Investigating models of affect: Relationships among EEG alpha asymmetry, depression, and anxiety.

The approach-withdrawal and valence-arousal models both predict that depressive and anxious profiles will be associated with relatively reduced left frontal and increased right frontal activity respectively, while the valence-arousal model also proposes a dissociation by lower and higher right parietotemporal activity, respectively. Recent work further suggests that subtypes of anxiety disorders may be characterized by distinctive patterns of activity depending on their type of arousal (anxious arousal/apprehension). The aim of this study was to investigate the relationships among nonclinical depression/anxiety and lateralized frontal/parietotemporal activity by categorizing participants (N=428) on the basis of both negative mood and alpha EEG. Key findings include: (i) greater right frontal lateralization in anxious participants, symmetrical frontal activity in depressed/comorbid, and left frontal lateralization in healthy controls; (ii) right frontal lateralization in anxious arousal participants, left frontal and right parietotemporal lateralization in anxious apprehension; (iii) bilateral increase in frontal and increased right parietotemporal activity in depressed/comorbid participants. Findings support predictions for frontal but not posterior regions. Grouping on the basis of EEG may not be reciprocally predictive of negative mood groupings, suggesting involvement of additional factors.