Researchers tested ketamine in healthy volunteers and scanned their brains to see what parts of the organ it affected / Getty Images

Monitoring the effects of ketamine on the brain has revealed neural pathways that could aid the development of fast-acting medications for treating depression

Ketamine could be used in new treatments for depression, according to scientists.

Researchers at the University of Auckland said monitoring the effects of the drug on the brain has revealed neural pathways that could aid the development of fast-acting medications.

Ketamine is a synthetic compound used as an off anaesthetic and analgesic drug, but is commonly used illegally as a hallucinogenic party drug.

Dr Suresh Muthukumaraswamy, a senior researcher at the university and a member of the institution’s Centre for Brain Research, used the latest technology in brain imaging to investigate what mechanisms ketamine uses to be active in the human brain.

Researchers tested ketamine in healthy volunteers and scanned their brains to see what parts of the organ it affected. Their findings are published in the Journal of Neuroscience.

Dr Muthukumaraswamy said that during depression two parts of the brain’s frontoparietal circuit work overtime in an over-connected way.

Ketamine, he found, disconnects those two parts of the brain and stops that over-connectivity, which may explain how the drug works as an anti-depressant. 

“Unlike other anti-depressants, ketamine is very fast acting,” said Dr Muthukumaraswamy.

The drug is “is important as a mechanism to identify potential biomarkers of anti-depressant activity in human patients,” he added.

Ketamine, developed in the 1960s, is an off-patent drug, primarily used as an anaesthetic and sometimes for chronic pain.

Only low doses of ketamine are needed, compared to anaesthetics, to create anti-depressant effects.

“It’s not licenced for depression because it is still very experimental in that role,” says Dr Muthukumaraswamy.

“Unfortunately,” he adds, “ketamine is also a drug of abuse, as it’s mildly hallucinogenic and it is unclear if it could be used in routine clinical practise.”

The research team said further work was needed to investigate how ketamine produced its anti-depressive effects at such a rapid speed.

This is not the first study to explore ketamine as an anti-depressant.

Last year, infusions of ketamine given to patients in an Oxford Health NHS Foundation Trust trial found the drug had a rapid beneficial effect on those who were not responding to more orthodox treatments.

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