Smoking marijuana can relieve muscle tightness, spasticity (contractions) and pain often experienced by those with multiple sclerosis, says research out of the University of California, San Diego School of Medicine.

The findings, just published in the Canadian Medical Association Journal, included a controlled trial with 30 participants to understand whether inhaled cannabis would help complicated cases where existing pharmaceuticals are ineffective or trigger adverse side effects.

MS is an unpredictable, often disabling disease of the central nervous system, which is made up of the brain and spinal cord.

The disease attacks the myelin, the protective covering wrapped around the nerves of the central nervous system, and — among other symptoms — can cause loss of balance, impaired speech, extreme fatigue, double vision and paralysis.

The average age of the research participants was 50 years with 63 per cent of the study population female.

More than half the participants needed walking aids and 20 per cent used wheelchairs.

Rather than rely on self-reporting by patients regarding their muscle spasticity — a subjective measure — health professionals rated each patient’s joints on the modified Ashworth scale, a common objective tool to evaluate intensity of muscle tone.

The researchers found that the individuals in the group that smoked cannabis experienced an almost one-third decrease on the Ashworth scale — 2.74 points from a baseline score of 9.3 — meaning spasticity improved, compared to the placebo group.

As well, pain scores decreased by about 50 per cent.

“We saw a beneficial effect of smoked cannabis on treatment-resistant spasticity and pain associated with multiple sclerosis among our participants,” says Dr. Jody Corey-Bloom of the university’s department of neuroscience.

Researchers found that, although generally well-tolerated, the cannabis had the expected short-term but acute cognitive effects.

Corey-Bloom says larger, long-term studies are needed to confirm findings and determine whether lower doses can result in beneficial effects with less cognitive impact.

The Multiple Sclerosis Society of Canada says Canadians have one of the highest rates of the disease in the world. The disease is the most common neurological diseases affecting young adults in this country and every day three more people in Canada are diagnosed with MS.