Many neuroimaging investigations report structural differences in subjects with bipolar disorder; however, conflicting results are common in the limited number of available investigations. Thus, the structural correlates of bipolar disorders remain poorly understood. The authors reviewed the early investigations using computed tomography and examined gross structural differences, such as cerebral atrophy, ventricular enlargement, or cerebellar atrophy. Many of these investigations report significant differences in these features compared with controls, whereas others found no such differences. More recent magnetic resonance imaging (MRI) investigations have employed increasingly sophisticated imaging and research methodologies, allowing for the quantitative examination of specific brain regions. Because neuropsychological and functional studies suggest abnormalities in frontal, temporal and subcortical regions, many investigators have focused their MRI neuromorphometric studies on these temporal limbic structures. However, the number of investigations examining each of these regions remains small, and conflicting results continue to be reported. It seems clear that for many brain regions, the structural changes from normal may be subtle, and that the differences in the reported studies may be due to differences in research methodologies between studies and across centers.
Copyright 2002 S. Karger AG, Basel