Some studies suggest that stress-induced effects of cortisol on memory are modulated by the valence of the stimuli to be learned and retrieved. The present study investigated the effect of acute stress-induced cortisol secretion on acquisition and retrieval of pleasant, unpleasant and neutral words. Sixty healthy men were randomly assigned to one of the three experimental groups. Participants were either exposed to a standardized laboratory stressor (the Trier Social Stress Test) before learning a wordlist, or before retrieval, or were not stressed. Free recall and recognition were tested 24 h later. Free recall was not affected by stress exposure. For recognition, there was no main effect of the stressor, but a main effect of valence and a valence by group interaction emerged: recognition for positive words was significantly impaired when subjects were stressed before retrieval. In addition, a positive correlation between the cortisol response and errors of commission was found. The results suggest that acute stress impairs memory for positive stimuli and that stress-induced cortisol secretion interferes with accuracy of memory retrieval, i.e. the ability to discriminate true memories from false ones.

No abstract

The data provide first evidence for a modulating effect of a single-dose ketamine on the severity and duration of posttraumatic stress symptoms in accident victims.

The glutamatergic N-methyl-D-aspartate receptor antagonist ketamine produces transient dissociative states and alters cognitive functioning in healthy humans, thus resembling the core symptoms of acute and chronic post-traumatic stress disorder (PTSD). First evidence exists that the common use of the analgesic and sedative properties of ketamine during emergency care correlates with sustained symptoms of PTSD in accident victims. The aim of the present study was to examine whether ketamine administration after moderate accidental trauma modulates dissociation and other symptoms of acute stress disorder (ASD) in the direct aftermath of the event. Accident victims were screened within the third day after admission to hospital for symptoms of ASD (Peritraumatic Dissociative Experiences Questionnaire, ASD Scale) and prior stressful life events (Traumatic Life Events Questionnaire). Subjects had received a single or fractionated dose of either racemic ketamine (n=13), opioids (n=24) or non-opioid analgesics (n=13) during initial emergency treatment. There were no significant differences between medication groups in demographic and clinical characteristics such as injury severity or prior traumatization. With respect to ASD symptomatology three days post-event there were significant associations between ketamine analgosedation and increased symptoms of dissociation, reexperiencing, hyperarousal and avoidance relative to the comparison groups.Growing evidence exists that ketamine might modulate or aggravate early post-traumatic stress reactions when given in the acute trauma phase, which in turn might contribute to long-lasting symptomatology.

The present study investigated the effect of a single oral dose of hydrocortisone (cortisol) on retrieval of verbal and nonverbal declarative memory. Fifty-nine healthy participants were randomly assigned to either receive 25 mg cortisol or a placebo 45 min before retrieval in a standardized memory test procedure. There was no global effect of cortisol on either verbal or nonverbal memory. However, a specific negative effect on free recall of associative verbal material appeared. In addition, high responders (salivary cortisol concentration>68.25 nmol/L) exhibited impaired verbal memory compared with low responders (<68.25 nmol/L). The results suggest specific nonlinear effects of cortisol on declarative memory retrieval, which appear to be more pronounced for verbal material.