Differential effect of Cannabis components (THC vs. CBD) on cognitive function in MS


Cannabis and cannabis-based medicines are used increasingly in Canada, including by people with MS. Studies demonstrate that cannabis negatively affects cognition. It is also well known that MS itself can negatively affect cognition, affecting 40-65% of MS patients. Cannabis has two main components: tetrahydrocannabinol (THC) and cannabidiol (CBD). THC is responsible for the signature “high” of cannabis, while CBD is not. Preliminary studies suggest that THC may be the component that negatively affects cognition, and that CBD alone does not. This differentiation would be important to know, as it would allow person with MS to weigh the risks of using products with THC, CBD, or both.
The purpose of this research study is to examine the effect of Cannabis components, THC and CBD, on cognition and bladder symptoms in people with MS.


Currently recruiting participants: Yes

Eligible gender: Male, Female, Transgender, Other

Eligible ages: 18 to 59

Inclusion criteria:

People 18 to 59 years old with confirmed diagnosis of Multiple Sclerosis and symptoms of neurogenic lower urinary tract dysfunction may be eligible to participate.

Exclusion criteria:

People will not be included if any of the following:
- Have a major psychiatric (e.g. schizophrenia or bipolar disorder) or neurological disorder (dementia, traumatic brain injury, seizure)
- Use of antipsychotic medication or benzodiazepines other than exclusively at night/bedtime
- Currently use cannabis or cannabis-based medication more than 3x/week.
- Currently use cannabis or cannabis-based medication less than 3x/week and are not willing to stop using for the duration of the study.
- Are Pregnant or Breastfeeding.


This study is not currently accepting expressions of interest via the website. Please see contact information below.

Additional information

Contact information

Contact the study coordinator at calgarymsresearch@ucalgary.ca

Principal investigator:

Sarah Morrow

Clinical trial: