Brain Structure and Function and the Outcomes of Treatment for Depression

Background: Depressed patients have a variety of brain structural alterations, the most commonbeing atrophy and deep white-matter lesions. Alterations in brain function also are common, particularlyregional decreases in cerebral metabolism and perfusion. Method: We review here theevidence that alterations in brain structure and function may explain some of the heterogeneity inoutcomes of depression. We also report initial results suggesting that measurement of brain structureand function may help to predict outcomes of treatment for depression. Brain structure wasexamined using three-dimensional reconstruction and volumetric analysis of magnetic resonanceimaging (MRI) scans. Brain function was examined using quantitative electroencephalography(QEEG), performed at baseline and serially during the course of treatment. QEEG measures includedcoherence (a measure of synchronized activity between brain regions) and cordance (ameasure strongly associated with regional cerebral perfusion). Results: Depressed patients havebeen reported to have larger volumes of white-matter lesions than controls. We have found thatsome types of white-matter lesions are associated with lower coherence and that subjects with lowcoherence had significantly poorer outcomes of treatment for depression at 2-year follow-up. Depressedsubjects had low cordance at baseline, which decreased further during the course of effectivetreatment. Subjects who did not improve had little or no change in cordance. Changes incordance were detected prior to the onset of clinical response, with decreases seen as early as 48hours after the initiation of treatment in subjects who showed eventual response. Conclusion:These preliminary results suggest that functional imaging using QEEG may be useful for assessing,and possibly predicting, outcomes of treatment for depression.