Cortisol, contingency learning, and memory in preterm and full-term infants

Cortisol plays an important role in learning and memory. An inverted-U shaped function has been proposed to account for the positive and negative effects of cortisol on cognitive performance and memory in adults, such that too little or too much impair but moderate amounts facilitate performance. Whether such relationships between cortisol and mental function apply to early infancy, when cortisol secretion, learning, and memory undergo rapid developmental changes, is unknown. We compared relationships between learning/memory and cortisol in preterm and full-term infants and examined whether a greater risk for adrenal insufficiency associated with prematurity produces differential cortisol-memory relationships. Learning in three-month old (corrected for gestational age) preterm and full-term infants was evaluated using a conjugate reinforcement mobile task. Memory was tested by repeating the same task 24h later. Salivary cortisol samples were collected before and 20 min after the presentation of the mobile. We found that preterm infants had lower cortisol levels and smaller cortisol responses than full-term infants. This is consistent with relative adrenal insufficiency reported in the neonatal period. Infants who showed increased cortisol levels from 0 to 20 min on Day 1 had significantly better memory, regardless of prematurity, than infants who showed decreased cortisol levels.     

Social Isolation and Stress-related Cardiovascular,Lipid, and Cortisol Responses

Background  Social support is a strong and consistent predictor of health outcomes, and social isolation predicts increased morbidity and mortality. The mediating processes are not completely understood. Purpose  The purpose of the study is to investigate associations between social isolation and cardiovascular and lipid responses to acute stress in the laboratory, and cortisol profiles over the day. Methods  Cardiovascular and lipid responses to acute stress tasks, and salivary cortisol monitoring, were carried out in 238 healthy middle-aged men and women from the Whitehall II cohort. Social isolation was measured using an adapted version of the Close Persons Questionnaire. Results  Social isolation was associated with slower post-task recovery of systolic blood pressure in men and women, a higher cholesterol response to stress in men only, and also with larger cortisol awakening responses and greater cortisol output over the day in both men and women. Conclusions  The impact of social isolation on cardiovascular disease risk may be mediated through stress-related dysregulation of cardiovascular, metabolic, and neuroendocrine processes.     

Cortisol, 11-deoxycortisol, and ACTH concentrations after dexamethasone in depressed patients and healthy volunteers

The 1 mg dexamethasone suppression test was used to assess pituitary-adrenal activity in 23 depressed patients and 8 healthy volunteers. At 1600h, after administration of the test dose of dexamethasone at 2300h, levels of cortisol, 11-deoxycortisol, and corticotropin were determined following a chromatographic extraction step applying highly specific radioimmunoassay techniques. Cortisol nonsuppressors had significantly increased adrenocorticotropic hormone (ACTH) values and cortisol/11-deoxycortisol ratios. The cortisol/11-deoxycortisol ratio was regarded as a measure of biologically active ACTH. The present results, which indicate a concordance of corticotropin and corticosteroid response, suggest that the parent abnormality of dexamethasone-resistant cortisol concentrations is elevation of biologically active corticotropin.     

Tissue aluminum concentrations stability over time, relationship to age, and dietary intake

Aluminum concentration was measured in serum, whole blood, hair, and urine by neutron activation analysis. Seventy-six nondemented subjects were investigated. Not all assays were done on all subjects (e.g., serum aluminum on 76 subjects, whole blood aluminum on 42 subjects), but tissue aluminum concentrations were estimated on more than one occasion on 32 subjects. The mean +/- SD aluminum concentration in serum was 0.219 +/- 0.063 micrograms/ml (N = 76), in whole blood 0.368 +/- 0.091 micrograms/ml (N = 42), in urine 0.092 +/- 0.076 micrograms/ml (N = 42), and in hair 6.42 +/- 2.22 micrograms/g (N = 42). Using product moment correlation coefficient there was no significant correlation between age and tissue aluminum concentrations, nor between dietary intake of aluminum and tissue aluminum. The tissue aluminum concentrations were not stable over time even when dietary intake was constant. Tissue aluminum concentrations were measured in 14 patients after 7 days of dietary control and repeated approximately 6 weeks later, again after 7 days of dietary control. There was no significant correlation between the two estimations in any tissue measured. These results suggest that raised tissue aluminum concentrations reported in Alzheimer's disease are not an exaggeration of a normal ageing process, are not likely to be simply secondary to increased dietary aluminum intake, and that Alzheimer's disease does not represent the chronic toxic effect of moderately raised aluminum levels at the upper end of the normal distribution.     

