Default Mode Network Electroencephalographic Activity in Depression and Depression Subtypes

Abstract

<p>The relationship between the electroencephalographic activity of the default mode network (DMN) and self-reported depression symptoms was investigated. Three research questions which emerged from a review of existing literature were: (a) whether quantitative electroencephalograph analysis can be used to reliably identify the DMN; (b) whether DMN activity measured in this way significantly correlates with reported depression, and; (c) whether this activity significantly correlates with Clinical Content Subtypes of depression. Depression and depression subtype were measured in a community sample of 100 participants using the Zung Self-Rating Depression Scale, and electroencephalographic data were investigated using field power analysis. Results indicated that the DMN could be observed by comparing recordings taken over cortical areas associated with the network with non-DMN areas. Hypothesised significant correlations between total depression scores and DMN field power values in eyes-open and eyes-closed conditions were not observed, nor was degree of fluctuation between conditions found to significantly correlate with total depression score. However, participants reporting total scores above the threshold of clinically significant depression demonstrated significantly more theta field power within the DMN than those reporting depression levels below the threshold. The degree of prefrontal theta power fluctuation between conditions was shown to positively correlate with somatic depression subtype scores. Increased alpha field power within the DMN at rest was observed to be significantly correlated with increased cognitive depression subtype score. These findings indicate the validity of measuring DMN activity using field power analysis, as well as the complexity of the DMN and its relationship with depression.</p>