Pathways from cannabis to psychosis: a review of the evidence

Cannabis use influences disorganized symptoms severity but not transition in a cohort of non-help-seeking individuals at-risk for psychosis from São Paulo, Brazil

BACKGROUND

Cannabis use is associated with an increased risk of developing a psychotic disorder. However, in individuals with at-risk mental states for psychosis (ARMS) this association is not clear, as well as the impact of cannabis use on symptom severity. The objective of this study was to evaluate the association of cannabis use patterns and ARMS risk status, transition to psychotic and psychiatric disorders, and psychopathology.

METHOD

A sample of 109 ARMS and 197 control individuals was drawn from the general population. Lifetime, maximum and current amount of cannabis use were assessed with the South Westminster modified questionnaire. Participants were followed-up for a mean of 2.5 years and reassessed for transition to any psychiatric disorder.

RESULTS

There were no differences between ARMS and controls regarding lifetime use, current amount of use, or maximum amount of cannabis use. There were also no differences between those who transitioned to a psychiatric disorder and those who did not regarding cannabis use variables. In ARMS individuals, cannabis use was significantly related to disorganization symptoms.

CONCLUSION

The results of this study suggest that cannabis plays a role in the psychopathology of ARMS individuals, leading to more severe symptomatology.

Remission with or without comorbid substance use disorders in early psychosis: long-term outcome in integrated care (ACCESS III study)

Introduction

Schizophrenia-Spectrum-Disorders are associated with poor long-term outcome as well as disability and often severely affect the lives of patients and their families often from symptom onset. Up to 70% of first episode psychosis (FEP) patients suffer from comorbid substance use disorders (SUD). We aimed at studying the course of illness in FEP patients within evidence-based care, with and without comorbid SUD, to examine how decreased, remitted or persistent substance use impacted rates of a combined symptomatic and functional long-term recovery compared with patients without SUD.

Methods

ACCESS III is an integrated care model for FEP or patients in the early phase of non-affective and affective psychotic disorders. Treatment trajectories of patients, who had been in ACCESS care for 1 year, with and without SUD were compared with regard to the course of illness and quality of life using Mixed Model Repeated Measures (MMRM) and recovery rates were compared using binary logistic regression. Change in substance use was coded as either persistent, decreased/remitted or no use.

Results

ACCESS III was a prospective 1-year study (N = 120) in patients aged 12-29 years. Of these, 74 (61.6%) had a comorbid SUD at admission. There were no group differences regarding the course of illness between patients with or without comorbid SUD or between patients with a substance abuse or substance dependence. The only outcome parameter that was affected by SUD was quality of life, with larger improvement found in the group without substance use (p = 0.05) compared to persistent and remitted users. Using LOCF, 44 patients (48.9%) fulfilled recovery criteria at the endpoint; recovery did not differ based on substance use status.

Discussion

SUD and especially substance dependence are common in psychotic disorders even in FEP patients. Evidence-based integrated care led to long-term improvement in patients with comorbid SUD and rate of recovery did not differ for patients with substance use.

Alcohol, smoke, cannabis, new psychoactive substances, and non-prescribed drugs consumption among school student in an area of Nord-West of Italy

BACKGROUND

Alcohol and/or substance use disorders are known to be a significant phenomenon in the Western world. The aim of the present study was to evaluate the consumption of alcohol, cigarette smoking, cannabis, new psychoactive substances (NSP) / non prescribed drug (NPD) in a student population in the north-west of Italy (metropolitan area of Genoa).

METHODS

Fourteen comprehensive schools in the metropolitan area of Genoa (Italy) have requested to participate in the education for correct lifestyles meetings (from December 16, 2021, to May 30, 2022). Before each meeting, a meeting was held with the reference teachers: 3805 students aged 9 to 17 were involved. The group was divided by age group: 9-11, 12-13, 14-15 and 16-17 years. Before the lesson, the students were given a questionnaire relating to various topics related to lifestyle or resulting from an incorrect lifestyle (alcohol consumption, cigarette smoking, cannabis, NPS/NPD, psychological path). The questionnaire was anonymous and was approved by the teachers in the preparation phase of the meeting.

RESULTS

Logistic regression analysis found that cannabis use in the age of 14-15 increases the risk of consuming NPD/NPD by more than 26 times (odd ratio 26.3012; 95% CI 15.9656 to 43.3275; P<0.0001). In the age of 16-17, this risk increases approximately 14 times (odd ratio 14.0625; 95% CI 6.1729 to 32.0360; P<0.0001). In the age of 14-15 years, cannabis consumption, alcohol consumption >2 alcoholic units (AUs) on one occasion, NPD increases the probability of the need for a psychological path (cannabis: odds ratio 14.0254, 95% CI 10.9-17.9, P<0.0001; alcohol: odds ratio 3.68, 95% CI 3-4.4, P<0.0001; NPS/NPD: odds ratio 20.98, 16.4-38.4, P<0.0001). In the age of 14-15 and 16-17 years, respectively, 53% (95% CI 50-58%) and 68% (95% CI 66-71%) of students declared that they had neither the parents nor the psychologist of having used alcohol and/or substances.

CONCLUSIONS

These data should be useful to policy makers to implement prevention and health promotion policies through teaching (education for correct lifestyles) to be permanently included in school programs and to be recognized in the curricular path.

