Alterations of long-term synaptic plasticity have been proposed to participate in the development of addiction. To preserve synaptic functions, homeostatic processes must be engaged after exposure to abused drugs. At the mouse cortico-accumbens synapses, a single in vivo injection of Delta9-tetrahydrocannabinol (THC) suppresses endocannabinoid-mediated long-term depression. Using biochemical...
ABSTRACT A comparison of personality factors on scales of the Minnesota Multiphasic Personality Inventory-Adolescent (MMPI-A) was conducted with a sample of adolescents referred to a residential substance abuse treatment program. A total of sixty adolescents identified with hallucinogen (n = 20), cannabis (n = 20), or methamphetamine (n = 20) as their drug of choice participated in the study....
Abstract Background Cannabis is the most commonly used illegal drug and its therapeutic aspects have a growing interest. Short-term psychotic reactions have been described but not clearly with synthetic oral THC, especially in occasional users. Case presentations We report two cases of healthy subjects who were occasional but regular cannabis users without psychiatric history who developed...
BACKGROUND: Few studies have examined samples of people with cannabis-induced psychotic symptoms. AIMS: To establish whether cannabis-induced psychotic disorders are followed by development of persistent psychotic conditions, and the timing of their onset. METHOD: Data on patients treated for cannabis-induced psychotic symptoms between 1994 and 1999 were extracted from the Danish Psychiatric...
To investigate if associations between cannabis use and psychotic symptoms occur independently, or occur as a consequence of previous-other types of-psychopathology. A 14-year follow-up study of 1580 initially 4- to 16-year-olds who were drawn randomly from the Dutch general population was conducted. At initial assessment, psychopathology was assessed with the Child Behavior Checklist. Across...
The prototypic cannabinoid CB1 antagonist SR 141716A is one important pharmacologic tool for examining CB1 receptors that mediate the behavioral and physiologic effects of delta9-tetrahydrocannabinol (delta9-THC). This study examined the effects of SR 141716A on the rate-decreasing, hypothermic and discriminative stimulus effects of delta9-THC in rhesus monkeys. In monkeys (n=4) responding...
This study investigated the contribution of different cannabinoids to the subjective, behavioral and neurophysiological effects of smoked marijuana. Healthy marijuana users (12 men, 11 women) participated in four sessions. They were randomly assigned to a low or a high delta9-tetrahydrocannabinol group (THC; 1.8% versus 3.6%). In the four sessions under blinded conditions subjects smoked...
Substance abuse and associated externalizing disorders are characterized by behavioural disinhibition and low impulse control, with reduced neural inhibition postulated to be the common underlying brain mechanism. The P3 component of event-related potentials (ERPs) is a widely used neurophysiological measure thought to reflect inhibitory brain processes, but as yet has not been assessed in...
3,4-Methylenedioxymethamphetamine (MDMA, 'Ecstasy') and cannabis are two of the most commonly used illicit drugs in the western world, and are often used in combination. Very little research has examined their effect on cognitive function or behavior when combined, The present study used a double Y-maze task to examine the acute effect of MDMA and delta9-tetrahydrocannabinol (THC, the principal...
Delta(9)-Tetrahydrocannabinol (THC) is frequently found in the blood of drivers suspected of driving under the influence of cannabis or involved in traffic crashes. The present study used a double-blind crossover design to compare the effects of medium (16.5 mg THC) and high doses (45.7 mg THC) of hemp milk decoctions or of a medium dose of dronabinol (20 mg synthetic THC, Marinol on several...
Abstract The recurrence of flashbacks without acute or chronic hallucinogen consumption has been recognized in the DSM IV criteria as the hallucinogen persisting perception disorder (HPPD). Perceptual disturbances may last for 5 years or more and represent a real psychosocial distress. We reported here a case of a 18-year-old young man presenting HPPD after a mixed intoxication with psylocibin...
Many behavioral effects of delta-9-tetrahydrocannabinol (THC), including its discriminative-stimulus effects, are modulated by endogenous opioid systems. To investigate opioid receptor subtypes involved in the discriminative effects of THC. Rats trained to discriminate 3 mg/kg i.p. of THC from vehicle using a two-lever operant drug-discrimination procedure, were tested with compounds that bind...
Persistent dose-related cognitive decrements have been reported in 28-day abstinent heavy marijuana (MJ) users. However, the neural substrates of these decrements in cognitive performance are not known. This study aimed to determine if 25-day abstinent MJ users show persistent dose-related alterations in performance and brain activity using PET H(2)(15)O during the Iowa Gambling Task-IGT (a...
Cannabis is one of the most common 'co-drugs' for ecstasy users. The aim of the present study was to explore self-reported psychobiological problems in ecstasy polydrug users in relation to their pattern of cannabis use. Two hundred and eighty ecstasy polydrug users were allocated into five cannabis groups according to the frequency of their cannabis use. The control group comprised 121...
AbstractPurposeTo test the hypothesis that recent onset psychotic patients who use cannabis will have psychotic symptoms that are more severe and more persistent than those who do not use cannabis.Subjects and methodsWe carried out a 4-year follow-up study of a cohort of 119 patients with recent onset of psychosis. The patients were divided into four groups according to duration of cannabis...
Illicit drug use can increase driver crash risk due to loss of control over vehicle trajectory. This study asks, does recreational use of +/-3,4-Methylenedioxymethamphetamine (MDMA; ecstasy) and tetrahydrocannabinol (THC; marijuana) impair cognitive processes that help direct our safe movement through the world? This study assesses the residual effects of combined MDMA/THC use, and of THC use...
Fergusson and colleagues assert that their results from a New Zealand cohort ‘add to the growing body of evidence that regular cannabis use may increase risks of psychosis’[1]. In fact, their study raises more questions than it answers. One obvious question is raised by their use of ten items from Symptom Checklist 90 as the only assessment tool for symptoms of psychosis. The items assessed...
Previous studies have established a relationship between marijuana use and risky behavior in natural settings. A limited number of laboratory investigations of marijuana effects on human risk taking have been conducted. The present study was designed to examine the acute effects of smoked marijuana on human risk taking, and to identify behavioral mechanisms that may be involved in drug-induced...
Neuropsychological investigations of substance abusers have reported impairments on tasks mediated by the frontal executive system, including functions associated with behavioral inhibition and decision making. The higher order or executive components which are involved in decision making include selective attention and short term storage of information, inhibition of response to irrelevant...
Recent advances in the neurobiology of cannabinoids have renewed interest in the association between cannabis and psychotic disorders. In a 3-day, double-blind, randomized, placebo-controlled study, the behavioral, cognitive, motor, and endocrine effects of 0 mg, 2.5 mg, and 5 mg intravenous Delta-9-tetrahydrocannabinol (Delta-9-THC) were characterized in 13 stable, antipsychotic-treated...