414 research outputs found
Hormonal measurement in psychobiological research
Three peripherally circulating hormones that can be measured in saliva have received growing attention in psychobiology research. Cortisol and dehydoepiandrosterone (DHEA) are steroid hormones indicative of activity in the hypothalamic–pitutary–adrenal (HPA) axis. The third, methoxyindole melatonin, is the hormonal product of the pineal neuroendocrine system. The development of reliable methods for salivary hormone assessment was a key turning point for psychobiology research, as it enabled new approaches to the study of a wide range of individual difference factors. These biological indices provide meaningful objective measures that can be analysed in parallel to self-reported variables (e.g. stress/well-being) as well as sociodemographic, developmental, psychological and health variables. Saliva is an easy-to-access biological fluid, collection of which is convenient and does not require trained personnel. Indeed, participants can be shown how to undertake self-collection of samples, which enables repeated sampling in ambulatory studies (with resultant ecological validity) as well as in relation to experimental manipulations within the laboratory. The purpose of this chapter is to guide the psychobiology researcher on appropriate approaches and methodologies for using salivary hormone measures for meaningful investigation of a virtually limitless range of potential research questions
Acute reduction in secretory immunoglobulin A following smoking cessation
Smokers report an increase in upper respiratory infections in the early phase of stopping smoking. One possible cause is a depletion in secretory immunoglobulin A (S-IgA) which has been observed in one study. The present study sought to establish this finding in smokers using nicotine patches. Ninety-two smokers, trying to stop smoking, were assessed whilst smoking and for up to six weeks of abstinence. All smokers were prescribed 15 mg 16-h nicotine patches. Among abstinent smokers, changes in S-IgA and saliva volume were assessed. During the preliminary analyses, we observed that for the pre-smoking cessation measure a longer time since the last cigarette was significantly related to Lower S-IgA levels (P = 0.006). Consequently, the main analysis, of changes in S-IgA from pre-cessation to post-cessation, was confined to those who had smoked within 0.5-1.5 h of the pre-cessation measure (n = 51). There was a significant decline in S-IgA, relative to pre-smoking abstinence levels, following abstinence of one day (P = 0.027), but Levels returned to pre-abstinence values after one week. There was no evidence of any significant changes in saliva volume following smoking cessation, relative to pre-cessation levels. Users of 15 mg patches are likely to experience a decline in S-IgA levels on the first day of smoking cessation, independent of saliva volumes, and this decline in S-IgA is Likely to occur acutely, within the first few hours of smoking abstinence. This acute drop in S-IgA appears to stem from a factor other than depletion of nicotine from the body. The observed decrease in S-IgA may help to explain the increased susceptibility of smokers to upper respiratory tract infections in the immediate post-cessation period. (C) 2004 Elsevier Ltd. ALL rights reserved
Magnetic flux reversal in laminated Ni-Fe films
Anomalously fast flux reversal has been observed in films made of Ni-Fe layers separated by SiO. The speed of reversal increases as the number of identical layers of Ni-Fe increases. For a 5-layer film, the anomalous speed is observed in films with the SiO thickness as great as 1600 Å. Reversal time curves presented as a family of curves of 1/τ = fh_┴ with h_s as a parameter have two regions. The high-drive region has a lower slope in the laminated films when compared to the single-layer films. For this family of curves, a switching coefficient S_(w') can be defined, as the inverse slope, in a manner similar to the definition of S_w for 1/τ = f(h_(s)) with h_┴ as a parameter. For films with from two to five layers, Sw' is constant at 1 x 10^(-3) μs and is smaller by an order of magnitude for the single-layer films. A dual loop experiment is used to confirm that coherent rotation is not a dominant mechanism. It is concluded that a model must satisfy the following criteria to successfully describe flux reversal in the laminated films: It must provide rapid flux reversal for fields less than H_k, an insensitivity to transverse fields either constant or pulsed, and an interaction that can survive over a wide range of SiO thicknesses
Physical fitness and prior physical activity are both associated with less cortisol secretion during psychosocial stress
Background: Evidence linking fitness and decreased psychosocial stress comes from studies of athletes and typically relies upon self-report measures. Furthermore, there is little evidence regarding the impact of physical activity (PA) prior to a stressor. The aims of this study were to determine whether fitness and prior PA influence cortisol concentrations during psychosocial stress.
Methods: Seventy-five non-athletic participants took part in a submaximal walk prior to the Trier Social Stress Test for Groups (TSST-G). During the walk, fitness was assessed using heart rate (HR). A further 89 participants took part in the TSST-G without the walk. Stress responsiveness was assessed using salivary cortisol collected at 10-min intervals on seven occasions.
Results: Hierarchical multiple regression revealed that average walking HR accounted for 9% of the variance in cortisol secretion (P = .016), where a higher HR was associated with higher cortisol secretion. Between-subjects ANCOVA revealed that the walking group had a significantly lower cortisol secretion than the non-walking group (P = .009).
