Worldwide cannabis dependence is increasing, as is the concentration of Delta(9)-tetrahydrocannabinol (THC) in street cannabis. At the same time, the concentration of the second most abundant cannabinoid in street cannabis, cannabidiol (CBD), is decreasing. These two cannabinoids have opposing effects both pharmacologically and behaviorally when administered in the laboratory. No research has...
Cannabis contains over 70 unique compounds and its abuse is linked to an increased risk of developing schizophrenia. The behavioural profiles of the psychotropic cannabis constituent Delta9-tetrahydrocannabinol (Delta9-THC) and the non-psychotomimetic constituent cannabidiol (CBD) were investigated with a battery of behavioural tests relevant to anxiety and positive, negative and cognitive...
Studies in laboratory animals strongly suggest reciprocal modulation of the opioidergic and endocannabinoid systems, a relationship that has not been demonstrated in humans. This study sought to clarify this interaction by assessing how a range of naltrexone doses altered the subjective, cognitive, and cardiovascular effects of marijuana. Daily marijuana smokers (n = 29) participated in this...
Drug interaction with P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) may influence its tissue disposition including blood-brain barrier transport and result in potent drug-drug interactions. The limited data obtained using in-vitro models indicate that methadone, buprenorphine, and cannabinoids may interact with human P-gp; but almost nothing is known about drugs of abuse and...
This study used a web-based questionnaire to investigate user perceptions of the benefits and harms of hallucinogenic drug use. Over 600 forms were submitted. Users were asked to comment on the acute and prolonged effects of different drugs and to provide more specific information on how particular drugs have harmed and/or helped them. Subjects reported relatively less harm associated with the...
Cannabis use is highly prevalent among people with schizophrenia, and coupled with impaired cognition, is thought to heighten the risk of illness onset. However, while heavy cannabis use has been associated with cognitive deficits in long-term users, studies among patients with schizophrenia have been contradictory. This article consists of 2 studies. In Study I, a meta-analysis of 10 studies...
We tested the hypothesis that THC disrupts self-timed actions in healthy volunteers, and that this effect is related to self-rated perceptions of time distortion. We found that THC impaired subjective time perception and reduced the rate of button pressing, although the change in the rate of button pressing was more closely related to impaired concentration and intoxication. We conclude that...
BACKGROUND: Several epidemiological studies have shown that cannabis; the most widely used illegal drug in the world, is associated with schizophrenia spectrum disorders (SSD). AIMS: To assess the characteristics of cannabis use and its association with SSD in a cohort of psychiatrically ill patients and discuss the implications for policy development METHODS: This is a retrospective analytical...
Marijuana-dependent individuals report using marijuana to alleviate withdrawal, suggesting that pharmacotherapy of marijuana withdrawal could promote abstinence. To identify potential pharmacotherapies for marijuana withdrawal, this study first characterized rimonabant-induced Delta(9)-tetrahydrocannabinol (Delta(9)-THC) withdrawal in rhesus monkeys by using drug discrimination and directly...
Cannabinoid withdrawal produces a hypofunction of mesencephalic dopamine neurons that impinge upon medium spiny neurons (MSN) of the forebrain. After chronic treatment with two structurally different cannabinoid agonists, Delta(9)-tetrahydrocannabinol and CP55 940 (CP) rats were withdrawn spontaneously and pharmacologically with the CB1 antagonist SR141716A (SR). In these two conditions,...
Cannabis intake has been reported to affect cognitive functions such as selective attention. This study addressed the effects of exposure to cannabis with up to 69.4mg Delta(9)-tetrahydrocannabinol (THC) on Event-Related Potentials (ERPs) recorded during a visual selective attention task. Twenty-four participants smoked cannabis cigarettes with four doses of THC on four test days in a...
Ayahuasca is a psychoactive beverage used for magico-religious purposes in the Amazon. Recently, Brazilian syncretic churches have helped spread the ritual use of ayahuasca abroad. This trend has raised concerns that regular use of this N,N-dimethyltryptamine-containing tea may lead to the medical and psychosocial problems typically associated with drugs of abuse. Here we assess potential drug...
It is intriguing that during human cultural evolution man has detected plant natural products that appear to target key protein receptors of important physiological systems rather selectively. Plants containing such secondary metabolites usually belong to unique chemotaxa, induce potent pharmacological effects and have typically been used for recreational and medicinal purposes or as poisons....
The antidepressant action of cannabis as well as the interaction between antidepressants and the endocannabinoid system has been reported. This study was conducted to assess the antidepressant-like activity of Delta(9)-THC and other cannabinoids. Cannabinoids were initially evaluated in the mouse tetrad assay to determine doses that do not induce hypothermia or catalepsy. The automated mouse...
Cannabis is one of the most widely used illicit drugs among adolescents, and most users first experiment with it in adolescence. Adolescence is a critical phase for brain development, characterized by neuronal maturation and rearrangement processes, such as myelination, synaptic pruning and dendritic plasticity. The endocannabinoid system plays an important role in fundamental brain...
BACKGROUND: Little is known about the experiential dynamics of the interaction between cannabis and vulnerability to psychosis. AIMS: To examine the effects of cannabis on psychotic symptoms and mood in patients with psychosis and healthy controls. METHOD: Patients with a psychotic disorder (n = 42) and healthy controls (n = 38) were followed in their daily lives using a structured...
Marijuana discontinuation has been recently reported to be anxiogenic in humans, which may predict relapse. Limited animal research has been carried out to model this withdrawal-associated negative affect. The current study sought to investigate the potential anxiety-like effects of cannabinoid withdrawal in mice. Male ICR mice were injected s.c. with delta9-tetrahydrocannabinol (THC) at...
Back to table of contents Previous article Next article Clinical & Research NewsFull AccessCannabis Use, Psychosis Symptoms Show Strong LinkMark MoranMark MoranSearch for more papers by this authorPublished Online:21 May 2010https://doi.org/10.1176/pn.45.10.psychnews_45_10_028AbstractMarijuana use among individuals with schizophrenia is associated with more severe positive psychotic symptoms...
Objective Despite the controversy surrounding the possible causal link between cannabis use and the onset of schizophrenia (SZ), data seeking to elucidate the effect of cannabis use disorders (CUD) on the clinical presentation of SZ have produced mixed results. Although several studies have suggested that CUD in patients with SZ may be associated with variation in cognitive function, clinical...
Introduction The purpose of this study is to determine if an earlier age at onset of positive symptoms in schizophrenia is associated with cannabis use disorders (CUD). Methods 49 first-episode schizophrenia subjects with CUD were compared to 51 first-episode schizophrenia subjects with no substance use disorders for demographic and clinical variables. A multivariate logistic regression was...