Nonlinear effect of depression symptoms on the time course of emotional reactivity

The literature on emotion reactivity among people with major depressive disorder (MDD) indicates that people with MDD show diminished reactivity to negative events as compared to non-depressed controls. This diminished reactivity may only be at the highest levels of depression symptoms, suggesting a nonlinear association between depression symptoms and emotion reactivity. Unfortunately, depression has not been examined as a continuum in this line of research; moreover, the time course of reactivity during an emotional event has not been adequately examined. Participants (N = 100) completed a measure of depression symptoms and then viewed a sadness-inducing 11-min film clip while their facial expressions were video recorded and coded separately for each minute of the film clip. Growth-curve analyses indicated a quadratic effect of depression symptoms on curves for facial expressions of sadness and happiness, such that the change in growth/decay first increased and then decreased from low to high levels of depression symptoms. This result supports the idea that the negative mood inherent in depression potentiates reactivity at lower ends of the depression continuum but that reactivity is dampened at higher levels of depression. This suggests that researchers specify the specific range of depression symptoms under investigation (e.g., mild, moderate, dysphoric, severely depressed) when studying the role of depression on emotional reactivity.