Cannabis May Not Be a Panacea

There is a growing social and medical impetus to legalize cannabis not only for recreational use, but also for the treatment of neurologic disorders such as multiple sclerosis (MS). Although some studies have shown that cannabis may relieve spasticity, pain, and other symptoms in patients with MS, a new study by Pavisian et al sounds a cautionary note. The authors suggest that cannabis further compromises a brain already impaired from tissue damage in MS. One reason that the authors found functional MRI changes, but not structural MRI changes, might be that physiologic changes occurred before structural changes, which would not be unexpected. In addition, smoking may be a factor in MS worsening. Could smoking cigarettes rather than cannabis be the reason for the cognitive change among study participants? In the end, these findings suggest that cannabis may be a double-edged sword in MS, and possibly in other brain disorders. Further testing, including a prospective study of patients randomized to smoking cannabis or placebo, would be an important step toward confirming Pavisian’s results.

—Stuart D. Cook, MD
Professor of Neurology, Department of Neurosciences,
Rutgers, the State University of New Jersey,
New Jersey Medical School,
Newark, NJ