Impact of stress response systems on forced choice recognition in an experimental trauma film paradigm

Abstract Introduction Traumatic events are often followed by memory impairments of key features of the trauma. Stress hormones are involved in emotional memory formation. However, little is known about their influence during trauma on subsequent recognition memory. Material and methods A pooled analysis of two double-blind, placebo-controlled studies (N = 175) was performed to assess the influence of the noradrenergic system and the hypothalamus-pituitaryadrenal (HPA) axis on intrusion formation. Participants received either 10 mg yohimbine (stimulating noradrenergic activity), 0.15 mg clonidine (inhibiting noradrenergic activity), or placebo (noradrenergic manipulation study) or 20 mg hydrocortisone or placebo (hydrocortisone manipulation study), each 60 min before watching a distressing film depicting severe sexual and physical violence. After seven days, the participants performed a 24-item forced choice recognition test. Memory was assessed for pre-, peri-, and post-trauma film scenes. Results A significant film scene by intervention interaction indicated a differential influence of drug intervention on the number of correct pre-, peri-, and post-trauma film scene memories one week after the distressing film. Post hoc tests revealed that clonidine led to significantly fewer correct peri-trauma film scene memories compared to placebo and, on a trend level, to yohimbine. Discussion Pharmacological inhibition of noradrenaline during a distressing film leads to impaired emotional recognition memory for the peri-trauma film scene.