Residual Learning Deficit After Heavy Exposure to Cannabis or Alcohol in Rats

Fehr, KA; Kalant, H.; LeBlanc, A. E.

doi:10.1126/science.1273591

Cited by 84 publications

(37 citation statements)

References 15 publications

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“…At least one month after drug discontinuation, animals were trained and tested on learning tasks. Compared to placebo-treated control rats, marijuana-treated rats demonstrated impairments on maze learning [63,64] and a differential reinforcement of lowrate responding task [65], and facilitated active avoidance learning on a shuttle-box task [66]. The authors note that these results are similar to findings among rats with hippocampal lesions [66], and suggest learning dysfunction associated with chronic marijuana administration.…”

supporting

confidence: 77%

“…Together, these results indicate a greater vulnerability to learning impairments when chronic marijuana exposure occurs during adolescence, and limited cognitive dysfunction when marijuana exposure occurs among mature animals [67]. Further, lighter THC doses of 10 mg/kg did not produce significant learning impairments [63], suggesting that only heavy marijuana use is associated with learning deficits in adolescents.More recently, prepulse inhibition, object recognition, and motivation were examined among rats that had received chronic treatment with the synthetic cannabinoid agonist WIN 55,212-2 either as adolescents or adults [68]. Adolescent treatment began at 40 days of age, while adult treatment began at 70 days.…”

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confidence: 74%

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The Influence of Marijuana Use on Neurocognitive Functioning in Adolescents

Schweinsburg

Brown²,

Tapert

2008

CDAR

217

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Marijuana use is common in adolescence, yet neural consequences have not been well delineated. This review seeks to ascertain whether heavy marijuana use in adolescence is associated with persistent neurocognitive abnormalities, and whether adolescents are more vulnerable to the impact of chronic marijuana use than adults.Among heavy marijuana using adults, neurocognitive deficits are apparent for several days following use, but may disappear after one month of abstinence. Studies of adolescent heavy users have identified impairments in learning and working memory up to six weeks after cessation, suggesting persisting effects, yet raise the possibility that abnormalities may remit with a longer duration of abstinence.Given ongoing neuromaturation during youth, adolescents may be more vulnerable to potential consequences of marijuana use than adults. This is supported by rodent models, which show greater memory impairments in animals exposed to cannabinoids as adolescents relative to those exposed as adults. Further, adult humans who initiated use in early adolescence show greater dysfunction than those who began use later. Together, these results suggest that adolescents are more vulnerable than adults to neurocognitive abnormalities associated with chronic heavy marijuana use; however, the impact of preexisting risk factors is unknown.Adolescents demonstrate persisting deficits related to heavy marijuana use for at least six weeks following discontinuation, particularly in the domains of learning, memory, and working memory. Further, adolescents appear more adversely affected by heavy use than adults. Longitudinal studies will help ascertain whether preexisting differences contribute to these abnormalities. KeywordsAdolescence; marijuana; cannabis; cognition; brain; development Marijuana is the most commonly used preparation of the psychoactive drug, Δ-9-tetrahydrocannabinol (THC), and is consistently the most widely used illicit drug among teenagers, and most users first experiment in adolescence [1]. While 17% of 8th graders have tried marijuana, by 12th grade almost half of teens have used [1,2]. After initial experimentation, many youths develop a regular pattern of use, with 20% of 12th graders reporting use in the past month, and 5% of 12th graders reporting daily use [2]. Adolescence *Address correspondence to this author at the Department of Psychiatry, University of California, 3350 La Jolla Village Drive, 151B San Diego, CA 92161, USA; Tel: (858)552-8585 x5592; stapert@ucsd.edu. NIH Public Access Author ManuscriptCurr Drug Abuse Rev. Author manuscript; available in PMC 2010 February 19. Published in final edited form as:Curr Drug Abuse Rev. 2008 January ; 1(1): 99-111. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscriptis also a period of continued neuromaturation, yet the potential neural consequences of marijuana use during these developments have not been well established, and may have implications for academic, occupational, and social achievements. This review will a...

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confidence: 77%

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confidence: 74%

The Influence of Marijuana Use on Neurocognitive Functioning in Adolescents

Schweinsburg

Brown²,

Tapert

2008

CDAR

217

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Section: Edge Hill College Of Higher Educationmentioning

confidence: 99%

“…With regard to the last of these cannabis use has been shown to adversely affect the maintenance of attention, short term memory and executive functions (Hall & Solowij, 1998; Pope & YurgelunTodd, 1996;Pope et al 2001). Animal studies have revealed that chronic administration of the cannabinoid THC causes hippocampal damage and impairs maze learning in rats (Fehr et al, 1976;Lawston et al 2000).However, the anti-inflammatory and anti-oxidative properties of cannabinoids have also raised the possibility that they may have beneficial effects in limiting neurological damage (Carter et al 2004;Grundy, 2002). For example, the inhibitory effects of cannabinoids on the excitotoxic neurotransmitter glutamate (Drysdale & Platt, 2003) and their capacity to counter the oxidative damage to dopaminergic neurones has raised the possibility that they may be of value in the treatment of At the neuronal level low doses of cannabinoids can elevate intracellular calcium levels and increase transmitter release (Sarne & Keren, 2004).…”

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confidence: 99%

The effects of concurrent cannabis use among ecstasy users: neuroprotective or neurotoxic?

