The Future of Treating PTSD with Cannabis


Culturally, the U.S. has informally associated cannabis use and Post-Traumatic Stress Disorder (PTSD) for decades. In fact, a shell-shocked war veteran relieving anxiety through cannabis use is somewhat of a cultural touchstone. This stereotype poses an interesting question: why? What is it about cannabis that lends itself as a natural medicine for PTSD? As has been the case with other areas of cannabis research, the cart has arrived before the horse: we are faced with a mountain of empirical evidence in the form of tens of thousands of individuals relying on cannabis for symptom relief, and yet only finally beginning to crack the science behind it.

PTSD is characterized by 3 major groups of symptoms:

  • persistent re-experience of the traumatic event
  • persistent increased psychological arousal (being overly “awake” or sensitive to stimuli)
  • persistent avoidance of stimuli associated with the traumatic incident.

To describe in layman’s terms, what has happened is that the memory and anxiety systems of the brain have been knocked out of normal functioning via a particularly traumatic event in the patient’s life. The memory of that event has been consolidated very deeply into the brain, and as an adaptive mechanism, the brain now accesses that memory over and over again, forcing the individual to relive the trauma on a frequent basis and preventing the memory from being dampened or extinguished healthily. While remembering trauma can keep us from injuring ourselves the same way twice, this is a case where the brain has become over-vigilant and is doing more damage than good. Currently, the mainstream medical approach to treating PTSD revolves around drugs that attack the agitation or depression that accompanies it, via anti-convulsive and/or anti-depressant medicines. However, the ideal drug would go even further: it would be capable of treating the sources of those symptoms as well.

Biologically speaking, it’s entirely conceivable that cannabis use is doing exactly that. The endocannabinoid system (which consists of endocannabinoids (eCBs), their receptors, and their regulators) is located all throughout the brain in both emotional and cognitive regions. While the specific functions are unclear, it’s clear that the system plays a large role in emotional behavior, which includes, of course, emotionally charged memories. Opponents may allege that a psychoactive substance such as THC is not appropriate for all environments or times, but treatment could include re-uptake inhibitor drugs (drugs that allow the body to use its natural eCBs longer and therefore have no abuse potential) or high-CBD strains. Rodent tests do confirm that administration of cannabinoid drugs influence memory. Specifically, they impair memory retrieval while facilitating memory extinction (lost house keys, anyone?). The way they affect the formation of memories themselves is still debatable.

This bodes well on a biochemical side, but what about in rigorous human testing? Unfortunately, little knowledge is available at this point in time. Aside from a host of conflating variables in individuals with PTSD, as well as all the different variations of PTSD (which vary in intensity and frequency of symptoms), a definitive clinical study has not been evaluated. However, we do have case reports of patients evaluated for cannabis use. Since New Mexico was the first state to list PTSD as a viable condition for cannabis use, one of the most interesting studies has revolved around one clinic’s accumulation of 80 patients in the state, who were all given the green light to use cannabis for PTSD (Greer, Grob, & Halberstadt 2014).  In this case, the doctor used the CAPS system (a system developed by the National Center for PTSD), to retrospectively quantify patients’ symptoms with and without cannabis use. The CAPS system breaks down the three major symptoms of PTSD (re-experience, avoidance, and arousal) which are comprised of 17 unique symptoms.  Patients rated their symptoms in each of the 17 on a scale of 1-4 for symptoms both during cannabis use and during periods without cannabis use. Afterwards, these CAPS scores were collected and statistical analysis was performed to confirm a statistically significant correlation between cannabis use and symptoms. This was compared to baseline scores for PTSD patients that were not treated with cannabis.

As it turned out, patients in the sample reported over 75% reduction in all three major areas of PTSD symptoms (Criteria B, C, & D) during cannabis use, as seen in the following figure:














With this response, it seems likely that the eCB system will play a role in future PTSD treatment. However, some serious caveats or considerations need to be observed along with this data. For starters, everyone participating in the study was actively seeking out cannabis for medication for PTSD. In other words, they had already decided for themselves that cannabis ameliorated their conditions. This introduces obvious bias in answering self-reported questions, but it also means that we can’t draw conclusions about the average population of PTSD patients. What if cannabis is effective in treating one form of PTSD and not another? What if these patients represent the group it reliably helps? Furthermore, as the doctor himself noted, there was no consistent standard for what constituted the period of “no cannabis use”. It is possible that some patients were experiencing cannabis withdrawal (which is the reverse process of tolerance to increased eCBs). Cannabis withdrawal symptoms mimic some symptoms of PTSD (trouble sleeping, nightmares, agitation, etc), which means that it is likely at least some of the difference in symptoms was exaggerated. Finally, an 80-patient group is considered an incredibly small population size in most areas of medicine.

With that said, the author noted that the statistical distribution of answers provided compelling evidence that the patients were not systematically attempting to exaggerate symptoms. Additionally, despite the small sample size, this data fits hand in hand with the experiences of hundreds of thousands of patients that form the basis of the cultural relationship between cannabis and PTSD mentioned earlier. While some large questions remain, such as investigating how cannabis use during different periods of PTSD affects symptoms (from immediately before or after trauma to decades later), the larger message is clear; there is a biochemical and patient-level basis for believing that the eCB system will hold some of the answers to treating PTSD patients and perhaps eventually, curing them.




George R. Greer M.D., Charles S. Grob M.D. & Adam L. Halberstadt Ph.D. (2014) PTSD Symptom Reports of Patients Evaluated for the New Mexico Medical Cannabis Program, Journal of Psychoactive Drugs, 46:1, 73-77, DOI: 10.1080/02791072.2013.873843

Viviana Trezza and Patrizia Campolongo. (2013)The endocannabinoid system as a possible target to treat both the cognitive and emotional features of post-traumatic stress disorder, Frontiers in Behavioral Neuroscience, 7:100, DOI: 10.3389/fnbeh.2013.00100