Faculty Bibliography

We sought to examine the impact of depression upon antiepileptic drug (AED) adherence in patients with epilepsy. We administered the Center for Epidemiologic Studies Depression Scale (CES-D), Neurological Disorders Depression Inventory for Epilepsy (NDDI-E), Seizure Severity Questionnaire (SSQ), and Quality of Life in Epilepsy-10 (QOLIE-10) and measured AED adherence by utilizing the medication possession ratio (MPR) in adult patients with epilepsy identified through a pharmacy claims database. From a sampling frame of over 10,000 patients identified in claims, 2750 were randomly selected and contacted directly by mail to participate in the cross-sectional survey. A total of 465 eligible patients completed a survey. Survey data were combined with administrative claims data for analysis. We conducted a path analysis to assess the relationships between depression, adherence, seizure severity, and quality of life (QOL). Patients with depression scored significantly worse on measures of seizure severity (p=.003), QOL (p<.001), and adherence (p=.001). On path analysis, depression and QOL and seizure severity and QOL were related, but only the NDDI-E scores had a significant relationship with medication adherence (p=.001). Depression as measured by the NDDI-E was correlated with an increased risk of AED nonadherence. Depression or seizure severity adversely impacted QOL. These results demonstrate yet another important reason to screen for depression in epilepsy.

Seizure-related head injury (SRHI) is an under-recognized condition frequently experienced by people with epilepsy (PWE). The purpose of this study is to investigate the potential impact of SRHI on health-related quality of life (HRQOL) among PWE receiving care in a tertiary epilepsy center. Consecutive adult PWE receiving care at the Baylor Comprehensive Epilepsy Center (BCEC) were recruited for the study. After their informed consent was obtained, patients were administered the QOLIE-31 to measure HRQOL and the NDDI-E to screen for depression. Simple linear regression was used to identify clinical variables associated with HRQOL and that included SRHI obtained systematically at each clinic visit. Data were also compared between the SRHI and non-SRHI groups. Participants included 172 subjects. Recurrent mild SRHI occurred in 50 (29%) subjects. Factors with a negative effect on HRQOL included depression (slope=-19.99 [95% CI -25.16, -14.81]; p<.0001), recurrent SRHI (-17.02 [-22.35, -11.69]; p<.0001), past SRHI (-13.46 [-18.43, -8.48]; p<.0001), and seizure frequency (-0.17 [-0.26, -0.07]; p=0.001) on univariate analysis. With stepwise multiple regression, depression and recurrent SRHI significantly impacted HRQOL with slopes (95% CI; p-value) of (-17.53 [-22.34, -12.73]; p<.0001) and (-14.03 [-18.78, -9.28]; p<.0001), respectively. Patient-derived HRQOL is negatively associated with depression and recurrent SRHI, independently. There has been a justifiable increased awareness of the potential effects of head injuries among healthy individuals. Our data suggest that head injuries can certainly be detrimental among PWE, and greater efforts should be made to recognize and formulate prevention strategies for SRHI.

Depression is the most frequent psychiatric comorbidity in people with epilepsy (PWE) with lifetime prevalence rates ranging between 30 and 35%. Multifactorial variables play a pathogenic role in the high comorbid occurrence of these two disorders. These variables were critically examined during an international symposium held in Chicago in September 2010, the results of which are presented in two companion manuscripts. The first manuscript summarizes new epidemiologic data highlighting the bidirectional relation between depression and epilepsy and related methodological issues in studying this relationship. An examination of the neurobiologic aspects of primary mood disorders, mood disorders in PWE and pathogenic mechanisms of epilepsy derived from studies in animal models and humans is allowing a better understanding of the complex relation between the two conditions. In the first manuscript, we review data from animal models of epilepsy in which equivalent symptoms of depression and anxiety disorders develop and, conversely, animal models of depression in which the kindling process is facilitated. Data from structural and functional neuroimaging studies in humans provide a further understanding of potential common pathogenic mechanisms operant in depression and epilepsy that may explain their high comorbidity. The negative impact of depression on the control of seizure disorders has been documented in various studies. In this manuscript, these data are reviewed and potential mechanisms explaining this phenomenon are proposed.