Aging or disease? Cardiovascular reactivity in Finnish men over the middle years

Exercise, Nrf2 and Antioxidant Signaling in Cardiac Aging

Aging is represented by a progressive decline in cellular functions. The age-related deformities in cardiac behaviors are the loss of cardiac myocytes through apoptosis or programmed cell death. Oxidative stress (OS) and its deleterious consequence contribute to age-related mechanical remodeling, reduced regenerative capacity, and apoptosis in cardiac tissue. The pathogenesis of OS in the elderly can predispose the heart to other cardiac complications such as atherosclerosis, hypertension, ischemic heart disease, cardiac myopathy, and so on. At the molecular level, oxidant-induced activation of Nrf2 (Nuclear erythroid-2-p45-related factor-2), a transcription factor, regulates several genes containing AREs (Antioxidant Response Element) and bring the respective translates to counteract the reactive radicals and establish homeostasis. Myriad of Nrf2 gene knockout studies in various organs such as lung, liver, kidney, brain, etc. have shown that dysregulation of Nrf2 severely affects the oxidant/ROS sensitivity and predispose the system to several pathological changes with aberrant cellular lesions. On the other hand, its gain of function chemical interventions exhibited oxidant stress resistance and cytoprotection. However, thus far, only a few investigations have shown the potential role of Nrf2 and its non-pharmacological induction in cardiac aging. Therefore, here we review the involvement of Nrf2 signaling along with its responses and ramifications on the cascade of OS under acute exercise stress (AES), moderate exercise training (MET), and endurance exercise stress (EES) conditions in the aging heart.

Older adults' hemodynamic responses to an acute emotional stressor: short report

BACKGROUND/STUDY CONTEXT: Vascular and myocardial activation can each increase blood pressure responses to stressors, but vascular responses are uniquely associated with negative affect, pernicious coping processes, and cardiovascular risk. These hemodynamic correlates of coping in response to acute stressors have not been well characterized in older adults.

METHODS

Adults 65 to 97 years of age (N = 74) either engaged in written disclosure about a distressing event (acute stressor) or wrote objectively about a neutral topic (control). Blood pressure, impedance cardiography, and affect measures were assessed at baseline and in response to writing. Moderating effects of age on affect, blood pressure, and vascular and myocardial responses to the acute stressor were tested using multiple linear regression models.

RESULTS

Follow-up tests of Age × Writing Group interactions indicated that the expected effects of written disclosure on systolic and diastolic blood pressure responses were diminished with increasing age. Regardless of age, compared with neutral writing, written disclosure increased negative affect and vascular responses, but not myocardial responses.

CONCLUSION

Blood pressure responses to an acute, emotionally evocative stressor were indistinguishable from blood pressure responses to a control condition among the eldest older adults in our sample. In contrast, characterizing the hemodynamic mechanisms of blood pressure responses revealed notable vascular effects of the acute, emotional stressor across a wide age range. Such characterization may be particularly useful for clarifying the psychophysiological pathways to older adults' cardiovascular health.

Impaired transcriptional activity of Nrf2 in age-related myocardial oxidative stress is reversible by moderate exercise training

Aging promotes accumulation of reactive oxygen/nitrogen species (ROS/RNS) in cardiomyocytes, which leads to contractile dysfunction and cardiac abnormalities. These changes may contribute to increased cardiovascular disease in the elderly. Inducible antioxidant pathways are regulated by nuclear erythroid 2 p45-related factor 2 (Nrf2) through antioxidant response cis-elements (AREs) and are impaired in the aging heart. Whereas acute exercise stress (AES) activates Nrf2 signaling and promotes myocardial antioxidant function in young mice (∼2 months), aging mouse (>23 months) hearts exhibit significant oxidative stress as compared to those of the young. The purpose of this study was to investigate age-dependent regulation of Nrf2-antioxidant mechanisms and redox homeostasis in mouse hearts and the impact of exercise. Old mice were highly susceptible to oxidative stress following high endurance exercise stress (EES), but demonstrated increased adaptive redox homeostasis after moderate exercise training (MET; 10m/min, for 45 min/day) for ∼6 weeks. Following EES, transcription and protein levels for most of the ARE-antioxidants were increased in young mice but their induction was blunted in aging mice. In contrast, 6-weeks of chronic MET promoted nuclear levels of Nrf2 along with its target antioxidants in the aging heart to near normal levels as seen in young mice. These observations suggest that enhancing Nrf2 function and endogenous cytoprotective mechanisms by MET, may combat age-induced ROS/RNS and protect the myocardium from oxidative stress diseases.

