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    Does Pot Use Hamper Thinking in MS?

    Study: Multiple Sclerosis Patients Who Smoke Marijuana May Have Slower Reaction Times
    WebMD Health News
    Reviewed by Louise Chang, MD

    Feb. 13, 2008 -- New research shows that among multiple sclerosis patients, those who smoke marijuana may have slower reaction times on mental skills tests and are more likely to report a history of psychiatric diagnoses.

    That news, published in today's advance online edition of Neurology, comes from a Canadian study.

    The researchers studied 140 multiple sclerosis patients, including 10 who said they smoke marijuana at least once a month.

    The patients took various mental skills tests and were interviewed about their mental health history.

    Marijuana smokers had slower average reaction times on a test that challenged them to process information quickly. And they were more likely to report a history of psychiatric diagnoses, most of which were depression or anxiety diagnoses.

    It's not clear if marijuana use caused those conditions. The study doesn't show which came first -- marijuana use or problems with emotions and thinking. It's also not clear if the patients, who all attended the same outpatient clinic, are representative of all MS users.

    But in a news release, researcher Anthony Feinstein, MPhil, PhD, FRCP, states that "this is important information because a significant minority of people with MS smokes marijuana as a treatment for the disease."

    Feinstein conducted the study with Omar Ghaffar, MD, FRCP. Both work in the psychiatry department at the Sunnybrook Health Sciences Centre in Toronto.

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