This study will compare the effects of smoked cannabis and nabilone on attentional bias toward trauma- related stimuli, subjective and emotional processing to a range of trauma-and non-trauma-related images and physiological reactivity to these stimuli in individuals with CUD and PTSD. Importantly, this study will also probe the abuse related potential of nabilone compared to smoked cannabis in this population, a critical aspect in determining the potential feasibility for its use clinically to treat CUD in PTSD populations. The effects of nabilone will be compared to propranolol as a positive control.