1. INTRODUCTION

Cannabis is the most widely used illicit substance in the United States (SAMHSA, 2012) and the legalization of cannabis for medicinal purposes has become a growing trend. The approved conditions for which cannabis may be doctor-recommended varies at the state level, but most states allow medical use of cannabis for certain medical disorders/problems (e.g., cancer, severe and chronic pain, HIV/AIDS). The use of medical cannabis for psychological disorders, however, is not as common. Currently, only 5 of 20 states with medical cannabis laws explicitly allow the medical use of cannabis as a treatment for those with posttraumatic stress disorder (PTSD).

Though there has been a general dearth of empirical research speaking to the use and effects of cannabis among those with PTSD, existing evidence suggests that individuals with PTSD, particularly those with heightened hyperarousal symptoms, use cannabis primarily for coping reasons (e.g., Boden et al., 2013; Bonn-Miller et al., 2007a; Passie et al., 2012), and that such coping-oriented use may be associated with heavier and more problematic cannabis use patterns (e.g., dependence), as documented in the general population (Bonn-Miller and Zvolensky, 2009). Following, there has been increasing interest in understanding, among those with PTSD, the specific motives for which cannabis is used. In a study among 20 adult females with PTSD, Bonn-Miller and colleagues (2010) found poor sleep quality to interact with PTSD symptom severity in the prediction of coping-oriented cannabis use. Here, individuals with elevated PTSD symptoms and sleep problems were particularly likely to use cannabis to cope.

Though Bonn-Miller and colleagues (2010) documented the importance of sleep problems in terms of understanding the association between PTSD and coping-oriented cannabis use, little research has been conducted to examine whether specific symptoms of PTSD are being “treated” with cannabis use, and, in particular, whether individuals with PTSD use cannabis specifically to improve sleep, or instead to cope with negative affect more broadly. Here, recent work has demonstrated that specific psychoactive components of cannabis may initially facilitate sleep onset (Russo et al., 2007; Schierenbeck et al., 2008), though long-term and problematic use has been associated with sleep disturbances, including altered sleep architecture (Bolla et al., 2008; Vandrey et al., 2011). Additionally, there has yet to be an investigation of how specific coping motivations are associated with use frequency within this context.

The present study sought to examine (1) the specific cannabis motives that distinguish a medicinal cannabis-using individual with PTSD from an individual without PTSD, and (2) whether the interaction of PTSD and PTSD-specific use motives are associated with more severe use frequency. We hypothesized that medical cannabis users with PTSD would be more likely to report cannabis use specifically to improve sleep, compared to those without PTSD. Further, due to the development of tolerance to the sleep-inducing effects of cannabis (Schierenbeck et al., 2008), as well as prior documented associations between coping-oriented use and heavy cannabis use patterns (Bonn-Miller and Zvolensky, 2009), we hypothesized that those with PTSD who also used for sleep motives would evidence greater cannabis use frequency. As research has demonstrated that depression and alcohol use are both associated with PTSD (McFarlane, 1998; Shalev et al., 1998) and cannabis use (Bovasso, 2001; Griffin et al., 2002), depressive symptoms and alcohol use were included as covariates.

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