Caroline E. Wright

Dispositional optimism and health behaviour in community-dwelling older people: associations with healthy ageing.

OBJECTIVE Dispositional optimism measured with the Life Orientation Test has been associated with a variety of health outcomes. We assessed whether optimism was related to indices of healthy ageing, and if effects were mediated through health behaviours. METHOD A community sample of 128 men and women aged 65 to 80 years was recruited from general practice lists. Optimism and health behaviours were assessed by questionnaire, and healthy ageing indexed by physical health summary scores from the Short Form 36, and by self-rated health. RESULTS Optimism was associated with not smoking, moderate alcohol consumption, brisk walking, and vigorous physical activities (women only), independently of socio-demographic factors and clinical condition. Physical health status was associated with optimism, independently of socio-demographic factors, clinical condition, negative affectivity, and body mass. This effect was attenuated when health behaviours were taken into account. Self-rated health was also positively related to optimism, and this association was not mediated by health behaviours. Neither the optimism nor pessimism subscales of the Life Orientation Test showed as consistent effects as the full scale. CONCLUSIONS We conclude that dispositional optimism is associated with healthy ageing. The relationship between optimism and healthy ageing was only partly mediated by the health behaviours assessed in this sample.

Self-esteem levels and cardiovascular and inflammatory responses to acute stress

Acute mental stress tests have helped to clarify the pathways through which psychosocial factors are linked to disease risk. This methodology is now being used to investigate potentially protective psychosocial factors. We investigated whether global self-esteem might buffer cardiovascular and inflammatory responses to acute stress. One hundred and one students completed the Rosenberg Self-Esteem Scale. Heart rate and heart rate variability (HRV) were recorded for 5 min periods at baseline, during two mental stress tasks, (a speech and a color-word task) and 10, 25 and 40 min into a recovery period. Plasma levels of tumor-necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6) and interleukin-1 receptor antagonist (IL-1Ra) were assessed at baseline, immediately post-stress and after 45 min recovery. Repeated measures analysis of variance demonstrated that heart rate levels were lower across all time points in those with high self-esteem, although heart rate reactivity to stress was not related to self-esteem. There were no differences in baseline HRV, TNF-alpha, IL-6 or IL-1Ra. Multiple linear regressions revealed that greater self-esteem was associated with a smaller reduction in heart rate variability during the speech task, but not the color-word task. Greater self-esteem was associated with smaller TNF-alpha and IL-1Ra responses immediately following acute stress and smaller IL-1Ra responses at 45 min post-stress. In conclusion, global self-esteem is associated with lower heart rate and attenuated HRV and inflammatory responses to acute stress. These responses could be processes through which self-esteem protects against the development of disease.

Stress-induced cytokine responses and central adiposity in young women

Background:Evidence suggests that people who are more responsive to psychological stress are at an increased risk of developing obesity. However, the biological mechanisms underlying this phenomenon are poorly understood. The cytokines leptin, interleukin-1 receptor antagonist (IL-1Ra) and interleukin-6 (IL-6) play a key role in fat metabolism and abnormal circulating levels of these proteins have been reported in obese people and in individuals subject to stress.Objective:This study investigated whether cytokine responses to acute mental stress are associated with adiposity in healthy young women.Design and Subjects:A laboratory study of 67 women, aged 18–25 years, recruited from University College London.Measurements:Height, weight and waist circumference were measured and body fat mass was estimated by bioelectrical impedance body composition analysis. Laboratory mental stress testing was carried out and blood pressure and heart rate were recorded at baseline, during two moderately challenging tasks (Stroop and speech) and during recovery 40–45 min post-stress. Blood samples taken at baseline, immediately post-stress and 45 min post-stress, were used for assessment of circulating cytokines. Saliva samples taken throughout the session were assessed for cortisol.Results:Women who had larger cytokine responses to stress were more abdominally obese than women with smaller cytokine stress responses. Specifically, there was a positive correlation between waist circumference and stress-induced increases in plasma levels of leptin (r=0.35, P<0.05) and IL-1Ra responses (r=0.29, P<0.05). There was also a significant positive correlation between prolonged diastolic blood pressure responses to stress and measures of total and abdominal obesity (r=0.28–0.33, P<0.05).Conclusion:Increased cytokine production could be a mechanism linking stress and abdominal obesity.

