Do mood instability symptoms in epilepsy represent formal bipolar disorder?

We aimed to assess rates of bipolar symptoms versus bipolar disorder in epilepsy, and the effect of bipolar symptoms on quality of life (QOL) in epilepsy. Bipolar, disability, and QOL instruments were administered to 99 tertiary epilepsy center patients. Patients who scored positive on the Mood Disorder Questionnaire (MDQ) also completed depression scales and a structured psychiatric interview. Results indicated MDQ+ patients (10.1%) had worse QOL and more work, social, and family life disruptions. Most MDQ+ patients did not have bipolar disorder. There was close overlap between depressive and bipolar symptomatology. Based on results of this study, bipolar symptom is not synonymous with bipolar disorder. Symptoms picked up by the MDQ may be epilepsy-related depressive symptoms. Bipolar symptoms are associated with more disability, worse QOL, and may have treatment implications.