Ketamine may do more than rapidly ease severe suicidal thoughts in people with depression.
Research from Columbia University suggests that a single dose can also improve some thinking abilities, and these cognitive changes may be connected with the reduction in suicidal thinking.
The findings could help scientists better understand why ketamine can work so quickly in some people.
Major depressive disorder can affect far more than mood. People with severe depression may have difficulty concentrating, making decisions, solving problems or thinking flexibly. When suicidal thoughts are also present, these difficulties can make an already dangerous situation even harder to manage.
Most traditional antidepressants take days or weeks to produce their full effects. This delay is a major problem when someone is experiencing an immediate suicidal crisis. Ketamine has attracted intense scientific interest because its effects can appear much faster, sometimes within hours.
Ketamine has been used in medicine for decades, mainly as an anesthetic. At lower doses, researchers discovered that it can produce rapid antidepressant effects in some people with difficult-to-treat depression. It affects brain signaling differently from most standard antidepressants, particularly through a chemical messenger called glutamate.
In the Columbia University study, researchers examined 78 people with major depressive disorder who were experiencing significant suicidal thoughts. Participants received an intravenous infusion of ketamine or a comparison drug. The researchers then assessed changes in suicidal thinking, depression and cognitive performance.
The comparison treatment was midazolam, a short-acting sedative that can reduce anxiety and produce sleepiness. Using an active comparison drug rather than an inactive placebo can make it harder for participants to guess which treatment they received. This can strengthen a clinical trial by reducing the influence of expectations.
Within 24 hours, people who received ketamine showed a greater reduction in suicidal thoughts. The researchers also found improvements in several measures of thinking and problem solving. These cognitive improvements appeared to be related to the reduction in suicidal thinking.
Importantly, the connection remained even when improvement in overall depression was taken into account. This suggests that ketamine’s anti-suicidal effects may not simply be a result of making a person feel less depressed. Changes in the way the brain processes information could also be involved.
Dr. John Mann and colleagues have studied the biology of depression and suicide for many years.
Their findings raise the possibility that difficulties with thinking, reasoning and responding flexibly to problems may be an important part of suicidal states. Improving these abilities could potentially help people see alternatives when they previously felt trapped.
Researchers do not yet know exactly how ketamine produces these rapid effects. Studies suggest that it may quickly change communication between brain cells and encourage changes in connections between neurons.
These effects are very different from the slower biological changes traditionally associated with many antidepressant medicines.
Ketamine is not a simple or risk-free treatment. It can temporarily increase blood pressure and cause dizziness, nausea, unusual perceptions or a feeling of being disconnected from oneself or the environment. For this reason, ketamine treatment is generally given under medical supervision, where patients can be monitored.
Ketamine itself has not been approved by the U.S. Food and Drug Administration specifically as a treatment for suicidal thoughts. It may nevertheless be used off-label by clinicians in appropriate settings.
A related medicine, esketamine, has separate regulatory approvals for certain forms of depression and is also administered under medical supervision.
The study is encouraging, but it does not mean that one ketamine infusion permanently removes suicide risk. Suicidal thinking can return, and people in crisis often need continuing treatment and support after the immediate symptoms improve.
Researchers are still studying how long ketamine’s benefits last and how repeated treatment should be used.
The relatively small number of participants is another reason for caution. Although a controlled clinical study can provide valuable evidence, larger studies are needed to confirm which cognitive changes matter most and whether they actually help explain ketamine’s anti-suicidal effect. Scientists also need to determine which patients are most likely to benefit.
The research is important because it changes the question from simply asking whether ketamine reduces suicidal thoughts to asking how it does so.
If improved thinking is part of the mechanism, future treatments might be designed to target those same brain processes without necessarily using ketamine itself. This could eventually expand the options available for people facing severe depression and suicidal crises.
The Columbia University research was published in The Journal of Clinical Psychiatry. The findings add to growing evidence that ketamine can produce rapid changes in severe depression and suicidal thinking, while offering a new clue that improved cognitive function may be part of that response.
Copyright © 2026 Knowridge Science Report. All rights reserved.
