Does Cannabis Cause, Exacerbate or Ameliorate Psychiatric Disorders? An Oversimplified Debate Discussed

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• Many with PTSD report using cannabis to cope with anxiety, stress, and insomnia (Cougle et al, 2011; Boden et al, 2013). Consistent with a potential therapeutic effect, oral cannabinoids such as dronabinol (synthetic Δ9-tetrahydrocannabinol (THC), the primary psychoactive constituent of cannabis) and nabilone (a synthetic analog of THC), have been shown to reduce the acute response to fear stimuli as well as trauma-related symptomatology in those with PTSD. Nabilone reduced nightmares and improved sleep in both an open label and placebo-controlled trial, while also increasing clinician ratings of improvement and self-reported measures of well being (Fraser, 2009; Jetly et al, 2015). A retrospective study of nabilone for PTSD-related nightmares also showed promising results (Cameron et al, 2014).

• Cannabinoids modulate this threat response: in healthy volunteers, dronabinol attenuated amygdala reactivity to fear stimuli in a social-threat procedure without altering performance of complex tasks (Phan et al, 2008), suggesting cannabinoids selectively reduce threat responding. Similarly, cannabidiol (CBD), a non-intoxicating constituent of cannabis, attenuated the amygdala response to fearful faces (Fusar-Poli et al, 2009).

• A final point is that both oral and smoked cannabinoids can be anxiogenic, particularly for those who do not use cannabis regularly (eg, Haney, 2007). Although regular cannabis smokers often report smoking for relaxation and tension relief, anxiety, and panic following cannabis use are not uncommon and in fact drive the high rates of emergency room visits attributed to cannabis use (Moreira et al, 2009; Crippa et al, 2009; Hall and Solowij, 1998). This raises the possibility that oral or smoked cannabinoids would worsen anxiety in some PTSD patients. Clearly, FDA-approved treatments for PTSD (antidepressants, anticonvulsants, atypical antipsychotics, benzodiazepines) have the potential to worsen mood as well. If cannabinoid agonists are proven beneficial, the risk/benefit of each approach would have to be weighed with the understanding that increased anxiety is a possible outcome from cannabinoid use.