Pituitary volume in patients with bipolar disorder and their first-degree relatives

Abstract

Background Hypothalamic–pituitary–adrenal (HPA) axis dysregulation has been reported in bipolar disorder (BD), but previous magnetic resonance imaging (MRI) studies of pituitary gland volume in BD have yielded inconsistent findings. In addition, the contribution of genetic factors to the pituitary changes in BD remains largely unknown. Method We used MRI to investigate the pituitary volume in 29 remitted patients with BD, 49 of their first-degree relatives (of whom 15 had a diagnosis of Major Depressive Disorder), and 52 age- and gender-matched healthy controls. Results BD patients had a significantly larger pituitary volume compared with their relatives and healthy controls. Pituitary volume did not differ between controls and healthy relatives or relatives diagnosed with major depression. Limitations Direct measures of HPA function (i.e., hormonal levels) were not available. Conclusions These findings suggest that enlarged pituitary volume is associated with disease expression but not genetic susceptibility to BD.