Ketamine is a safe and powerful cure for elderly people with depression, study claims: 50% of patients 'cured of symptoms after taking the club drug'

Australian researchers carried out the first trial on elderly people with ketamine

All of the participants were over 60 and had treatment-resistant depression

After 6 months, almost half of the group claimed to be symptom-free

Ketamine is a safe and effective treatment for elderly people with depression, a major new study claims.

The illegal drug is a powerful anesthetic, first used as an animal tranquilizer before turning into a popular club drug. 

In the last few years, researchers have been investigating the substance as a potential antidepressant. 

Now, Australian researchers have completed the first trial assessing the safety of ketamine in elderly patients - and found it halved their symptoms of depression. 

While the research team at the University of New South Wales admits the sample size - 16 people - is small, they claim it is a major step to showing the effectiveness of the drug in an age group that has not been examined.

"These findings take us a big step forward as we begin to fully understand the potential and limitations of ketamine's antidepressant qualities" said lead author UNSW Professor Colleen Loo, who is based at Black Dog Institute.

"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 (a small injection under the skin) was also shown to be an acceptable method for administering the drug in a safe and effective way"

The participants were all aged over 60 and all had 'treatment-resistant depression'.

The trial started with an intensely controlled period of five weeks, in which each patient received increasing doses of ketamine.

One week the researchers gave them a placebo sedative to put their responses into context.

Throughout the trial the researchers monitored their mood and side effects.

By the end of the five weeks, the patients were then give 12 ketamine dosing sessions each, which took place at various times over the course of six months.

By the six-month follow up, almost half of the participants (43 percent) said they had no symptoms of depression. 

Five of them said they were free of symptoms before they had reached the standard dosing level - 0.5mg/kg - suggesting even a small amount could be effective.   

'Elderly patients with severe depression face additional barriers when seeking treatment for the condition. Many medications may cause more side effects or have lower efficacy as the brain ages,' said co-author Dr Duncan George from UNSW Sydney. 

'Older people are also more likely to have co-morbidities like neurodegenerative disorders and chronic pain, which can cause further complications due to ketamine's reported side effects. 

'Our results indicate a dose-titration method may be particularly useful for older patients, as the best dose was selected for each individual person to maximise ketamine's benefits while minimizing its adverse side effects.'

Previous studies into ketamine treatments for older people with depression - which are limited to just five case reports - show mixed success, with findings limited by small sample sizes.

Little is known about ketamine's potential side effects at different doses, which include cognitive and dissociative effects, elevated blood pressure and heart rate, liver inflammation and urinary problems. 

In this study, patients were given IV drip infusions of 0.5 mg/kg of ketamine.

In comparison, street forms of the drug which can be cut with other substances and horses tend to be given much larger amounts to be sedated.

Illegal versions of the drug to snort tends to provide the human body with the equivalent of 25mg/kg.

When the drug enters the body, it provides hallucinogenic effects - similar to that of LSD. It can also leave some completely unable to move.

While horses can receive in excess of 150mg/kg when it is given to the animals as a tranquiliser.

"These results are a promising early piece of the puzzle, but the risks of ketamine use are still not wholly understood. Future studies with greater sample sizes are needed to formally assess ketamine's side effects, such as its impact on liver function" Professor Loo added.