|06-29-2003, 04:45 PM||#1|
Marijuana Long-Term, Minimal Effects in Brain
Marijuana Long-Term, Minimal Effects in Brain
Keywords: LONG-TERM RECREATIONAL MARIJUANA NEUROCOGNITIVE FUNCTIONING
Description: An analysis of research studies with long-term, recreational users of marijuana has failed to reveal a substantial, systematic effect on the neurocognitive functioning of users. (J. of the International Neuropsychological Society, Jul-2003)
EMBARGOED by the Journal of the International Neuropsychological Society for 12:01 a.m. EDT Friday, June 27, 2003
Minimal Long-Term Effects Of Marijuana Use Found in Central Nervous System by UCSD Researchers
An analysis of research studies with long-term, recreational users of marijuana has failed to reveal a substantial, systematic effect on the neurocognitive functioning of users. According to researchers at the University of California, San Diego (UCSD) School of Medicine, the only deleterious side effect found was a minimal malfunction in the domains of learning and forgetting.
The findings were particularly significant considering the movement by several states to make cannabis (marijuana) available as a medicinal drug, and questions regarding its potential toxicity over long-term usage.
Published in the July issue of the Journal of the International Neuropsychological Society, the study involved a quantitative synthesis of 15 previously published research studies on the non-acute (residual) effects of cannabis on the neurocognitive performance of adult human subjects.
The studies included 704 long-term cannabis users and 484 non-users. The neurocognitive performance measurements included simple reaction time, attention, verbal/language, abstraction/executive functioning, perceptual/motor skills, motor skills, learning and forgetting.
"Surprisingly, we saw very little evidence of deleterious effects. The only exception was a very small effect in learning new information," said Igor Grant, M.D., the study's senior author, a UCSD professor of psychiatry, and director of the Center for Medicinal Cannabis Research (CMCR), a collaborative, state-supported program between UCSD and UC San Francisco, that oversees 11 studies of the safety and efficacy of medicinal cannabis to treat certain diseases.
In describing the negative effects in the study, the research team said the problems observed in learning and forgetting suggest that chronic long-term cannabis use results in selective memory defects. They added that "while the results are compatible with this conclusion, the effected size for both domains was of a very small magnitude."
Grant added that the minimal side effects seen "raised the question of practical significance. If we barely find this tiny effect in long-term heavy users of cannabis, then we are unlikely to see deleterious side effects in individuals who receive cannabis for a short time in a medical setting."
In addition, Grant said that heavy marijuana users often abuse other drugs, such as alcohol and amphetamines, which also might have long-term neurological effects. This raises the question of the extent to which the other drugs contributed to the minimal problems found in learning and forgetting in the marijuana users.
The paper's authors also noted that many of the research studies examined had significant limitations, either with small numbers of subjects or insufficient information about potential confounding factors, such as exposure to other drugs or presence of neuropsychiatric factors such as depression or personality disorders.
They noted that only studies that begin with the examination of children and young adolescents before they enter the period of risk to cannabis exposure, can sufficiently reduce the influence of these additional factors.
In addition to Grant, the paper's authors included doctoral students Raul Gonzalez, M.S., and Catherine L. Carey, M.S. and Loki Natarajan, Ph.D., UCSD HIV Neurobehavioral Research Center (HNRC) and UCSD Department of Family and Preventive Medicine, and Tanya Wolfson, M.A., UCSD HNRC.
The study was supported by the CMRC.
|07-07-2003, 12:20 PM||#2|
IACM: Cannabis Does Not Cause Permanent Brain Damage
IACM: Cannabis Does Not Cause Permanent Brain Damage
BBSNews - 2003-07-06 -- IACM USA: Surplus in medical marijuana program of Oregon
Oregon's medical marijuana program is running a financial surplus, and will get rid of it by reducing fees for people with low income.
Since 1999 the state issued 5,500 medical marijuana cards to seriously ill people for $150 each. The popularity of the program has brought a $300,000 surplus over the past two years, said Mary Leverette, the program's director. Low-income people now can apply for a card for $50. Everybody else will continue to pay $150 for new applications. The annual renewal fee for everybody was reduced from $150 to $100.
The other eight states with medical marijuana laws are: California, Washington, Alaska, Hawaii, Maine, Nevada, Maryland and Colorado. Some state's charge only low fees, such as Hawaii's $25. There is no fee in California.
(Source: Associated Press of 25 June 2003)
Science: Cannabis does not cause permanent brain damage
The use of cannabis does not cause permanent brain damage, researchers from the University of California at San Diego (UCSD), who reviewed the available data on the issue, said on 27 June. "The findings were kind of a surprise. One might have expected to see more impairment of higher mental function," said Dr. Igor Grant, a UCSD professor of psychiatry and the study's lead author. Other drugs, including alcohol, can cause brain damage.
