SAN FRANCISCO—Ketamine can quickly alleviate symptoms of obsessive-compulsive disorder (OCD) in patients with constant intrusive thoughts, and the drug’s effects can last for one to two weeks in certain patients. Researchers reported these findings in a poster presented at the American Psychiatric Association’s (APA) annual meeting.

The rapid symptom relief seen from ketamine is substantially different from symptom relief in current first-line treatments for OCD. With current treatments, patients wait up to six to 10 weeks to see clinically meaningful improvement and may only experience a 40% to 60% reduction in symptoms, according to lead author Carolyn Rodriguez, MD, PhD, Assistant Professor at Columbia University in New York. “We need more effective medications and medications with faster onset,” she said.

The investigators decided to study ketamine, a glutamate N-methyl-D-aspartate (NMDA) receptor antagonist, based on evidence suggesting that glutamate plays a role in the pathogenesis of OCD.

Ten patients were included in the randomized, double-blind, placebo-controlled study—all patients had OCD, were unmedicated, and did not have moderate or severe comorbid depression.

Patients received two intravenous infusions with at least a one-week period between the infusions. One infusion was 0.5 mg/kg of ketamine and the other infusion was saline, and randomization determined which infusion came first.

Using the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS), Dr. Rodriguez and colleagues measured symptoms at baseline and a week after infusion. Results showed that half of the 10 patients responded to treatment after a week, with response defined as at least a 35% reduction in OCD scores on the Y-BOCS.

The five patients who received ketamine in the first infusion were also evaluated two weeks after the infusion, and 40% responded to treatment at that time.

Dr. Rodriguez was pleased with the findings. “This really holds promise and is the first study to show rapid treatment for OCD,” she told Psych Congress Network.

Future research may seek to understand the mechanism driving the sustained effect and the rapid reduction in OCD symptoms. However, ketamine is not yet ready for direct clinical use because its effects can cause people to dissociate, cautioned Dr. Rodriguez.

“I think one of the research directions that holds promise is modulating different parts of the NMDA receptor so you can get the rapid effect but without the psychotomimetic properties,” said Dr. Rodriguez. She added that the research team’s findings give people hope that faster acting medications for OCD are coming.

—Lauren LeBano