Voxelwise meta-analysis of gray matter abnormalities in bipolar disorder

We conducted a meta-analysis of gray matter abnormalities in bipolar disorder (BD) using voxel-based morphometry studies to help clarify the structural abnormalities underpinning this condition. Methods: A systematic review was conducted for voxel-based morphometry studies of patients with BD. Meta-analyses of gray matter differences between BD and control subjects were undertaken using signed differential mapping, a novel method that, in contrast to previously used techniques, allows inclusion of negative findings and ensures that single studies do not exert undue influence on the results. Meta-regression and subgroup analyses were used to examine the effect of moderator variables on gray matter abnormalities.