Volumetric asymmetries in late-onset mood disorders: an attenuation of frontal asymmetry with depression severity

The purpose of the study was to examine global and regional volumetric asym metries in patients with late-onset mood disorders and non-depressed contro l subjects. Our sample comprised 34 patients with late-onset major depressi on, 18 patients diagnosed with late-onset minor depression and 30 control s ubjects. All subjects were scanned using a 1.5 Tesla GE Scanner, and quanti tative estimates of global and focal brain volumes were obtained. Control s ubjects and patients displayed significant right-left Volumetric difference s across several regions, with right-sided regions being larger than the le ft. In the frontal lobes, the asymmetry differed significantly in the three groups (P = 0.02). It was most pronounced in the control group and decreas ed significantly in the minor and major depression groups. There was a sign ificant trend (P = 0.005) in the magnitude of frontal asymmetry across grou ps, with the frontal asymmetry decreasing with increasing severity of depre ssion. Hemispheric and temporal asymmetries were comparable in all three gr oups. These data suggest that an attenuation of the 'normal' volumetric asy mmetry in the frontal regions may provide a structural basis to late-onset mood disorders (C) 2000 Elsevier Science Ltd. All rights reserved.