Researchers from The National Mental Health Institute (NIMH) at the National Institutes of Health have been studying the antidepressant effects of ketamine — a hallucinatory drug commonly known as “special k” — for years now. While prior studies confirmed the drug can rapidly reduce disordered symptoms, the latest from NIMH refines these findings to emphasize ketamine effects bipolar and depression patients differently.
“Our findings help to deconstruct what has traditionally been lumped together as depression,” Dr. Carlos Zarate, of NIMH, said in a press release. “We break out a component that responds uniquely to a treatment that works through different brain systems than conventional antidepressants — and link that response to different circuitry than other depression symptoms.” Zarate and his team were able to do this after infusing the drug or a placebo into 36 patients in the depressive phase of bipolar disorder.
When patients were on the drug and placebo, researchers could detect any mood changes on a scale of anhedonia (the inability to experience pleasure from enjoyable activities) and depression. Isolating the two helped researchers to see that ketamine triggers a strong anti-anhedonia effect sooner, and independent of, other effects. Specifically, researchers discovered levels of anhedonia improved within 40-minutes of patients taking ketamine compared to those who took a placebo; depressive symptoms improved within two hours.