Purpose: Research has revealed a well-established relationship of depressive symptoms and hopelessness with a variety of physical illnesses that are associated with a dysfunction of the hypothalamic-pituitary-adrenal-axis. The purpose of this study was to test if depressive symptoms mediate the relationship between hopelessness and cortisol, a measure of the hypothalamic-pituitary-adrenal-axis. Methods: Hopelessness, depressive symptoms, and diurnal cortisol rhythm were measured in 257 adults (128 women and 129 men; age range: 20-74 years) in this cross-sectional study. To test the hypothesis, two linear regression analyses and asymmetrical confidence intervals around the regression weights were conducted. A second set of analyses was calculated to be able to exclude the possibility of hopelessness as a mediator between depressive symptoms and cortisol. Results: As predicted, after adjusting for age, gender, awakening time, medication use, more hopelessness predicted more depressive symptoms and more depressive symptoms predicted a flatter diurnal cortisol rhythm. The 95% confidence intervals revealed that the indirect relationship between hopelessness and diurnal cortisol rhythm was significant. The analyses with hopelessness as a potential mediator revealed that hopelessness does not mediate the association between depressive symptoms and cortisol.
Conclusions:While the relationship between hopelessness and cortisol was mediated by depressive symptoms in this cross-sectional study, many other risk factors of depression have not been examined. Thus, future longitudinal studies should examine the relationships between those risk factors of depression and the hypothalamic-pituitary-adrenal-axis.Keywords: population-based; cross-sectional study; mediation model; hopelessness; depressive symptoms; diurnal cortisol rhythm Running head: Depressive Symptoms, Hopelessness, and Cortisol 3 Presently, psychosocial factors in general, and depressive symptoms in particular, are prospectively associated with incidents of both cancer and cardiovascular disease (CVD) [for meta-analyses see 1 and 2; 3; 4, respectively]. In the field of clinical psychology, two prominent models explaining the development of depressive symptoms based on cognitive risk factors have been well-supported by decades of research: Beck's cognitive theory [5] and the hopelessness model [6]. One crucial risk factor for the development and maintenance of depressive symptoms in both models is hopelessness. Hopelessness is a negative view of the future, or in other words, hopeless persons make long-range projections, anticipating that current difficulties or suffering will continue indefinitely [5,6]. Hopelessness is important for the purpose of this study, as empirical studies have also found it to be associated with cancer and CVD incidents. For example, a 6-year longitudinal study with middle aged men without a history of CVD or other serious illness at baseline revealed that hopelessness is associated with incidence rates of myocardial infarct...