Cortisol levels and hippocampus volumes in healthy preadolescent children.

BACKGROUND: Research in animal models has demonstrated that elevated levels of glucocorticoids can inflict damage within the hippocampus. In adult humans, elevated cortisol levels have been associated with reduced hippocampal volumes; however, normative data in children are not available. The objective of this study was to examine possible associations of serum cortisol levels with hippocampal volumes and morphology in healthy children. METHODS: Morning serum cortisol levels and hippocampus magnetic resonance imaging were measured in 17 healthy children (8 girls, 9 boys) between 7 and 12 years of age. RESULTS: Cortisol levels were not associated with total hippocampal volumes; however, with an analysis of surface morphology, significant associations were found for regionally specific portions of the hippocampus. Positive associations were detected for the anterior segment of the hippocampus and inverse associations along the lateral aspects of the hippocampus. CONCLUSIONS: Associations of cortisol levels with regionally specific variations in hippocampal morphology were detected during early development in healthy preadolescent children.     

Cortisol secretory activity in older people in relation to positive and negative well-being

Secretion of the hormone cortisol, a physiological correlate of affect, has been studied mostly in relation to negative states, especially stress. By contrast, policy initiatives aimed at older populations now routinely emphasise well-being and a 'positive ageing' perspective. In this study, we examined diurnal salivary cortisol profiles from 50 active seniors recruited into a wider community research project (mean age 74 years; 34 F/16 M). Participants' wrist activity was continuously monitored by actimeters in their homes over a 48 h period. During this time two diurnal cycles of cortisol data were collected (8 samples per day); with actimeter data providing a compliance check in regard to timing of self-administered saliva collections. Prior to the trial, participants had completed the GHQ-30 which was scored separately to yield both positive and negative well-being scores which matched closely normative data from over 6000 cases in a large survey. Our data suggest that positive and negative psychological well-being are quite strongly and inversely correlated. However, neither on their own was associated with basal levels of cortisol. Rather, for cortisol secretion in the 45-min period following awakening, but not during the rest of the day, we found a significant interaction between positive and negative well-being (p<0.024). Further analysis of this interaction showed that among participants low on negative well-being, higher positive well-being was significantly associated with lower cortisol; equally, among participants high on positive well-being, lower negative well-being was significantly associated with lower cortisol. Thus, a powerful synergy seemed to be operating in this early morning period such that cortisol secretion was 27% lower in participants with both higher-than-average positive well-being and lower-than-average negative well-being (comprising 34% of the sample). We conclude that cortisol secretion in the first 45 min following awakening is distinct from the rest of the day and most able to discriminate well-being states.     

