Chronic defensiveness and neuroendocrine dysfunction reflect a novel cardiac troponin T cut point: The SABPA study.

Background: Sympatho-adrenal responses are activated as an innate defense coping (DefS) mechanism during emotional stress. Whether these sympatho-adrenal responses drive cardiac troponin T (cTnT) increases are unknown. Therefore, associations between cTnT and sympatho-adrenal responses were assessed. Methods: A prospective bi-ethnic cohort, excluding atrial fibrillation, myocardial infarction and stroke cases, was followed for 3 years (N=342; 45.6±9.0 years). We obtained serum high-sensitive cTnT and outcome measures [Coping-Strategy-Indicator, depression/Patient-Health-Questionnarie-9, 24h BP, 24h heart-rate-variability (HRV) and 24h urinary catecholamines]. Results: cTnT levels of the cohort remained similar over 3 years but recovery to cTnT-negative levels was higher in Blacks. Blacks showed moderate depression (45% vs. 16%) and 24h hypertension (67% vs. 42%) prevalence compared to Whites. A receiver-operating-characteristics cTnT cut-point 4.2 ng/L predicting hypertension in Blacks was used as binary exposure measure in relation to outcome measures [AUC 0.68 (95% CI 0.60-0.76); sensitivity/specificity 63/70%; P≤0.001]. In cross-sectional analyses, elevated cTnT was related to DefS [OR 1.08 (95% CI 0.99-1.16); P=0.06]; 24h BP [OR 1.03-1.04 (95% CI 1.01-1.08); P≤0.02] and depressed HRV [OR 2.19 (95% CI 1.09-4.41); P=0.03] in Blacks, but not in Whites. At 3 year follow-up, elevated cTnT was related to attenuated urine norepinephrine:creatinine ratio in Blacks [OR 1.46 (95% CI 1.01-2.10); P=0.04]. In Whites, a cut point of 5.6 ng/L cTnT predicting hypertension was not associated with outcome measures. Conclusion: Central neural control systems exemplified a brain-heart stress pathway. Desensitization of sympatho-adrenal responses occurred with initial neural- (HRV) followed by neuroendocrine dysfunction (norepinephrine:creatinine) in relation to elevated cTnT. Chronic defensiveness may thus drive the desensitization or physiological depression, reflecting ischemic heart disease risk at a 4.2 ng/L cTnT cut-point in Blacks

Association between objectively measured physical activity, chronic stress and leukocyte telomere length

BACKGROUND: Physical activity (PA) attenuates chronic stress and age-related and cardiovascular disease risks, whereby potentially slowing telomere shortening. We aimed to study the association between seven-day objectively measured habitual PA, chronic stress and leukocyte telomere length. METHODS: Study participants were African (n=96) and Caucasian (n=107) school teachers of the Sympathetic activity and Ambulatory Blood Pressure in Africans study. All lifestyle characteristics (including PA) were objectively measured. The general health questionnaire and serum cortisol were assessed as psychological and physical measures of chronic stress. Leukocyte telomere length was measured using the quantitative real-time polymerase chain reaction. RESULTS: Africans had significantly shorter telomeres (p<.001) and greater psychological distress (p=0.001) than Caucasians, whereas no group difference was seen for cortisol levels. Higher age [ß=-0.28 (-0.40, -0.16), p≤0.000], higher alcohol consumption [ß=-0.21 (-0.36, -0.08), p=0.003] and increased central obesity [ß=-0.17 (-0.30, -0.03), p=0.017] were all significantly associated with shorter telomeres. Habitual PA of different intensity was not significantly associated with markers of chronic stress or telomere length. However, more time spent with light intensity PA time was significantly and independently correlated with lower waist circumference (r=-0.21, p=0.004); in turn, greater waist circumference was significantly associated shorter telomeres [β=-0.17 (-0.30, -0.03), p=0.017]. CONCLUSION: Habitual PA of different intensity was not directly associated with markers of chronic stress and leukocyte telomere length in this biethnic cohort. However, our findings suggest that light intensity PA could contribute to lowered age-related disease risk and healthy ageing by facilitating maintenance of a normal waist circumference

Progression of cardiovascular risk factors in black Africans: 3 year follow up of the SABPA cohort study

