Citizens With Disabilities - Ontario


Smoking Pot To Ease MS Symptoms May Impair Mental Acuity, Study Suggests

TORONTO - Some people with multiple sclerosis have turned to street marijuana in a bid to ease pain and other symptoms of the disabling neurological disorder, but new research suggests smoking pot may further harm already vulnerable cognitive abilities.

The study compared mental skills and emotional status of MS patients who smoked cannabis for symptom relief against others with the disease who did not use the illicit street drug.

"We found that the individuals who smoked cannabis performed more poorly on the tests that measured the speed of thinking, speed of cognition, speed of information processing," said co-investigator Dr. Anthony Feinstein.

"So they were not as quick when it came to their thinking."

Feinstein, a neuropsychiatrist at Sunnybrook Health Sciences Centre in Toronto, said study subjects who partook of the weed were about 50 per cent slower on average in cognitive tests than non-marijuana users.

"We also found that the group that smoked cannabis had a higher lifetime prevalence of psychiatric disorders in general," he said, referring to depression, anxiety and other mood alterations.

"Now we don't know whether it was the cannabis that led to this disorder or the disorder was there before they smoked cannabis, so we couldn't really attribute the direction of that relationship. It was just an association."

Multiple sclerosis affects an estimated 55,000 to 75,000 Canadians, the majority of them female. Depending on its severity, MS can cause vision disturbances, pain, co-ordination problems, muscle stiffness and spasticity, and partial or complete paralysis. The disorder can also impair mood and cognitive abilities.

Feinstein said the researchers undertook the study of cannabis, which is even prescribed by some MS physicians under Canada's Medical Marijuana Access Regulations, to determine its effects on patients.

To conduct the study, published online Wednesday in the journal Neurology, they enrolled 140 people with MS, 10 of whom had smoked marijuana within the previous month and were defined as current users.

The pot smokers were each matched by age, sex, length of time they had MS, and level of physical and neurological disability with four other MS patients who did not use the drug. Subjects had a mean age of about 35 and almost three-quarters were female.

The researchers then evaluated the participants for emotional problems such as depression, anxiety and other psychiatric disorders. They also tested the participants' thinking skills and memory.

While pot users scored more poorly compared to non-users, Feinstein conceded the researchers don't know for sure that it was the cannabis and not the natural progression of MS behind the toking patients' reduced mental acuity.

"I don't think you can have any definitive result on the basis of 10 subjects. It's just an interesting observation," he acknowledged. "Having said that ... there were no differences between the cannabis smokers and the non-cannabis smokers when it came to the MS disease and there were no demographic differences."

"But the one difference came when we tested them cognitively. So that's where the suggestion comes from, that smoked cannabis might be bad for your cognition."

Feinstein said that while the researchers are not going to make any "absolute statements" based on the findings from 10 patients, the study makes it clear a larger study is needed to see if their findings can be replicated.

Dr. Virginia Devonshire, director of the University of British Columbia MS clinic, called the study interesting, but agreed there were too few participants to draw a strong conclusion on the possible negative effects of marijuana.

"People who have cognitive impairment who are starting to notice those cognitive differences also tend to report more anxiety, more depression," she said from Vancouver. "Are they perhaps more likely to become cannabis users because of that?"

"So you don't know in the beginning are you looking at different levels of cognitive impairment before people started smoking cannabis?"

Still, she said prescription drugs - pills and an oral spray - that contain the active cannabinoid found in marijuana are known to cause drowsiness and to dull mental agility.

"And I think what this study highlights for the patients who are sort of using cannabis on their own is that it's not that simple," said Devonshire, who advises her patients that marijuana is like any other drug or medication: "You have to know that the benefits are going to outweigh the side-effects."

Aprile Royal, a spokeswoman for the MS Society of Canada, said that despite the study's small size, its findings are significant in that they deal with an issue of concern to the organization that advocates for patients - an area she said needs much more research.

"It's been suggested that it helps things like some of the pain syndromes, that it helps spasticity, that it helps mood," said Royal, noting that there is no data on how many Canadians with MS use pot. "This is all kind of anecdotal information we have out there."

"But I think we have to keep in mind that we have really good tried-and-true, more traditional therapies, medications, that are highly effective in the hands of a skilled practitioner."

"And certainly it would always be best advised that one had exhausted all the therapies that we know so much more about and then have a good conversation with a physician before going to any alternatives, just to be sure that you've explored all the possibilities."

Reproduced from

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