Conclusions: These findings indicate that fitter individuals have reduced cortisol secretion during psychosocial stress. They also indicate that prior PA can reduce cortisol concentrations during psychosocial stress and are suggestive of a role of PA in reducing the impact of stress on health
Biological stress regulation in female adolescents: a key role for confiding
Attachment behaviors play a critical role in regulating emotion within the context of close relationships, and attachment theory is currently used to inform evidence-based practice in the areas of adolescent health and social care. This study investigated the association between female adolescents’ interview-based attachment behaviors and two markers of hypothalamic–pituitary–adrenal axis activity: cortisol and dehydroepiandrosterone (DHEA). Unlike the classic stress hormone cortisol, there is very limited investigation of DHEA—a quintessential developmental hormone—in relation to attachment, especially in adolescents. Fifty-five healthy females mean age 14.36 (±2.41) years participated in the attachment style interview. A smaller cortisol awakening response was related to anxious attachment attitudes, including more fear of rejection, whereas greater morning basal DHEA secretion was only predicted by lower levels of reported confiding in one’s mother. These attachment–hormone relationships may be developmental markers in females, as they were independent of menarche status. These findings highlight that the normative shifts occurring in attachment to caregivers around adolescence are reflected in adolescents’ biological stress regulation. We discuss how studying these shifts can be informed by evolutionary– developmental theory
Detailed time course of the cortisol awakening response in healthy participants
The cortisol awakening response (CAR) can be assessed from saliva samples collected at home, which
confers ecological validity but lacks researcher oversight. Participant non-adherence to requested saliva
sampling regimes leads to inaccurate CAR estimates. Moderate sampling delays of just 8 (5–15) min
between awakening and commencement of saliva sampling are reported to result in over-estimated
CAR magnitude and earlier peaking. This has been attributed to an observed ‘latent’ period in which
cortisol secretion does not increase for up to 10-min after awakening. Replication of this finding
is essential as the findings have considerable implications for CAR research. Healthy participants
(n = 26) collected saliva samples at 5-min intervals for 60 min on 2 consecutive typical weekdays.
Full electronic monitoring of awakening and sampling enabled exclusion of non-adherent data (i.e.,
delays of greater than 5 min between awakening and collection of the first sample). In the 0–15 min
post awakening segment of the CAR a quadratic effect was observed, with no difference between
the awakening and 5 and 10 min samples. Moderate sampling delays will shift assessment of the
CAR just sufficiently along the time axis to not impact upon measurement of the first sample but
to remove the immediate post-awakening latent period from CAR estimates—whilst retaining later
estimates of elevated cortisol secretion. The implication from these results is that accurate CAR
measures can only be determined from data with strict adherence to commencement of saliva sampling
following awakening
Anxious attachment style predicts an enhanced cortisol response to group psychosocial stress
Insecure attachment style is associated with poor health outcomes. A proposed pathway implicates the hypothalamic pituitary-adrenal axis (HPA-axis), dysregulation of which is associated with a wide range of mental and physical ill-health. However, data on stress reactivity in relation to attachment style is contradictory. This relationship was examined using the novel Trier Social Stress Test for groups (TSST-G): a group based acute psychosocial stressor. Each participant, in the presence of other group members, individually performed public speaking and mental arithmetic tasks. Seventy-eight healthy young females (20.2 ± 3.2 years), in groups of up to six participants completed demographic information and the Vulnerable Attachment Style Questionnaire (VASQ), and were then exposed to the TSST-G. Physiological stress reactivity was assessed using salivary cortisol concentrations, measured on seven occasions at 10-min intervals. Vulnerable attachment predicted greater cortisol reactivity independent of age, smoking status, menstrual phase and body mass index. Supplementary analysis indicated that insecure anxious attachment style (high scores on the insecurity and proximity-seeking sub-scales of the VASQ) showed greater cortisol reactivity than participants with secure attachment style. Avoidant attachment style (high scores for insecurity and low scores for proximity seeking) was not significantly different from the secure attachment style. Attachment style was not associated with the timing of the cortisol peak or post-stress recovery in cortisol concentrations. These findings in healthy young females indicate subtle underlying changes in HPA axis function in relation to attachment style and may be important for future mental health and well-being
The cortisol awakening response predicts a same-day index of executive function in healthy young adults
The cortisol awakening response (CAR) is associated with various aspects of cognition, including executive function, in older adult and clinical samples. However, the association between these variables in the healthy functioning population is not well understood due to the limited number of appropriately controlled studies. This study explored the association between the CAR and a set shifting index of executive function in 55 (44 females) healthy participants aged 20.2 ± 3.0 years. Notoriously, assessment of the CAR from self-collected saliva samples within the domestic setting is subject to sample timing error, so electronic monitoring of both awakening and sampling times were employed. Participants attended the laboratory in the afternoon of CAR assessment for testing on the Attention Switching Task of the CANTAB neuropsychological testing battery. A positive association was found between CAR magnitude and attention-switching performance in the afternoon of the same day. This was independent of known relevant CAR covariates, but only evident in CAR data collected without delay exceeding 8 min post-awakening. These findings offer insight into a potential role for the CAR in modulating cognitive functions associated with the pre-frontal cortex
Hair cortisol concentrations in relation to ill-being and well-being in healthy young and old females
Hair cortisol concentration (HCC) provides a retrospective measure of long-term (i.e. over a period of months)
cortisol secretion and has been shown to be elevated in relation to chronic stress conditions. However associations
in healthy participants with subjective ill-being are less clear and associations with well-being have not
been explored. The current study examined HCC in relation to independent comprehensive measures of illbeing
(stress, depression, anxiety) and well-being (subjective happiness, life satisfaction, psychological wellbeing)
in healthy young and old females (mean ± SD: 19.5 ± 2.2 years and 78.6 ± 6.7 years respectively, total
N = 115). The data supported evidence of increased total cortisol secretion with increased age. No association
between ill-being and HCC was found in either the young or older group of participants. A positive association
between HCC and well-being was found in the older participant group which was independent of ill-being and
potential confounds. These findings do not support associations between HCC and ill-being in healthy young
or old females. However the results suggest that HCC is able to distinguish levels of well-being in healthy older
females
Salivary cortisol, stress and arousal following five weeks training in kinesthetic meditation to undergraduate students
- …