Interaction of noradrenaline and cortisol predicts negative intrusive memories in posttraumatic stress disorder

Recent evidence suggests that an interaction of noradrenaline (NE) and cortisol (CORT) during encoding leads to greater consolidation of emotional memories. Convergent models of posttraumatic stress disorder (PTSD) suggest the release of CORT and NE lead to greater intrusive memories in PTSD. This study examined the effect of NE and CORT during encoding on recall and intrusive memories in PTSD. Fifty-eight participants (18 participants with PTSD, 20 trauma-exposed controls, and 20 non-trauma exposed controls) provided saliva samples of NE (indexed by salivary alpha amylase; sAA) and CORT at (a) baseline and (b) after viewing negative emotional stimuli. Delayed memory recall and number of intrusive memories of negative, neutral and positive stimuli were recorded two days after this initial testing session. The PTSD group had greater NE levels to negative stimuli and reported greater numbers of intrusive memories of negative stimuli than controls. Regression analyses revealed that the interaction of CORT and NE significantly predicted negative intrusive memories in the PTSD group. The trauma-exposed group reported significantly greater recall of negative images compared to controls, but did not differ significantly from the PTSD group. The PTSD group reported greater levels of suppression of negative images during encoding compared to the other groups. Our results confirm that the interaction of NE and CORT significantly predicts greater negative intrusive memories, but this occurs specifically in the PTSD group. This suggests that a level of heightened arousal is required for the relationship between stress hormones and emotional memory to manifest in PTSD.