The CannTeen Study: Cannabis use disorder, depression, anxiety, and psychotic-like symptoms in adolescent and adult cannabis users and age-matched controls.

Background: Adolescence is characterised by psychological and neural development. Cannabis harms may be accentuated during adolescence. We hypothesised that adolescents would be more vulnerable to the associations between cannabis use and mental health and addiction problems than adults.

Predictors and rates of PTSD, depression and anxiety in UK frontline health and social care workers during COVID-19.

: Studies have shown that working in frontline healthcare roles during epidemics and pandemics was associated with PTSD, depression, anxiety, and other mental health disorders. : The objectives of this study were to identify demographic, work-related and other predictors for clinically significant PTSD, depression, and anxiety during the COVID-19 pandemic in UK frontline health and social care workers (HSCWs), and to compare rates of distress across different groups of HCSWs working in different roles and settings. : A convenience sample () of frontline UK HCSWs completed an online survey during the first wave of the pandemic (27 May - 23 July 2020).

The acute effects of cannabidiol on the neural correlates of reward anticipation and feedback in healthy volunteers.

Background: Cannabidiol has potential therapeutic benefits for people with psychiatric disorders characterised by reward function impairment. There is existing evidence that cannabidiol may influence some aspects of reward processing. However, it is unknown whether cannabidiol acutely affects brain function underpinning reward anticipation and feedback.

Acute effects of MDMA on trust, cooperative behaviour and empathy: A double-blind, placebo-controlled experiment.

Background: 3,4-Methylenedioxymethamphetamine (MDMA) is being actively researched as an adjunct to psychotherapy. It may be beneficial to trust, empathy and cooperative behaviour due to its acute prosocial effects.

Aim: To test (a) the acute effects of MDMA on measures of empathy, trust and cooperative behaviour, and (b) subacute changes in mood three days after MDMA administration.

The effects of psychosocial stress on dopaminergic function and the acute stress response.

Chronic psychosocial adversity induces vulnerability to mental illnesses. Animal studies demonstrate that this may be mediated by dopaminergic dysfunction. We therefore investigated whether long-term exposure to psychosocial adversity was associated with dopamine dysfunction and its relationship to psychological and physiological responses to acute stress.

Dissociable effects of cannabis with and without cannabidiol on the human brain's resting-state functional connectivity.

Background: Two major constituents of cannabis are Δ-tetrahydrocannabinol (THC) and cannabidiol (CBD). THC is the main psychoactive component; CBD may buffer the user against the harmful effects of THC.

Aims: We examined the effects of two strains of cannabis and placebo on the human brain's resting-state networks using fMRI.

The effect of perinatal brain injury on dopaminergic function and hippocampal volume in adult life.

Perinatal brain injuries, including hippocampal lesions, cause lasting changes in dopamine function in rodents, but it is not known if this occurs in humans. We compared adults who were born very preterm with perinatal brain injury to those born very preterm without perinatal brain injury, and age-matched controls born at full term using [18F]-DOPA PET and structural MRI. Dopamine synthesis capacity was reduced in the perinatal brain injury group relative to those without brain injury (Cohen's = 1.

Elevated Striatal Dopamine Function in Immigrants and Their Children: A Risk Mechanism for Psychosis.

Migration is a major risk factor for schizophrenia but the neurochemical processes involved are unknown. One candidate mechanism is through elevations in striatal dopamine synthesis and release. The objective of this research was to determine whether striatal dopamine function is elevated in immigrants compared to nonimmigrants and the relationship with psychosis.

Treatment-Resistant Schizophrenia: Treatment Response and Resistance in Psychosis (TRRIP) Working Group Consensus Guidelines on Diagnosis and Terminology.

Objective: Research and clinical translation in schizophrenia is limited by inconsistent definitions of treatment resistance and response. To address this issue, the authors evaluated current approaches and then developed consensus criteria and guidelines.

Method: A systematic review of randomized antipsychotic clinical trials in treatment-resistant schizophrenia was performed, and definitions of treatment resistance were extracted.

The effects of Δ-tetrahydrocannabinol on the dopamine system.

The effects of Δ-tetrahydrocannabinol (THC), the main psychoactive ingredient in cannabis, are a pressing concern for global mental health. Patterns of cannabis use are changing drastically owing to legalization, the availability of synthetic analogues (commonly termed spice), cannavaping and an emphasis on the purported therapeutic effects of cannabis. Many of the reinforcing effects of THC are mediated by the dopamine system.

Acute and chronic effects of cannabinoids on effort-related decision-making and reward learning: an evaluation of the cannabis 'amotivational' hypotheses.

Rationale: Anecdotally, both acute and chronic cannabis use have been associated with apathy, amotivation, and other reward processing deficits. To date, empirical support for these effects is limited, and no previous studies have assessed both acute effects of Δ-9-tetrahydrocannabinol (THC) and cannabidiol (CBD), as well as associations with cannabis dependence.

Objectives: The objectives of this study were (1) to examine acute effects of cannabis with CBD (Cann + CBD) and without CBD (Cann-CBD) on effort-related decision-making and (2) to examine associations between cannabis dependence, effort-related decision-making and reward learning.

Effects of Cannabis Use on Human Behavior, Including Cognition, Motivation, and Psychosis: A Review.

