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

https://doi.org/10.1016/j.biopsycho.2004.07.008Get rights and content

Abstract

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.

Introduction

There is an inverse relationship between coronary heart disease and socioeconomic status (SES), with higher levels of disease incidence and mortality in lower SES groups (Kaplan and Keil, 1993, Marmot and Bartley, 2002). There are also higher levels of subclinical atherosclerosis in lower SES groups (Lynch et al., 1995), and these associations are only partly accounted for by health behaviors such as smoking and physical inactivity (Lynch et al., 1996, Steenland et al., 2002). It has been proposed that low SES is characterized by greater activation of autonomic and neuroendocrine processes that in turn promote inflammatory responses, metabolic dysfunctions and atherogenesis (McEwen and Seeman, 1999, Steptoe and Marmot, 2002).

Laboratory mental stress testing has been used to evaluate SES differences in cardiovascular and neuroendocrine responsivity, but results to date have been mixed, with lower SES being associated with both increased and decreased reactivity (Steptoe and Marmot, 2002). Analyses of post-task recovery may show more consistent effects. We recently tested 228 middle-aged men and women who were members of the Whitehall II epidemiological cohort, using occupational position as the indicator of SES. Differences in blood pressure reactivity were observed in women but not men, with greater systolic and diastolic pressure reactions in lower SES participants (Steptoe et al., 2002). In addition, men and women in lower SES categories showed impaired post-stress recovery in systolic and diastolic pressure and in heart rate variability, suggesting that lower SES might induce failure of homeostatic regulation. The association of lower SES with delayed cardiovascular recovery has been confirmed in a second investigation (Brydon et al., 2004), and is consistent with the notion of greater allostatic load in lower SES groups (Seeman et al., 2004a, Seeman et al., 2004b). By contrast, no differences in salivary cortisol stress responses were observed (Kunz-Ebrecht et al., 2003). Other studies of white women (Adler et al., 2000) and African American men (Kapuku et al., 2002) have also shown no SES differences in cortisol responses to acute stress, although Kristenson et al. (2001) observed lower cortisol responsivity in lower SES men from Sweden and Lithuania.

Our studies and others in the literature were carried out with men and women of working age. However, SES differences in cardiovascular disease persist and are even accentuated in absolute terms in old age (Manton et al., 1997, Marmot and Shipley, 1996). Advancing age is characterized by a number of changes in cardiovascular and neuroendocrine regulation. Heart rate responses to mental stress are typically reduced at older ages (Barnes et al., 1982, Ditto et al., 1987, Garwood et al., 1982, Steptoe et al., 1996). Blood pressure results have been less consistent, but several studies have shown that systolic pressure reactions increase with age (Ditto et al., 1987, Gotthardt et al., 1995, Steptoe et al., 1990). Heart rate variability is lower in old age (Hrushesky et al., 1984, Kingwell et al., 1994), but evidence concerning changes in responses to behavioral stimuli have not been reported. These cardiovascular responsivity changes appear to be due to reduced cardiac reactivity to sympathetic stimulation (Stratton et al., 1992), but there is also some evidence that cardiac vagal control is reduced with advancing age (Stratton et al., 2003).

Average cortisol levels over 24 h tend to increase with age (Van Cauter et al., 1996), but changes in stress responsivity with age are less well understood. Animal research would suggest poorer post-stress recovery in cortisol in older individuals due to a decrease in resilience (Seeman and Robbins, 1994), but recovery effects are difficult to study in experimental settings owing to the prolonged time course of responses. Gotthardt et al. (1995) observed larger cortisol responses to a signal detection task in older participants, while the reverse pattern was described by Nicolson et al. (1997) in responses to a speech task. No differences in cortisol response to the Trier Social Stress Test with age have been noted in studies of men (Rohleder et al., 2002) and women (Kudielka et al., 1999). Sex differences in age-related changes in response to a battery of cognitive challenges were reported by Seeman et al. (2001), with older women showing larger responses than older men.

