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| Volume 9, Number 6 | November 2, 2001 |
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Study shows lithium may ease cannabis withdrawalBy Elizabeth Frogley
A promising new direction for medical treatment developed at the University of Saskatchewan may help recovering cannabis addicts cope with withdrawal. In an animal study to be published in the Dec. 15 issue of The Journal of Neuroscience, Dr. Xia Zhang, an MD and assistant professor in the neuropsychiatric research unit, has shown that the mood-stabilizing drug lithium blocks all symptoms of cannabis withdrawal. "I’m optimistic that lithium will be equally effective in combating cannabis withdrawal symptoms in humans," Zhang said, adding that the U of S department of psychiatry is now planning a small-scale study involving humans. Because lithium is already approved for human drug use, the move from laboratory research to medical treatment would occur relatively quickly if the human trials prove successful, Zhang says. Commonly in the form of marijuana and hashish, cannabis is the most widely used drug in developed countries. In the United States, the lifetime prevalence of marijuana dependence is higher than for any other illicit drug. Each year some 100,000 Americans seek treatment for cannabis dependence. Withdrawal symptoms include irritability, difficulty sleeping, restlessness, anxiety, stomach pain, reduced appetite, and depression, and may contribute to continued use. To mimic the effects of cannabis in animals, Zhang’s team used a drug called HU-210 which is commonly used in such studies. It is about 100 times as powerful as the street drug THC (the active ingredient in marijuana), but was administered in doses that reproduced the intoxicating effects experienced by recreational drug users. The researchers chose to study the effect of lithium because some symptoms of cannabis withdrawal are similar to symptoms of the mood disorders that lithium is used to treat. The researchers expected lithium to inhibit some of the withdrawal symptoms, but to their surprise, lithium blocked all withdrawal symptoms. The effect of lithium on cannabis withdrawal symptoms seems unrelated to its effect as a mood stabilizer. For example, lithium has to build up for days to affect unstable moods, but in this instance there was an immediate effect. As well, another mood stabilizer was tested and had no effect on cannabis withdrawal symptoms. The study, funded by the Saskatchewan Health Services Utilization and Research Commission, found that lithium increases production of oxytocin, a hormone that stimulates contractions and milk letdown in pregnant and breastfeeding women. Zhang has already begun further research to find out why oxytocin apparently blocks cannabis withdrawal symptoms. This ground-breaking research has been honored by the Society for Neuroscience, which has selected Zhang’s article from 15,000 submissions for inclusion in the press book for its mid-November annual general meeting in San Diego – the world’s largest gathering of neuroscientists. The book is distributed to hundreds of international media. Another ground-breaking area of neuroscience for Zhang’s team is the study of kindling – the process in which seizures develop as a result of repeated electrical stimulation of the brain. In humans, kindling can occur naturally and make the brain more susceptible to epilepsy. With funding from the Canadian Institutes of Health Research, Zhang’s team studied kindling in the claustrum, a small, tadpole-shaped structure buried deep in the forebrain. By electrically stimulating rats’ brains, the researchers found that the claustrum is part of the network of structures that spreads seizures through the body. "This discovery is an important step towards understanding how epilepsy develops," he said. Zhang published this finding last May in The Journal of Neuroscience in collaboration with U of S psychology researchers Michael Corcoran and Deborah Saucier.
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