While ketamine might be more well known for either its illicit use as a recreational drug (”Special K”) or as a general dissociative anaesthetic on animals and occasionally humans, researchers from the National Institute of Mental Health (NIMH) have recently conducted a study into its utility as a possible treatment for depression. And as the results just published in the medical journal Archives of General Psychiatry have shown, a low dose of ketamine administered to depression sufferers found symptom relief in a matter of hours.
Scientists from the NIMH conducted the study on 18 men and women who were suffering from depression and had previously undergone at least two unsuccessful treatments. In addition, none of them had any substance abuse problems and hadn’t used any drugs for at least a two-week period leading up to the start of the study.
The patients were first randomly administered, via a drip, either ketamine - 0.5mg per kg of body weight or 0.23mg per pound - or a placebo of saline solution. A week later the roles were reversed. The results were impressive:
- Within 110 minutes of being given ketamine, half the patients showed a 50% decrease in symptoms.
- One day after being injected with ketamine, 71 percent “responded with 50 percent or greater improvement on a standard scale used to measure depression and 29 percent met the criteria for remission”.
- For 35% of the patients, one dose lasted at least a week.
- Those who received the placebo experienced no changes.
Although researchers recognised that these results don’t necessarily apply to the whole spectrum of depression sufferers, they were encouraged that the relatively low dosage of ketamine managed to work in a matter of hours compared to an antidepressant like Prozac - a so-called “selective serotonin reuptake inhibitor” (SSRI) - which can take weeks or even months to be effective.
The reason for this, according to Dr. Carlos Zarate Jr., the chief of the mood disorders research unit at NIMH in Bethesda, Maryland, is that ketamine goes closer to the problem - by blocking a brain chemical receptor called the N-methyl-D-aspartate (NMDA) receptor - than the SSRI’s, which attend to serotonin levels further away. Or in plain English:
If you had a leaky faucet, we start in the kitchen at the source of the leak, [the NMDA receptor], while other antidepressants may begin at the water processing plant, [the serotonin and other brain chemicals believed to play a role in depression]. We can localize it to right where the leak is, so we don’t have to be satisfied anymore with not getting results for weeks to months.
So will doctors be prescribing ketamine anytime soon? Dr. Zarate Jr. cautioned that because of some safety concerns - high doses of ketamine can cause amnesia, delirium, depression, high blood pressure, respiratory problems and hallucinations - it should only be studied in a research setting. Going forward, the useful aspects of ketamine must be isolated with the perceptual or hallucinatory effects excluded; there were some patients in the study who reported side effects, including feeling woozy, euphoric or off-kilter perceptions.
In other words, there is a way to go.
