Diffuse cortical reduction of neuronal activity in unipolar major depression: a retrospective analysis of 337 patients and 321 controls

Reduction of neuronal activity in frontocortical and limbic circuits is con sidered a characteristic of depression. WE aimed to test this hypothesis by pooling all available data from experimental literature. All investigation s were included comparing regional cerebral blood flow (rCBF) or glucose me tabolism (rCMRGlc) between acutely depressed unipolar major depressive pati ents and healthy controls. For cortical and subcortical regions we computed the percentage difference between depressives (n = 337) and controls (n = 321). In patients with unipolar major depression rCBF and rCMRGlc were lowe red in left (-4.4%, P = 0.022) and right frontal (-3.2%, P = 0.053), left ( -1.7%, P = 0.061) and right temporal(-3.0%, P = 0.003), left (-6.5%, P = 0. 002), and right parietal (-8.8%, P = 0.001), and left (-6.6%:, P = 0.083) a nd right occipital cortex (-4.2%, P = 0.002). Moreover, there were reductio ns in left (-6.3%, P = 0.029) and right basal ganglia (-4.8%, P = 0.002), l eft (-3.4%, P = 0.114) and right thalamus (-3.1%, P = 0.036), and left limb ic system (-2.2%, P = 0.127). Parameters were increased by 1.0% (P = 0.714) only in the right limbic system. There were no hemispheric asymmetries (P > 0.05). Moreover, there was no indication for an anterior-posterior gradie nt (P > 0.05), and thus no 'hypofrontality'. In contrast to the current vie w, the data indicate a diffuse cortical rather than regionalized reduction of neuronal activity in unipolar major depression. ((C) 2000 Lippincott Wil liams & Wilkins).