Physiological correlates of cognitive functioning in an elderly population

Cognitive decline in old age is not universal or inevitable. Associations have been observed with neuroendocrine function, but the relevance of other physiological processes is unclear. We predicted that impairment of memory in an ageing population would be related to the dysregulation of neuroendocrine and cardiovascular responses. One hundred and thirty-nine participants (65-80 years) were recruited from general practice in London. Two standardised verbal paired-associates recall tasks were administered in order to determine declarative memory performance, and a fluid intelligence task (matrix reasoning) was also performed. Salivary cortisol samples were collected every 10 min, while blood pressure and heart rate were measured before, during and after each task. Illness history and medication use were obtained from medical records. Multiple linear regression analysis, adjusted for age, gender, education, chronic illness, and medication use, revealed that cortisol responses were inversely related to memory performance. Additionally, superior memory was associated with more effective post-task recovery of heart rate (in both men and women) and diastolic blood pressure recovery in men. Cardiovascular recovery effects were independent of covariates, and of levels of heart rate and blood pressure measured during tasks themselves. These associations were also independent of subjective ratings of stress and perceived performance. Neither neuroendocrine nor cardiovascular responses were related to performance of the reasoning task. We conclude that memory in the elderly is associated both with hypothalamic-pituitary-adrenocortical function and cardiovascular regulation. Disturbances of neuroendocrine and hemodynamic function may be related to greater vulnerability to cognitive decline.

Poor sleep the night before an experimental stress task is associated with reduced cortisol reactivity in healthy women.

Sleep disruption is a growing problem that may have serious health effects. As stress-induced increases in cortisol are thought to be a key adaptive process it is important to examine how this response is affected by sleep. The current study investigated the association of four sleep parameters (objective/subjectively measured sleep quality and quantity) and subsequent salivary cortisol reactivity (maximal change from baseline) to an experimental stressor in 53 healthy women. Objective actigraphy monitoring and self-report diaries were used to assess sleep. Results revealed that individuals with lower objective sleep quality (wake percentage during sleep) had a blunted response to the experimental stressor. No associations were found between cortisol reactivity and actigraphy-derived sleep quantity, or either of the self-reported sleep variables. Results are discussed with regard to the possible adverse health effects that may result from poor sleep quality and a blunted cortisol response to stress.

Poor sleep the night before an experimental stressor predicts reduced NK cell mobilization and slowed recovery in healthy women.

Sleep is important for health; however, poor sleep is a growing problem in many Western societies, particularly among women. Alterations in immune function following poor sleep (defined by duration and disruption) may be linked to ill health. Not yet investigated are the possible effects on stress-induced mobilization of lymphocytes. As natural killer (NK) cells are particularly responsive to acute stress, the present study examined whether sleep period duration and percentage of time awake after sleep onset (WASO) the night before a laboratory stressor would predict reduced NK cell mobilization. Sleep was monitored by actigraphy in 39 healthy women. NK cell peripheral blood numbers were determined at baseline (post-20 min rest), 4 min into a Stroop task, immediately post-task and 30 min after task completion. Participants with high WASO had significantly less NK cell mobilization to the stressor and failed to return to baseline levels after 30 min compared to women with low WASO. No effects were found for sleep period duration. Findings raise the possibility that inadequate NK cell mobilization to, and poor recovery from acute stress may be one pathway by which sleep could impact health.

Circulating Leptin and Stress-induced Cardiovascular Activity in Humans

Obesity is associated with an elevated risk of hypertension and cardiovascular disease. The adipocyte hormone leptin, which stimulates energy expenditure in animals by activating the sympathetic nervous system (SNS), is believed to play a role in this association. However, evidence in humans remains sparse. We investigated the relationship between circulating leptin and cardiovascular and inflammatory responses to acute psychological stress in humans. Participants were 32 men and 62 women aged 18–25 years. Cardiovascular activity was assessed using impedance cardiography at baseline, during acute laboratory stress, and during a 45‐min recovery period. Plasma cytokines were measured in blood drawn at baseline and 45‐min poststress. In women only, baseline plasma leptin was significantly associated with stress‐induced changes in heart rate (β = 0.53, P = 0.006), heart rate variability (HRV) (β = −0.44, P = 0.015), and cardiac preejection period (PEP) (β = −0.51, P = 0.004), independent of age, adiposity, and smoking. Womens plasma leptin levels also correlated with stress‐induced elevations in the proinflammatory cytokine interleukin‐6 (IL‐6) (β = 0.35, P = 0.042). Circulating leptin is an independent predictor of sympathetic cardiovascular activity, parasympathetic withdrawal, and inflammatory responses to stress in women. Because cardiovascular and inflammatory stress responses are predictive of future cardiovascular disease, leptin may be a mechanism mediating the adverse effects of stress and obesity on womens cardiovascular health.

