Depression and cardiovascular reactivity: the role of motivation and early life adversity

The overarching aim of this thesis was to extend theoretical understanding of the mechanistic association between depression and blunted cardiovascular reactivity to acute psychological stress. As such, it examined two underlying psychosocial factors proposed to influence this relationship; motivation and early life adversity. The programme of research employed both  primary data collection and secondary analyses of large population-based datasets, all of  which employed a laboratory procedure to manipulate the experience of acute stress. Depression was assessed using established self-report scales of depressive symptoms. Study 1 presented evidence that intrinsic motivation mediated the relationship between depression  and blunted cardiovascular reactivity to stress in healthy individuals. Blunted cardiovascular responses to stress were less pronounced in those with depression through the pathway of low intrinsic motivation. Study 2 established that the influence of early life adversity on current depression is associated with blunted cardiovascular responses to stress. The psychological impact of early life adversity was related to higher symptoms of depression which, in turn, was associated with differentiated patterns of cardiovascular reactivity to stress. Study 3 extended these findings and established that a distinct behavioural cluster of greater exposure to early life adversity, coupled with higher levels of behavioural disengagement and symptoms of depression was cross-sectionally associated with blunted cardiovascular reactivity. Finally, study 4 sought to replicate and extend findings arising from Study 3 in a midlife sample and revealed that a behavioural cluster characteristic of blunted reactivity was cross-sectionally associated with psychological vulnerability. Overall, the research reported in this thesis provides further evidence that motivational and early life adversity factors not only underlie the relationship between depression and blunted cardiovascular reactivity to acute psychological stress, but that behavioural factors previously examined in isolation, cluster in ways characteristic of reactivity profiles that relate to health outcomes.