Portable Neuroimaging-Guided Noninvasive Brain Stimulation of the Cortico-Cerebello-Thalamo-Cortical Loop—Hypothesis and Theory in Cannabis Use Disorder

Background: Maladaptive neuroplasticity-related learned response in substance use disorder (SUD) can be ameliorated using noninvasive brain stimulation (NIBS); however, inter-individual variability needs to be addressed for clinical translation. Objective: Our first objective was to develop a hypothesis for NIBS for learned response in SUD based on a competing neurobehavioral decision systems model. The next objective was to develop the theory by conducting a computational simulation of NIBS of the cortico-cerebello-thalamo-cortical (CCTC) loop in cannabis use disorder (CUD)-related dysfunctional “cue-reactivity”—a construct closely related to “craving”—that is a core symptom. Our third objective was to test the feasibility of a neuroimaging-guided rational NIBS approach in healthy humans. Methods: “Cue-reactivity” can be measured using behavioral paradigms and portable neuroimaging, including functional near-infrared spectroscopy (fNIRS) and electroencephalogram (EEG) metrics of sensorimotor gating. Therefore, we conducted a computational simulation of NIBS, including transcranial direct current stimulation (tDCS) and transcranial alternating current stimulation (tACS) of the cerebellar cortex and deep cerebellar nuclei (DCN) of the CCTC loop for its postulated effects on fNIRS and EEG metrics. We also developed a rational neuroimaging-guided NIBS approach for the cerebellar lobule (VII) and prefrontal cortex based on a healthy human study. Results: Simulation of cerebellar tDCS induced gamma oscillations in the cerebral cortex, while transcranial temporal interference stimulation induced a gamma-to-beta frequency shift. A preliminary healthy human study (N = 10) found that 2 mA cerebellar tDCS evoked similar oxyhemoglobin (HbO) response in the range of 5 × 10⁻⁶ M across the cerebellum and PFC brain regions (α = 0.01); however, infra-slow (0.01–0.10 Hz) prefrontal cortex HbO-driven phase–amplitude-coupled (PAC; 4 Hz, ±2 mA (max)) cerebellar tACS evoked HbO levels in the range of 10⁻⁷ M that were statistically different (α = 0.01) across these brain regions. Conclusion: Our healthy human study showed the feasibility of fNIRS of cerebellum and PFC and closed-loop fNIRS-driven ctACS at 4 Hz, which may facilitate cerebellar cognitive function via the frontoparietal network. Future work needs to combine fNIRS with EEG for multi-modal imaging for closed-loop NIBS during operant conditioning.

Substance use among patients in specialized mental health services in Norway: prevalence and patient characteristics based on a national census

PURPOSE

The aim of this study was to investigate the clinical and demographic variation in the prevalence of substance use among the general psychiatric population in Norway.

METHODS

A national census in psychiatric institutions and outpatient clinics was conducted. Data were returned for 2358 inpatients (response rate, 65%) and 23,167 outpatients (response rate, 60%). Substance use was measured based on substance use disorder diagnosis or reported substance use in the last 4 weeks (alcohol 2-4 days a week or more frequently/illicit drug use). Regression analyses controlling for demographic and sociodemographic characteristics were carried out.

RESULTS

Substance use was identified in 32.4% of inpatients and 13.9% of outpatients. The most frequently reported substances used were alcohol, sedatives and cannabis. Among inpatients, the prevalence of substance use was highest in patients with schizophrenia, personality disorders and anxiety disorders. Among outpatients, the prevalence was highest in patients with schizophrenia and other psychoses. Inpatients with anxiety disorders and outpatients with schizophrenia and other psychoses had a significantly higher risk of substance use than other patients. In both samples, the prevalence of substance use was higher among males, 24 to 29-year-olds and the most socially deprived.

CONCLUSIONS

This study provides further knowledge about patients at risk for co-morbid substance abuse and poor treatment outcomes. Clinicians may consider targeting patients with schizophrenia and other psychoses, young males and those who are socially deprived in efforts to prevent emerging substance abuse and improve outcomes.

Catatonia Related to Cannabis and Synthetic Cannabinoids: A Review

Cannabis and synthetic cannabinoids (SC) are related to several neuropsychiatric symptoms and disorders, especially psychotic symptoms and disorders. Interestingly, catatonia-like symptoms associated with cannabis and SC have been generally neglected in research and scarcely described despite the clinical repercussions. Hence, this review aims to analyze current clinical publications on catatonia induced by cannabis or SC in a systematized way. Methods: A search using PRISMA guidelines was performed on three databases based on a specific inclusion and exclusion criteria. Results: 11 publications describing 14 patients (10 males; mean age 22.50 ± 6.67 years old) with catatonia apparently precipitated by the use of cannabis (n = 6) or SC (n = 8) were found. Clinical features and treatment are described and discussed. Conclusion: From a clinical perspective, cannabis and SC use may be related to catatonia-like symptoms and catatonia syndrome in the same way these substances (cannabis and SC) are related to induced-psychotic episodes. However, further research will be required to understand the exact nature of that relationship. Additionally, investigations focused on the clinical significance (i.e., prognosis, evolution, and outcomes) of catatonia-like symptoms induced by cannabis and SC use in patients are also needed.

[Asthma and cannabis, cocaine or heroin use]

INTRODUCTION

The use of cannabis, cocaine or heroin can be responsible for many respiratory complications including asthma.

