Neuroreport
June 11, 2003
Daniel S O'Leary, Robert I Block, Beth M Turner et al.
The effects of marijuana on brain perfusion and internal timing were assessed using [15O] water PET in occasional and chronic users. Twelve volunteers who smoked marijuana recreationally about once weekly, and 12 volunteers who smoked daily for a number of years performed a self-paced counting task during PET imaging, before and after smoking marijuana and placebo cigarettes. Smoking marijuana...
Psychopharmacology
February 2003
Margaret Haney, Adam Bisaga, Richard W Foltin
Studies in non-human animals suggest that opioid antagonists block the reinforcing effects of cannabinoids. The present studies in humans investigated how naltrexone modulates (1) the subjective and physiological effects of oral THC in comparison to methadone, (2) the reinforcing effects of oral THC, and (3) plasma levels of oral THC. In study 1, marijuana smokers (n=9) received naltrexone (0,...
Psychopharmacology
January 2003
Margaret Haney, Carl L. Hart, Amie S Ward et al.
Symptoms of marijuana withdrawal include increased irritability, depression and anxiety, and decreased sleep quality. Nefazodone, which is an antidepressant with sedative properties, may attenuate symptoms of marijuana withdrawal. The present within-subject, placebo-controlled study investigated the effects of nefazodone during marijuana withdrawal. Marijuana smokers [ n=7; averaging 6.0...
Psychological Medicine
2003
Helene Verdoux, C. Gindre, F. Sorbara et al.
Background. Epidemiological findings suggest that cannabis use is a risk factor for the emergence of psychosis, and that the induction of psychotic symptoms in the context of cannabis use may be associated with a pre-existing vulnerability for psychosis. This study investigated in a non-clinical population the interaction between cannabis use and psychosis vulnerability in their effects on...
Griffith Research Online
2003
Leanne M Hides
There has been concern about the impact of cannabis use on the onset, course and relapse of psychosis. Evidence from retrospective and a small number of prospective studies has suggested that cannabis use may precipitate a latent psychosis, exacerbate psychotic symptoms and increase the likelihood of psychotic relapse. The purpose of the current study was to examine the influence of cannabis...
Psychological Medicine
December 23, 2002
Louisa Degenhardt
34 citations
The issue of whether an association exists between cannabis and psychosis exists, and why, has received considerable attention in recent years (Hall, 1998; Mueser et al. 1998; Blanchard et al. 2000; Degenhardt & Hall, 2002). There are probably a number of reasons for the sustained interest. First, psychotic disorders such as schizophrenia are often chronic or recurring (Mason et al. 1996), are...
Life Sciences
December 20, 2002
Kenichi Mishima, Nobuaki Egashira, Yoshiaki Matsumoto et al.
To clarify the mechanism by which Delta9-tetrahydrocannabinol, a major psychoactive component of marijuana, impairs spatial memory in the 8-arm radial maze in rats via the cholinergic system, we used two acetylcholinesterase inhibitors, physostigmine and tetrahydroaminoacridine. Moreover, we examined the effect of Delta9-tetrahydrocannabinol on acetylcholine release in the frontal cortex and...
Pharmacology, Biochemistry, and Behavior
December 2002
M S Delatte, P J Winsauer, J M Moerschbaecher
Tolerance to the effects of the cannabinoid agonist Delta(9)-tetrahydrocannabinol (Delta(9)-THC) was characterized in rats responding under a multiple schedule of repeated acquisition and performance. During the acquisition component, subjects acquired a different three-response sequence each session, whereas in the performance component the sequence was the same each session. Responding was...
The Journal of Clinical Pharmacology
November 2002
Margaret Haney
This article presents data from two avenues of marijuana research. First, the author shows that daily marijuana smoking in healthy individuals produces dependence, as demonstrated by withdrawal symptoms such as increased irritability and depression and decreased food intake. In addition, two antidepressant medications were evaluated to assess their potential effectiveness in the treatment of...
Brain Research
October 18, 2002
Nobuaki Egashira, Kenichi Mishima, Katsunori Iwasaki et al.
The purpose of this study was to identify brain sites that contribute to the delta(9)-tetrahydrocannabinol (delta(9)-THC)-induced impairment of spatial memory in rats. Rats were tested in the eight-arm radial maze after microinjections of delta(9)-THC into one of 14 different brain regions. The bilateral microinjection of delta(9)-THC (20 microg/side) impaired spatial memory when injected into...