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Synthetic Δ-9-Tetrahydrocannabinol (Dronabinol) Can Improve the Symptoms of Schizophrenia

Schwarcz, Glenn MD*†‡; Karajgi, Basawaraj MD*; McCarthy, Richard MD, PhD§∥

Journal of Clinical Psychopharmacology: June 2009 - Volume 29 - Issue 3 - p 255-258
doi: 10.1097/JCP.0b013e3181a6bc3b
Original Contributions

We are reporting improvement of symptoms of schizophrenia in a small group of patients who received the cannabinoid agonist dronabinol (synthetic Δ-9-tetrahydrocannabinol). Before this report, cannabinoids had usually been associated with worsening of psychotic symptoms. In a heuristic, compassionate use study, we found that 4 of 6 treatment-refractory patients with severe chronic schizophrenia but who had a self-reported history of improving with marijuana abuse improved with dronabinol. This improvement seems to have been a reduction of core psychotic symptoms in 3 of the 4 responders and not just nonspecific calming. There were no clinically significant adverse effects. These results complement the recent finding that the cannabinoid blocker rimonabant does not improve schizophrenic symptoms and suggest that the role of cannabinoids in psychosis may be more complex than previously thought. They open a possible new role for cannabinoids in the treatment of schizophrenia.

From the *Rockland Psychiatric Center, Orangeburg; †New York University School of Medicine; ‡Stroud Center in the Columbia University Faculty of Medicine; §Consultation Service, State of New York Office of Mental Health, New York; and ∥Pilgrim Psychiatric Center, West Brentwood, NY.

Received June 19, 2008; accepted after revision March 23, 2009.

Reprints: Glenn Schwarcz, MD, Rockland Psychiatric Center, 140 Old Orangeburg Rd, Bldg 60, Orangeburg, NY 10962 (e-mail:

© 2009 Lippincott Williams & Wilkins, Inc.