Cognitive bias in healthy participants with symptoms of depression or seasonal affective disorder

Exaggerated cognitive bias is observed in affective disorder patients, and is often probed using the Emotional Stroop (eStroop) task. Few studies of the eStroop have employed Event-Related Potentials (ERPs). Here, High-density ERPs were recorded while healthy subjects with and without sub-syndromal Depression and Seasonal Affective Disorder (SAD) performed eStroop variations containing disorder-congruent words. RTs did not reliably differentiate between groups. Emotional relative to neutral words elicited either a P1 or a new component with anterior frontal topography, the Early Anterior Positivity (EAP), maximal 200-400ms post-onset. In study 1, an EAP was elicited by depression words in subjects with and without depression, while amplitude of the Late Posterior Positivity (LPP) was greater in the depression group. In study 2, an EAP to winter-related words was observed in SAD participants during the winter, while only a P1 occurred in the summer. The EAP may index automatic processing of aversive self-relevant stimuli.