Scientists at the Rockland Psychiatric Center in Orangeburg, New York, reported improvement of symptoms of schizophrenia in 4 patients who received oral THC (dronabinol). The study was initiated after a dramatic improvement in one patient. The researchers found that further 3 of 5 treatment-refractory patients with severe chronic schizophrenia but who had a self-reported history of improving with cannabis use improved also with THC. They only selected patients whose severe, refractory condition made the possible benefits outweigh the risks.

From approximately 200 patients with chronic psychosis, 5 patients met the inclusion criteria. Dronabinol was initiated at 2.5 mg twice a
day and subsequently raised to 5 mg twice a day at the second week and 10 mg twice a day at the just third week. No significant adverse effects were observed. One of the patients needed 8 weeks to reach significant improvement, while the others responded within a shorter period of time. Researchers noted that “this improvement seems to have been a reduction of core psychotic symptoms in 3 of the 4 responders and not just non-specific calming.” The results would 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.”

(Source: Schwarcz G, Karajgi B, McCarthy R. Synthetic delta-9-tetrahydrocannabinol (dronabinol) can improve the symptoms of schizophrenia. J Clin Psychopharmacol 2009;29(3):255-8.)