Although patients suffering from major depression respond to antidepressant treatment within several weeks, full reinstatement of premorbid capabilities requires much longer. Nevertheless, most research in major depression seeking the pathophysiological correlates of remission has focused upon the acute post-treatment period. Brain imaging research offers no exception. We have recently shown that cerebral perfusion in depressed patients responding to 6-wk antidepressant medication increases in parieto/cerebellar regions and becomes similar to that of healthy control subjects. We now present technetium-99m hexamethylpropylene amine oxime single-photon emission computed tomography (99mTc-HMPAO SPECT) data collected from 11 of these patients 2 years in remission. Images were analysed using Statistical Parametric Mapping. After 2 years, perfusion normalization found immediately after treatment was maintained, with further increases in frontal and decreases in parieto/cerebellar regions. These findings suggest that perfusion increases in parieto/cerebellar regions may be involved in acute response to treatment whereas increases in frontal regions may be related to its consolidation.
