A volumetric magnetic resonance imaging study of monozygotic twins discordant for bipolar disorder

Six monozygotic (MZ) twin pairs discordant for bipolar disorder were compar ed with normal MZ twins with magnetic resonance imaging (MRI) on volumes of basal ganglia (BC), amygdala-hippocampus (AH), and cerebral hemisphere. Ca udate nuclei were larger in both affected and unaffected bipolar twins than in normal MZ twins. The right hippocampus was smaller in the sick vs. well bipolar twins. The hippocampus was also less asymmetric in the affected bi polar twins than in the well cotwins and the normal MZ twins. These anatomi cal structures continue to be of interest in bipolar disorder research. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.