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

BackgroundHypothalamic–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.MethodWe 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.ResultsBD 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.LimitationsDirect measures of HPA function (i.e., hormonal levels) were not available.ConclusionsThese findings suggest that enlarged pituitary volume is associated with disease expression but not genetic susceptibility to BD.