| Summary: | Rationale/statement of the problem: Cortisol levels have been extensively studied in patients with posttraumatic stress disorder (PTSD), but their specific relationship to intrusive memory symptoms is unknown. Salivary alpha-amylase (sAA), an index of sympathetic activation, has never been studied in the context of PTSD. This study adopted the Trauma Film Paradigm to assess how changes in cortisol and sAA levels during memory encoding are related both to subsequent intrusive memories of the film and to individuals’ pre-existing characteristics. Methods: Saliva samples were collected in the afternoon (considering the circadian rhythm of cortisol and sAA) from 58 healthy adult participants at baseline, during the film, and post-film. Measurements of pre-existing PTSD symptoms, dissociation and anxiety traits as well as intrusions of the traumatic film over the week following film viewing were assessed. Results: Results showed that cortisol levels increased, whereas sAA levels decreased in response to the film. The vividness of intrusive memories was negatively correlated with cortisol levels during and after the film. Pre-existing PTSD symptom severity was negatively correlated with cortisol levels at the post-film stage and positively correlated with sAA in both during the film and post-film stages. Moreover, dissociative traits (especially dissociative amnesia) were negatively correlated with sAA levels at baseline and during the film, while anxiety traits were positively correlated with post-film sAA levels. Conclusions: This is the first study to investigate the relationship between cortisol, sAA, intrusive trauma memories and pre-existing psychological traits. The results supported the hypothesis that insufficient cortisol release in the immediate aftermath of trauma is a risk factor for the development of intrusive symptoms. The findings also shed light on how pre-existing characteristics affect physiological reactions to traumatic stimuli.
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