Ketamine, discovered in 1962 and mostly used as a horse tranquiliser and illicit recreational drug, has recently come under investigation as a potential treatment option for clinical depression in patients who had failed to benefit from other, more conventional, approaches.
While research into the effects of ketamine on depression is still in its infancy, preliminary trials have shown it to have a significant positive effect, which usually becomes evident several hours after injection, as opposed to weeks or even months in the case of medication and psychotherapy.
In the study, which is the first randomised control trial on the effects of ketamine in people over 60 years of age, 16 elderly volunteers with treatment-resistant depression were given increasing subcutaneous doses of ketamine over a period of five weeks, with the exact dosage personalised for each patient.
Contrary to the idea that increased mental well-being comes about as an acute, euphoric, short-term side effect of the drug, improvements in mood actually kick in hours later and peak about 20 hours after injection when patients are fully alert and back to their usual state of mind.
As many as 11 of the study participants reported an improvement in their condition while being treated with ketamine, and 43 percent said they had no significant symptoms of depression at the conclusion of the study six months later.
“This study highlights that ketamine can be given in a variety of ways (not just intravenous), that it’s a good idea to adjust the dose, and that the more resistant someone’s depression is, the higher the dose that they are likely to need,” said Rupert McShane, leader of the Oxford Ketamine Treatment Programme.
Despite the promising results, though, adopting ketamine as a standard intervention in clinical practice requires further study as people’s reactions to the drug are highly variable, necessitating more fine-grained data.
“There are ‘super-responders’, who after a single treatment can be well for several months,” said study leader Colleen Loo, a professor at the University of New South Wales in Australia. Most people, however, tend to relapse after three to seven days, which requires repeated dosages.
Future trials with larger sample sizes should help researchers formally assess the efficacy of ketamine on depression, as well as its potential impact on blood pressure, liver function and heart rate.