Daniela Schoofs

Psychosocial stress induces working memory impairments in an n-back paradigm

In contrast to the substantial number of studies investigating the effects of stress on declarative memory, effects of stress on working memory have received less attention. We compared working memory (numerical n-back task with single digits) in 40 men exposed either to psychosocial stress (Trier Social Stress Test (TSST)) or a control condition. Task difficulty was varied using two conditions (2-back vs. 3-back). Salivary cortisol (as a marker of hypothalamus-pituitary-adrenal (HPA) activity) and salivary alpha-amylase (sAA as a marker of sympathetic nervous system (SNS) activity) were assessed immediately before and three times after the stress or control condition. As expected stress resulted in an increase in cortisol, sAA, and negative affect. Subjects exposed to stress showed significant working memory impairments in both workload conditions. The analysis of variance indicated a main effect of stress for reaction time as well as accuracy. In addition, for reaction time a stress-block interaction occurred. Follow up tests revealed that only during the first block at each level of difficulty performance was significantly impaired by stress. Thus, the effects of stress became smaller the longer the task was performed. Results provide further evidence for impaired working memory after acute stress and illustrate the time course of this phenomenon.

Cold pressor stress impairs performance on working memory tasks requiring executive functions in healthy young men.

The current study investigated the effects of cold pressor stress (CPS) on 2 working memory (WM) tasks differing in the demand they put on maintenance and executive processing. For this purpose 72 healthy young men were exposed either to a stress group or a nonstressful control group. Subsequently, WM performance on the O-Span task (Turner & Engle, 1989) and the digit span task was assessed. Salivary cortisol was measured before and 2 times after the treatment as a marker of hypothalamus-pituitary-adrenal (HPA) axis activity. Results revealed a significant performance impairment of the O-Span and the digit span task backward in stressed subjects that correlated negatively with CPS-induced cortisol increases. Digit span forward was neither affected by CPS nor related to the ensuing cortisol increases. These results indicate that acute stress impairs WM performance for tasks requiring executive functions that operate on the stored material but not for WM tasks that only require maintenance.

Interactive effects of sex hormones and gender stereotypes on cognitive sex differences—A psychobiosocial approach.

Biological and social factors have been shown to affect cognitive sex differences. For example, several studies have found that sex hormones have activating effects on sex-sensitive tasks. On the other hand, it has been shown that gender stereotypes can influence the cognitive performance of (gender-) stereotyped individuals. However, few studies have investigated the combined effects of both factors. The present study investigated the interaction between sex hormones and gender stereotypes within a psychobiosocial approach. One hundred and fourteen participants (59 women) performed a battery of sex-sensitive cognitive tasks, including mental rotation, verbal fluency, and perceptual speed. Saliva samples were taken immediately after cognitive testing. Levels of testosterone (T) were analysed using chemiluminescence immunoassay (LIA). To activate gender stereotypes, a questionnaire was applied to the experimental group that referred to the cognitive tasks used. The control group received an identical questionnaire but with a gender-neutral content. As expected, significant sex differences favouring males and females appeared for mental rotation and verbal fluency tasks, respectively. The results revealed no sex difference in perceptual speed. The male superiority in the Revised Vandenberg and Kuse Mental Rotations Tests (MRT-3D) was mainly driven by the stereotype-active group. No significant sex difference in MRT-3D appeared in the control group. The MRT-3D was also the task in which a strong gender-stereotype favouring males was present for both males and females. Interestingly, T levels of the stereotype-activated group were 60% higher than that of male controls. The results suggest that sex hormones mediate the effects of gender stereotypes on specific cognitive abilities.

