BRAIN STRUCTURE AND FUNCTION AND THE OUTCOMES OF TREATMENT FOR DEPRESSION

Depressed patients have a variety of brain structural alterations, the most common being atrophy and deep white-matter lesions. Alterations in brain function also are common, particularly regional decreases in cerebral metabolism and perfusion. Method: We review here the evidence that alterations in brain structure and function may explain some of the heterogeneity in outcomes of depression. We also report initial re sults suggesting that measurement of brain structure and function may help to predict outcomes of treatment for depression. Brain structure was examined using three-dimensional reconstruction and volumetric ana lysis of magnetic resonance imaging (MRT) scans. Brain function was ex amined using quantitative electroencephalography (QEEG), performed at baseline and serially during the course of treatment. QEEG measures in cluded coherence (a measure of synchronized activity between brain reg ions) and cordance (a measure strongly associated with regional cerebr al perfusion). Results: Depressed patients have been reported to have larger volumes of white-matter lesions than controls. We have found th at some types of white-matter lesions are associated with lower cohere nce and that subjects with low coherence had significantly poorer outc omes of treatment for depression at 2-year follow-up. Depressed subjec ts had low cordance at baseline, which decreased further during the co urse of effective treatment. Subjects who did not improve had little o r no change in cordance. Changes in cordance were detected prior to th e onset of clinical response, with decreases seen as early as 48 hours after the initiation of treatment in subjects who showed eventual res ponse. Conclusion: These preliminary results suggest that functional i maging using QEEG may be useful for assessing, and possibly predicting , outcomes of treatment for depression.