Smoked cannabis significantly reduced MS spasticity and pain in a placebo-controlled trial | Research

The takeaway

In 30 MS patients, smoked cannabis reduced spasticity by 2.74 points more than placebo and pain by 5.28 points more, but also impaired cognitive performance.

Read this if you have MS spasticity and want to know whether smoked cannabis is backed by clinical trial data.

Spasticity reduction: 2.74 points better than placebo (p<0.0001)

What the researchers found

Thirty MS patients with treatment-resistant spasticity completed a placebo-controlled crossover trial. Each participant smoked cannabis or identical placebo cigarettes once daily for three days, with an 11-day washout between periods.

Smoked cannabis reduced spasticity scores (modified Ashworth scale) by 2.74 points more than placebo (p<0.0001), a highly significant result. Pain scores on a visual analogue scale also improved by 5.28 points more than placebo (p=0.008).

However, cognitive performance on the Paced Auditory Serial Addition Test decreased by 8.67 points more with cannabis than placebo (p=0.003). Walking speed did not significantly differ. No serious adverse events occurred.

The authors concluded smoked cannabis was superior to placebo but recommended future studies examine whether different doses could provide benefits with less cognitive impact.

Why it matters

This was one of very few randomized trials of smoked cannabis (rather than oral or spray formulations) for MS spasticity. The strong effect on spasticity and pain, combined with the cognitive tradeoff, gave clinicians concrete data for shared decision-making.

The numbers in context

30 completers out of 37 randomized. Spasticity reduction: 2.74 points better than placebo (p<0.0001). Pain reduction: 5.28 points better (p=0.008). Cognitive decline: 8.67 points worse (p=0.003). Timed walk: no significant difference (p=0.2).

How the study worked

Placebo-controlled, crossover trial. 37 randomized, 30 completed. Cannabis or identical placebo cigarettes smoked once daily for 3 days, with 11-day washout. Primary outcome: modified Ashworth scale. Secondary: VAS pain, timed walk, PASAT cognitive test.

What this study cannot tell us

Small sample size (30 completers). Very short treatment period (3 days). The crossover design with 11-day washout may not have been long enough to eliminate carry-over effects. Blinding of smoked cannabis is inherently difficult despite identical-looking cigarettes.

How to read the evidence

Randomized, placebo-controlled crossover trial. Strong design but small sample and very short treatment period. Blinding challenges inherent to smoked cannabis.

When this study was published

Published in 2012. This remains one of the few controlled trials of smoked cannabis for any medical condition.

The bigger picture

The cognitive impairment finding was clinically important. Patients and clinicians must weigh genuine spasticity and pain relief against cognitive costs. This tradeoff highlights why dose optimization and alternative delivery methods remain important research priorities.

Questions still open

Could lower cannabis doses provide spasticity relief without cognitive impairment? Would longer-term use show tolerance to cognitive effects while maintaining spasticity benefits? How does smoked cannabis compare to Sativex spray for MS spasticity?

Common questions

Does smoked cannabis help MS spasticity?

In this trial, smoked cannabis significantly reduced spasticity and pain compared to placebo. The spasticity improvement was highly statistically significant (p<0.0001). However, it also impaired cognitive performance, creating a tradeoff that patients and doctors need to discuss.

Is smoking cannabis better than Sativex for MS?

This study did not directly compare them. Smoked cannabis showed large effects in this small trial, while Sativex spray showed more modest but consistent effects across larger trials. Smoking delivers THC faster, which may produce stronger effects but also more side effects.

Read the original research

Smoked cannabis for spasticity in multiple sclerosis: a randomized, placebo-controlled trial.

CMAJ : Canadian Medical Association journal = journal de l'Association medicale canadienne, 184(10), 1143-50

View on PubMed ↗Publisher’s paper ↗

Citation

Corey-Bloom, Jody; Wolfson, Tanya; Gamst, Anthony; Jin, Shelia; Marcotte, Thomas D; Bentley, Heather; Gouaux, Ben. (2012). Smoked cannabis for spasticity in multiple sclerosis: a randomized, placebo-controlled trial.. CMAJ : Canadian Medical Association journal = journal de l'Association medicale canadienne, 184(10), 1143-50. https://doi.org/10.1503/cmaj.110837