Ketamine, which is often used recreationally, has also long been studied as a way to treat depression. It’s never been quite understood exactly how it works to treat symptoms, but a team of scientists believe they have the answer.

Researchers at UT Southwestern Medical Center found a key protein that helps ketamine have rapid antidepressant effects.

Read: Ketamine May Not Help With Post-Surgery Pain Or Delirium, Despite Widespread Use

“Now that we have a target in place, we can study the pathway and develop drugs that safely induce the antidepressant effect,” study author Dr. Lisa Monteggia said in a statement.

The study, published in the journal Nature, shows the drug works by blocking a portion of the brain known as the NMDA receptor. Although past research has identified it blocks this receptor, this team’s findings identify a more specific region that helps trigger antidepressant effects.

“We think that the specificity is what's important to trigger this signaling cascade,” Monteggia told TIME. “This receptor is very complicated in terms of its function, and not all blockers are the same.”

Read: Unique Exercises For Depression: Tai Chi And Rock Climbing May Help Ease Symptoms, Studies Find

While the researchers’ work seems promising, it’s important to note their study was conducted on mice. In the future, more research must be done, especially on humans, to better understand their findings.

“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,” Monteggia said in a statement. Common serotinin-based drugs include Prozac and Zoloft.

Although classic antidepressants work for some patients, others with severe depression may not have much luck with FDA-approved treatments. That’s when ketamine comes in and may be prescribed off-label by a healthcare provider. Some studies have shown low-doses of the drug are able to reduce a person’s symptoms within hours or even minutes. Unfortunately, the drug, also known as “Special K,” can come with a long list of severe side effects. In a study on ketamine and its effect on patients with chronic pain, it was found the drug may lead to hallucinations, panic attacks, nausea, memory problems, and bladder complications.

Finding new ways to treat depression is important, considering the disorder affects more than 300 million people worldwide and is the leading cause of disability across the globe, according to the World Health Organization. Medications and psychotherapy help most people; however, those with a severe form of the disorder may require a hospital stay or outpatient program to help them get better, Mayo Clinic reports. At its worst, it can lead to suicide.

See also: Global Depression Rates Have Soared In Last Decade; Half Of People With Condition Do Not Get Treatment: WHO

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