Participation in this study will require three study visits over 6 weeks. Subjects will be evaluated with the Structured Diagnostic Interview for DSM-IV to confirm diagnosis. They will also be administered the Hamilton Anxiety and Depression Rating Scales. Eligible subjects will then complete questionnaires related to their symptoms as well as decision-making and risk-taking, including: the Barratt Impulsiveness Scale, the Spielberger State-Trait Anxiety Inventory, and the Flinders Decision-making questionnaire. The Montgomery-Asburg Depression Severity scale to assess changes in depression symptom severity and the Young Mania Rating Scale to assess changes in manic symptom severity, will be conducted at screening, baseline, and endpoint. Patients will also be given the Childhood Trauma Questionnaire at baseline visit, to assess for a history of childhood trauma. The subjects will then complete the computer-generated decision-making tasks. Upon completion, the study physician will initiate standard-of-care treatment with a mood stabilizer (either lithium, valproate, or lamotrigine). Standard-of-care laboratory testing and psychiatric follow-up will be performed during the patient's study participation. After six weeks of treatment with a mood stabilizer, patients will again complete the decision-making computerized assessment.