Ketamine, known mostly as a party drug, has assumed a new identity in recent years—as a promising antidepressant. And, though research is still under way, it seems to reduce symptoms of depression very quickly, and in people who 
haven’t been helped by traditional antidepressants. Now, a study published in the American Journal of Psychiatry finds that for depressed people who have suicidal thoughts, it may also help alleviate these thoughts much faster than anything that exists currently—within hours.
The study, carried out at the Columbia University Medical Center and the New York State Psychiatric Institute, looked at 80 patients with clinical depression. They all had suicidal thoughts that were intrusive enough to fall into the category of clinical suicidal ideation. The participants were randomized to receive a low-dose infusion of either ketamine or midazolam, a sedative; they were followed for six weeks, during which time the participants all received usual psychiatric care. To measure their depressive symptoms and suicidal ideation (thoughts or urges), the participants filled out questionnaires, like the Scale for Suicidal Ideation and the Beck Depression Inventory.
Within 24 hours, the participants who’d received ketamine reported significant changes in symptoms compared to those receiving midazolam. They had a reduction in suicidal thoughts, depressive symptoms, and fatigue. In fact, the participants who didn’t respond to midazolam were later given ketamine, and they showed the same improvements.
And these changes seemed to last for up to six weeks. The side-effects, which were mainly dissociation—a sense of detachment—and increased blood pressure, resolved within minutes or hours after the ketamine injection.
When the researchers teased apart the variables, they found that the reduction in depressive symptoms accounted for only a third of the reduction in suicidal thoughts, which suggests that ketamine’s effects on suicidality comes from more than just a reduction in depression. What that might be still needs to be explored.
“Adjunctive ketamine demonstrated a greater reduction in clinically significant suicidal ideation in depressed patients within 24 hours compared with midazolam, partially independently of antidepressant effect,” the authors write.
Suicide rates in the U.S. have risen a lot in recent years—according to the CDC, they’ve increased by almost 27% percent between 1999 and 2015. It’s particularly concerning since young adults and teens—especially girls—represent an especially large part of the rise.
The study builds on a growing body of literature suggesting that ketamine may be a real player in depression treatment, which hasn’t changed much over the years. As most people know, the usual antidepressants can be ineffective for some people; and for those for whom they work, it can take many months to find the right one, since they can take several weeks to kick in. For people who are suicidal, it’s especially critical to find faster and more effective treatments.
“There is a critical window in which depressed patients who are suicidal need rapid relief to prevent self-harm,” said study author Michael Grunebaum in a statement. “Currently available antidepressants can be effective in reducing suicidal thoughts in patients with depression, but they can take weeks to have an effect. Suicidal, depressed patients need treatments that are rapidly effective in reducing suicidal thoughts when they are at highest risk.”
More work will need to be done to understand ketamine dosing, especially over the long-term, as well as long-term side-effects that may develop. Some doctors are already offering ketamine infusions for people with treatment-resistant depression, although it’s not approved by the FDA for this purpose. (And people should not be self-administering ketamine, since at the wrong dose it can be harmful, addictive, or fatal.)
So far the results are encouraging, and it will be exciting to watch the developments as they come in. “Additional research to evaluate ketamine’s antidepressant and anti-suicidal effects,” said Grunebaum, “may pave the way for the development of new antidepressant medications that are faster acting and have the potential to help individuals who do not respond to currently available treatments.”