Does Your Child Experience Mood Swings OR Have a Diagnosis of Bipolar Disorder? We are looking for children aged 8 - 17 to participate in a research study being held at UMass Medical School. Participants must: (1) have a diagnosis of Bipolar Disorder OR (2) experience mood swings and have a parent with a mood or anxiety disorder or sibling with Bipolar Disorder. Participants will undergo two non-invasive MRI scans, cognitive testing, and take a daily Vitamin D Supplement. Contact Info: phone: 508-856-5896 or email: ChildResearch@umassmed.edu.