Psychological coping styles and cortisol over the day in healthy older adults

Patterns of psychological coping are associated with a variety of health outcomes but the underlying pathways are not yet established. The purpose of this study was to assess the relationship between salivary cortisol output over the course of a day and coping style. Data were available from 350 men and 192 women with an average age of 60.9 years. Participants were drawn from the Whitehall II cohort, and had no history of cardiovascular disease. Individuals who were taking medication that might affect cortisol levels were also excluded. Saliva samples were provided on waking, then 0.5, 2.5, 8 and 12 h after waking, and just before the participant went to sleep. Coping style was measured with a standard instrument, the COPE, and data were factor analysed to generate three factors: seeking social support, problem engagement and problem avoidance. The relationships between these factors and the cortisol awakening response (CAR), the slope of cortisol change over the day and total cortisol output over the day (excluding the waking period) were assessed using multiple linear regression. Cortisol output over the day was inversely associated with coping with stress by seeking social support (p=0.034) and by problem engagement (p=0.003), independently of age, gender, body mass index, smoking, depression, self-rated health, time of waking and income. Individuals who coped by problem engagement and seeking support had lower cortisol levels. Additionally, gender, BMI, smoking, self-rated health and time of waking were independently related to cortisol output over the day. There were no significant associations between coping and the CAR or cortisol slope over the day. The results indicate that adaptive coping styles are related to low levels of cortisol over the day, suggesting that neuroendocrine pathways may partly mediate relationships between psychological coping and health.     

Cortisol response to acute trauma and risk of posttraumatic stress disorder

This study sought to characterize the variability of the acute cortisol response following trauma and its relationship to posttraumatic stress disorder (PTSD). Forty eight participants were recruited within 24h of a traumatic accident requiring hospital admission. A saliva sample was collected at 08.00 h and 16.00 h 2 days, 1 month and 6 months after hospital admission, together with 24-h urine collection. Participants completed a dexamethasone suppression test (0.5mg DEX at 21.00 h) at each follow up, together with self-report questionnaires. The Clinician Administered PTSD Scale (CAPS) was administered at 1 and 6 months to identify PTSD. Prevalence of PTSD was 27% at 1 month and 21% at 6 months. PTSD symptoms at 6 months were negatively correlated with salivary cortisol at 08.00 h on day 2 (r=-0.36, p=0.04), but positively correlated with 16.00 h cortisols (r=0.41, p=0.03). A lower rise in cortisol at 08.00 h on day 2 was associated with an increase in risk of PTSD at both 1 month (OR=1.411 (1.017, 1.957)) and 6 months (OR=1.411 (1.066, 1.866)). At 1 month, 70% of participants with PTSD suppressed cortisol to more than 90% of pre-dex levels compared with 25% without PTSD (χ(2)=6.77, p=0.034). Urinary cortisol excretion was not different between groups at any time point. The findings support a hypothesis that sensitization of the HPA axis and enhanced suppression of cortisol following the dexamethasone suppression test are established early in the disease process.     

Seizure-Refractory Period After a Single Stimulation and Inhibition of Seizures After Repetitive Stimulation in the Gerbil: Effects on Blood Cortisol Levels

Summary: Purpose: To determine the epileptic response of gerbils to external shock stimulus, assessing blood cortisol levels as a parameter to determine stress conditions.
Methods: Five sets of two-month-old Mongolian gerbils were stimulated to elicit seizures by the clapping of a sheaf of papers. Stimulation was done once a week over a 10-week period to obtain a stable situation and a similar response in all the animals. Four of the sets were killed to collect blood samples: those not manipulated; those stimulated twice a day for 5 days; those stimulated once to obtain samples immediately after seizure recovery; and those stimulated once to obtain samples 30 min after seizure recovery. Blood samples from the fifth set of animals were taken in vivo from the retro-orbital plexus.
Results: Eliciting seizures with this stimulus, twice a day in a repetitive way, prevented further induced seizures from the second day of stimulation on. Changes in the gerbils'behavior—from exploratory to escape mode—were also observed. The blood cortisol levels found in the sets of animals killed without induced seizures were similar to the others, regardless of whether the animals had been subjected to repetitive stimulation. Additionally, significant decreases in blood cortisol levels were detected in the animals killed immediately and 30 min after recovering from an induced epileptic episode.
Conclusions: The normal refractory period in gerbils can be estimated at 1 h. The lack of correlation between cortisol levels and the inhibition of seizure-elicitation through repetitive stimulation supports the environmental and exploratory hypothesis of seizure generation rather than a stress hypothesis.