Biomedical subjects

C Kirschbaum

Publications and source records attributed to C Kirschbaum.

At least 55 records · Page 3Linked to original sources

PubMed1997

Social hierarchy and adrenocortical stress reactivity in men.

Baseline and stress induced salivary cortisol levels were investigated in 63 army recruits at the beginning and the end of six week boot camp training. At the beginning of the training, the recruits were randomly distributed to nine groups, and weekly measurements of the social hierarchy within each group were obtained. Independent of the social position, baseline levels increased over the first weeks of the training period. Under experimental psychological stress, salivary cortisol levels highly increased in socially dominant subjects (14.0 nmol/l), while only a modest elevation was observed in subordinate men (2.9 nmol/l). Similar differences in response patterns were observed under physical stress. At the end of the training, blunted cortisol responses were observed to both psychological and physical stress. The data suggest a close relationship between social status and pituitary-adrenal responsiveness to psychological stress in men.

Adrenal Cortex↗

PubMed1997

Increasing correlations between personality traits and cortisol stress responses obtained by data aggregation.

Attempts to link personality traits and cortisol stress responses have often been inconclusive. The aim of this paper was to investigate this association by aggregating cortisol stress responses. Therefore, 20 healthy men were exposed to a task consisting of public speaking and mental arithmetics in front of an audience on five days. Six cortisol levels were measured in relation to the stressful task obtained at 10-min intervals on each day. Psychological assessment included the Questionnaire for Competence and Control (FKK) and the Giessen-Test (G-T). These questionnaires focus on assessing personality traits, i.e. locus of control and self-concept. Areas under the response curve (AUC) of the six cortisol samples were computed to obtain an index of the individual's cortisol stress response on each day. Since novelty is a random situational factor likely to mask individual differences in the stress response, the AUC cortisol stress responses of days two to five were consecutively aggregated, excluding the first day. Scales of the two questionnaires employed did not correlate with the AUC cortisol stress response of the first stress trial. The correlation pattern of the AUC cortisol measures of days two to five with the questionnaire scales was inconclusive. However, significant correlations emerged with an increasing number of cortisol stress responses aggregated. Correlations between the measure of social dominance and aggregated AUC cortisol stress responses rose from r = -.47 on day two of the experimental session to r = -.70 after aggregating days two to five. Similarly, measures of locus of control and cortisol stress responses became increasingly correlated with aggregation of several stress exposures. These data provide preliminary evidence for a relationship between questionnaire scales aiming at assessing personality traits and cortisol stress responses uncovered by repeated stress exposure and data aggregation. While novelty may mask the impact of personality on the cortisol stress response on the first exposure, differences in the ability to cope with the stressful situation may lead to different cortisol stress response patterns on subsequent stress exposures. With data aggregation, an association between the trait component of cortisol stress responses and questionnaire scales might be uncovered. For reliable investigation of correlations between personality variables and cortisol stress responses, repeated stress exposure and data aggregation is suggested.

Adult↗

PubMed1997

Effects of fasting and glucose load on free cortisol responses to stress and nicotine.

The availability of energy appears to exert important regulatory functions in pituitary-adrenal stress responses. In two studies, the effects of short-term fasting and subsequent glucose administration on the free cortisol response to psychological stress and nicotine consumption were investigated. Study 1: After fasting for 8-11 h, healthy young men ingested either 100 g glucose (n = 13) or water (n = 12). One hour later they were exposed to a psychosocial stress task (Trier Social Stress Test). A third group also ingested 100 g glucose, but they were not exposed to any additional treatment (n = 10). Capillary blood glucose levels were in the lower euglycemic range before and significantly elevated after the glucose load (64.9 +/- 9.8 vs. 162.5 +/- 43.5 mg/dL; F = 149.04, P < 0.001). Although glucose load per se did not affect free cortisol levels, psychosocial stress induced a large cortisol response in glucose-treated subjects. In contrast, fasted subjects who received tap water did not respond to the Trier Social Stress Test with significant changes in cortisol levels (F = 6.27, P < 0.001). Both groups responded with a similar increase in heart rates (F = 33.53, P < 0.001) with no statistically significant difference between glucose and water-treated subjects. Study 2: Twelve habitual smokers received 100 g glucose or tap water after fasting for at least 8 h on two separate sessions (cross-over, random sequence). Forty-five min after glucose/water ingestion, they smoked two cigarettes with a nicotine content of 1.0 mg/cigarette. Subjects were euglycemic before smoking, with a significant rise of glucose levels after consumption of 100 g glucose (64.4 +/- 8.3 vs. 143.5 +/- 40.0 mg/dL; F = 40.25, P < 0.001). As in Exp 1, subjects showed a substantially larger free cortisol response to nicotine under glucose load compared with water load (F = 4.91, P < 0.001). From these data we conclude that the free cortisol response to stimulation is under significant control of center responsible for monitoring energy availability. Low glucose levels appear to inhibit adrenocortical responsiveness in healthy subjects. In agreement with results from animal studies, the present results suggest that ready access to energy is a prerequisite for hypothalamus-pituitary-adrenal stress responses.

