Additive and Interactive Effects of Comorbidity During Emotion Processing

112 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2009.This investigation examined the shared, unique, and interactive effects of anxious apprehension, anxious arousal, and anhedonic depression on brain activation as measured by fMRI while individuals performed an emotion-word Stroop task. As predicted, brain activation distinguished anxious groups in a left inferior frontal region associated with speech production and in a right-hemisphere temporal area. A second hypothesis about left-frontal involvement in emotion was also supported, with distinct left-frontal regions associated with anxious apprehension versus processing of positive information. Using a dimensional approach and hierarchical regression, this investigation also separated regions where comorbidity is inconsequential (i.e., where additive effects dominate) from regions where comorbidity is critical (i.e., where interactive effects dominate) to observed patterns of activation. Consistent with EEG findings, asymmetrical activation of prefrontal cortex was found for depression, but rightward frontal lateralization in depression was dependent on elevated comorbid anxious arousal and simultaneously low comorbid anxious apprehension. Comorbid anxious arousal also moderated the relationship between depression and right posterior activation. These findings highlight the necessity of considering effects of comorbidity on both anterior and posterior brain regions and may help to explain the diversity of brain activity patterns observed in individuals with depression and anxiety.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD