We further sought to determine whether gender, dose, cannabinoid content of cannabis used and/or cannabis use sessions across time would predict changes in symptom severity. Results revealed that, on average, respondents self-identifying as having PTSD reported a 62% reduction in the severity of intrusive thoughts, a 51% reduction in flashbacks, a 67% reduction in irritability, and a 57% reduction in the severity of anxiety, from before to after inhaling cannabis. Moreover, these symptom reductions were reported in the majority of cannabis use sessions for intrusive thoughts , flashbacks , irritability , and anxiety . While inhaled cannabis resulted in significant and substantial reductions in ratings of all four of the PTSD symptoms that we assessed, it is important to note that we detected significant heterogeneity in these effects across individuals, indicating that cannabis may not uniformly reduce PTSD symptoms for everyone. Concretely, while the four baseline LCS models confirmed that the reported symptom reductions were statistically significant, the variance estimates for all four models revealed significant individual differences in the rates of change among participants for each symptom. Taken together, these results provide strong evidence that cannabis can provide temporary relief from symptoms of PTSD, but that the magnitude of these effects varies across individuals. One source of this heterogeneity may have stemmed from differences in baseline ratings of the symptoms. The LCS models revealed significant covariance estimates between symptom severity before cannabis use and the latent change factor for each symptom, which indicates that those with more severe symptoms reported greater reductions in their symptoms after cannabis use. This may indicate that cannabis is more effective for more severe symptoms. Alternatively, this finding could also simply reflect the fact that there is more room for improvement of more severe symptoms. While the LCS models indicated that gender did not predict changes in symptom severity from before to after cannabis use ,cannabis drying racks comparisons of men and women’s mean severity ratings before and after cannabis use revealed small but statistically significant gender differences.
Specifically, women reported significantly greater symptom severity before cannabis use for all four PTSD symptoms we assessed. Women also reported significantly greater post-cannabis use severity for intrusions, flashbacks, and anxiety. This finding that women reported more severe symptoms of PTSD than did men is consistent with previous research indicating women are more likely to meet criteria for PTSD and to demonstrate worse symptom severity . The results further revealed that women reported significantly more cannabis use sessions during which flashback and anxiety severity were reduced than did men. In contrast, men reported significantly more sessions during which irritability was reduced than women. Nevertheless, while these differences were statistically significant, they were small in size and rather trivial . Both genders reported that their symptoms were reduced in the vast majority of cannabis use sessions. Concentrations of THC, CBD, and interactions between THC and CBD appeared to have no influence on changes in any of the four symptoms assessed. Cannabis can contain up to 120 cannabinoids, over 250 terpenes, around 50 flavonoids, as well as a number of other molecules that may exert biological action and therefore it may be one of these other constituents or an entourage effect that is responsible for the therapeutic effects of cannabis on these PTSD symptoms. Unfortunately, information on these other constituents was too sparse in the obtained data to permit for meaningful analyses. Clinical trials are needed where THC, CBD, minor phytocannabinoids and/or terpenes are directly manipulated by investigators to determine the concentrations of these constituents that provide the greatest relief from PTSD symptoms. Results pertaining to the time/cannabis use session predictor in the LCS models revealed no changes in the efficacy of cannabis in reducing anxiety or flashback severity across cannabis use sessions over time. In contrast, time was a significant predictor of reductions in intrusions and irritability, with later cannabis use sessions predicting greater symptom relief than earlier cannabis use sessions. These findings may indicate that cannabis becomes a more effective treatment for intrusions and irritability as it continues to be used to manage these symptoms over time.
Alternatively, this finding may represent a statistical artifact, such that individuals who obtain the greatest relief in intrusions and irritability from cannabis may simply be the most likely to use cannabis for longer periods of time. Further longitudinal studies are required to better establish the direction of this effect. Moreover, results of multilevel models further revealed that the dose of cannabis used increased significantly across time/cannabis use sessions for anxiety, which may be an indicator of tolerance. Collectively these two sets of results indicate that people are using consistent doses to achieve larger reductions in intrusions over time and higher doses to achieve larger reductions in anxiety over time. The escalations in dose for anxiety adds credence to concerns of individuals with PTSD developing cannabis dependence , especially given that excess cannabis use has been associated with more negative long-term outcomes in individuals with PTSD . Interestingly, the severity of baseline symptom ratings did not change significantly across time/cannabis use sessions. This may suggest that while acute use of cannabis leads to perceived reductions in acute symptom severity, these effects may not extend beyond the period of intoxication and regular use of cannabis may simply maintain the disorder over time. In other words, while cannabis intoxication can provide transient relief from PTSD symptoms, long-term cannabis use may not ultimately improve the severity of this disorder. These findings, however, contradict longitudinal data demonstrating long-term benefit of THC on PTSD symptoms and diagnosis over the course of one year as well as previous research demonstrating that cannabis/cannabinoids impair retrieval of emotionally aversive memories and promote the extinction of fear memories . Alternatively, it is possible that the present finding of consistent baseline symptoms over time simply reflects a tendency for people to self-medicate with cannabis once their symptoms reach a specific threshold.
More controlled longitudinal research is clearly needed to disentangle these complex bi-direction temporal associations.The present study has a number of limitations that should be noted. First, respondents self-identified as having PTSD and it was not possible to verify these diagnoses. As such, some of the individuals in the present sample may have been experiencing sub-clinical PTSD. Further, not all clinically recognized symptoms of PTSD were assessed.The evidence for individual differences in the efficacy of cannabis in reducing symptoms further supports this idea that not all individuals will find cannabis equally effective at reducing their symptoms. Finally, it was not possible for us to include a placebo control group. In the absence of this group, it is likely that some of the reported effects were driven by expectations about the therapeutic potential of cannabis for reducing symptoms of PTSD. Finally, because the app was created for industry, rather than research, purposes only a single item was used to assess each symptom and standard definitions of these symptoms were not provided for users. While single item indicators of constructs such as stress have been demonstrated to possess content, criterion, and construct validity , it is unclear whether this would generalize to indicators of intrusions, flashbacks, irritability, and anxiety. Further, users may have varied in what they considered an intrusion vs. a flashback. Thus, future research should attempt to replicate these findings with a larger sample of patients with clinician-verified diagnoses of PTSD, using a double-blind placebo controlled clinical trial, and standardized measures of the symptoms being assessed. These limitations are offset by numerous strengths of the study. First, this study utilized a large sample of over 400 medical cannabis users who tracked over 11,000 cannabis use sessions over a 31-month period of time. These medical users were able to use a large variety of cannabis products in their own natural environment, affording our study very high ecological validity. We also limited analyses to sessions during which lab-verified THC and CBD data were obtained in order to increase confidence in the THC and CBD concentrations. Thus, the present study has excellent ecological validity, and threats to internal validity are more likely to be implicit, in the form of expectancy effects.Cannabis is currently legal for adult use in 11 US states, the District of Columbia, Canada, and several other countries, and retailer licensing laws vary widely . California legalized cannabis for medicinal use in 1996 and for adult use in 2016 . The 2016 Control, Regulate, and Tax Adult Use of Marijuana Act allows the state, counties, and cities to regulate commercial medicinal and adult-use retail cannabis grow tray sales. effective January 1, 2018, cannabis retailers must obtain a state license from the California Bureau of Cannabis Control as well as local authorization .
State law grants cities and counties the right to allow, prohibit, or choose not to regulate cannabis businesses in their jurisdictions . Incorporated cities may have their own local ordinances for regulating commercial cannabis activities that are separate from county regulations. The BCC began accepting applications for retail licenses in December 2017. To obtain a license, retailers must document acceptable procedures for transportation, inventory, quality control, and security, provide the business formation and ownership documents, demonstrate compliance with environmental and labor laws, and prove that they own or lease a location that is not near schools or on Tribal land. Licensed retailers were allowed to open on January 1, 2018. Washington State established a similar retailer licensing process in 2012. Individual counties and cities implemented various temporary and permanent restrictions on retail cannabis sales, resulting in a patchwork of local ordinances throughout the state. Furthermore, numerous unlicensed retailers appeared during the two years following legalization of adult-use cannabis, but prior to the issuance of cannabis retail licenses . This sequence of events appears to be repeating in California. Numerous unlicensed cannabis retailers opened throughout the state following the law’s passage in November 2016 but before the licensing application process began in December 2017 . Even after licensing began, the number of applications quickly outpaced the BCC’s ability to review them, creating a backlog of pending applications. Enforcement efforts to close unlicensed retailers also lagged; local regulators stated whenever they closed an unlicensed retailer, several more appeared . Therefore, in 2018–2019, a combination of licensed and unlicensed retailers operated throughout California . This illustrates some of the challenges faced by state and local governments in regulating adult-use retail cannabis. The high prevalence of unlicensed cannabis retailers might thwart municipalities’ efforts to prevent youth access to cannabis and cannabis-related health emergencies such as acute psychosis . A comparison of 37 licensed and 92 unlicensed cannabis retailers in Los Angeles County found that unlicensed dispensaries were more likely to sell high potency cannabis products, allow onsite consumption, sell products designed to be attractive to children, and sell products without child-resistant packaging. As of 2019, only 108 of California’s 485 municipalities allow any type of cannabis business to operate in their jurisdictions, and 18 of the 58 counties permit cannabis businesses in their unincorporated areas ; these numbers have fluctuated throughout 2018 and 2019 as municipalities without regulations began to pass new ordinances . The licensing process has been slower than expected because of the high cost of establishing a cannabis business, as well as public safety concerns associated with cannabis operations in a community. Meanwhile, unlicensed retailers have proliferated . Studies in several states have found that both licensed and unlicensed cannabis retailers tend to locate in areas with more racial and ethnic minority residents, more poverty, and more alcohol outlets . This is similar to alcohol and tobacco retailers, which are more concentrated in areas with more racial and ethnic minorities, more low-income households, and lower social capital . A high concentration of unlicensed retailers in disadvantaged communities could exacerbate health disparities in chronic respiratory diseases, acute respiratory distress from contaminated THC, motor vehicle accidents, and unintentional overdoses of mislabeled products . Research is needed to understand the disparities created by locations of unlicensed vs. licensed cannabis retailers.