Emotion Regulation and Vulnerability to Depression: A Longitudinal Test of the Diathesis-Stress Model

Maladaptive emotion regulation is an established vulnerability marker for depression. Within a diathesis-stress framework individual differences in emotion regulation constitute sensitivity to stress, such that people who are less able to effectively regulate their emotions are more likely to become depressed when stress is encountered. Markers of maladaptive emotion regulation have been examined from affective, neurological, and cognitive perspectives and, for the most part, have been examined in independent lines of research. As such, the independent and interactive contributions of maladaptive emotion regulation markers are still unknown. The current thesis addresses this gap with a longitudinal study. Emotion regulation markers and depression were assessed at the outset of the study (time one) then life stress and depression were measured three months (time two) and twelve months (time three) later. Three trait measures of emotion regulation were assessed: spontaneous emotion regulation (as indexed by startle reactivity following negative images), frontal and parietal resting EEG asymmetries, and brooding rumination. All emotion regulation markers were found to be independent markers of vulnerability to depression. The emotion regulation markers measured at time one were then tested within a diathesis stress framework to predict stress sensitivity at time two. Poorer online regulation interacted with life stress to predict depression. That is, poor online regulators were sensitive to stress at three months, whereas good online regulators were not. Stress sensitivity was tested again at time three, twelve months after the initial assessment. At this time point frontal asymmetry, parietal asymmetry and life stress interacted to predict depression. When right parietal activity was low, rightward frontal asymmetries showed more sensitivity to stress. However, people with leftward asymmetries showed less stress sensitivity. Brooding predicted depression at three months but not at twelve months and did not interact with stress at either time point. The findings of this thesis show that, within the diathesis-stress framework, online regulation measures indicate short-term sensitivity to stress; however, EEG asymmetry measures show sensitivity to stress in the longer term.