His team analyzed data from 15 previously published, controlled studies involving 704 long-term cannabis users and 484 nonusers into the impact of long-term, recreational cannabis use on the neurocognitive ability of adults. The results, published in the July issue of the Journal of the International Neuropsychological Society, show that marijuana has only a marginally harmful long- term effect on learning and memory. No effect at all was seen on other functions, including reaction time, attention, language, reasoning ability, and perceptual and motor skills.
Researchers said the problems observed in learning and forgetting suggest that long-term marijuana use results in selective memory defects, but said the impact was of a very small magnitude. Earlier reviews had come to similar results.
(Source: Reuters of 27 June 2003, dpa of 29 June 2003)
USA: Vaporizer study will be funded
The California Center for Medical Cannabis Research has agreed to fund a vaporizer research study by Dr. Donald Abrams of the University of California. To carry out the study it will be necessary to get approval by the Federal Drugs Administration (FDA).
The phase I study was granted 137,000 US dollars. It will compare subjective effects, cannabinoid blood levels and carbon monoxide levels in exhaled breath in subjects on six different conditions, three days smoking 400 milligrams of cannabis cigarettes containing 1.7%, 3.5%, or 7% THC, and three days vaporizing 400 milligrams of cannabis containing 1.7%, 3.5%, or 7% THC by the Volcano vaporizer.
(Source: Information by Rick Doblin, MAPS, of 24 June 2003)
News in brief
***Germany: THC Pharm
THC Pharm announced its intention to start clinical trials to get pharmaceutical approval for its dronabinol. In 1998 the small Frankfurt firm started to manufacture dronabinol (THC) from fibre hemp by isomerization of cannabidiol (CBD). It is selling the drug to pharmacies in Germany and some other European countries, so that pharmacists can make dronabinol capsules or liquids thereof. In a press release the firm reports of negotiations with possible partners and its intention to start a first study this year. (Source: Press release of THC Pharm of 30 June 2003)
***USA: American Nurses Association
On their annual meeting from 24-27 June in Washington the American Nurses Association overwhelmingly adopted a resolution stating that patients should "have safe access to therapeutic marijuana/cannabis under appropriate prescriber supervision" and that penalties for patients and prescribers of cannabis should be removed. (Source: Press release of Patients out of Time of 1 July 2003)
***Science: Neuroprotection and hypothermia
Some of the neuroprotective effects of cannabinoids may be caused by lowered body temperature. Israelian researchers found that the body temperature of rats injected with a synthetic cannabinoid dropped from about 37 to 32 degrees Celsius. Brain infarction was induced by occlusion of a brain artery. Infarction size was smaller in rats that had received the cannabinoid, but this effect was completely abolished by warming the animals. (Source: Leker RR, et al. Stroke. 2003 Jun 26 [Electronic publication ahead of print].)
***Science: CB2 receptors and neuropathic pain
It is known that the "brain" cannabinoid receptor (CB1) is involved in pain modulation and that the peripheral CB2 receptor seems to be also involved in pain modulation. Now researchers found that the CB2 receptor may also be involved in central pain modulation. In animals with peripheral nerve injury the number of CB2 receptors was found to be increased in some areas of the spinal cord. (Source: Zhang J, et al. Eur J Neurosci. 2003 Jun;17(12):2750-4.)
***Science: Detection of THC use by urine test
Excretion of THC-COOH in urine was investigated after oral ingestion of different amount of THC. Seven individuals received 0, 0.39, 0.47, 7.5, or 15 mg THC per day for five days and concentrations of the metabolite in their urine was analysed for the following weeks. The two low doses typical of hemp oil THC concentrations were rarely found positive (<0.2%) in immunoassays at a cutoff of 50 micrograms per litre, while the two high doses typical for the treatment with dronabinol (Marinol) produced mean detection rates of 23-46%. Analysis by gas chromatography showed maximum metabolite concentrations of 5.4-38.2 micro g/L for the two low doses and 19.0-436 micro g/L for the two high doses. (Source: Gustafson RA, et al. Clin Chem. 2003 Jul;49(7):1114-1124.)
ONE YEAR AGO:
- Germany: Second firm to manufacture dronabinol (THC)
TWO YEARS AGO:
- Canada: New regulations will take effect at the end of July
- Science: News at the 2001 meeting of the ICRS
The preceding report was provided to BBSNews by the International Association for Cannabis as Medicine (IACM).
Michael Hess is the Editor of BBSNews in Charlotte, NC. Write to the editor here. Not all submissions are published. Or visit the completely new discussion forum at nugod.net.