Marijuana has been shown to be an effective treatment to prevent post-traumatic stress disorder (PTSD) in rats, according to a recently published study in the journal Neuropsychopharmacology. Roughly 2.5 million combat veterans have returned to the United States from Iraq and Afghanistan, many of them coping with the often crippling symptoms of severe PTSD.

The study, performed by Nachshon Korem and Irit Akirav of the University of Haifa’s Department of Psychology in Israel, examined the interactions between cannabis and trauma reminders. A trauma reminder is a stimulus that would not be stressful out of context, say a picture of a helicopter, but which reminds a PTSD sufferer of a traumatic event, for instance an event related to war, which can cause intense stress. The study found that rats who were given an electric shock, then injected with synthetic marijuana, showed significantly reduced symptoms of PTSD compared to rats not treated with cannabinoids. Specifically, when exposed to a trauma reminder, these rats did not have typical symptoms, such as an increased startle response, altered pain sensitivity and neurological issues related to learning and the brain’s reward response. Cannabinoids also did markedly better than the pharmaceutical drug sertraline in the same study. Sertraline is in the SSRI family along with many common antidepressants such as Prozac.

It is difficult to come up with a good estimate for the number of people with PTSD—symptoms are often invisible, and can even difficult to identify even for the sufferer. According to the US Department of Veterans' Affairs, an estimated 7.8 percent of Americans will experience PTSD at some point in their lives. The study lends scientific backing to the claims of many veterans who have long advocated for marijuana as a way to manage PTSD. The Iraq War is finally over, and the war in Afghanistan is reportedly coming to a close this year. Approximately 2.5 million veterans from these wars are now living in the U.S. Due to the obstinate stance of the federal government that cannabis is a criminal drug, many of those veterans will be denied an effective medicine with negligible side effects.

With 23 states having a medical marijuana law on the books, and a handful more allowing for high CBD/low THC pot for a short list of conditions, most of the U.S. has now acknowledged the healing power of cannabis. By maintaining its Schedule I status, and even mandating an additional review process for research that only applies to marijuana, the federal government remains stodgily behind the times.

The study by Korem and Akirav shows a pressing need, both for additional research on cannabis and a loosening of the restrictions that have kept it out of the hands of patients who stand to benefit from its use. It is past time for the U.S. to undo the holds on the study and use of marijuana.