Journal of psychopharmacology
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J. Psychopharmacol. (Oxford) · May 2009
Randomized Controlled TrialNeurocognitive performance during acute THC intoxication in heavy and occasional cannabis users.
Performance impairment during Delta(9)-tetrahydrocannabinol (THC) intoxication has been well described in occasional cannabis users. It is less clear whether tolerance develops to the impairing effects of THC in heavy users of cannabis. The aim of the present study was to assess neurocognitive performance during acute THC intoxication in occasional and heavy users. ⋯ THC did not affect the performance of heavy cannabis users except in the stop signal task, i.e. stop reaction time increased, particularly at high THC concentrations. Group comparisons of overall performance in occasional and heavy users did not reveal any persistent performance differences due to residual THC in heavy users. These data indicate that cannabis use history strongly determines the behavioural response to single doses of THC.
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J. Psychopharmacol. (Oxford) · Jan 2009
Clinical TrialLithium carbonate in the management of cannabis withdrawal in humans: an open-label study.
Cannabis is the most widely used illicit substance in the world. Estimates suggest that approximately 10-20% of cannabis users meet criteria for cannabis dependence and a significant proportion experience withdrawal discomfort on cessation of use. To date, there has been an absence of any clinically validated treatments to manage withdrawal. ⋯ Significant reductions in symptoms of depression and anxiety and cannabis-related problems were also reported. This study provides evidence for the potential clinical utility and safety of lithium in the management of cannabis withdrawal. A randomised, placebo-controlled trial is recommended.
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J. Psychopharmacol. (Oxford) · Sep 2008
Endocannabinoid modulation of fear responses: learning and state-dependent performance effects.
Recently, disruption of the endogenous cannabinoid (endocannabinoid, eCB) system was found to impair extinction in delay and contextual fear conditioning models. However, conditioning procedures used in that work precluded investigation of possible eCB effects on acquisition of learned fear. We therefore examined the role of eCBs in modulating fear responses using multiple-trial versions of trace (hippocampal-dependent) and delay (amygdala-dependent) Pavlovian fear conditioning. ⋯ CB1 antagonism did not affect short-term memory (STM) or long-term memory (LTM) consolidation processes. Together, these results suggest that during acquisition and recall of aversive learning, eCBs prevent the expression and retention of inappropriate generalized and learned responses. These findings have important implications for the therapeutic use of CB1 antagonists.
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J. Psychopharmacol. (Oxford) · Jul 2008
Cognitive performance in recreational ecstasy polydrug users: a two-year follow-up study.
There is important preclinical evidence of long lasting neurotoxic and selective effects of ecstasy MDMA on serotonin systems in non-human primates. In humans long-term recreational use of ecstasy has been mainly associated with learning and memory impairments. The aim of the present study was to investigate the neuropsychological profile associated with ecstasy use within recreational polydrug users, and describe the cognitive changes related to maintained or variable ecstasy use along a two years period. ⋯ After two years ecstasy users showed persistent deficits on verbal fluency, working memory and processing speed. These findings should be interpreted with caution, since the possibility of premorbid group differences cannot be entirely excluded. Our findings support that ecstasy use, or ecstasy/cannabis synergic effects, are responsible for the sub-clinical deficits observed in ecstasy polydrug users, and provides additional evidence for long-term cognitive impairment owing to ecstasy consumption in the context of polydrug use.