Adult↗

PubMed1997

Effects of a two-week physiological dehydroepiandrosterone substitution on cognitive performance and well-being in healthy elderly women and men.

The levels of dehydroepiandrosterone (DHEA) and its sulfate ester DHEAS decrease with age after a peak around 25 yr. Animal studies as well as the first studies in humans have generated the idea that DHEA replacement in elderly subjects may have beneficial effects on well-being and cognitive functions. In the present experiment 40 healthy elderly men and women (mean age, 69 yr) participated in a double blind, placebo-controlled DHEA substitution study. For 2 weeks subjects took 50 mg DHEA daily, followed by a 2-week wash-out period and a 2-week placebo period. The treatment sequence was randomized in a cross-over design. After 2 weeks of DHEA or placebo, psychological and physical well-being as well as cognitive performance were assessed using several questionnaires and neuropsychological tests. All subjects had low DHEAS baseline levels. DHEA substitution lead to a 5-fold increase in DHEAS levels in women (from 0.67 +/- 0.1 to 4.1 +/- 0.4 micrograms/mL; P < 0.001) and men (from 0.85 +/- 0.1 to 4.5 +/- 0.4 micrograms/mL; P < 0.001). DHEA, androstenedione, and testosterone levels also increased significantly in both sexes (all P < 0.001). No significant changes were observed in insulin-like growth factor I or insulin-like growth factor-binding protein-3 levels. DHEA replacement had no strong beneficial effect on any of the measured psychological or cognitive parameters. Only women tended to report an increase in well-being (P = 0.11) and mood (P = 0.10), as assessed with questionnaires. They also showed better performance in one of six cognitive tests (picture memory) after DHEA. However, after Bonferroni alpha adjustment, this difference was no longer significant. No such trend was observed in men (P > 0.20). Likewise, no beneficial effects of DHEA substitution could be observed in any of the other tests of the neuropsychological test battery in either sex (all P > 0.20). In conclusion, the present data do not support the idea of strong beneficial effects of a physiological DHEA substitution on well-being or cognitive performance in healthy elderly individuals.

Affect↗

PubMed1997

Salivary cortisol: a non-invasive measure of hypothalamo-pituitary-adrenocortical activity in the squirrel monkey, Saimiri sciureus.

Salivary cortisol is a non-invasive and easy-to-assess measure of the activity of the hypothalamo-pituitary-adrenocortical (HPA) system. Here we report that salivary cortisol determination can be used in squirrel monkeys (Saimiri sciureus) to monitor variations in HPA system activity induced by both housing and experimental conditions. Saliva cortisol assessment has several advantages over blood cortisol analysis such as stress-free frequent sampling, laboratory independence and lower costs. Therefore, this non-invasive measure can be the method of choice in primatological research projects and routine programmes related to the well-being of these laboratory animals.

Animals↗

PubMed1996

Cigarette smoking and psychophysiological stress responsiveness: effects of recent smoking and temporary abstinence.

Studies comparing the cardiovascular function and stress responsiveness of regular smokers and non-smokers have produced mixed results, possibly because of variable intervals between stress tests and recency of smoking. This experiment compared the cardiovascular, cortisol and affective responses to a problem solving task of non-smoking young men (n = 16) and regular smokers randomised to overnight abstinence (n = 14) and smoking 30 min prior to testing (n = 19). Smoking status was validated biochemically. Overnight abstinence was associated with reduced diastolic blood pressure at rest and with enhanced diastolic pressure and emotional responses to the task compared with other conditions. Recent smokers showed elevated heart rates, suppressed cardiac baroreceptor reflex sensitivity and reduced cortisol responsiveness, but did not differ from non-smokers in blood pressure responses. The behavioral performance of the abstinent group was impaired, and their craving was greater than that of recent smokers. Both groups of smokers reported more dysphoric mood than non-smokers, and showed only limited recovery of emotional equilibrium following tests. The results are discussed in relation to mechanisms linking smoking, stress responsiveness and cardiovascular disease risk. The methodological implications for including regular smokers in psychophysiological studies are also considered.

