Response by Climie et al to Letter Regarding Article “Individual and Neighborhood Deprivation and Carotid Stiffness: The Paris Prospective Study III”

In Response: We thank Lambert et al for their insight regarding our article “Individual and Neighborhood Deprivation and Carotid Stiffness: The Paris Prospective Study III.”1 We agree with the authors that loneliness may contribute to increased carotid stiffness; however, we did not measure loneliness per se within our cohort. It is interesting to note that neighborhood deprivation was not related to carotid stiffness in females, however it was in males. This may be due to differences in patterns of socialization between males and females, which favor females and result in increased social connectedness and speculatively, reduced loneliness, independent of occupational or domestic responsibilities.2 Thus, despite the effects of living alone or depression, females living in deprived areas may have more access to support at the neighborhood level compared to males, ultimately reducing the effect of these factors on health. A direct measure of sympathetic activity is not available within the Paris Prospective 3 Study however, a measure of baroreflex sensitivity is. Reduced baroreflex function has been observed in patients with depression3 and social isolation in rats4 and is associated with cardiac mortality and sudden death.5 Global baroreflex function is traditionally assessed based on fluctuations in blood pressure and is a combination of both the vascular (dependent on the stiffness of the arterial wall) and neural components of the baroreflex pathway. However, baroreceptors respond to deformation and not pressure per se, thus in the presence of increased arterial stiffness, peripheral changes in blood pressure may not reflect changes in carotid distension. In our current article,1 we have examined the effect of deprivation on the vascular component of the baroreflex arc, however whether loneliness, depression or more generally, deprivation, are associated with an impairment in the neural component warrants further investigation. Furthermore, combining the 2 components to determine the extent at which impaired baroreflex function contributes to the association between deprivation and increased carotid stiffness would be of value, but is complex given the interconnectedness and statistical correlation of the 2 components.