One way that higher SES might contribute to reducing risk of coronary heart disease with advancing age is by maintaining the cardiovascular regulatory profile of younger individuals. We therefore carried out a study in which cardiovascular and cortisol responses during the mild challenge of cognitive testing were compared in older adults divided into higher and lower SES groups. Educational attainment was used as the marker of SES. A third group of younger, higher educated men and women was also tested. We hypothesized that old age would be associated with diminished heart rate and enhanced blood pressure responses, but that these differences would be greater in lower SES older individuals. We also predicted that in old age, higher SES participants would show more effective post-task recovery in blood pressure than lower SES groups, as has been observed in middle-aged adults. We anticipated that enhanced systolic pressure reactions in the presence of reduced heart rate responses might be due in part to greater increases in stroke volume. Baseline differences in heart rate variability and in indices of myocardial contractility were expected, but no firm predictions concerning differences in responsivity with respect to age or SES were made. We hypothesized that cortisol responses would be greater in older individuals, and that if higher SES protects against age-related changes, then responsivity would be less in higher than lower SES groups.

Older age is characterized by increasing body mass, chronic illness and medication use. Selecting older participants who are free of chronic illness would introduce bias into the comparison. We therefore measured body mass index (BMI) and collected information concerning medication and chronic illness from patients and physicians’ notes, and included these factors as covariates in the cardiovascular and neuroendocrine analyses.

Section snippets

Participants

Participants in this study were 132 men and women aged 65–80 years (mean 70.5 years), and 26 aged 27–42 years (mean 33.5 years). The older participants were recruited from two general practices in the London area. The patient databases were searched for men and women aged between 65 and 80 who were dwelling in the community, and had no record of coronary heart disease, tachycardia, aortic valve regurgitation, dementia, or psychosis, and no cancer evident in the last 5 years. Names were selected

Results

The characteristics of participants of the three groups are summarized in Table 1. Sixty seven men and 91 women took part, and the proportion of men and women did not differ across groups. The average age of the two older groups was just above 70 years. All the participants were of white European origin. The three groups differed not only in objective SES defined by education, but also in self-reported SES. The younger and older/higher education groups rated themselves higher on the social

Discussion

This study was based on the hypothesis that higher SES might protect against age-related changes in cardiovascular and cortisol dysregulation during cognitive performance. Lower SES is associated with premature development of serious illnesses such as coronary heart disease, hypertension and diabetes, so protective factors might be expected to operate in elderly higher SES individuals. Lower SES groups adopt older age identities than more affluent groups, and old age is perceived as commencing

Acknowledgements

This study was supported by the Medical Research Council. We are grateful to Dr Steve Iliffe for assistance with patient selection and recruitment, and to Elizabeth Cort, Lindsey Emmerson, and Marlous Knol for their involvement with data collection, to Clemens Kirschbaum for analysing the cortisol samples, and to Oliver Foese for advice about cognitive testing.

References (47)

  • N.E. Adler et al.

    Relationship of subjective and objective social status with psychological and physiological functioning: preliminary data in healthy white women

    Health Psychology

    (2000)
  • R.F. Barnes et al.

    The effects of age on the plasma catecholamine response to mental stress in man

    Journal of Clinical Endocrinology Metabolim

    (1982)
  • A.E. Barrett

    Socioeconomic status and age identity: the role of dimensions of health in the subjective construction of age

    Journals of Gerontology B Psychological Science and Social Science

    (2003)
  • D.J. Crews et al.

    A meta-analytic review of aerobic fitness and reactivity to psychosocial stressors

    Medicine and Science in Sports and Exercise

    (1987)
  • M. Garwood et al.

    Autonomic nervous system function and aging: response specificity

    Psychophysiology

    (1982)
  • U. Gotthardt et al.

    Cortisol, ACTH, and cardiovascular response to a cognitive challenge paradigm in aging and depression

    American Journal of Physiology

    (1995)
  • T.M. Hess et al.

    The impact of stereotype threat on age differences in memory performance

    Journal of Gerontology B Psychological Science and Social Science

    (2003)
  • W.J.M. Hrushesky et al.

    The respiratory sinus arrhythmia: a measure of cardiac age

    Science

    (1984)
  • T.W. Kamarck

    Recent developments in the study of cardiovascular reactivity: contributions from psychometric theory and social psychology

    Psychophysiology

    (1992)
  • G.A. Kaplan et al.

    Socioeconomic factors and cardiovascular disease: a review of the literature

    Circulation

    (1993)
  • G.L. Kapuku et al.

    Relationships among socioeconomic status, stress induced changes in cortisol, and blood pressure in African American males

    Annals of Behavioral Medicine

    (2002)
  • A. Kaufman et al.

    Essentials of WAIS-III Assessment

    (1999)
  • B.A. Kingwell et al.

    Heart rate spectral analysis, cardiac norepinephrine spillover, and muscle sympathetic nerve activity during human sympathetic nervous activation and failure

    Circulation

    (1994)
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