Adult↗

PubMed1996

Stress- and treatment-induced elevations of cortisol levels associated with impaired declarative memory in healthy adults.

Two studies investigated the association between cortisol levels and memory performance in healthy adults. In a first study, 13 subjects were exposed to a brief psychosocial laboratory stress ("Trier Social Stress Test") with a subsequent test of declarative memory performance. Results indicated a significant negative relationship between stress-induced cortisol levels and performance in the memory task, i.e. subjects with high cortisol response to the stressor showed poorer memory performance. In a second experiment it was investigated if cortisol, alone, i.e. independent of psychological stress, would also impair memory function. In this study, 40 healthy subjects received either 10 mg cortisol or placebo orally. One hour later they were tested for procedural and declarative memory and spatial thinking. Subjects who received cortisol showed impaired performance in the declarative memory and spatial thinking tasks but not in the procedural memory task. From these results we conclude that in healthy adults elevated free cortisol levels are associated with impaired memory function.

Adult↗

PubMed1996

Conditioned increase in peripheral blood mononuclear cell (PBMC) number and corticosterone secretion in the rat.

Femoral artery catheters were surgically implanted into male Lewis/N rats to allow blood sampling and drug infusion in the freely moving animal. After recovery, conditioned animals received four pairings of a peppermint odor, the conditioned stimulus (CS), and an infusion of 0.1 mg/kg nicotine bitartrate, an unconditioned stimulus (US) for an increase in the number of peripheral blood mononuclear cells (PBMC) and an increase in corticosterone concentration. When reexposed to the peppermint odor, conditioned animals showed a significant increase in PBMC number and corticosterone secretion when compared to saline and unpaired control groups and previously conditioned animals that were not reexposed to the CS. Increased PBMCs were found on the fifth unreinforced CS trial. Conditioned CORT responses were lost after the initial test trial. The data indicate that the distribution of immune cells can be influenced by learning processes and support the role of learning in the regulation of corticosterone secretion.

Animals↗

PubMed1996

Short-term estradiol treatment enhances pituitary-adrenal axis and sympathetic responses to psychosocial stress in healthy young men.

Evidence from animal studies and clinical observations suggest that the activity of the pituitary-adrenal axis is under significant influence of sex steroids. The present study investigated how a short term elevation of estradiol levels affects ACTH, cortisol, norepinephrine, and heart rate responses to mental stress in healthy men. In a double blind study, 16 men received a patch delivering 0.1 mg estradiol/day transdermally, and age- and body mass index-matched control subjects received a placebo patch. Twenty-four to 48 h later, they were exposed to a brief psychosocial stressor (free speech and mental arithmetic in front of an audience). In response to the psychosocial stressor, ACTH, cortisol, norepinephrine, and heart rate were increased in both experimental groups (all P < 0.0001). However, the estradiol-treated subjects showed exaggerated peak ACTH (P < 0.001) and cortisol (P < 0.002) responses compared to the placebo group. Also, the norepinephrine area under the response curve was greater in the estradiol group (P < 0.05). Although heart rate responses differences failed to reach statistical significance, they, too, tended to be larger in the estradiol group. Neither mood ratings before or after the stressor, nor ratings of the perception of the stressor could explain the observed endocrine response differences. In conclusion, short term estradiol administration resulted in hyperresponses of the pituitary-adrenal axis and norepinephrine to psychosocial stress in healthy young men independent of psychological effects, as assessed in this study.

Adrenal Glands↗

PubMed1995

Preliminary evidence for reduced cortisol responsivity to psychological stress in women using oral contraceptive medication.

In two studies, saliva cortisol responses to the psychological stress of public speaking and mental arithmetic were investigated in women using oral contraceptives (OC; n = 28) and in control women (n = 29). While no significant differences in baseline levels were observed, altered adrenocortical responses were found in OC users. These women showed significantly attenuated cortisol responses to the experimental stressor in both studies, with peak cortisol levels only slightly elevated above baseline levels. These differences could not be attributed to affective responses as indicated in ratings on visual analogue scales assessing subjective stress responses (Study 2). A comparison between control women and men (n = 19) again revealed the previously reported result of larger cortisol responses to psychological stress in males. We conclude that the use of OC may interfere with the adrenocortical response to psychological stress and should therefore be viewed as an important intervening variable. While it appears that differences at a supra-adrenal site is responsible for the observed cortisol hyporesponsiveness in OC users, the physiological mechanisms remain to be elucidated.

