Family history of cardiovascular disease is associated with cardiovascular responses to stress in healthy young men and women
Introduction
Cardiovascular disease is the leading cause of death and morbidity in western countries. Coronary atherogenesis, increased left ventricular mass, plaque rupture, thrombus formation, vasospasm and arrhythmogenesis have all been associated with heightened cardiovascular responsivity to acute stress (Manuck, 1994). It has been argued that heightened cardiovascular reactivity to stress contributes to the development of future cardiovascular disease (Treiber et al., 2003). However, because studies are often carried out among people with existing cardiovascular disease, it is difficult to determine the causal order between heightened reactivity and disease onset. It is also uncertain what causes heightened cardiovascular responses.
Cardiovascular diseases have strong heritable components and young people whose parents suffer from these conditions are at elevated risk. Family history may contribute to heightened cardiovascular stress reactions, and a family history design makes it possible to determine whether physiological dysfunction precedes cardiovascular disease onset. A large and complex literature has investigated whether normotensive individuals with a positive family history of hypertension display greater cardiovascular responses to stress than persons with a negative family history of hypertension (Pierce et al., 2005). Early meta-analytic reviews of family history of hypertension indicated that individuals with a positive family history have greater physiological reactivity to a stressor than those with no family risk (Fredrikson and Matthews, 1990, Manuck et al., 1993). Healthy offspring of hypertensive individuals have also been found to exhibit slower and less complete recovery from acute laboratory stress (Hocking Schuler and O'Brien, 1997, O'Brien et al., 1998, Schneider et al., 2003).
A positive family history of cardiovascular disorders other than hypertension is strongly associated with future incidence of cardiovascular disease, even when environmental risk factors are taken into account (Williams et al., 2001, Andresdottir et al., 2003). To date, few studies have investigated cardiovascular reactivity to stress and family history of cardiovascular disease risk defined more broadly. There is evidence that normotensive individuals with a family history of myocardial infarction exhibit greater blood pressure increases or less attenuation of total peripheral resistance following stress than those with a negative family history (Stoney et al., 1988, Treiber et al., 1991, Treiber et al., 1993). However, to our knowledge, no studies have examined the relationship between cardiovascular responsivity to stress and family history of cardiovascular disease risk defined in broader terms, including such factors as diabetes and high cholesterol as well as hypertension and coronary heart disease. A criticism of previous literature relating family history of hypertension with stress reactivity is that family history has been reported by offspring who may not be aware of their parents’ health status, and that risk has been defined by a single generation (Schneiderman et al., 2000). As a result, it is now recommended that studies should obtain reports from parents, with information from at least two generations (Silberberg et al., 1999).
The present study investigated whether disturbances of cardiovascular stress responsivity were evident in persons with a raised family risk of cardiovascular disease defined broadly. We tested a sample of young male and female healthy normotensive volunteers, and hypothesised that participants with a positive family history of cardiovascular disease risk (including high cholesterol, coronary heart disease, diabetes and hypertension) would show larger cardiovascular responses (reactivity and recovery) to two behavioural challenges in comparison with participants with negative family histories. The analyses controlled for possible confounders such as participant's own baseline physiological activity, body mass index, abdominal adiposity and smoking status. In addition, we examined the relationship between cardiovascular responsivity and family history of hypertension as an individual risk factor.
Section snippets
Participants
One hundred and three young adults aged between 18 and 25 years were recruited through email notices to academic departments in University College London. Participants were screened by structured interview to ensure that they were generally healthy, not taking any medication (including antidepressants), were without cold or flu symptoms, were not taking antibiotics, and had at least one contactable blood-related parent. Participants were asked to avoid aspirin or ibuprofen for 10 days prior to
Sample characteristics
The characteristics of the sample are summarised in Table 1. Average hours of exercise taken per week were above the UK government's recommended level, only 15.5% smoked, and alcohol consumption was low. Comparisons showed that family history (FH) positive and FH negative individuals (for both cardiovascular disease risk and hypertension risk alone) were of a similar age and ethnicity, had comparable BMIs, drank a similar amount of alcohol per week and reported similar amounts of exercise.
Discussion
In the present study it was hypothesised that participants with a positive family history of cardiovascular disease risk would exhibit greater physiological responses and impaired recovery from two laboratory-based mental stress tasks. Using a cumulative score for parents and grandparents, the results revealed that a positive family history of hypertension was not associated with exaggerated cardiovascular response in young adults. However, a positive family history of cardiovascular disease
Acknowledgements
The study was supported by the British Heart Foundation and Cancer Research UK. We are grateful to Bev Murray for her assistance with data collection.
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