1. How Ketamine Works
In the Opening New Possibilities section of this website, I described how depression, trauma, and anxiety can narrow our sense of what is possible. Thoughts become repetitive. Emotional responses become familiar. Over time, the same patterns can begin to repeat themselves even when we are actively trying to change them.
One of the reasons ketamine has generated significant interest in psychiatry is that it appears to affect brain systems involved in learning, adaptation, and neural flexibility in ways that may temporarily increase the capacity for change.
How this happens is still being actively studied, but researchers have learned a great deal over the past two decades.
For more than twenty-five years of practicing psychiatry, and since founding Nashville Ketamine Center in 2012 as the Southeast’s first outpatient ketamine clinic, I have watched hundreds of people describe remarkably similar experiences during ketamine treatment. One of the questions I am asked most often is:
“How does ketamine actually work?”
The honest answer is that we still don’t fully know.
What has become increasingly clear, however, is that ketamine appears to work very differently from virtually every traditional antidepressant that came before it.
Most psychiatric medications exert their primary effects through neurotransmitters such as serotonin, norepinephrine, or dopamine. Ketamine, on the other hand, appears to work primarily through the brain’s glutamate system.
Glutamate is the most abundant excitatory neurotransmitter in the brain. It plays a central role in learning, memory, adaptation, and how the brain reorganizes itself in response to experience.
One of ketamine’s primary actions is to block a specific glutamate receptor known as the NMDA receptor. However, this receptor blockade alone does not appear to explain its antidepressant effects. Rather, it seems to initiate a cascade of downstream changes that increase signaling through other glutamate pathways, particularly AMPA receptors.
2. Why Is This Important?
One prevailing theory is that depression and trauma become associated with patterns of thinking, feeling, and responding that gradually become more rigid over time. These patterns are not only psychological, they are reflected in the activity of neural networks throughout the brain. Eventually, the brain becomes remarkably efficient at producing the very thoughts and emotional responses we are trying to escape.
Ketamine appears to temporarily increase the brain’s capacity for change. Researchers often describe this as increased neuroplasticity, the brain’s ability to form new connections, adapt, and reorganize itself in response to experience.
Researchers have observed activation of signaling pathways associated with neuroplasticity, including brain-derived neurotrophic factor (BDNF) and the mTOR pathway. These systems are involved in the formation and strengthening of synaptic connections between neurons.
In practical terms, ketamine appears to create a temporary state in which the brain is more able to form new connections and reorganize existing ones.
This may help explain why some patients experience relatively rapid shifts in mood, perspective, and behavior compared to traditional antidepressant treatments.
3. Biology Meets Experience
Yet biology is only part of the story.
During treatment, many individuals also report a shift in how they relate to their thoughts, emotions, memories, and sense of self. While every person’s experience is different, many patients describe becoming less caught in automatic patterns of thinking and more able to observe them with curiosity rather than certainty.
Thoughts that normally feel automatic may become more observable. Emotional responses that feel fixed may become less absolute. Many describe gaining a sense of distance from familiar patterns or long-standing narratives.
From my perspective, one of the most interesting questions in ketamine treatment is whether these biological and psychological effects are truly separate processes. They may instead represent different expressions of the same underlying phenomenon.
As the brain becomes more flexible, experience often becomes more flexible as well. Patients frequently describe seeing familiar problems from a new vantage point, feeling less identified with long-standing narratives, or recognizing possibilities that previously felt unavailable.
Much remains unknown, and ongoing research continues to refine our understanding. What appears increasingly clear is that ketamine does more than simply alter neurotransmitters. It appears to create a temporary state in which both brain function and subjective experience become more adaptable.
Perhaps this is why so many patients describe ketamine not as simply feeling better, but as feeling that new possibilities have become imaginable again. The depression may not disappear overnight. Life’s problems may still be present. Yet many people describe a renewed sense that change is possible, and sometimes that is where healing begins.