When it comes to ketamine many might leap to thoughts of electronic music, psychedelic visions and out-of-body experiences. But new research has added to existing evidence that this party drug could be a safe, fast, and effective treatment for severe depression.

The new findings represent a glimmer of hope in cases where antidepressant medications, counselling and other therapies have failed to relieve depressive symptoms, and particularly for the elderly.

"These findings take us a big step forward as we begin to fully understand the potential and limitations of ketamine's antidepressant qualities," says lead researcher Colleen Loo from the University of New South Wales in Australia.

Also known as 'Special K' on the illicit drug scene, ketamine was developed as a fast-acting anaesthetic in the 1960s. Before making its way into clubs and music festivals, it was used to treat injured soldiers on the battlefield and children who suffered bad reactions to other anaesthetics.

Apart from relieving severe pain, ketamine is also a strong psychedelic that produces vivid hallucinations, euphoria, and out-of-body sensations. Soon after its release, the drug began showing up at dance parties and nightclubs almost as often as in hospitals.

But ketamine isn't limited to pain relief and tripping out. In recent years, researchers have begun exploring how the drug can be used to treat severe depression, especially in cases where other treatments haven't worked.

While studies have been small and short term, results have shown that ketamine can treat depression in just a few hours.

This is exciting, because even though over 300 million people worldwide suffer from depression, finding the right treatment is still a challenge for many sufferers.

While antidepressant medications like Prozac and Lexapro have become popular treatments, they can take around three to eight weeks to kick in and may not work at all in some cases.

Additionally, trying to figure out which of these selective serotonin reuptake inhibitors (SSRIs) work best for someone is a matter of trial and error, which can mess with the brain's chemical makeup even further.

If that isn't enough, these antidepressants also come with unpleasant side effects, including nausea, dizziness, weight gain and even insomnia.

In older patients, tackling depression is even harder, with studies showing that antidepressants are less effective and other treatments like electroconvulsive therapy are too risky.

"Elderly patients with severe depression face additional barriers when seeking treatment for the condition," says one of the researchers Duncan George from UNSW. "Many medications may cause more side effects or have lower efficacy as the brain ages."

So far, there are only five case reports on ketamine treatment for depression in older people. But the reports were limited to small sample sizes and had mixed results.

In this blind clinical trial, Loo and her team treated 16 patients over the age of 60 with low-dose injections of ketamine.

Each of the participants had been suffering from severe depression for several years, showing no sign of improvement with medications and counselling.

Over five weeks, the researchers treated the participants with different doses of ketamine. In one of these sessions, the patients received a dose of another sedative treatment as a control.

Following this phase, the participants were given 12 ketamine injections twice a week to see whether multiple doses had a more lasting effect.

While the idea of having a euphoric out-of-body experience in a clinic sounds like a lot of fun, the patients felt woozy and drowsy for the first hour.

"We consider it a side effect, an adverse effect. We haven't had a single person who said, 'this actually feels good'," Loo told ABC Online.

But after these effects passed, the antidepressant effects quickly took hold.

Just seven days after the first ketamine dose, half of the participants reported that they felt completely well.

"Not only was ketamine well-tolerated by participants, with none experiencing severe or problematic side effects, but giving the treatment by a simple subcutaneous injection was also shown to be an acceptable method for administering the drug in a safe and effective way," says Loo.

When the team checked in with the participants after six months, they found that depressive symptoms had vanished in 43 percent of the patients, five of which had been treated with doses below the standard amount.

While previous studies on treating older depression sufferers with ketamine showed patchy results, 70 percent of the participants in Loo's study reported no signs of depression at some point during the trial.

But before we ditch standard antidepressant medications and therapies, Loo says that we still have a lot to learn about ketamine's effects before it is approved as a treatment for depression.

"These results are a promising early piece of the puzzle, but the risks of ketamine use are still not wholly understood," she says.

"Future studies with greater sample sizes are needed to formally assess ketamine's side effects, such as its impact on liver function."

Still, the results are an exciting start to the long-term research Loo and her team are conducting, which is the world's largest study on the potential of ketamine as a treatment for severe depression.

For now, the future looks a little brighter.

The research has been published in The American Journal of Geriatric Society.

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