UT Southwestern Medical Center scientists have identified a key protein that helps trigger ketamine’s rapid antidepressant effects in the brain, a crucial step to developing alternative treatments to the controversial drug being dispensed in a growing number of clinics across the country.
Ketamine is drawing intense interest in the psychiatric field after multiple studies have demonstrated it can quickly stabilize severely depressed patients.
But ketamine – sometimes illicitly used for its psychedelic properties – could also impede memory and other brain functions, spurring scientists to identify new drugs that would safely replicate its antidepressant response without the unwanted side effects.
A new study from the Peter O’Donnell Jr. Brain Institute has jumpstarted this effort in earnest by answering a question vital to guiding future research: What proteins in the brain does ketamine target to achieve its effects?
The study published in Nature shows that ketamine blocks a protein responsible for a range of normal brain functions.
- The blocking of the N-methyl-D-aspartate (NMDA) receptor creates the initial antidepressant reaction, and a
- metabolite of ketamine is responsible for extending the duration of the effect.
The blocking of the receptor also induces many of ketamine’s hallucinogenic responses. The drug – used for decades as an anesthetic – can distort the senses and impair coordination.
But if taken with proper medical care, ketamine may help severely depressed or suicidal patients in need of a quick, effective treatment, Dr. Monteggia said.
Studies have shown ketamine can stabilize patients within a couple of hours, compared to other antidepressants that often take a few weeks to produce a response – if a response is induced at all.
“Patients are demanding ketamine, and they are willing to take the risk of potential side effects just to feel better,”
I question the use of the phrase “just to feel better” here because it trivializes the torment of a severe and relentless depression. To escape the potentially lethal grip of this miserable affliction, patients are sometimes willing to take very high risks (like ECT).
Dr. Monteggia’s lab continues to answer these questions as UT Southwestern conducts two clinical trials with ketamine, including an effort to administer the drug through a nasal spray as opposed to intravenous infusions.
Ketamine, due to the potential side effects, is mainly being explored as a treatment only after other antidepressants have failed.
But for patients on the brink of giving up,
waiting weeks to months to find the right therapy
may not be an option.
Just like naloxone is the emergency treatment for a high that turns into an overdose, perhaps ketamine should be the emergency treatment for a depression that turns suicidal.
Because the (NMDA) receptor that is the target of ketamine is not involved in how other classical serotonin-based antidepressants work, our study opens up a new avenue of drug discovery,