Socioeconomic position and cardiovascular and neuroendocrine responses following cognitive challenge in old age

Social disparities in health persist into old age, and differences in psychophysiological responsivity may contribute to this pattern. We assessed whether higher socioeconomic status (SES) is associated with attenuated cardiovascular and neuroendocrine responses elicited by cognitive tasks in old age. We tested 132 community-dwelling men and women aged 65-80 years, divided on the basis of educational attainment into higher and lower SES groups, and compared them with 26 higher educated participants aged 27-42 years. Blood pressure, hemodynamic variables and salivary cortisol were assessed in response to the performance of three cognitive tasks, and then during recovery. Older groups showed smaller heart rate and larger cortisol changes than younger participants. Post-task recovery in heart rate, stroke volume, pre-ejection period, and systolic blood pressure was greatest in the younger group, least in the older/lower education group, and intermediate in the older/higher education group. SES did not influence the increased cortisol responsivity of older participants. The results are consistent with the notion that higher SES protects against age-related changes in cardiovascular response profiles, particularly during recovery.

Psychological Factors Associated with Poor Sleep Prior to Breast Surgery: An Exploratory Study

This study explored the relationship between psychological factors (including intrusive thoughts, anxiety, well-being, depressed mood) and poor sleep the night before surgery. Patients (N = 39) scheduled for breast surgery (mean age = 47 years) wore an actiwatch at home the night before surgery to provide an objective indication of sleep duration and sleep efficiency. Participants also completed 3 measures of their psychological experience during the week prior to surgery. In separate regression analyses, intrusive thoughts, anxiety, and emotional well-being were each related to sleep duration the night before surgery, when controlling for age, body mass index, ethnicity, and marital status. No relationships were found between depressed mood, physical or social well-being, and sleep duration. In a multiple regression model that included all significant variables, intrusive thoughts were most strongly associated with sleep duration. Intrusive thoughts were also significantly related to sleep efficiency. Results suggest that patients’ intrusions about impending surgery are associated with lower sleep duration and sleep efficiency the night before surgery. Additional research is warranted to explore the implications of these associations for patients, as well as possible interventions to improve sleep in this clinical setting.

Poorer sleep quality objectively assessed the night before an experimental stress task predicts reduced natural killer cell mobilization and slowed recovery in healthy women

Decreased time available for sleep and increased sleep disturbance are growing problems for many individuals and may have serious effects on health. Sleep is known to be related to basal immunological levels on a variety of measures, however, little is known about the effects that sleep may have on stress-induced responsivity of immune measures. Stress-induced increases in natural killer (NK) cell numbers in peripheral blood are thought to be a robust, key element of an adaptive process, valuable to health, it is important, therefore, to investigate how this response is affected by sleep. The current prospective study compared participants with high and low sleep quality (median split defined by percentage of minutes awake during sleep) with regard to their subsequent NK cell number responsivity (CD3 CD16/56+ lymphocytes) to a battery of experimental Stroop tasks (15 min stressor period). Objective actigraphy monitoring in 39 healthy women (mean age 37.7 years) assessed sleep the night preceding the stress task. NK cell numbers were determined in peripheral blood samples collected from an intravenous catheter at baseline (post 20 min rest), 4 min into the task, immediately post-task, and 30 min post-task. Consistent with the study hypotheses, results revealed a significant group by time interaction between sleep quality the night before the stress task and NK cell count in response to the stressor (F (2,74) = 5.24, p = .007). Follow-up analyses revealed that participants with poorer sleep experienced a significantly lower increase in NK cells in reaction to the task, in comparison with participants who slept well (F (1, 37) = 4.50, p = .041). In addition, NK cell counts in the low sleep quality group failed to return to their baseline levels following the stressor, indicating a poorer recovery from the task, when compared with the high sleep quality group (F (1,37) = 87.63, p = .006). The effects of task performance, task appraisal, task-induced anxiety, as well as fatigue levels immediately before the stress task and perceived stress over the week before were also statistically explored and rejected as possible mediators of the relationship between sleep quality and NK cell responsivity. The findings suggest that an inadequate reaction to, and poor recovery from stress may act as a pathway by which sleep could, over time, impact long-term health, and wellbeing.