OPRM1 and post-traumatic stress disorder: Interestingly, opiates, generally MOR agonists, use is particularly important in comorbid PTSD and SUD (Danovitch, 2016; Elman and Borsook, 2019), this may result from the fact that avoidance symptoms (Phifer et al., 2011), numbing of emotions (Dworkin et al., 2018), and hyperarousal symptoms are strongly associated with opiates use and misuse (Dworkin et al., 2018; Takemoto et al., 2020).