Clinical research from New Mexico suggests smoking cannabis can reduce post-traumatic stress disorder (PTSD) symptoms in some patients. The study is published in the special issue of Journal of Psychoactive Drugs. New Mexico was the first state to list PTSD as a condition for the use of medical marijuana. At that time there were no published studies of the effects of cannabis on symptoms of PTSD, only case reports.
The study was completed in order to statistically analyze psychometric data on PTSD symptoms and report its findings. To perform the study, data was collected from 80 psychiatric evaluations of patients which were applying to the New Mexico Medical Cannabis Program over a two-year period. At the end of the study the research team concluded that in some patients cannabis is associated with reductions in PTSD symptoms. In order to determine the efficacy of cannabis and its constituents in treating PTSD a prospective, placebo-controlled study would be needed.
The research took place from 2009 through 2011 and included pre-screened patients who completed telephone interviews. In order to qualify for the study participants must have first had the experience of an emotional response to a trauma that met the DSM-IV Criterion A for PTSD, significant relief of several major PTSD symptoms when using medical marijuana, the presence of several of the major symptoms in reoccurring avoidance and hyperarousal of PTSD when not using cannabis and the lack of any problems or harm in functioning resulting from marijuana use.
According to one of the researchers Dr. George Greer,
Many PTSD patients report symptom reduction with cannabis, and a clinical trial needs to be done to see what proportion and what kind of PTSD patients benefit, with either cannabis or the main active ingredients of cannabis.
Participants were measured using CAPS method. CAPS is an instrument in PTSD research that asks questions about the presence of traumatic experiences and the immediate emotional response to them, then establishes a rating of the frequency and intensity of symptoms on a scale of 0 to 4. Totals were then calculated.
Patients in this sample reported over 75 percent reduction in all three areas of PTSD symptoms while using cannabis. Because this was a highly select group of pre-screened patients who had already found that cannabis reduced their PTSD symptoms and who sought entry to the NM Medical Cannabis Program to avoid criminal penalties for cannabis possession, reports of significant symptom reduction could be expected. Some degree of intentional or unintentional exaggeration of symptom differences on the part of the patients is likely, and some unintentional bias on the part of the psychiatrist conducting the evaluations is also possible.
Another factor is that some patients may have reported their non-cannabis PTSD symptoms when they were also experiencing a cannabis-withdrawal syndrome. Nightmares, anger, and insomnia have been reported as common symptoms of cannabis withdrawal. Those three symptoms are among the 17 symptoms of PTSD, and so could have resulted in higher non-cannabis CAPS scores for those symptoms. However, no information was collected on the length of the time periods without cannabis use; therefore, there is no valid way to quantify the degree to which cannabis-withdrawal symptoms may have increased the CAPS scores for those three PTSD symptoms. However, even with the confounding variables, the amount of reported symptom relief is noteworthy.
Finally, the variability in scores with cannabis use was relatively high, with the standard deviation being almost equal to the mean total scores and the scores of the three symptom clusters. If patients had consistently reported frequent and severe symptoms without cannabis and almost no symptoms with cannabis in order to make sure they qualified for the Program, one would expect less variability in the cannabis scores.
Because only patients who reported benefit from cannabis in reducing their PTSD were studied, no conclusions can be drawn as to what proportion or type of PTSD patients would benefit from treatment with cannabis or its constituents. The reported anxiety relieving properties of cannabidiol may partly explain the reported benefit, though the cannabis in the Israeli study reportedly contained almost no cannabidiol. That small, open-label prospective study comes closer to showing a benefit, at least for people with combat-related PTSD. It has also been reported that the synthetic cannabinoid nabilone can reduce the incidence and severity of nightmares in PTSD patients.
The finding that use of cannabis can reduce symptoms of PTSD is consistent with preclinical evidence showing that the endocannabinoid system is involved in the regulation of emotional memory. There is extensive evidence that cannabinoids may facilitate extinction of aversive memories. Given the role that the endocannabinoid system plays in fear extinction, it is possible that the marked reduction in PTSD symptomatology reported with cannabis use in the present study was due to facilitated extinction of fear memories. Additional studies are necessary to identify the specific mechanism by which cannabis use attenuates the symptoms of PTSD.
Though currently there is no substantial proof of the efficacy of cannabis in PTSD treatment, the study results support the conclusion that cannabis is associated with PTSD symptom reduction in some patients, and that a prospective, placebo-controlled study of cannabis or its constituents for treatment of PTSD is warranted.
By: Cherese Jackson (Virginia Beach)