Adult↗

PubMed1994

Pituitary and adrenal hormone responses to pharmacological, physical, and psychological stimulation in habitual smokers and nonsmokers.

Hormone responses to injection of corticotropin-releasing hormone following bicycle ergometry and psychological stress were studied in ten habitual smokers and ten nonsmokers. Compared to injection of saline, significant increases were found in adrenocorticotropin, prolactin, growth hormone, total serum cortisol, and salivary cortisol under all three stimulations except for salivary cortisol under ergometry. Furthermore, the smokers showed significant elevations of all five hormones investigated following the smoking of two cigarettes of the subject's preferred brand. Comparisons of hormone responses between smokers and nonsmokers revealed a general trend towards stronger responses in nonsmokers. However, due to the small number of subjects investigated and considerable variation in the individual hormone responses these differences reached statistical significance only for growth hormone responses following ergometry and salivary cortisol responses after psychological stress. In addition, the circadian rhythm of salivary cortisol was measured on two occasions between 9 a.m. and 9 p.m. in the subject's natural environment. The typical circadian pattern of decreasing cortisol levels was observed, with no significant differences between smokers and nonsmokers. We conclude that chronic nicotine consumption may lead to lower responses of multiple hormones not only to nicotine but to a variety of stimuli, and that these alterations do not necessarily affect unstimulated circadian profiles of free cortisol.

Adrenocorticotropic Hormone↗

PubMed1994

Conditioned manipulation of natural killer (NK) cells in humans using a discriminative learning protocol.

There is growing evidence indicating that the immune function can be modified by classical conditioning techniques. This phenomenon, initially explored in animals, is further documented by studies providing evidence that the human immune response can also be influenced by classical conditioning processes. In the present study, we tested the hypothesis that human immune parameters can be modulated by discriminative learning processes. Using a classical discriminative conditioning design, healthy volunteers were provided with a CS+ (sherbet sweet/white noise), which was repeatedly paired with an injection of epinephrine (unconditioned stimulus, US). After epinephrine injections (0.2 mg subcutaneously), a transient increase of natural killer (NK) cell activity (unconditioned response, UR) could be observed. A second stimulus complex (herbal sweet/auditory stimulus, conditioned stimulus, CS-) remained without reinforcement. After repeated presentation of the stimuli, re-exposure of the CS+ on the test trial 1 resulted in a significantly increased number of NK positive (NK+) cells and in slightly elevated NK cell activity. No alteration of NK cells, however, could be observed after presentation of the CS-. A second re-exposure of the CS+ on test trial 3, again resulted in a marked increase of NK+ cell number as well as in significantly elevated NK cell activity. The data presented here extend previous observations of conditioned alteration of immune responses in humans and indicate that the human organism might be able to react differentially to external stimuli, which have been associated with different immunological consequences.

Adult↗

PubMed1994

Salivary cortisol in psychoneuroendocrine research: recent developments and applications.

The assessment of cortisol in saliva has proven a valid and reliable reflection of the respective unbound hormone in blood. To date, assessment of cortisol in saliva is a widely accepted and frequently employed method in psychoneuroendocrinology. Due to several advantages over blood cortisol analyses (e.g., stress-free sampling, laboratory independence, lower costs) saliva cortisol assessment can be the method of choice in basic research and clinical environments. The determination of cortisol in saliva can facilitate stress studies including newborns and infants and replace blood sampling for diagnostic endocrine tests like the dexamethasone suppression test. The present paper provides an up-to-date overview of recent methodological developments, novel applications as well as a discussion of possible future applications of salivary cortisol determination.

Adult↗

PubMed1994

Association between smoking status and cardiovascular and cortisol stress responsivity in healthy young men.

Acutely, cigarette smoking stimulates increases in blood pressure (BP), heart rate (HR), and cortisol, but little evidence is available concerning the impact of habitual smoking status on cardiovascular stress responsivity. This relation was assessed in 86 healthy male firefighters, age 19 to 31. comprising 52 nonsmokers and 34 smokers. Measures of BP, HR, salivary free cortisol, breathing pattern, and self-reported stress and alertness were obtained while subjects performed nonverbal mental arithmetic and a socially evaluative speech task. Systolic and diastolic BP were higher at rest in nonsmokers than smokers, and a consistent difference in stress responsivity was also found. BP, HR, and cortisol responses to mental arithmetic were significantly smaller in smokers than nonsmokers, with mean changes in BP (adjusted for body weight) averaging 19.3/11.0 mmHg and 28.5/15.4 mmHg in smokers and nonsmokers, respectively. There were no effects of smoking status on task performance or subjective stress responses and no differences between groups in family health history, health-related behaviors, o r psychological characteristics that might account for the reactivity difference. Possible explanations of the results are discussed, and methodological implications for cardiovascular stress reactivity studies are outlined.