OBJECTIVES

The aim of this systematic literature review of data was to expose the relations between cannabis, cocaine or heroin use and asthma.

RESULTS

Cannabis, cocaine or heroin use by inhalation may be responsible for respiratory symptoms (cough, wheezing), asthma onset, acute asthma exacerbations (which may require intubation and invasive ventilation) or deaths related to asthma. Lower adherence to asthma treatment is also observed. Cannabis induces a rapid bronchodilator effect. In contrast, its chronic use may induce a decrease in specific airway conductance. Studies on forced expiratory volume in one second (FEV1) reduction or decline are discordant.

CONCLUSION

Cannabis, cocaine or heroin use must be considered in cases of acute respiratory symptoms or asthma exacerbation in young persons and practitioners must help illicit substance users to stop their consumption.

Cannabis, Cannabinoids, and Brain Morphology: A Review of the Evidence

Cannabis and cannabinoid-based products are increasingly being accepted and commodified globally. Yet there is currently limited understanding of the effect of the varied cannabinoid compounds on the brain. Exogenous cannabinoids interact with the endogenous cannabinoid system that underpins vital functions in the brain and body, and they are thought to perturb key brain and cognitive function. However, much neuroimaging research has been confined to observational studies of cannabis users, without examining the specific role of the various cannabinoids (Δ⁹-tetrahydrocannabinol, cannabidiol, etc.). This review summarizes the brain structural imaging evidence to date associated with cannabis use, its major cannabinoids (e.g., Δ⁹-tetrahydrocannabinol, cannabidiol), and synthetic cannabinoid products that have emerged as recreational drugs. In doing so, we seek to highlight some of the key issues to consider in understanding cannabinoid-related brain effects, emphasizing the dual neurotoxic and neuroprotective role of cannabinoids, and the need to consider the distinct role of the varied cannabinoids in establishing their effect on the brain.

The need for early intervention for psychosis to persist throughout the COVID-19 pandemic and beyond

In the last three decades, early intervention for psychosis (EIP) services have been established worldwide and have resulted in superior symptomatic and functional outcomes for people affected by psychotic disorders. These improved outcomes are a result of reducing delays to treatment and the provision of specialised, holistic interventions. The COVID-19 pandemic poses significant challenges to the delivery of these services, such as undetected cases or long delays to treatment. Furthermore, the COVID-19 pandemic will likely increase the mental health needs of communities, including the incidence of psychotic disorders. In this perspective piece, we provide suggestions as to how EIP services can adapt within this environment, such as utilising novel technologies. Finally, we argue that despite the economic consequences of the pandemic, the funding for mental health services, including EI services, should be increased in line with the need for these services during and beyond the pandemic.

Neighborhood-level predictors of age at onset and duration of untreated psychosis in first-episode psychotic disorders

OBJECTIVE

Recent years have witnessed growing interest in the role of the social environment in the development and outcomes of schizophrenia. We investigated whether neighborhood characteristics are associated with two important prognostic factors in early-course psychosis, age at onset of psychosis (AOP) and duration of untreated psychosis (DUP).

METHODS

Data were collected from patients admitted to the hospital for first-episode schizophrenia-spectrum disorder. We collected data on perceived neighborhood disorder during childhood/adolescence and extracted data on 13 neighborhood characteristics from the American Community Survey based upon individual addresses. Four neighborhood-level factors were derived from factor analysis. Multiple logistic regression analyses assessed the association between specific neighborhood characteristics and the two prognostic factors (earlier AOP and longer DUP) in early-course psychosis.

RESULTS

143 participants had valid addresses geo-coded. Neighborhood-level residential instability was associated with an earlier AOP (OR = 1.760; p = 0.022) even after controlling for known risk factors (OR = 2.026; p = 0.020) and also after controlling for individual-level residential instability (OR = 1.917; p = 0.037). The general socioeconomic status neighborhood factor (OR = 1.119; p = 0.019) and perceived neighborhood disorder (OR = 1.075; p = 0.005) were associated with a longer DUP. But only perceived neighborhood disorder (OR = 1.146; p = 0.011) remained significant, and general socioeconomic status was close to significant (OR = 1.215; p = 0.062), after controlling for individual-level predictors and socioeconomic status.

CONCLUSIONS

This study found evidence that neighborhood-level characteristics (in this case, residential instability) may be associated with earlier AOP, and perceptions of neighborhood disorder are associated with a longer treatment delay. Socioenvironmental factors should be more consistently considered going forward in research on early psychotic disorders.

Assessing the impacts of daily Cannabis versus alcohol and methamphetamines on young Australians in youth AOD treatment

BACKGROUND

Cannabis is the most widely used illicit substance by Australian young people, including those engaged with youth alcohol and other drug (AOD) systems. While recreational cannabis use in young people may be a developmental activity for some, for others, this usage becomes regular and be associated with poorer long term outcomes. This study reports on the rates of cannabis use and co-existing psychosocial complexity factors in the Youth Needs Census (2013 and 2016) where workers report on all clients in the youth AOD system, a cohort considered highly vulnerable.

METHODS

Data was examined for two rounds of data collection for the Youth Needs Census, including 823 youth AOD service engaged young people in 2016 and 1000 AOD service engaged young people in 2013, to identify usage rates, psychosocial outcomes, and changes over time.

