Social and emotional influences on cardiovascular vulnerability in women : exploration of biological mechanisms

Abstract

Background: During the last decades evidence has been accumulating that psychosocial factors including social isolation, depressive symptoms and work stress increase risk for CHD incidence and prognosis. Although depression has been shown to be around twice as common in women as in men and women with CHD have a poorer prognosis than men in terms of both physical health and psychosocial recovery, most studies of psychosocial risk factors and CHD, have been performed in predominantly male populations. Furthermore, knowledge on possible mechanisms explaining these relations is insufficient, especially in women.

Aims of the study: 1) To examine the effect of social isolation on extent and severity of CHD in women, 2) To examine the effect of psychosocial factors (including social isolation, depressive symptoms, marital- and work stress) on prognosis of CHD in women, 3) To examine the associations between psychosocial factors (including social isolation and depressive symptoms) and physiological risk factors for CHD (including the Metabolic Syndrome and heart rate variability) in women.

Material and Methods: This doctoral thesis is based on data from the Stockholm Female Coronary Risk (FemCorRisk) study. The FemCorRisk study is a population-based case-control study which comprises all women aged 65 years or younger who were admitted for an acute event of CHD between 1991 and 1994 in any of the coronary care units of all hospitals in the greater Stockholm area. Healthy controls from the census register were matched with CHD patients with regard to age and catchment area. To study the association between social isolation and extent and severity of CHD cross-sectional analyses on the subgroup of the CHD-patients in the Stockholm Female Coronary Risk Study that underwent quantitative coronary angiography were done. To study the effect of psychosocial factors CHD prognosis, CHD patients were followed for 5 years after an acute event of CHD. Deaths from CHD, recurrent myocardial infarctions, and revascularizations were monitored. To study the associations between psychosocial factors and physiological risk factors for CHD, cross-sectional analyses of the population-based healthy women (control group) of the FemCorRisk study were done.

Results: Social isolation is associated with increased vulnerability to CHD in women. Poor social support (as measured by standardized questionnaires) was associated with extent and severity of CHD, worse CHD prognosis and atherogenic physiological CHD risk profile (central obesity, high blood pressure, hemostatic dysfunction and a decreased heart rate variability). Other psychosocial factors associated with worse CHD prognosis were depressive symptoms and marital stress. After adjustment for standard CHD risk factors, the risk ratio for stenosis greater than 50% among women in the lower relative to women in the upper social integration quartile was 2.5 (95% CI 1.2-5.3), while that of women in the two middle quartiles was 2.0 (95% CI 0.9-4.3) (p-trend = 0.003). In addition, the multivariately adjusted hazard ratio for a recurrent event associated with low (lowest quartile) as compared to high social integration (upper quartile) was 2.3 (95% CI 1.2-4.5). Women who were socially integrated (upper two quartiles) and had no or just one depressive symptom had an actuarial probability of 91% (95% CI 79% to 97%) of being free from recurrent cardiac events after five years of the follow-up, compared to 65 % (95% CI 55% to 73%) for women who both lacked social integration (lowest two quartiles) and had two or more depressive symptoms. Similarly, after five years of follow-up, women who reported no marital stress (lowest quartile) and no or just one depressive symptom had an actuarial probability of 93% (95% CI 75% to 98%) of being free from recurrent events, compared to 62 % (95% CI 52% to 71%) for women who reported both marital stress and two or more depressive symptoms. In the population-based healthy control group, poor social support was associated with the Metabolic Syndrome and decreased heart rate variability. Such associations were less clear for depressive symptoms.

Conclusions: Social isolation was consistently associated with CHD vulnerability in women, The Metabolic Syndrome and decreased heart rate variability are suggested as possible mediaters of this association. Social isolation and marital stress were independent from depressive symptoms associated with an increased risk for recurrent events. The worst CHD prognosis was found in women with combinations of these adverse psychosocial factors. Findings in this thesis underline the importance of psychosocial factors in women with CHD. Future intervention studies should focus on improving these factors along with the more traditional CHD risk factors.