Stress-Induced Cortisol Level Elevations Are Associated With Reduced Negative Affect After Stress: Indications for a Mood-Buffering Cortisol Effect

Objective Stress is associated with increased negative affect and activation of the sympathetic nervous system and of the hypothalamic-pituitary-adrenal axis. However, the relationship between these stress systems and negative affect is incompletely understood. We therefore investigated positive and negative affects in relationship with salivary cortisol and salivary &agr;-amylase (sAA) levels in a large sample of participants exposed to a psychosocial stressor or a control condition. Methods Cortisol and sAA levels from five studies with a total sample size of 232 participants were reanalyzed using hierarchical linear modeling. In these studies, we measured affective responses to the Trier Social Stress Test (TSST) and its control condition (placebo TSST) with the Positive and Negative Affect Schedule. Results An inverse relationship between cortisol and negative affect was observed across all participants (&bgr;06 = −0.13, p = .002). Higher level of negative affect was associated with lower mean cortisol levels 10 minutes after the TSST or the control condition. When the two conditions were tested separately, the effect was significant in the stress condition (&bgr;06 = −0.05, p = .02) but not in the control condition (&bgr;06 = −0.0008, p > .05). In contrast to the results for cortisol, a positive relationship was found between sAA and negative affect within the stress condition (&bgr;06 = 0.10, p = .005). Conclusions The present findings suggest that cortisol is associated with an attenuated negative emotional arousal in response to acute stress, whereas sAA levels seem to reflect the degree of negative emotional arousal. Together with previous pharmacological studies, these data seem to support the hypothesis of mood-buffering effects of cortisol. Abbreviations GC = glucocorticoid; HLM = hierarchical linear modeling; HPAA = hypothalamic-pituitary-adrenal axis; KS = Kolmogorov-Smirnov; PANAS = Positive and Negative Affect Schedule; P-TSST = placebo TSST; sAA = salivary &agr;-amylase; SNS = sympathetic nervous system; TSST = Trier Social Stress Test

Stress and Memory Retrieval in Women: No Strong Impairing Effect During the Luteal Phase

Stress has been shown to impair delayed memory retrieval, but so far no study has been conducted solely with naturally cycling women. In a crossover design, 36 women (all in the luteal phase) participated in two experimental conditions (stress vs. control). Delayed memory retrieval of a wordlist learned 24 hours earlier was tested after stress or control treatment. Although stressed subjects showed a strong cortisol increase following stress, no influence on memory retrieval occurred. In an additional data analysis, subjects were split up into a cortisol responder and a cortisol nonresponder group. However, again no evidence for a stress-induced retrieval impairment became apparent. Similarly, no correlation was observed between the stress-induced cortisol increase and memory. This study failed to find an influence of stress on memory retrieval in women tested in the luteal phase. The findings are in contrast to our previous results obtained with men. Evidence is discussed that the luteal phase, which is characterized by elevated gonadal steroids, is associated with reduced glucocorticoid sensitivity. This might underlie the missing impact of stress on memory.

Working memory is differentially affected by stress in men and women

Stress has been shown to influence working memory. However, sex differences and the potential impact of stimulus emotionality have not received much attention. In a first experiment the effects of stress on a neutral working memory (WM) paradigm were tested in male and female participants (Experiment 1). Experiment 2 employed the same paradigm but used emotional stimuli. For this purpose, healthy participants were exposed either to a stressful (Trierer Social Stress Test (TSST)) or to a non-stressful control condition. Subsequently, WM performance in an n-back task was assessed. In Experiment 1, single digits were used as stimuli, while in Experiment 2 neutral and negative pictures were additionally employed. Salivary cortisol and Alpha-Amylase (sAA) were measured before and three times after the treatment as a marker of hypothalamus-pituitary-adrenal (HPA) axis- and sympathetic nervous system (SNS) activity. In both experiments, stress caused a substantial cortisol and sAA increase. For WM performance (response time) a stress by sex interaction was apparent. Stress enhanced performance in men, while impairing it in women. In both experiments stress had no effect on response accuracy. No modulating effect of the emotional quality of stimuli on n-back performance was observed (study 2). The results indicate that the effect of acute stress on n-back performance differs between the sexes. In contrast to long-term memory, the influence of stress on WM appears not to be modulated by the emotionality of the employed stimuli if stimuli are potential targets as it is the case in the n-back task.