RESULTS

Daily use of cannabis alone significantly exceeded daily usage rates for methamphetamines, alcohol, and cannabis used alongside other substances. Daily cannabis use was significantly associated with mental health problems, employment problems, education problems, family problems, and housing problems. Daily cannabis use was associated with most psychosocial complexity factors to the same extent as daily methamphetamine use and daily alcohol use, with daily cannabis users only showing lower incidence of the drug-related harm measure. Notably, daily cannabis use also increased from 2013 (47.5%) to 2016 (54.2%).

CONCLUSIONS

It is imperative that the number of individuals using cannabis is considered alongside the severity of harm when assessing the social impact of this substance. Within cannabis users engaged with the youth AOD system, who often have high levels of psychosocial complexity, cannabis is used daily by a large proportion of these youths and may play a role in negatively impacting their lives.

[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.

Association of smoked cannabis with treatment resistance in schizophrenia

Association of cannabis use with schizophrenia is a well-established finding. Its role in causation, however, is debated. Different studies have found that cannabis use impacts the outcome of schizophrenia and is associated with treatment non-adherence and a higher rate of relapses. In this paper, we investigated the impact of self-reported cannabis use on treatment response in a cohort of schizophrenia patients from Pakistan, a middle-income country. The data was collected from a psychiatric hospital in Khyber Pakhtunkhwa province of Pakistan where cannabis use is prevalent. Clinical evaluation and therapeutic response were established using the Positive and Negative Syndrome Scale (PANSS), and Clinical Global Impressions Scales-Severity (CGI-S) and Improvement (CGI-I) scale. Lack of response to adequate treatment with two trials of antipsychotics was classed as treatment resistance. We compared the treatment-resistant and treatment responsive groups for different variables including cannabis use, age at onset of illness, duration of untreated psychosis and consanguinity. We had data on 230 patients. More than ninety percent of our participants were men. The rate of treatment resistance was over 60%. Ongoing use of cannabis had an association with treatment resistance. We only included cases where treatment adherence was not a problem.

[Spontaneous pneumothorax and lung emphysema in cannabis users]

INTRODUCTION

If pulmonary complications of tobacco smoking are well documented, those associated with cannabis use are less known.

OBJECTIVES

Systematic literature review of data on pneumothorax and lung emphysema in cannabis users.

DOCUMENTARY SOURCES

Medline, on the period 1980-2018 with the following keywords cannabis or marijuana and pneumothorax or emphysema, limits "title/abstract". Among 97 articles, 42 abstracts have given use to a dual reading to select 20 studies.

RESULTS

Eighteen case reports (8 with SP) showed bullae in the upper lobes in combined cannabis and tobacco smokers (CS) and in the 2 cannabis only smokers (COS). The risk of SP was increased in CS, but not in COS. In patients less than 35-years old presenting with SP, the incidence of bullae on thoracic computed tomography (CT) was higher in CS than in tobacco only smokers (TOS). CT in patients with SP showed no significant difference as regards of the prevalence, location and type of emphysema between CS and TOS. Proportion of low lung density areas was higher in CS than in non-smokers (NS), but was similar in TOS and NS.

CONCLUSION

These results suggest a cumulative toxic effect of tobacco and cannabis on the risk of SP and lung emphysema.

Demographic and socioenvironmental predictors of premorbid marijuana use among patients with first-episode psychosis

OBJECTIVE

We identified, in subjects with first-episode psychosis, demographic and socioenvironmental predictors of three variables pertaining to premorbid marijuana use: age at initiation of marijuana use, trajectories of marijuana use in the five years prior to onset of psychosis, and the cumulative "dose" of marijuana intake in that same premorbid period.

METHODS

We enrolled 247 first-episode psychosis patients and collected data on lifetime marijuana/alcohol/tobacco use, age at onset of psychosis, diverse socioenvironmental variables, premorbid adjustment, past traumatic experiences, perceived neighborhood-level social disorder, and cannabis use experiences. Bivariate tests were used to examine associations between the three premorbid marijuana use variables and hypothesized predictors. Regression models determined which variables remained independently significantly associated.

RESULTS

Age at initiation of cigarette smoking was linked to earlier initiation, faster escalation, and higher cumulative dose of premorbid marijuana use. During childhood, poorer academic performance was predictive of an earlier age at initiation of marijuana use, while poorer sociability was related to more rapid escalation to daily use and a higher cumulative dose. As expected, experiencing euphoric effects was positively correlated with trajectories and cumulative dose, but having negative experiences was unrelated. Traumatic childhood/adolescent experiences were correlated with rapid escalation and amount of marijuana used, but not with age at initiation of marijuana use.

CONCLUSION

These data expand the very limited literature on predictors of premorbid marijuana use in first-episode psychosis. Given its association with earlier age at onset of psychosis, and poorer outcomes among first-episode patients, prevention and treatment efforts should be further developed.

Synthetic and Non-synthetic Cannabinoid Drugs and Their Adverse Effects-A Review From Public Health Prospective

There is a growing use of novel psychoactive substances containing synthetic cannabinoids. Synthetic cannabinoid products have effects similar to those of natural cannabis, yet, these drugs are more potent and dangerous, and have been associated with dangerous adverse effects. Here, we review current literature on the epidemiology, acute, and chronic effects of synthetic and natural cannabinoid-based drugs. Synthetic drugs contain a mixture of psychoactive compounds that mostly bind cannabinoid receptors with high potency. These synthetic drugs replicate the effects of natural cannabis and Δ9-tetrahydrocannabinol but they induce more severe adverse effects including respiratory difficulties, hypertension, tachycardia, chest pain, muscle twitches, acute renal failure, anxiety, agitation, psychosis, suicidal ideation, and cognitive impairment. Chronic use of synthetic cannabinoids has been associated with serious psychiatric and medical conditions and even death. Given the growing popularity in the use of cannabinoid-based drugs and their harmful potential, there is a need for further research in this field.

