Coping and endothelial dysfunction : the SABPA study
Abstract
Motivation: It has been shown that the coping styles used to cope with psychosocial stress are related to the development of cardiovascular disease, with each coping style having a different physiological effect on the cardiovascular system. A defensive Active Coping (AC) style has a more negative impact on cardiovascular health than an avoidance style in urban black South Africans (hereafter referred to as Africans), owing to the enhanced α-adrenergic response of urban Black Africans. However, contradicting literature exists regarding the long-term effect of specific coping styles on the cardiovascular system. Africans have a greater prevalence of hypertension than their rural Black African and Caucasian counterparts, which has been attributed to the psychosocial stress and changes in diet and lifestyle during urbanization. Previous studies have indicated that endothelium and the vascular structure are adversely affected during psychological stress, leading to cardiovascular pathology. This necessitates research into the effect of AC on endothelial function and vascular remodelling.
Objectives: The purpose of this study was to determine whether the use of a defensive AC style in reaction to stress showed a difference in endothelial function between Africans and Caucasians, and whether the vascular structure is differently affected in these two groups. Methodology: This sub-study forms a part of the SABPA (Sympathetic activity and Ambulatory Blood Pressure in Africans) study, which was conducted from 2008 to 2009. This sub-study is a target population study on African and Caucasian men. The study sample included 80 African and 97 Caucasian men, and the sample was selected to ascertain homogeneity regarding socio-economic status and working environment. The study was approved by the Ethics Review Board of the North-West University, and procedures complied with terms and guidelines of the 2008 Declaration of Helsinki. Each participant completed psychosocial questionnaires, including the Coping Strategy Indicator (CSI) under the supervision of clinical psychologists. Ambulatory blood pressure (24 hours) was recorded with the Cardiotens CE120® apparatus. Anthropometric measurements were performed by level II registered anthropometrists, using standardised methods, and the physical activity of each participant was determined, using the Actical® omnidirectional accelerometer. Blood samples were collected by a registered nurse and information regarding the participant‟s medication use and medical history was obtained. Resting blood samples were assessed for the biochemical markers gamma glutamyl transferase (as a measure of alcohol consumption), total cholesterol, high-density lipoprotein cholesterol, C-reactive protein, haemoglobin A1c, cotinine (as a marker of smoking status), and the endothelial markers nitric oxide metabolites (NOx) and von Willebrand factor (VWF). Blood samples were also collected after participants had completed the Stroop colour-word conflict test, to determine NOx and VWF reactivity to stress. Reactivity was calculated as the percentage increase from the baseline value. HIV/AIDS status was determined, using antibody tests. Left common carotid intima-media thickness of the far wall (L-CIMTf) was measured and the left common carotid cross-sectional wall area (L-CSWA) was calculated via ultrasonography and by applying the appropriate formulas.
Regarding statistical analyses, T-tests were used to describe the population by ethnic status. Of the 80 African and 97 Caucasian men, 59 Africans and 80 Caucasians were identified as using the AC style by the Coping Strategy Indicator. Interaction with CIMT was only demonstrated in AC groups, and further analyses with avoidance groups were ceased. Analyses of covariance (ANCOVA) were used to show significant differences between the ethnically grouped AC men, with significance levels determined using the Benjamini-Hochberg correction for false discovery. Hierarchical regression analyses were performed in different models to determine independent associations of selected structural and functional vascular markers with 24-hour blood pressure markers. Significant values were noted as R ≥ 0.15, adjusted R2 ≥ 0.25, and p ≤ 0.05. Results: Defensive AC African men showed more pronounced endothelial dysfunction when compared to their Caucasian counterparts. Nitric oxide metabolite reactivity was -52.47 % for the AC Africans and 895.33 % for the AC Caucasians (p < 0.0001). VWF reactivity was 15.78 % for the AC Africans compared with 53.58 % for the AC Caucasians (p < 0.001). Furthermore, 24-hour pulse pressure was strongly associated with L-CIMTf in AC Africans (ΔR2 = 0.11 and ΔR2 = 0.08, respectively, p < 0.001) in comparison with the total African group (ΔR2 = 0.08 and ΔR2 = 0.06, respectively, p < 0.05). No associations between ambulatory blood pressure markers were shown for Caucasians. Conclusion: A defensive AC response to stressors facilitates vascular remodelling and endothelial dysfunction in African men. Vascular remodelling was also present in a larger group which included non-AC users, but the effect was greater in defensive AC African men. Therefore, the defensive AC style holds a cardiovascular risk for African men.
Collections
- Health Sciences [2060]