A new study in the American Journal of Psychiatry reveals that repeated doses of ketamine brings about "large-magnitude improvements in post-traumatic stress disorder (PTSD) symptoms" and is generally safe and well-tolerated by patients suffering from the condition. Participants in the study received a two-week course of treatment and experienced a significant reduction in symptoms that lasted, on average, for almost a month.
Notoriously difficult to treat, PTSD is characterized by intrusive symptoms such as flashbacks and nightmares, as well as depression, avoidance behaviors and negative mood. Among the most prescribed medications are anti-depressants like selective serotonin re-uptake inhibitors (SSRIs), although a large proportion of patients fail to respond to these treatments.
Unlike SSRIs, ketamine does not interfere with serotonin signaling, but instead interacts with a glutamate receptor called NMDA, and has been found to alleviate depression in treatment-resistant patients. A previous study also indicated that a single dose of the drug brings about rapid relief from PTSD symptoms, with this effect lasting for at least 24 hours.
To build on this prior finding, the study authors recruited 30 PTSD patients, several of whom had already tried conventional treatments without success. Study participants had been suffering from the condition for an average of 15 years, with primary traumas including sexual and physical abuse, military combat exposure and witnessing the 9/11 terror attacks.
Over a period of two weeks, patients were given six intravenous doses of either ketamine or a drug called midazolam, which produces certain psychoactive effects similar to those of ketamine, but which belongs to a class of drugs called benzodiazapines and is not considered to be therapeutic for PTSD. Symptom severity was clinically assessed at the start of the experiment and after both the first and second weeks.
A total of 67 percent of participants who received ketamine were found to respond to treatment, meaning their symptoms decreased by at least 30 percent. In contrast, the response rate among those who received midazolam was just 20 percent. By the end of the two weeks, the average PTSD score for participants in the ketamine group was 11.88 points lower than that of those in the midazolam group, with these improvements lasting for an average of 27.5 days.
Numerous participants reported experiencing a decrease in symptoms such as intrusions, avoidance behaviors and negative alterations in cognition and mood within 24 hours of their first ketamine dose, while depression was also rapidly alleviated in many patients. Given that SSRIs generally take weeks or even months before they start producing results, the speed at which ketamine appears to act is seen as one of its main advantages.
In a statement, study author Dennis Charney explained that “the data presented in our current study not only replicates, but also builds on our initial findings about ketamine for PTSD, indicating that in addition to being rapid, ketamine’s effect can be maintained over several weeks.”