Ketamine Observed to Prevent PTSD

Ketamine may be able to prevent post-traumatic stress disorder (PTSD) symptoms in soldiers and individuals at high risk for psychological trauma, according to a new study published by Neuropsychopharmacology.

The investigators found that a single, small dose of ketamine administered 1 week prior to a stressful event was able to reduce the fear response in mice. These findings suggest that the drug, commonly used as an anesthetic or antidepressant, may also prevent PTSD in humans.

"Ketamine is a powerful drug, and we wouldn't advocate widespread use for preventing or reducing PTSD symptoms,” said study leader Christine A. Denny, PhD. “But if our results in mice translate to humans, giving a single dose of ketamine in a vaccine-like fashion could have great benefit for people who are highly likely to experience significant stressors, such as members of the military or aid workers going into conflict zones.”

There are relatively few effective treatments for PTSD, despite the fact that one-quarter of individuals facing psychological trauma develop the disorder, according to the study.

Patients with PTSD experience repeated flashbacks, hyperarousal, and hyperactivity. They may also experience mood changes, psychological numbing, and physical symptoms. PTSD symptoms depend on the trauma experience and the response to the event.

In human and animal trials, the findings have shown that ketamine can reduce stress-related symptoms. However, these previous studies were not able to determine when the drug should be administered to elicit its protective effects.

In the new study, mice were administered a small dose of intravenous ketamine or placebo at an interval of 1 month, 1 week, or 1 hour before a series of small shocks. The mice were conditioned to associate the environment with shocks, and were returned to the same environment.

The investigators assessed the mice for their freezing behavior, which is associated with fear response.

Only the mice administered ketamine 1 week before the event were observed to have reduced freezing upon return to the fear response, according to the study.

"Our findings indicate that the timing of ketamine administration is critical for buffering fear expression," said first author Josephine C. McGowan, doctoral student.

Their findings do not suggest whether there is a more immediate window than 1 week where the drug would have a protective effect.

Additionally, the authors found that administering ketamine 1 hour after the event would not decrease fear expression. This suggests that there may be another window after the initial trauma when ketamine may be effective, according to the study.

The researchers are currently examining how ketamine impacts the brain to influence its stress response. They hope that further research will lead to prophylactic ketamine use among individuals who face a high likelihood of experiencing trauma, the study concluded.