Journal Article↗

PubMed1993

Psychobiological factors related to human natural killer cell activity and hormonal modulation of NK cells in vitro.

The present report investigated whether percentages of circulating natural killer (NK) cells and NK cell activity (NKCA) are associated with psychological variables. Subjects (n = 95) were selected, based on a combination of low or high scores on questionnaires on daily hassles and self-reported symptoms, to create four extreme groups. NK cell percentages were different between two of the four groups, only when the analysis was not controlled for gender, life style and endocrine parameters. No evidence was found for a relationship between group membership and NKCA. NKCA, however, was found to differ between men and women and to be associated with percentages of NK cells and intracellular levels of cAMP. Furthermore, the hypothesis was tested, that hormone-induced changes in NKCA in vitro are dependent on the individual's current stress profile. To investigate this issue, NKCA was measured after cells had been incubated with hydrocortisone (10(-6) or 10(-7) M) or the beta-adrenergic agonist isoprenaline (10(-5) or 10(-7) M) in vitro. Changes in NKCA were found to be related to plasma adrenaline levels, but no evidence was found for involvement of psychological variables. It is concluded that, in the current setting, there is no association between the combination of scores on the two psychological questionnaires, and NKCA or hormone-induced changes therein.

Adolescent↗

PubMed1993

Attenuated cortisol response to psychological stress but not to CRH or ergometry in young habitual smokers.

Salivary cortisol and heart rate responses to a) psychological stress (public speaking and mental arithmetic), b) human corticotropin-releasing hormone (hCRH), and c) bicycle ergometry until exhaustion were investigated in 10 smokers and 10 nonsmokers. Compared to d), an injection of physiological saline, psychological stress as well as hCRH resulted in significant elevations of salivary cortisol levels in the total group. Ergometry workload induced only moderately enhanced cortisol concentrations. Profound changes in heart rates were observed following bicycle ergometry [+83 beats per minure (bpm)] and after the psychological stress (+29 bpm). hCRH injection increased heart rate by 5 bpm while heart rates dropped after saline administration (-2 bpm). Smokers showed an attenuated cortisol response to the psychological stressor. Mean cortisol increases reached only one third in smokers compared to nonsmokers. Similarly, cortisol levels in smokers tended to be lower after hCRH injection; however, this difference was not statistically significant. Cortisol responses to ergometry did not differ between the two groups. Likewise, heart rates did not reveal different profiles in any of the three stimulations in smokers compared to nonsmokers.

Adult↗

PubMed1993

The 'Trier Social Stress Test'--a tool for investigating psychobiological stress responses in a laboratory setting.

This paper describes a protocol for induction of moderate psychological stress in a laboratory setting and evaluates its effects on physiological responses. The 'Trier Social Stress Test' (TSST) mainly consists of an anticipation period (10 min) and a test period (10 min) in which the subjects have to deliver a free speech and perform mental arithmetic in front of an audience. In six independent studies this protocol has been found to induce considerable changes in the concentration of ACTH, cortisol (serum and saliva), GH, prolactin as well as significant increases in heart rate. As for salivary cortisol levels, the TSST reliably led to 2- to 4-fold elevations above baseline with similar peak cortisol concentrations. Studies are summarized in which TSST-induced cortisol increases elucidated some of the multiple variables contributing to the interindividual variation in adrenocortical stress responses. The results suggest that gender, genetics and nicotine consumption can influence the individual's stress responsiveness to psychological stress while personality traits showed no correlation with cortisol responses to TSST stimulation. From these data we conclude that the TSST can serve as a tool for psychobiological research.

Adrenal Cortex Hormones↗

PubMed1992

'Normal' cigarette smoking increases free cortisol in habitual smokers.

In habitual smokers salivary cortisol responses to cigarette smoking were investigated. In the first study, 31 adults assigned to two experimental groups smoked either one or two cigarettes of their preferred brand. Mean salivary cortisol levels were significantly elevated after smoking of two cigarettes. In the second study, 10 smokers and 10 nonsmokers provided saliva samples at 20 min intervals over a 12-hr period. While environmental stimuli were paralleled in both groups overall cortisol output was significantly elevated in the smokers. These data suggest that 'normal' cigarette smoking can increase free cortisol levels.

Adult↗