Post-traumatic stress disorder (PTSD) is characterized by substantial psychological or physiological distress following exposure to trauma.¹ According to the most recent Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), criteria for PTSD diagnosis includes either direct, or indirect (e.g., as a witness, or having learned that a close family member or friend has experienced a traumatic event), exposure to situations of actual or threatened death, violence, sexual assault, or serious injury. Individuals with PTSD have at least one intrusion symptom defined as recurrent, involuntary nightmares, flashbacks, and/or psychological or physiological distress at reminders of the trauma, lasting for greater than one month.^1,2 These intrusive and distressing symptoms have a significant effect on a person’s quality of life, often leading to persistent avoidance of stimuli associated with the trauma, negative alterations in cognition, detachment from others, distorted blame, irritability, aggressive or reckless behavior, and sleep disturbances.¹ Approximately 75% of individuals with PTSD have comorbid psychiatric disorders such as major depressive disorder, substance abuse disorder, and/or alcohol dependence.³ Suicidality increases in the PTSD population approximately 2 to 3-fold and odds of lifetime suicide attempts increase with the presence of comorbid conditions.⁴ Economically, PTSD is associated with more frequent and longer hospitalizations, in addition to a greater utilization of mental health services.⁵ Lifetime prevalence of PTSD in Canada was estimated at 9.2%, with one-month prevalence rates being more than double in women (3.4%) versus men (1.3%), according to a national survey conducted in 2002.³ Approximately, 76% of Canadians in the survey reported exposure to at least one significantly traumatic event in their lifetime most commonly reported as the sudden death of a loved one, sexual assault, and seeing someone badly injured or killed.³ The majority (68.5%) of individuals reported symptoms of PTSD lasting for more than a year.³Treatment for PTSD is generally centered on education and psychological therapies (with or without pharmacological intervention) mainly cognitive behavioral therapy (CBT) protocols, such as trauma-focus CBT (TF-CBT), or eye movement desensitization and reprocessing (EMDR) therapeutic techniques.^1,6 According to the Anxiety Disorders Association of Canada/Association Canadienne des troubles anxieux Canadian clinical practice guidelines, first line pharmacological intervention calls for the use of antidepressants classified as selective serotonin re-uptake inhibitors (SSRIs) (e.g., fluoxetine, paroxetine) or serotonin and norepinephrine re-uptake inhibitors (SNRIs) (e.g., venlafaxine, duloxetine).¹ Second line and third line agents include additional antidepressants demonstrating less clinical efficacy (e.g., fluvoxamine, mirtazapine), with third line agents including anticonvulsant (e.g., topiramate, lamotrigine) and atypical antipsychotic drugs (e.g., risperidone, aripiprazole).¹ Currently, synthetic cannabinoids are not listed within the Canadian guidelines for treatment of PTSD. Nabilone is a synthetic cannabinoid that activates Cannabinoid receptor type 1 (CB1) cell receptors (abundantly expressed in the central nervous system), and has previously been approved for the treatment of nausea and vomiting induced by chemotherapy treatments in Canada for over 30 years.^7–9 The first open label study of nabilone, demonstrated positive outcomes in the treatment of PTSD related symptoms.⁷ The majority of study participants (72%) reported total cessations or lessening of severity of recurrent nightmares, a hallmark symptom of PTSD.⁷ Additionally, some study participants noted reduction in PTSD-related flashbacks, and improved sleep time with mild to moderate side effects.⁷ The current Rapid Response Report is an update to a previous CADTH Rapid Response Report¹⁰ and will seek to identify and synthesize the evidence around the clinical effectiveness, and evidence-based guidelines for nabilone treatment for PTSD.

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