PHILADELPHIA — Symptoms of bipolar disorder are prevalent among patients with epilepsy, and are also highly associated with depressive symptoms in this cohort, according to a recent analysis of 54 epilepsy patients seen at a tertiary care center.
Patients with epilepsy and both bipolar and depressive symptoms may also have the mood instability of interictal dysphoric disorder, Dr. Alan B. Ettinger and his associates reported in a poster at the annual meeting of the American Epilepsy Society.
The researchers evaluated adult patients who were managed at the Comprehensive Epilepsy Center of Long Island Jewish Hospital in New Hyde Park, N.Y. Using the Mood Disorders Questionnaire (MDQ), they identified bipolar symptoms in seven of the patients overall (13%). This was a close match with a 12% rate that the researchers had previously reported in a community-based cohort of epilepsy patients.
Six of the seven MDQ-positive patients also had a positive diagnosis on the Bipolar Spectrum Diagnostic Scale, as did another seven of the remaining 47 patients (15%) with epilepsy who were negative on the MDQ.
The MDQ-positive patients also showed evidence of increased functional impairment, documented by their scores on the Sheehan Disability Scale, and they perceived themselves as having a reduced quality of life, based on their scores on the Quality of Life in Epilepsy-89 Patient Inventory.
The researchers found a high association between a positive MDQ score and depressive symptoms, measured on the Center for Epidemiologic Studies-Depression Scale.
Among the seven patients who had positive MDQ scores, a total of six underwent assessment with the depression scale and all six were positive for depressive symptoms, reported Dr. Ettinger, who is the director of the Comprehensive Epilepsy Center at Long Island Jewish Hospital.
But only two of these six patients were also positive on the Neurological Disorders Depression Inventory for Epilepsy.
This finding suggests that the type of depression seen in patients who test positive on the mood disorders questionnaire, with its apparent link to bipolar symptoms, is not the same as the depression that is identified in many other patients with epilepsy.
Interictal dysphoric disorder may therefore affect a minority of epilepsy patients, Dr. Ettinger and his associates concluded.