Scientists focus on 'magic' effect of dance drug on depression.
The drug quickly induces the regeneration of synaptic connections between nerve cells in the brain, a study has shown.
Understanding the way the drug works could lead to better anti-depressant treatments, the scientists believe.
Studies have shown that depressed patients who have resisted all other treatments improve within hours after receiving ketamine.
The drug is not a practical therapy because it has to be administered intravenously to work as an antidepressant, and can cause short-term psychotic symptoms. But scientists say ketamine could act as a guide to highly-promising new treatments for depression. "It's like a magic drug," said Professor Ronald Duman, a psychiatrist at Yale University in the US. "One dose can work rapidly and last for seven to 10 days."
Most antidepressants, such as Prozac, take weeks or even months to kick in. In contrast, ketamine's effects are felt within hours.
Ketamine, originally designed as an anaesthetic and tranquilliser, was made a Class C banned recreational drug in 2006.
During the 1990s it became popular among clubbers who took the drug in pills to experience its trippy and hallucinogenic effects.
Although relatively harmless in small doses, ketamine can cause psychological dependency and leave users helpless and vulnerable. It has a notorious reputation as a date rape drug. Ketamine can also be dangerous when mixed with alcohol or other drugs.
Ketamine's antidepressant potential has been highlighted in clinical experiments in the US dating back 10 years.
The studies have shown that almost 70% of difficult-to-treat patients respond well to injected ketamine within hours. Ketamine has also been shown to rapidly prevent suicidal thoughts, a benefit not usually seen until weeks of treatment with traditional antidepressants.
Prof Duman's team, whose research is reported in the journal Science, mapped the molecular action of the drug on the brains of rats.
The scientists found that ketamine acts on a pathway that rapidly forms new connections between neurons, a process called synaptogenesis.
Co-author Professor George Aghajanian, from Yale School of Medicine, said: "The pathway is the story. Understanding the mechanism underlying the antidepressant effect of ketamine will allow us to attack the problem at a variety of possible sites within that pathway."
A key player in the ketamine effect was an enzyme called mTOR, which controls the protein synthesis required for building nerve connections. An estimated 40% of depressed patients do not respond to medication, the researchers pointed out. Many others only respond after many months or years trying different treatments.
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|Publication:||Western Mail (Cardiff, Wales)|
|Date:||Aug 20, 2010|
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