Meta-analysis of neurocognition in young psychosis patients with current cannabis use

OBJECTIVE

Adult psychosis patients (i.e. over the age of 25 years) who are also lifetime cannabis users (CANN±) appear to exhibit superior cognition compared to never-using patients (CANN-). The objective of this meta-analysis was to evaluate the cognitive differences between CANN- and patients who currently use cannabis (CANN+) (i.e. during the CANN± patients' cannabis-using stage). Specifically, focusing on young patients under the age of 25 years, the typical stage of both psychosis- and cannabis-onset.

METHOD

Of the 308 studies identified through database searches and secondary referencing, 14 compared neurocognition of CANN+ and CANN- in young people with psychotic disorders (mean age between 15 and 45 years). Effect sizes were extracted using neurocognitive test performance between CANN+ and CANN- and random effects modelling was conducted on pooled ES and moderator analyses.

RESULTS

CANN+ performed worse on several cognitive domains (i.e. premorbid IQ, current IQ, verbal learning, verbal working memory, motor inhibition) compared to CANN-. The association between age and performance in CANN+ cognition was varied, with older age predictive of worse performance in processing speed, sustained attention, verbal memory, and better performance in verbal learning and very fluency. Of note, CANN+ outperformed CANN- in tests of conceptual set-shifting.

CONCLUSION

These results are consistent with previous findings indicating that CANN+ demonstrate poorer neurocognition than CANN-; and that this is exacerbated with increasing age. Our findings demonstrate significant cognitive differences between patients with CANN+ versus CANN- even at early-onset psychosis, which could suggest a different underlying mechanism towards psychosis for cannabis users.

The Effects of Cannabinoids on Executive Functions: Evidence from Cannabis and Synthetic Cannabinoids-A Systematic Review

Background—Cannabis is the most popular illicit drug in the Western world. Repeated cannabis use has been associated with short and long-term range of adverse effects. Recently, new types of designer-drugs containing synthetic cannabinoids have been widespread. These synthetic cannabinoid drugs are associated with undesired adverse effects similar to those seen with cannabis use, yet, in more severe and long-lasting forms. Method—A literature search was conducted using electronic bibliographic databases up to 31 December 2017. Specific search strategies were employed using multiple keywords (e.g., “synthetic cannabinoids AND cognition,” “cannabis AND cognition” and “cannabinoids AND cognition”). Results—The search has yielded 160 eligible studies including 37 preclinical studies (5 attention, 25 short-term memory, 7 cognitive flexibility) and 44 human studies (16 attention, 15 working memory, 13 cognitive flexibility). Both pre-clinical and clinical studies demonstrated an association between synthetic cannabinoids and executive-function impairment either after acute or repeated consumptions. These deficits differ in severity depending on several factors including the type of drug, dose of use, quantity, age of onset and duration of use. Conclusions—Understanding the nature of the impaired executive function following consumption of synthetic cannabinoids is crucial in view of the increasing use of these drugs.

Toward the Identification of a Specific Psychopathology of Substance Use Disorders

Addiction is a mental illness in which psychiatric conditions imply a prominent burden. Psychopathological symptoms in substance use disorder (SUD) patients are usually viewed as being assignable to the sphere of a personality trait or of comorbidity, leaving doubts about the presence of a specific psychopathology that could only be related to the toxicomanic process. Our research group at the University of Pisa has shed light on the possible definition of a specific psychopathological dimension in SUDs. In heroin use disorder patients, performing an exploratory principal component factor analysis (PCA) on all the 90 items included in the SCL-90 questionnaire led to a five-factor solution. The first factor accounted for a depressive "worthlessness and being trapped" dimension; the second factor picked out a "somatic symptoms" dimension; the third identified a "sensitivity-psychoticism" dimension; the fourth a "panic-anxiety" dimension; and the fifth a "violence-suicide" dimension. These same results were replicated by applying the PCA to another Italian sample of 1,195 heroin addicts entering a Therapeutic Community Treatment. Further analyses confirmed the clusters of symptoms, independently of demographic and clinical characteristics, active heroin use, lifetime psychiatric problems, kind of treatment received, and, especially, other substances used by the patient such as alcohol or cocaine. Moreover, these clusters were able to discriminate patients affected by addiction from those affected by psychiatric diseases such as major depressive disorder. Our studies seem to suggest the trait-dependent, rather than the state-dependent, nature of the introduced psychopathology dimensions of SUDs.

Behavioral sequelae of astrocyte dysfunction: focus on animal models of schizophrenia

Astrocytes regulate multiple processes in the brain ranging from trophic support of developing neurons to modulation of synaptic neurotransmission and neuroinflammation in adulthood. It is, therefore, understandable that pathogenesis and pathophysiology of major psychiatric disorders involve astrocyte dysfunctions. Until recently, there has been the paucity of experimental approaches to studying the roles of astrocytes in behavioral disease. A new generation of in vivo models allows us to advance our understanding of the roles of astrocytes in psychiatric disorders. This review will evaluate the recent studies that focus on the contribution of astrocyte dysfunction to behavioral alterations pertinent to schizophrenia and will propose the possible solutions of the limitations of the existing approaches.

