Researchers Note Cannabis Impacts Cognitive Function — But So Do Other Multiple Sclerosis Drugs
Smoking marijuana cuts spasticity and pain that’s resistant to conventional treatments in patients with multiple sclerosis (MS), although it does have some cognitive effects as well, a small clinical trial in 2012 unsurprisingly confirmed.
Spasticity scores on the modified Ashworth scale dropped by an average 2.74 points more with smoked cannabis than with a placebo, researchers at the University of California San Diego found, reports Crystal Phend at MedPage Today.
A difference or two or more points is considered clinically meaningful on the 30-point Ashworth scale which covers mobility of elbows, hips, and knees, report Jody Corey-Bloom, M.D., Ph.D., and colleagues at UCSD. The researchers reported their findings online in CMAJ.
Besides the positive effects on spasticity, pain scores decreased by about 50 percent as well, the researchers reported. “We saw a beneficial effect of smoked cannabis on treatment-resistant spasticity and pain associated with multiple sclerosis among our participants,” Corey-Bloom said.
The findings regarding smoked marijuana support anecdotal evidence from many multiple sclerosis patients who say smoking the herb relieves spasticity, the researchers noted. About 400,000 pepole in the United States have MS, an unpredictable, often disabling chronic disease in which the protective coating around nerve fibers starts breaking down.
The disease attacks the myelin, which is wrapped around the nerves of the central nervous system, and among other symptoms, cash cause loss of balance, impaired speech, extreme fatigue, double vision and paralysis, reports Paul Irish at The Star.
The body naturally produces cannabinoids, a group of chemicals also found in marijuana. Studies have suggested that the cannabinoid receptors on our cells help regulate muscle spasticity, reports Amy Norton of Reuters.
But trials that focus on orally administered cannabinoids have had mixed results, according to the researchers.
“Any reductions in spasticity have generally only been seen on subjective ratings,” Corey-Bloom and colleagues noted.
“We’ve heard from patients that marijuana helps their spasticity, but I think a lot of us thought, ‘Well, it’s probably just making you feel good,’ ” said lead researcher Dr. Corey-Bloom. “I think this study shows that yes, [marijuana] may help with spasticity, but at a cost.”The “cost,” according to Corey-Bloom and colleagues, is that pot smoking causes fatigue and dizziness in some users, and generally slowed down people’s mental skills soon after using cannabis. That seems a pretty cheap “cost” to me — I’d even go so far as to call it a “good deal.”
The trial included 30 multiple sclerosis patients with treatment-resistant spasticity randomized to double-blind use of a placebo cigarette or smoked cannabis, once daily for three frays with crossover after an 11-day washout period. The average age of participants was 50 years, with 63 percent of them being female. More than half needed walking aids, and 20 percent used wheelchairs.
Pain scores, though relatively low at the start, with an average 12 or 13 points on the 100-point Visual Analogue Scale, fell an additional 5.28 points on average with medical marijuana compared to a placebo.
Not surprisingly, according to researchers, smoking marijuana also “reduced cognitive function acutely,” that is to say it got people stoned. Paced Auditory Serial Addition Test scores measured 45 minutes after smoking were down 8.67 points more with cannabis than with a placebo.However, “the clinical significance of this result is uncertain; despite the transient decrease in scores, patients were still within normal ranges [emphasis added] for their ages and levels of education,” the investigators pointed out.
But conventional, pharmaceutical treatments for MS may also affect cognition, making such arguments — when used against cannabis — seem rather specious.
“It is worth noting that conventional treatments, such as baclofen and tizanidine hydrochloride, may also affect cognition, although published data are scarce,” the researchers noted.
For comparison with marijuana’s 2.74-point drop in Ashworth scores of spasticity, in a previous study, sublingual tizanidine hydrochloride (Zanaflex) resulted in a three-point decline in Ashworth scores after a week of treatment; oral tizanidine showed a 1.81-point decline compared with a 1.19-point decline with placebo in prior studies.
“Larger, long-term studies are needed to confirm our findings and determine whether lower doses can result in beneficial effects with less cognitive impact,” the researchers suggested.