Marijuana slows thinking in MS patients

TORONTO, Feb. 14 (UPI) -- Smoking marijuana may make cognitive and emotional problems worse in multiple sclerosis patients, a Canadian study finds.

The study, published online in Neurology, found marijuana smokers with multiple sclerosis performed 50 percent slower on tests of information processing speed compared to multiple sclerosis patients who did not smoke marijuana.

Study author Anthony Feinstein of the University of Toronto says there was also a significant association between smoking marijuana and emotional problems such as depression and anxiety. "This is important information because a significant minority of people with multiple sclerosis smoking marijuana as a treatment for the disease, even though there are no scientific studies demonstrating that it is an effective treatment for emotional difficulties," Feinstein says in a statement.

The researchers interviewed 140 patients of whom 10 had smoked marijuana with the last month and they were matched on a number of factors such as age, sex, and the length of time they had multiple sclerosis with patients that did not smoke marijuana.

Feinstein said he is concerned because multiple sclerosis itself can cause cognitive problems that can "greatly affect the quality of life for both patients and their caregivers."