Fisk

Montgomery

Wareing

et al. 2006

Human Psychopharmacology

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Edge Hill College of Higher EducationRunning head: concurrent cannabis use among ecstasy users. The research evidence regarding the potential effects of ecstasy suggests that it may be neurotoxic and that its use is associated with cognitive impairment. In recent years evidence has emerged suggesting that cannabinoids, the active ingredients in cannabis, can be neuroprotective under certain conditions. Given that many ecstasy users also consume cannabis at the same time, the possibility emerges that these individuals might be less susceptible to ecstasy-related impairment. The present paper reanalyses the data from a number of previous studies, contrasting the performance of those individuals who generally consume cannabis and ecstasy at the same time with those who generally consume ecstasy on its own. The two ecstasy-using groups are compared with non-ecstasy users on a range of measures including processing speed, random letter generation, verbal and visuo-spatial working memory span, reasoning and associative learning. The two ecstasy user groups did not differ significantly from each other on any of the measures. Both user groups were significantly worse than non-ecstasy users on measures of associative learning, verbal and visuo-spatial working memory, and reasoning. The results suggest that consuming cannabis at the same time as ecstasy does not reduce the likelihood of cognitive impairment.There is abundant evidence that ecstasy (MDMA) is neurotoxic, disrupting serotonergic systems in diverse brain regions. There is also a considerable body of evidence that cannabis can have neuroprotective as well as neurotoxic properties.Given that most ecstasy users are also cannabis users (Morgan, 2000) the question arises as to whether concurrent use of cannabis by ecstasy users might make them less susceptible to MDMA related neurotoxicity. The present paper is intended to investigate this issue.Although there is abundant evidence that MDMA is neurotoxic in a range of animal species, evidence of neurotoxicity in humans is less extensive and sometimes controversial (Curran, 2000). A review of the neuroimaging evidence can be found in Reneman et al (2006). A number of studies have found evidence of neurotoxicity among ecstasy users. For example, using PET neuroimaging, McCann, et al (1998), investigated 5-HT neural damage in the brains of ecstasy users. Regions of interest included the frontal cortex, pariental cortex, temporal cortex, occipital cortex and cingulate cortex, as well as the caudate, putamen, thalamus, mid-brain, pons, hypothalamus and cerebellum. The results showed that, compared to a control group, ecstasy users had significantly lower densities of 5HT transporter sites in all brain regions. Further, the reductions observed were correlated with the extent of ecstasy use. Reneman, et al (2002a) also assessed neural injury in ecstasy users using single-voxel (1H) MR spectroscopy imagining. N-Acetylasportate (NAA)/Creatine (CR), NAA Choline (CHO), and Myoinositol (MI) CR ratios in ecstasy users were meas...

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“…The psychoactive properties of cannabis are mainly due to one of these cannabinoids, Δ 9 tetrahydrocannabinol, (THC). Animal studies have revealed that chronic administration of THC causes hippocampal damage and impairs maze learning in rats (Fehr et al, 1976;Lawston et al, 2000). In humans, cannabinoids may be neurotoxic or neuroprotective depending on their concentration, the timing of delivery and the cell type (Doble, 1999;Guzman et al, 2001;Hubert & Doble, 1998).…”

mentioning

confidence: 99%

Real-world memory and executive processes in cannabis users and non-users

Fisk

Montgomery

2008

J Psychopharmacol

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Real-world memory and executive processes in cannabis users and non-users http://researchonline.ljmu.ac.uk/1101/ Article LJMU has developed LJMU Research Online for users to access the research output of the University more effectively. Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Users may download and/or print one copy of any article(s) in LJMU Research Online to facilitate their private study or for non-commercial research. You may not engage in further distribution of the material or use it for any profit-making activities or any commercial gain.The version presented here may differ from the published version or from the version of the record. Please see the repository URL above for details on accessing the published version and note that access may require a subscription.For more information please contact researchonline@ljmu.ac.uk http://researchonline.ljmu.ac.uk/ Citation (please note it is advisable to refer to the publisher's version if you intend to cite from this work) The relationships between executive processes, associative learning and different aspects of real world memory functioning were explored in a sample of cannabis users and nonusers. Measures of executive component processes, associative learning, everyday memory, prospective memory, and cognitive failures were administered. Relative to nonusers, cannabis users were found to be impaired in several aspects of real world memory functioning. No other group differences were apparent. The absence of cannabis related deficits in those executive component processes and aspects of learning that are believed to support real world memory processes is surprising given that cannabis related deficits were obtained in real world memory. The present results are discussed within the context of neuroimaging evidence which suggests that cannabis users may exhibit different patterns of neural activation when performing executive tasks while not always exhibiting deficits on these tasks.Keywords: Cannabis, executive processes, prospective memory, cognitive failures 3 The focus of the present paper is real world memory functioning in abstinent cannabis users. More specifically we intend to explore the basis of cannabis-related deficits in prospective memory, everyday memory, and cognitive failures, and the extent to which these impairments are underpinned by deficits in pre-frontal executive processes. Given that cannabis is clearly the most popular illicit drug in North America, Europe and in other parts of the world (Andersson et al, 2005) it is of considerable importance to investigate whether consumption of the drug is associated with cognitive deficits.Cannabis contains a number of chemical compounds collectively known as cannabinoids. The psychoactive properties of cannabis are mainly due to one of these cannabinoids, Δ 9 tetrahydrocannabinol, (THC). Animal studies have revealed that chronic administration of THC causes hippocampal damage and impairs maze learning in rats ...

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Residual Learning Deficit After Heavy Exposure to Cannabis or Alcohol in Rats

Cited by 84 publications

References 15 publications

The Influence of Marijuana Use on Neurocognitive Functioning in Adolescents

The Influence of Marijuana Use on Neurocognitive Functioning in Adolescents

The effects of concurrent cannabis use among ecstasy users: neuroprotective or neurotoxic?

Real-world memory and executive processes in cannabis users and non-users

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