Positive affect and biological function in everyday life

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Abstract

There is accumulating evidence that positive affect may protect against ill–health and risk of disease. Here, we summarize results from our research program into the biological correlates of positive affect. Data have been collected from middle-aged men and women, with positive affect assessed through repeated ratings of happiness over a working day. The results indicate that greater happiness is associated with lower salivary cortisol both on working and nonworking days, reduced fibrinogen stress responses, and lower ambulatory heart rate in men. These effects are independent of age, socioeconomic status, smoking, body mass and psychological distress. A 3 year follow-up has confirmed these biological associations with happiness. In addition, we found that happiness was inversely related to ambulatory systolic blood pressure on follow-up, again independently of potential confounders including negative affect. These results suggest that positive affective states are linked to favorable health outcomes through their influence on health-related biology, and may be particularly relevant in old age, when the accumulation of risk factors leads to increased risk of chronic disease.

Introduction

There is compelling evidence that negative affective traits, such as depression and anxiety are associated with adverse health outcomes. Longitudinal observational studies have established relationships with cardiovascular disease risk, diabetes, progression of disability, and premature mortality [9], [15]. A notion that is being increasingly studied is the converse possibility that positive well-being and affect have favorable effects, reducing the rate of premature mortality and the development of various physical illnesses [2], [7]. Such effects may be particularly relevant to older sectors of the population, among whom aging processes and the accumulation of risk factors lead to a high incidence of chronic disease. The maintenance of positive well-being with advancing years may help protect against in age-related morbidity.

If positive affect is associated with good health, the question arises as to which pathways underlie this relationship. This question has lead to research into the biological correlates of positive affect. Some studies have indicated that positive affect is associated with characteristic patterns of electrocortical activation [16], although findings are not entirely consistent [17]. Positive mood in everyday life also appears to be associated with high levels of central serotonergic function [1], a potentially important relationship in view of the links between deficient serotonergic function and higher body mass index (BMI), insulin resistance and blood pressure [5]. Neuroendocrine and immune responses have also been examined as possible mediators of the health effects of positive affect with some positive results [7].

Since positive and negative affect are inversely correlated, the demonstration that positive states are associated with reduced biological responses may be trivial, merely reflecting the absence of negative affect [7]. The conclusions that can be drawn from studies that have measured the biological correlates of positive affect without controlling for negative states are therefore ambiguous. We recently reported an investigation of late middle-aged men and women in which positive affect was associated with lower cortisol, lower heart rate, and reduced fibrinogen stress responsivity [13]. These effects were independent of known confounders, such as age and socioeconomic position, and also of negative mood states as indexed by the General Health Questionnaire (GHQ). In this article, we provide a summary of these findings, then present new data demonstrating the stability of the biological correlates of positive affect over a 3 year period.

Section snippets

Biological function in everyday life

Several methods are used to study biological factors in relation to psychological variables, such as positive affect, including laboratory experiments and epidemiological surveys. A particularly attractive strategy is measurement of biological function under naturalistic conditions, since it overcomes some of the limitations of other methods. The criticism is often made of laboratory studies that the situation is unrepresentative of real life, and that the acute responses observed

Whitehall psychobiology study

The analyses that we have carried out were part of the Whitehall psychobiology study, an investigation of the biological processes associated with psychosocial risk factors for coronary heart disease [12]. This study involved monitoring of biological function in everyday life and measurement of responses to mental stress testing in the laboratory in a subgroup of the larger Whitehall II epidemiological cohort. A major focus was on socioeconomic disparities in health, and the greater

Cross-sectional findings

The study involved men and women aged 47–59 years. All were of white European origin, living within the London area, and with no history of coronary heart disease or hypertension. Satisfactory happiness ratings were provided by 216 of the 227 participants (116 men and 100 women). The remainder either did not carry out ambulatory monitoring for the complete day and evening, or did not fill in the accompanying diary. We computed the proportion of happiness ratings for each person that were

Longitudinal associations

We have recently had an opportunity to assess the consistency of the associations between happiness and biological function in everyday life in a longitudinal study. Three years after the original ambulatory monitoring phase, 162 of the 216 participants agreed to a further round of assessment. The majority of people who were not retested had either withdrawn from the full Whitehall II study, had moved out of the London area so were no longer accessible, or refused because they had found the

Conclusions

This analysis of 3 year follow-up data from our original study group suggests that the associations between biological responses and happiness are quite robust. The cortisol gradient across quintiles of happiness was similar to that observed at Time 1, although the strength of relationship was reduced. The smaller sample size may account in part for this diminution of statistical power. However, the consistency is impressive, bearing in mind that the activities of a typical day had greatly

Acknowledgements

We are grateful to Michael Marmot for collaborating with this work, to Lena Brydon, Sabine Kunz-Ebrecht, Pamela J. Feldman, Bev Murray, Natalie Owen, Gonneke Willemsen, and Caroline Wright for their involvement in data collection, and Clemens Krischbaum for analysis of cortisol samples. This research was funded by the Medical Research Council. Andrew Steptoe is supported by the British Heart Foundation, and Jane Wardle by Cancer Research, UK.

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