The stressed student: Influence of written examinations and oral presentations on salivary cortisol concentrations in university students

Laboratory research has demonstrated that social-evaluative threat has an influence on the hypothalamus pituitary adrenal axis (HPA). In two studies using independent samples, we evaluated the anticipatory cortisol response to a written university examination (n = 35) and to an oral presentation (n = 34). Saliva samples were collected before and after the examinations and on a control day. Additionally, saliva samples were collected on the day before the written examination and a control day. Results revealed significantly elevated cortisol concentrations on the day prior to the examination; however, this effect occurred only in those participants who had their control day after the examination. Cortisol concentrations were elevated on the examination day, with increased concentrations before but not after the examination. For the oral presentation study, the results revealed substantially elevated cortisol concentrations before and after the oral presentation. Taken together the results indicate that written examinations cause a mild anticipatory HPA response while oral presentations induce a strong HPA response. These findings appear to support the idea that social-evaluative threat is an important factor determining the size of the HPA response to laboratory stressors as well as to real-life stressors.

Paradoxical Effects of Stress and an Executive Task on Decisions Under Risk

In everyday life, decisions are often made under stress and while being occupied with multiple tasks. It has recently been shown that acute stress impairs decision making under risk. Performing a parallel executive task also caused riskier decision making. To investigate the effects of a combination of these two factors on decision making, we conducted a large (N = 126) experimental study with a 2 × 2 design (stress vs. no stress and parallel task vs. no parallel task). Stress was induced using the Trier Social Stress Test (TSST) and controls underwent the placebo TSST. Salivary samples were collected to assess cortisol and alpha amylase concentrations as markers of the two stress response systems. Decision making was measured using the Game of Dice Task (GDT). A 2-back task served as parallel executive task. Our results revealed a significant interaction between stress and the parallel executive task. In line with our earlier findings, acute stress and a parallel executive task individually tended to impair decision making under risk, manifested by more high risky than low risky choices. Interestingly, stressed participants in the parallel-task condition (GDT plus 2-back) showed similar decision-making behavior as nonstressed single-task participants. Regression analyses revealed executive functions to moderate stress effects on decisions under risk. Reasons for these paradoxical findings are discussed with respect to stress-evoked cognitive alterations that may benefit decision making under risk, if an executive task is performed simultaneously.

Associations between endogenous cortisol levels and emotional memory in young women: Influence of encoding instructions

The stress hormone cortisol is known to influence memory. Elevated cortisol levels as a consequence of stress or as a consequence of cortisol administration have been repeatedly shown to enhance encoding and consolidation of (emotional) memory. Whether similar associations exist between basal cortisol levels and emotional memory remains to be established. The present study therefore evaluated if resting cortisol levels are correlated with memory for emotionally arousing and neutral pictures in a sample of young healthy females (n = 56). A second aim of the study was to explore if the relationship between basal cortisol levels and memory might be modulated by encoding instructions (intentional vs. incidental encoding). A significant positive correlation between basal salivary cortisol levels and memory for emotionally arousing pictures in a 24 h delayed free recall test was found. Further analyses revealed that this association only occurred in the group receiving intentional encoding instructions. Results indicate that basal cortisol levels, similarly to stress induced cortisol levels, are associated with emotional memory formation. Moreover this effect seems to be modulated by encoding instructions, suggesting a role of focussed attention or arousal induced by testing in this relationship.

Associations between fear-avoidance and endurance responses to pain and salivary cortisol in the context of experimental pain induction

Recent clinical studies in patients with lower back pain indicate that maladaptive fear-avoidance- and endurance-related pain responses (FAR and ER) have an influence on pain-induced physiological stress levels. The aim of the present study was to follow-up these results under well-controlled laboratory conditions. For this purpose, 30 healthy adults were asked to indicate their usual responses to pain, and were then confronted with an experimental pain stimulus (cold pressor test). Cortisol served as a measure of physiological stress. The results reveal positive associations between cortisol and FAR patterns, and negative associations between cortisol and behavioral ER. Conceivably, FAR contribute to long-lasting elevated stress levels in patients with stress-related musculoskeletal pain. In contrast, short-term, stress-lowering effects of ER might even be considered an advantage in coping with pain.