Cannabinoid Transmission in the Hippocampus Activates Nucleus Accumbens Neurons and Modulates Reward and Aversion-Related Emotional Salience

BACKGROUND

Cannabinoid receptor transmission strongly influences emotional processing, and disturbances in cannabinoid signaling are associated with various neuropsychiatric disorders. The mammalian ventral hippocampus (vHipp) is a critical neural region controlling mesolimbic activity via glutamatergic projections to the nucleus accumbens. Furthermore, vHipp abnormalities are linked to schizophrenia-related psychopathology. Nevertheless, the mechanisms by which intra-vHipp cannabinoid signaling may modulate mesolimbic activity states and emotional processing are not currently understood.

METHODS

Using an integrative combination of in vivo electrophysiological recordings and behavioral pharmacologic assays in rats, we tested whether activation of cannabinoid type 1 receptors (CB1R) in the vHipp may modulate neuronal activity in the shell subregion of the nucleus accumbens (NASh). We next examined how vHipp CB1R signaling may control the salience of rewarding or aversive emotional memory formation and social interaction/recognition behaviors via intra-NASh glutamatergic transmission.

RESULTS

We demonstrate for the first time that vHipp CB1R transmission can potently modulate NASh neuronal activity and can differentially control the formation of context-dependent and context-independent forms of rewarding or aversion-related emotional associative memories. In addition, we found that activation of vHipp CB1R transmission strongly disrupts normal social behavior and cognition. Finally, we report that these behavioral effects are dependent upon intra-NASh alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid/N-methyl-D-aspartate receptor transmission.

CONCLUSIONS

Together, these findings demonstrate a critical role for hippocampal cannabinoid signaling in the modulation of mesolimbic neuronal activity states and suggest that dysregulation of CB1R transmission in the vHipp→NASh circuit may underlie hippocampal-mediated affective and social behavioral disturbances present in neuropsychiatric disorders.

Adverse effects of marijuana use

Marijuana has consistently been reported as the most commonly used illicit substance in the United States each year. Currently, the legalization of marijuana is up for debate across the nation. While marijuana use is prevalent among the adolescent population, research has shown that there can be devastating effects on health and well-being. A review of the literature shows that marijuana use can have a negative impact on physical health, psychological well-being, and multiple psychosocial outcomes. Adolescents who used marijuana more frequently and began using marijuana at an earlier age experienced worse outcomes and long-lasting effects.

LAY SUMMARY

This article reviews recent literature regarding adverse effects of marijuana use. Negative effects of marijuana use relating to physical health, psychological well-being, and outcomes such as academic performance are discussed, especially in relation to the adolescent population.

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.

Cannabis use in first episode psychosis: Meta-analysis of prevalence, and the time course of initiation and continued use

OBJECTIVES

Cannabis use is prevalent among people with first episode psychosis and the epidemiology of its use in early psychosis is unclear. We performed a meta-analysis of observational studies to determine; (1) the interval between age at initiation of cannabis use and age at onset of first episode psychosis, (2) the prevalence of cannabis use at time of first episode psychosis, and (3) the odds of continuing cannabis following treatment for first episode psychosis.

DATA SOURCES

Search of electronic databases MEDLINE, EMBASE, PsycINFO, Web of Science and CINAHL for English-language papers using search terms (psychosis OR schizophrenia) AND (cannabis OR marijuana) IN (title OR keyword OR abstract), current to October 2014.

STUDY SELECTION

Studies were included if they reported on prevalence of current cannabis use in first episode psychosis cohorts. A total of 37 samples were included for meta-analysis.

DATA EXTRACTION

Rates of cannabis use in each sample were extracted to determine prevalence estimates. The age at initiation of regular cannabis and age at onset of psychosis were used to determine the length of cannabis use preceding psychosis. Prevalence estimates at first episode psychosis and various time points of follow-up following first episode psychosis were analysed to determine odds ratio of continuing cannabis use. Data synthesis was performed using random-effects meta-analyses.

RESULTS

The pooled estimate for the interval between initiation of regular cannabis use and age at onset of psychosis was 6.3 years (10 samples, standardised mean difference = 1.56, 95% confidence interval = [1.40, 1.72]). The estimated prevalence of cannabis use at first episode psychosis was 33.7% (35 samples, 95% confidence interval = [31%, 39%]). Odds of continued cannabis use between 6 months and 10 years following first episode psychosis was 0.56 (19 samples, 95% confidence interval = [0.40, 0.79]).

