Reward sensitivity in depression: a biobehavioral study

The approach-withdrawal model posits 2 neural systems of motivation and emotion and hypothesizes that these systems are responsible for individual differences in emotional reactivity, or affective styles. The model also proposes that depression is characterized by a deficit in reward-seeking behavior (i.e., approach motivation) and is associated with a relative decrease in left frontal brain activity. The authors tested aspects of this model by comparing the electroencephalogram alpha power of depressed and nondepressed individuals during a task that manipulated approach motivation. The study found that control participants and individuals with late-onset depression exhibited the hypothesized increase in left frontal activity during the approach task but individuals with early-onset depression did not. This suggests that early-onset depression may be associated with a deficit in the hypothesized approach motivation system.