Marijuana may be effective in preventing post-traumatic stress symptoms, according to new research on rats conducted at Haifa University's Department of Psychology.

“The findings of our study suggest that the connectivity within the brain’s fear circuit changes following trauma, and the administration of cannabinoids (synthetic marijuana) prevents this change from happening," the researchers said in a press release.

The study was conducted by Nachshon Korem and Irit Akirav and published in the journal Neuropsychopharmacology.

"This study can lead to future trials in humans regarding possible ways to prevent the development of PTSD and anxiety disorders in response to a traumatic event,” the researchers concluded.

Approximately nine percent of the population of Israel suffers from post-traumatic stress disorder (PTSD,) with the percentage increasing among at-risk groups, such as combat soldiers, according to the Israel Medical Association

A common phenomenon among those who suffer from trauma is that exposure to a “trauma reminder” — an event that is not traumatic in itself but that evokes the memory of the experience of the traumatic event — can further heighten the negative effects of the trauma. For example, for a person who has developed post-traumatic syndromes as a result of “Color Red” sirens (air raid sirens), a trauma reminder can occur following a loud car alarm.

The study found that rats injected with synthetic marijuana after experiencing both a trauma and trauma reminders showed no PTSD symptoms, such as increased startle response, changes in sensitivity to pain and impaired learning, compared to those not injected with the drug.

In fact, for some of the symptoms, the rats injected with the drug showed similar behavior to rats exposed to trauma but not exposed to trauma reminders. In other words, cannabis made the effects of trauma reminders “disappear”.

According to the study, trauma and trauma reminders are expressed in two receptors in the brain associated with emotional processing. That expression was prevented in the rats that received the drug in two areas of the brain that are involved in forming and saving traumatic memories, the hippocampus and prefrontal cortex.

“The importance of this study is that it contributes to the understanding of the brain basis of the positive effect cannabis has on PTSD and thus supports the necessity to perform human trials to examine potential ways to prevent the development of PTSD and anxiety disorders in response to a traumatic event,” the researchers noted.