Hippocampal cannabinoid transmission modulates dopamine neuron activity: impact on rewarding memory formation and social interaction

Disturbances in cannabinoid type 1 receptor (CB1R) signaling have been linked to emotional and cognitive deficits characterizing neuropsychiatric disorders, including schizophrenia. Thus, there is growing interest in characterizing the relationship between cannabinoid transmission, emotional processing, and dopamine (DA)-dependent behavioral deficits. The CB1R is highly expressed in the mammalian nervous system, particularly in the hippocampus. Activation of the ventral hippocampal subregion (vHipp) is known to increase both the activity of DAergic neurons located in the ventral tegmental area (VTA) and DA levels in reward-related brain regions, particularly the nucleus accumbens (NAc). However, the possible functional relationship between hippocampal CB1R transmission and VTA DA neuronal activity is not currently understood. In this study, using in vivo neuronal recordings in rats, we demonstrate that activation of CB1R in the vHipp strongly increases VTA DA neuronal firing and bursting activity, while simultaneously decreasing the activity of VTA non-DA neurons. Furthermore, using a conditioned place preference procedure and a social interaction test, we report that intra-vHipp CB1R activation potentiates the reward salience of normally sub-threshold conditioning doses of opiates and induces deficits in natural sociability and social recognition behaviors. Finally, these behavioral effects were prevented by directly blocking NAc DAergic transmission. Collectively, these findings identify hippocampal CB1R transmission as a critical modulator of the mesolimbic DA pathway and in the processing of reward and social-related behavioral phenomena.

A critical assessment of the equal-environment assumption of the twin method for schizophrenia

The classical twin method (CTM) is central to the view that schizophrenia is ~80% heritable. The CTM rests on the equal-environment assumption (EEA) that identical and fraternal twin pairs experience equivalent trait-relevant environmental exposures. The EEA has not been directly tested for schizophrenia with measures of child social adversity, which is particularly etiologically relevant to the disorder. However, if child social adversity is more similar in identical than fraternal pairs in the general twin population, the EEA is unlikely to be valid for schizophrenia, a question which we tested in this study. Using results from prior twin studies, we tested if intraclass correlations for the following five categories of child social adversity are larger in identical than fraternal twins: bullying, sexual abuse, physical maltreatment, emotional neglect and abuse, and general trauma. Eleven relevant studies that encompassed 9119 twin pairs provided 24 comparisons of intraclass correlations, which we grouped into the five social exposure categories. Fisher's z-test revealed significantly higher correlations in identical than fraternal pairs for each exposure category (z ≥ 3.53, p < 0.001). The difference remained consistent across gender, study site (country), sample size, whether psychometric instruments were used, whether interviewing was proximate or distant to the exposures, and whether informants were twins or third persons. Combined with other evidence that the differential intraclass correlation for child social adversity cannot be explained by evocative gene-environment covariation, our results indicate that the CTM does not provide any valid indication of genomic effects in schizophrenia.

mHealth App for Cannabis Users: Satisfaction and Perceived Usefulness

OBJECTIVE

The aim of this study was to describe the characteristics of cannabis users and their levels of satisfaction with Stop-cannabis, an app intended for cannabis users who want to stop or reduce their cannabis use or prevent relapse.

METHODS

A cross-sectional online survey was administered to users of Stop-cannabis, a French-language app for iOS and Android devices. All app users were invited to participate in the survey via a message sent to the app.

RESULTS

For hundred and eighty-two users answered the survey. The app was used daily by 348 of the participants (around 70%). More than 80% of participants (397) considered the app to have helped them "a little" or "a lot" to stop or reduce cannabis consumption. Most of the users' suggestions were related to the number or the quality of the messages sent by, or displayed in, the app.

CONCLUSION

This pilot study supports the feasibility of such an app and its perceived usefulness. A self-selection bias, however, limits the conclusions of the study. The efficacy of the app should be evaluated in a randomized controlled trial.

Informed consent in the psychosis prodrome: ethical, procedural and cultural considerations

Research focused on the prodromal period prior to the onset of psychosis is essential for the further development of strategies for early detection, early intervention, and disease pre-emption. Such efforts necessarily require the enrollment of individuals who are at risk of psychosis but have not yet developed a psychotic illness into research and treatment protocols. This work is becoming increasingly internationalized, which warrants special consideration of cultural differences in conceptualization of mental illness and international differences in health care practices and rights regarding research participation. The process of identifying and requesting informed consent from individuals at elevated risk for psychosis requires thoughtful communication about illness risk and often involves the participation of family members. Empirical studies of risk reasoning and decisional capacity in young people and individuals with psychosis suggest that most individuals who are at-risk for psychosis can adequately provide informed consent; however ongoing improvements to tools and procedures are important to ensure that this work proceeds with maximal consideration of relevant ethical issues. This review provides a discussion of these issues in the context of international research efforts.

Neuronal substrates and functional consequences of prenatal cannabis exposure

Cannabis remains one of the world's most widely used substance of abuse amongst pregnant women. Trends of the last 50 years show an increase in popularity in child-bearing women together with a constant increase in cannabis potency. In addition, potent herbal "legal" highs containing synthetic cannabinoids that mimic the effects of cannabis with unknown pharmacological and toxicological effects have gained rapid popularity amongst young adults. Despite the surge in cannabis use during pregnancy, little is known about the neurobiological and psychological consequences in the exposed offspring. In this review, we emphasize the importance of maternal programming, defined as the intrauterine presentation of maternal stimuli to the foetus, in neurodevelopment. In particular, we focus on cannabis-mediated maternal adverse effects, resulting in direct central nervous system alteration or sensitization to late-onset chronic and neuropsychiatric disorders. We compare clinical and preclinical experimental studies on the effects of foetal cannabis exposure until early adulthood, to stress the importance of animal models that permit the fine control of environmental variables and allow the dissection of cannabis-mediated molecular cascades in the developing central nervous system. In sum, we conclude that preclinical experimental models confirm clinical studies and that cannabis exposure evokes significant molecular modifications to neurodevelopmental programs leading to neurophysiological and behavioural abnormalities.

