an auditory event-related potential indicating auditory sensory memory and information processing. The present study tested the hypothesis that chronic cannabis use is associated with deficient MMN generation. MMN was investigated in age- and gender-matched chronic cannabis users (n = 30) and nonuser controls (n = 30). The cannabis users were divided into two groups according to duration and quantity of cannabis consumption. The MMNs resulting from a pseudorandomized sequence of 2 × 900 auditory stimuli were recorded by 32-channel EEG. The standard stimuli were 1,000 Hz, 80 dB SPL and 90 ms duration. The deviant stimuli differed in duration (50 ms) or frequency (1,200 Hz). There were no significant differences in MMN values between cannabis users and nonuser controls in both deviance conditions. With regard to subgroups, reduced amplitudes of frequency MMN at frontal electrodes were found in long-term (≥8 years of use) and heavy (≥15 joints/week) users compared to short-term and light users. The results indicate that chronic cannabis use may cause a specific impairment of auditory information processing. In particular, duration and quantity of cannabis use could be identified as important factors of deficient MMN generation.

Cannabis use and the course of schizophrenia: 10-year follow-up after first hospitalization

OBJECTIVE

The authors examined the relationship between cannabis use and the course of illness in schizophrenia over 10 years of follow-up after first psychiatric hospitalization.

METHOD

The authors assessed 229 patients with a schizophrenia spectrum disorder five times: during the first admission and 6 months, 2 years, 4 years, and 10 years later. Ratings of cannabis use and psychiatric symptoms (psychotic, negative, disorganized, and depressive) were made at each assessment.

RESULTS

The lifetime rate of cannabis use was 66.2%, and survival analysis revealed that lifetime use was associated with an earlier onset of psychosis. The rates of current use ranged from 10% to 18% across assessments. Cannabis status was moderately stable, with tetrachoric correlation coefficients between waves ranging from 0.48 to 0.78. Mixed-effects logistic regression revealed that changes in cannabis use were associated with changes in psychotic symptoms over time even after gender, age, socioeconomic status, other drug use, antipsychotic medication use, and other symptoms were controlled for. Structural equation modeling indicated that the association with psychotic symptoms was bidirectional.

CONCLUSIONS

Cannabis use is associated with an adverse course of psychotic symptoms in schizophrenia, and vice versa, even after taking into account other clinical, substance use, and demographic variables.

Lessons from an audit of psychoeducation at an older adolescent inpatient unit

OBJECTIVES

The aim of this paper was to determine if patients undergoing treatment at an older adolescent inpatient unit receive psychoeducation according to the unit philosophy of providing timely and pertinent information regarding illness/diagnosis, medication, diet, outpatient follow-up, and alcohol/ drug use.

METHODS

Data were gathered prospectively as part of a quality assurance initiative at the Christchurch Youth Inpatient Unit. Patients were interviewed by a registered nurse using a structured audit tool.

RESULTS

Participants reported receiving adequate information on medication and illness, and most received information on outpatient follow-up and alcohol and drug use. However, the majority reported a lack of information/ advice about diet. Patients' reported awareness of relapse prevention and the relationship of alcohol and other drugs use to medication and treatment was lower than expected.

CONCLUSIONS

The audit highlighted areas of discrepancy between information staff believed they had delivered and information youth perceived as received. Psychiatric staff working with young people need be aware of the timing, language and mode of delivery of psychoeducation to enable their patients to 'take in' the information provided.

A transcranial magnetic stimulation study of the effects of cannabis use on motor cortical inhibition and excitability

Active compounds in cannabis such as tetrahydrocannabinol (THC) interact with the inhibitory neurotransmitter delta-aminobutyric acid (GABA) but little is known about the functional effects of cannabis on human cortical brain processes. Therefore, the aim of the study was to investigate whether patients with chronic cannabis use demonstrate abnormalities in cortical inhibition or excitability. In all, 42 chronic cannabis using subjects (divided into heavy and light using subjects) and 19 controls were included in the study. Single and paired pulse transcranial magnetic stimulation were used to assess a number of parameters of cortical inhibition and cortical excitability. In addition, psychomotor function and THC plasma levels were measured. Both cannabis using groups (heavy and light use) demonstrated a reduction in short interval cortical inhibition compared with healthy controls, but there was no difference in other measures of cortical inhibition or cortical excitability. There was also no difference between the two groups on measures of psychomotor performance. Chronic cannabis use is associated with a reduction in cortical inhibition potentially related to activity at the GABA(A) receptors. Further research is required to explore whether this results from chronic cannabis use or reflects an underlying predisposition to developing chronic substance use problems.