With a political debate about the potential risks and benefits of cannabis use as a backdrop, the wave of legalization and liberalization initiatives continues to spread. Four states (Colorado, Washington, Oregon, and Alaska) and the District of Columbia have passed laws that legalized cannabis for recreational use by adults, and 23 others plus the District of Columbia now regulate cannabis use for medical purposes. These policy changes could trigger a broad range of unintended consequences, with profound and lasting implications for the health and social systems in our country.

Treatment-Resistant Schizophrenia Patients Show Elevated Anterior Cingulate Cortex Glutamate Compared to Treatment-Responsive.

Introduction: Resistance to antipsychotic treatment is a significant clinical problem in patients with schizophrenia with approximately 1 in 3 showing limited or no response to repeated treatments with antipsychotic medication. The neurobiological basis for treatment resistance is unknown but recent evidence implicates glutamatergic function in the anterior cingulate cortex. We examined glutamate levels of chronically ill treatment-resistant patients directly compared to treatment-responsive patients.

Microglial Activity in People at Ultra High Risk of Psychosis and in Schizophrenia: An [(11)C]PBR28 PET Brain Imaging Study.

Objective: The purpose of this study was to determine whether microglial activity, measured using translocator-protein positron emission tomography (PET) imaging, is increased in unmedicated persons presenting with subclinical symptoms indicating that they are at ultra high risk of psychosis and to determine whether microglial activity is elevated in schizophrenia after controlling for a translocator-specific genetic polymorphism.

Method: The authors used the second-generation radioligand [(11)C]PBR28 and PET to image microglial activity in the brains of participants at ultra high risk for psychosis. Participants were recruited from early intervention centers.

Treatment resistant or resistant to treatment? Antipsychotic plasma levels in patients with poorly controlled psychotic symptoms.

A large proportion of individuals with schizophrenia show an inadequate response to treatment with antipsychotics. It can be unclear whether this is secondary to subtherapeutic antipsychotic plasma levels or to medication ineffectiveness. The purpose of the present study was to determine the extent of subtherapeutic antipsychotic plasma levels in a group of patients clinically identified as treatment-resistant.

Prevalence of serum N-methyl-D-aspartate receptor autoantibodies in refractory psychosis.

N-methyl-d-aspartate receptor (NMDA-R) autoantibodies have been reported in people with acute psychosis. We hypothesised that their presence may be implicated in the aetiology of treatment-refractory psychosis. We sought to ascertain the point prevalence of NMDA-R antibody positivity in patients referred to services for treatment-refractory psychosis.

Dopamine function in cigarette smokers: an [¹⁸F]-DOPA PET study.

Tobacco addiction is a global public health problem. Addiction to tobacco is thought to involve the effects of nicotine on the dopaminergic system. Only one study has previously investigated dopamine synthesis capacity in cigarette smokers.

The link between dopamine function and apathy in cannabis users: an [18F]-DOPA PET imaging study.

Rationale: Cannabis is the most widely used illicit drug in the world, and regular use has been associated with reduced motivation, i.e. apathy.

The Effects of Acutely Administered 3,4-Methylenedioxymethamphetamine on Spontaneous Brain Function in Healthy Volunteers Measured with Arterial Spin Labeling and Blood Oxygen Level-Dependent Resting State Functional Connectivity.

Background: The compound 3,4-methylenedioxymethamphetamine (MDMA) is a potent monoamine releaser that produces an acute euphoria in most individuals.

Methods: In a double-blind, placebo-controlled, balanced-order study, MDMA was orally administered to 25 physically and mentally healthy individuals. Arterial spin labeling and seed-based resting state functional connectivity (RSFC) were used to produce spatial maps displaying changes in cerebral blood flow (CBF) and RSFC after MDMA administration.

Does human presynaptic striatal dopamine function predict social conformity?

Socially desirable responding (SDR) is a personality trait which reflects either a tendency to present oneself in an overly positive manner to others, consistent with social conformity (impression management (IM)), or the tendency to view one's own behaviour in an overly positive light (self-deceptive enhancement (SDE)). Neurochemical imaging studies report an inverse relationship between SDR and dorsal striatal dopamine D₂/₃ receptor availability. This may reflect an association between SDR and D₂/₃ receptor expression, synaptic dopamine levels or a combination of the two.

Dopaminergic function in cannabis users and its relationship to cannabis-induced psychotic symptoms.

Background: Cannabis is the most widely used illicit drug globally, and users are at increased risk of mental illnesses including psychotic disorders such as schizophrenia. Substance dependence and schizophrenia are both associated with dopaminergic dysfunction. It has been proposed, although never directly tested, that the link between cannabis use and schizophrenia is mediated by altered dopaminergic function.

Presynaptic striatal dopamine dysfunction in people at ultra-high risk for psychosis: findings in a second cohort.

Background: Using positron emission tomography (PET), we previously observed increases in 3,4-dihydroxy-6-[(18)F]fluoro-L-phenylalanine ((18)F-DOPA) uptake in the striatum of subjects at ultra-high risk (UHR) for psychosis, indicating elevated presynaptic dopamine synthesis capacity. The purpose of this study was to test if this finding would be replicated in a second UHR cohort.

Methods: (18)F-DOPA PET was used to estimate dopamine synthesis capacity in the striatum of an entirely new cohort of 26 individuals at UHR for psychosis (14 males, mean±SD age = 22.