Marijuana Use Does Not Seem to Cause Irreversible Cognitive Deficits
WESTPORT, CT (Reuters Health) Oct 16 - Cognitive impairment associated with heavy marijuana use is apparently reversible with abstinence, according to a report in the October issue of the Archives of General Psychiatry. Another paper in the journal indicates that marijuana withdrawal symptoms in habitual users are similar to those seen with nicotine withdrawal.
The lead author of the first report, Dr. Harrison G. Pope, Jr., from McLean Hospital in Belmont, Massachusetts, told Reuters Health, "It appears that cognitive impairment from marijuana use is temporary and related to the amount of marijuana that has been recently smoked rather than permanent and related to an entire lifetime consumption."
Dr. Pope and colleagues collected data on three groups of marijuana users. One group consisted of 63 users who had smoked marijuana at least 5000 times in their lives and were daily marijuana users.
In the second group, there were 45 former marijuana users who had smoked marijuana at least 5000 times but had used it less than 12 times in the past 3 months. The third group was made up of 72 controls who had not smoked marijuana more than 50 times.
The subjects abstained from marijuana for 28 days, during which the researchers administered neuropsychological tests that assessed general intellectual function, abstract ability, sustained attention, verbal fluency and the ability to learn and recall verbal and visuospatial data. Tests were given at baseline, and on days 1, 7, and 28.
Heavy marijuana users had significantly lower scores on word recall lists at baseline and on the day 1 and day 7 tests compared with controls. However, by day 28 there were no significant differences between the groups in any of the tests, with no significant difference in cumulative lifetime marijuana use and test scores, Dr. Pope's group found.
"People who are regular heavy marijuana smokers will exhibit some impairment that lasts days, and possibly even a couple of weeks after they stop smoking, that's the bad news. The good news is that if they abstain from marijuana for longer than 4 weeks, then the residual effects seem to disappear," Dr. Pope said.
In the second report, Dr. Alan J. Budney from the University of Vermont in Burlington and colleagues studied withdrawal effects in 12 daily marijuana smokers.
"Comparing our results to studies of nicotine withdrawal, it looks like the magnitude of the severity of withdrawal is similar," Dr. Budney said in an interview with Reuters Health. "So as people try to quit smoking marijuana, one can expect them to have problems with withdrawal."
The researchers had the subjects smoke marijuana as usual for 5 days, then abstain for 3 days, smoke again for 5 days and abstain for another 3 days.
Craving for marijuana, decreased appetite, sleep difficulty, and weight loss were more common in abstaining periods. Aggression, anger, irritability, restlessness, and strange dreams were also significantly increased during abstinence, the researchers found.
"This highlights the issue that when you treat marijuana-dependent folk, they are going to complain about withdrawal — it is real. If you consider tobacco withdrawal real, you should consider marijuana withdrawal real," Dr. Budney stressed.
Arch Gen Psychiatry 2001;58:909-915,917-924.
Cannabis 'dramatically improves pain relief'
By BBC News Online's Helen Briggs
Results from Britain's first clinical trial of cannabis as a medicine show that it has a dramatic impact on controlling patients' pain.
Some individuals who were suffering chronic pain reported that cannabis had changed their lives, said consultant anaesthetist William Notcutt, of James Paget Hospital, Norfolk.
"We've had some patients say: `This is brilliant, it stopped my pain in its tracks'."
Several trials of medical extracts of cannabis are underway in the UK. Dr Notcutt is studying the effects of the drug on chronic pain in patients with multiple sclerosis and spinal injuries.
Speaking at the British Association Festival of Science in Glasgow, Dr Notcutt said the majority of the 23 patients studied so far had experienced pain relief from using the drug.
In other patients, the only benefit was that they were able to sleep at night, he said.
Two experienced no benefit at all, and another two complained of side effects, with one having to withdraw from the trial.
Dr Notcutt said the results of the trial were "going well" and he hoped to publish the full research next year.
"I hope it will not be long before this new medicine can be used much more widely," he told the BBC. "We need to study this in many more patients than we have done so far."
The extracts being tested were taken from special plants grown in the UK by GW Pharmaceuticals.
The drugs are self-administered using an under-the tongue spray.
Other possible medical applications of cannabis extracts include pain relief for cancer, nerve damage and rheumatoid arthritis, said Dr Notcutt.
Patients with advanced multiple sclerosis (MS) often suffer bladder problems - and cannabis may be able to help.
Early results of a clinical trial at the National Hospital for Neurology and Neurosurgery suggest that the cannabis improves bladder complaints.
All the patients taking part were wheelchair users and no previous treatments had been able to improve their bladder problems.
Professor Clare Fowler, who is leading the trial, said: "Bladder dysfunction is a significant problem for many sufferers of advanced MS.
"The results show this is an effective treatment, which could improve quality of life, but further research is needed."
The cannabis was provided in an under the tongue spray, and patients were able to take as much or as little as they liked, up to a maximum dose.
Paulene Winn, a patient taking part in the
trial, said: "My bladder functioning is vastly improved.
"Previously I needed to empty my bladder 17 to 20 times every 24 hours.
"I was plagued with urgency, frequency and incontinence. Now I feel
much more confident about going out and my bladder doesn't seem to rule my
The study was funded by the Medicinal Cannabis Research Foundation and
the MS Research Trust.
This is just one of several trials testing extracts of cannabis against
both other symptoms of MS, and other problems like cancer and
Patients have reported that cannabis -often obtained illegally - can
offer relief to symptoms such as muscle stiffness.
"Previously I needed to empty my bladder 17 to 20 times every 24 hours.
"I was plagued with urgency, frequency and incontinence. Now I feel much more confident about going out and my bladder doesn't seem to rule my life."
The study was funded by the Medicinal Cannabis Research Foundation and the MS Research Trust.
This is just one of several trials testing extracts of cannabis against both other symptoms of MS, and other problems like cancer and post-operative pain.
Patients have reported that cannabis -often obtained illegally - can offer relief to symptoms such as muscle stiffness.
WCP: Survey Of MS Patients Suggests Widespread Use of Cannabis for Pain and Symptom Relief
By Peggy Peck