Marijuana (Cannabinoids)Multiple Sclerosis

Neuropsychological effects of cannabis in patients with MS

Researchers at the University of Toronto, in Ontario studied the relationship.

First, the details.

  • 50 patients with multiple sclerosis (MS) were evaluated using a battery to tests of cognitive function and anxiety and depression.
  • The patients were divided into 2 groups  (cannabis users and nonusers) matched for the effects of age, sex, education, premorbid intelligence, disability, and disease course and duration on cognitive function.

And, the results.

  • Cannabis users performed significantly more poorly than nonusers on measures of information processing speed, working memory, executive functions, and visuospatial perception.
  • They were also twice as likely as nonusers to be classified as globally cognitively impaired.
  • There were no between-group differences on measures of depression and anxiety or psychiatric diagnoses.

The bottom line?

The authors concluded, “Prolonged use of inhaled or ingested street cannabis in patients with MS is associated with poorer performance on cognitive domains commonly affected in this population.”

They continue, “Whatever subjective benefits patients may derive from using street cannabis (eg, pain and spasticity relief) should be weighed against the associated cognitive side effects.”

3/29/11 20:55 JR

Hi, I’m JR

John Russo, Jr., PharmD, is president of The MedCom Resource, Inc. Previously, he was senior vice president of medical communications at, a complementary and alternative medicine website.