A review has shown that ketamine therapy is able to rapidly reduce symptoms of depression and suicidal thoughts in the short-term.
Led by the University of Exeter and funded by the Medical Research Council, the systematic review analysed evidence from 83 published research papers on ketamine therapy.
It showed that the strongest evidence emerged around the use of ketamine to treat both major depression and bipolar depression, with symptoms reducing as quickly as one to four hours after a single treatment, and lasting up to two weeks.
Single or multiple doses of ketamine resulted in moderate to large reductions in suicidal thoughts. This improvement was seen as early as four hours following ketamine treatment and lasted on average three days, and up to a week.
Additionally, some evidence suggested that repeated treatment may prolong the effects, however, the researchers involved say more high-quality research is needed to determine by how long.
The review, which included 33 systematic reviews, 29 randomised control trials and 21 observational studies, has been published in the British Journal of Psychiatry Open.
Lead author Merve Mollaahmetoglu, of the University of Exeter, said: “Our research is the most comprehensive review of the growing body of evidence on the therapeutic effects of ketamine to date.
“Our findings suggest that ketamine may be useful in providing rapid relief from depression and suicidal thoughts, creating a window of opportunity for further therapeutic interventions to be effective.
“It’s important to note that this review examined ketamine administration in carefully controlled clinical settings where any risks of ketamine can be safely managed.”
For other psychiatric disorders, including anxiety disorders, post-traumatic stress disorders (PTSD) and obsessive-compulsive disorders, the review noted that there is early evidence to suggest the potential benefit of ketamine treatment, and that for individuals with substance use disorders, ketamine treatment led to short-term reductions in craving, consumption and withdrawal symptoms.
Senior author professor Celia Morgan, of the University of Exeter, said: “We’re finding that ketamine may have promising benefits for conditions that are notoriously hard to treat in clinic.
“We now need bigger and better-designed trials to test these benefits.
“For example, due to ketamine’s unique subjective effects participants may be able to tell whether they have been given ketamine or a saline solution as the placebo, potentially creating an expectation about the effects of the drug.
“This effect may be better controlled by having active placebo-controlled trials, where the control group receives another drug with psychoactive properties.”
Ketamine’s therapeutic effects for psychiatric conditions other than depression and suicidal thoughts are based on small number of studies that did not randomise people into different treatment arms. The authors highlight that these effects require replication in larger randomised placebo-controlled trials, which are considered as gold standard.
A number of questions remain unanswered so far, including the optimal dose, route of administration and number of doses of ketamine treatment.
The authors highlight that there is also a need for further research on the added and interactive benefit of psychotherapy alongside ketamine treatment.
Additionally, the importance of ketamine’s acute subjective effects in its therapeutic benefits has not been fully explored, and more research is also needed on how to optimise participants’ preparation for ketamine treatment and the setting in which ketamine treatment is delivered.
The research involved collaboration with the University of British Columbia, and received support from the Society for the Study of Addiction.
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