Cannabis use and first manic episode

BACKGROUND

Cannabis is the most commonly abused drug among patients with bipolar disorder. Available data has shown that the risk of psychotic disorders increases with the frequency and intensity of cannabis abuse. The present purpose was to review relevant studies to investigate whether cannabis use can be linked to the onset of mania in bipolar disorder.

METHODS

Articles published between 1972 and December 2013 were searched on Medline and PsychInfo using the following keywords: first manic episode, or onset mania, or bipolar disorder and cannabis. Relevant papers cited in the references of selected articles were further considered for inclusion into the review.

RESULTS

Lifetime use of cannabis among bipolar patients appears to be around 70% and approximately 30% of patients with a bipolar disorder present a comorbidity of cannabis abuse or dependence. Cannabis use is associated with younger age at onset of first mania and with more frequent depressive or manic episodes, although the evidence is somewhat inconsistent. Likewise cannabis consumption is related to poorer outcome and an increased risk of rapid cycling or mixed episodes. In contrast, neuro-cognitive functioning seems to be positively affected in patients with psychiatric comorbidity. While cannabis use often precedes first manic episodes, the causal direction remains to be determined.

LIMITATIONS

Variations in definition of cannabis use/dependence. Lack of controlled studies limiting definite conclusions about a putative causal relationship between cannabis and onset of mania.

CONCLUSIONS

Further investigations are needed to clarify the relationships between cannabis use and first manic episode.

Cannabis Use and Dependence among French Schizophrenic Inpatients

BACKGROUND

To assess the prevalence of cannabis use and dependence in a population of schizophrenic inpatients and to compare schizophrenics with and without cannabis consumption.

METHODS

One hundred one schizophrenic patients were examined during their first week of hospitalization. They answered the PANNS scale of schizophrenia, the CAGE and the Fagerström questionnaire, and the DSM-IV-TR criteria for cannabis, alcohol, opiates, and nicotine use dependence were checked. We also assessed socio-demographic characteristics, the motive of cannabis consumption, and the number of cannabis joints and alcoholic drinks taken.

RESULTS

The prevalence of cannabis consumption was 33.6% among schizophrenic inpatients. Schizophrenics consuming cannabis were younger than non-schizophrenics (33.3 vs. 44.7 years p < 0.0001), more often male (77 vs. 54%, p = 0.02) and had been hospitalized for the first time in psychiatry earlier (24.3 vs. 31.3 p = 0.003). Eighty-eight percent of cannabis consumers were dependent on cannabis. They were more often dependent on opiates (17 vs. 0%) and alcohol (32 vs. 7.4%, p = 0.001) and presented compulsive buying more often (48 vs. 27%, p = 0.04). Logistic regression revealed that factors associated to cannabis consumption among schizophrenics were cannabis dependence, male gender, pathological gambling, opiate dependence, number of joints smoked each day, and compulsive buying.

CONCLUSION

33.6% of the schizophrenic patients hospitalized in psychiatry consume cannabis and most of them are dependent on cannabis and alcohol. Hospitalization in psychiatry may provide an opportunity to systematically identify a dependence disorder and to offer appropriate information and treatment.

Psychopathological symptoms of patients with heroin addiction entering opioid agonist or therapeutic community treatment

BACKGROUND

The relationship between substance use disorders and psychiatric pathology is still an open question. The main aim of the present study was to verify whether the five psychopathological dimensions identified through the SCL-90 tool in a previous study carried out on patients with heroin addiction entering an outpatient opioid agonist treatment (OAT) were also observable in those entering a residential treatment community (TC). Further aims were to look at differences in the psychopathological profiles of patients entering a TC versus an OAT treatment and at the correlation between gender and the observed psychopathology.

METHODS

A confirmatory factor analysis was performed on the results of SCL-90 filled by 1,195 patients with heroin dependence entering TC treatment. It replicates the extraction method previously used on 1,055 OAT patients with heroin addiction by using a principal component factor analysis (PCA). The association between the kind of treatment received (TC or OAT), gender, and the psychopathological dimensions was assessed through logistic regression and general linear model (GLM) analysis.

RESULTS

The PCA carried out on the SCL-90 results of patients entering a TC yielded a five-factor solution, confirming the same dimensions observed in patients entering an OAT: 'worthlessness and being trapped', 'somatization', 'sensitivity-psychoticism', 'panic anxiety', and 'violence-suicide'. The logistic regression analysis showed a statistically significant association between 'somatization' and 'violence-suicide' severity score and OAT. GLM analysis showed that psychopathological factorial scores for 'worthlessness-being trapped', 'somatic symptoms', and 'panic anxiety' dimensions were more severe in OAT vs TC male patients and in TC vs OAT female ones. 'Violence suicide' followed the same severity pattern for males, but did not differ in TC vs OAT females, while 'sensitivity-psychoticism' did not differ in OAT vs TC patients. The five dimensions did not differ in OAT males vs females.

CONCLUSIONS

Our research appears to confirm the existence of a specific aggregation of psychological/psychiatric features within the category of individuals with heroin addiction. It also shows a correlation between the dominant psychopathological subgroup and the assignment to TC versus OAT. Further research is needed to clarify the differences between the five psychopathological subgroups and their determinants.