The first randomised controlled trial using GR activation to disturb retrieval (and facilitate extinction) showed a positive effect of cortisol treatment on reducing the re‐experience of PTSD‐like symptomatology and nightmares.170 A second study conducted in a larger cohort with patients receiving medication failed to replicate this outcome.171 Surís et al172 showed, in a double‐blind placebo‐controlled study, that glucocorticoid treatment after reactivation of memory reduced PTSD symptoms experienced 1 week later. This evidence concerns the gene NR3C1 and post-traumatic stress disorder.