Recent work identified a high prevalence of modifiable risk factors for cardiovascular disease (CVD) among urban black South Africans. The aim was to track the progression of CVD risk factors in a multiethnic sample of South Africans. Participants were 173 black (aged 47.5 ± 7.8 yrs) and 186 white teachers (aged 49.6 ± 9.9 yrs) that were examined at baseline and 3 years follow-up. Blacks demonstrated a substantially higher prevalence of composite CVD burden (defined as history of physician diagnosed heart disease, use of anti-hypertensives, anti-diabetic, or statin medications at either time point) compared to whites (49.1 vs. 32.0%, p ¼ 0.012) respectively. After controlling for baseline, the black participants demonstrated greater increases in 24 h systolic and diastolic blood pressure, total cholesterol, fasting glucose, fibrinogen, D-dimer, and waist circumference in comparison with whites. In summary, an adverse progression of CVD risk factors was observed in the whole sample, although to a larger degree in black participants. Aggressive treatment strategies for controlling risk factors in black Africans are needed to reduce the increasing burden of CVD in South Africa

The association between seven-day objectively measured habitual physical activity and 24 hr ambulatory blood pressure: the SABPA study

Few studies have examined objective physical activity in relation to 24 hour ambulatory blood pressure (BP). We aimed to assess the association of seven-day objectively measured habitual physical activity with ambulatory BP in a sample of African and Caucasian school teachers (n=216, age 49.7 yrs) from the Sympathetic Activity and Blood Pressure in Africans prospective cohort study. Hypertension (ambulatory systolic BP≥130 and / or Diastolic BP≥80 mmHg) was prevalent in 53.2% of the sample, particularly in black Africans. The hypertensive group spent significantly more awake time in sedentary activity (51.5 vs. 40.8 % of waking hours, p=0.001), as well as doing less light (34.1 vs. 38.9%, p=0.043) and moderate- (14.0 vs. 19.7%, p=0.032) intensity activities compared with normotensives, respectively. In covariate adjusted models, light intensity activity time was associated with lower 24-hr and day-time ambulatory systolic BP (β=-0.15 ,95% CI: -0.26, -0.05, p=0.004; β=-0.14, -0.24, -0.03, p=0.011) and diastolic BP (β=-0.14, -0.25, -0.03, p=0.015; β=-0.13 ,-0.24, -0.01, p=0.030), as well as resting Systolic BP (β=-0.13 ,-0.24, -0.01, p=0.028). Sedentary time was associated only with 24 hr Systolic BP (β=0.12; 0.01, 0.22), which was largely driven by night time recordings. Participants in the upper sedentary tertile were more likely to be “non-dippers” (odds ratio=2.11, 95% CI, 0.99, 4.46, p=0.052) compared with the lowest sedentary tertile. There were no associations between moderate to vigorous activity and BP. In conclusion, objectively assessed daily light physical activity was associated with ambulatory BP in a mixed ethnic sample

Chronic depression symptoms and salivary NOx are associated with retinal vascular dysregulation: the SABPA study.

Background Depression has been associated with impaired nitric oxide (NO)-mediated vasodilation and vascular dysregulation (VD). Whether depression and NO levels will disturb retinal hemodynamics is not clear. Objectives and methods Associations between the retinal vasculature, diastolic ocular perfusion pressure (DOPP) as measure of hypoperfusion, NO metabolites (NOx) and depression symptoms were assessed. Chronic VD risk markers [depression symptoms (Patient Health Questionnaire/PHQ-9 ≥ 10) and 24h pulse pressure] were determined in a bi-ethnic cohort (n=313; 48.6 ± 9 years; 53.9% men). At 3 year follow-up, retinal vessel calibre and retinopathy signs were quantified from digital images. Salivary NOx, a novel approach, was obtained pre- and post-flicker light-induced provocation (FLIP). DOPP was defined as diastolic blood pressure minus intraocular pressure. Results Chronic VD risk was evident in Blacks opposed to acute risk in Whites (P<0.05). At follow-up, retinopathy (Blacks 60.4%/Whites 39.6%), lower pre-FLIP (µM) and higher post-FLIP NOx (%), arteriolar narrowing and wider venular calibre values were evident in Blacks compared to Whites, independent of confounders. A wider venular calibre, an index of stroke risk, was associated with chronic depression symptoms [cut point 248 MU: Area under the curve 0·61 (95% CI: 0·51, 0·72); 71% sensitivity; 55% specificity] as well as with hypoperfusion in the Blacks. In this group, arteriolar narrowing was associated with hypoperfusion; and attenuated arteriolar dilation with increased FLIP NOx responses (%). Conclusions Higher NOx increased arteriolar vasoconstriction, presumably impeded perfusion and facilitated VD. Chronic depression symptoms may trigger disturbed NOx and retinal hemodynamics in Blacks and thereby potentiate stroke ris