Conflict and collaboration in middle-aged and older couples: II. Cardiovascular reactivity during marital interaction

Marital strain confers risk of cardiovascular disease (CVD), perhaps though cardiovascular reactivity (CVR) to stressful marital interactions. CVR to marital stressors may differ between middle-age and older adults, and types of marital interactions that evoke CVR may also differ across these age groups, as relationship contexts and stressors differ with age. The authors examined cardiovascular responses to a marital conflict discussion and collaborative problem solving in 300 middle-aged and older married couples. Marital conflict evoked greater increases in blood pressure, cardiac output, and cardiac sympathetic activation than did collaboration. Older couples displayed smaller heart rate responses to conflict than did middle-aged couples but larger blood pressure responses to collaboration-especially in older men. These effects were maintained during a posttask recovery period. Women did not display greater CVR than men on any measure or in either interaction context, though they did display greater parasympathetic withdrawal. CVR to marital conflict could contribute to the association of marital strain with CVD for middle-aged and older men and women, but other age-related marital contexts (e.g., collaboration among older couples) may also contribute to this mechanism.

Cardiac vagal activity during psychological stress varies with social functioning in older women

The polyvagal theory states that social behavior is linked to cardiac vagal control. This theory has been tested widely in infants and children, but less so in adults. Thus, we examined if resting or stress-related changes in high-frequency heart rate variability (HF-HRV; a presumed index of vagal control) varied with social functioning in 50 healthy women (mean age 68 years). After completing assessments of social functioning, women were exposed to laboratory stressors with concurrent psychophysiological monitoring. Although stressor-induced suppression of HF-HRV was common, women with less stressor-induced suppression of HF-HRV reported more positive social functioning. Resting HF-HRV was not related to social functioning. These findings are at apparent odds with the polyvagal theory; however, they complement prior work suggesting that emotional self-regulation could plausibly modulate cardiac vagal control in association with social functioning.

Social support and behavior in a stressful situation in relation to myocardial infarction and mortality: who is at risk? Results from prospective cohort study "Men born in 1914," Malmö, Sweden

Coronary heart disease remains an important cause of morbidity and mortality. Much data support the view that social support is associated with coronary heart disease. Participants of the study "Men born in 1914," (414 men) were followed from a baseline measurement in 1982/83 until the end of 1996. At baseline, the men answered a questionnaire on social support and participated in a stressful test where their behavior was categorized as adaptive or maladaptive. This study examined whether social support had a prospective impact on the incidence of myocardial infarction and all-cause mortality when behavior in the stressful task was taken into consideration. The conclusion of the study was that unsatisfactory levels of social support is associated with an increased risk of incident myocardial infarction (HR 2.40, CI 1.36-4.25, p = .003) and premature death (HR 1.99, CI 1.32-3.00, p = .001) but only in men who had shown maladaptive behavior in the test.

Incidence of cardiac events in hypertensive men related to adaptive behavior in stressful encounters

The Serial Color Word Test was administered at baseline to 253 hypertensive men participating in the prospective cohort study of cardiovascular diseases "Men born in 1914" in Malmö, Sweden. This test of psychological adaptation to a stressful encounter was used to investigate whether susceptibility to stress moderates the risk of a cardiac event in association with hypertension. Adaptive behavior, as measured by test performance, can be categorized in two dimensions. The regression dimension refers to linear change of time spent in the test session whereas the variability dimension refers to nonlinear change. Both dimensions consist of four different patterns. At follow-up (mean time = 8.2 +/- 3.5 years), the risk of a cardiac event varied between men with different adaptive patterns. One pattern, the Cumulative-Dissociative pattern of the variability dimension, characterized by a discontinuous and fluctuating time-consumption, was associated to an almost three-fold risk of a cardiac event during follow-up (relative risk [RR], 2.99; 95% confidence interval [CI], 1.33 - 6.70, p = .010) after adjustment for medical-, socioeconomic-, and lifestyle-related factors. No association existed between adaptive patterns and overall mortality.