Abstracts

Rationale: Patients with temporal lobe epilepsy (TLE) may suffer from significant neuropsychological/neuropsychiatric complications, including cognitive impairment and depression. Depression can affect up to one half of all TLE patients, and is itself associated with cognitive impairment. Thus, patients with TLE and comorbid depression may suffer from a double cognitive burden. The existence and nature of this double burden have been inconsistently reported (Paradiso et al., J Neurol Neurosurg Psychiatry 2001; 70:180-185; Dulay et al., Epilepsy Behav 2004; 5:522-531; Helmstaedter et al., Epilepsy Behav 2004; 5:696-701). The purpose of this study was to explore the relationship of depression and cognition in TLE in an urban population, where the prevalence of depression is high and potentially more severe than that of previously studied cohorts. Methods: A retrospective study was conducted on 42 adult pre-surgical patients diagnosed with medically intractable unilateral TLE. Subjects had electrographically confirmed left or right unilateral TLE, had failed treatment with at least 2 anti-epileptic drugs (AEDs), and were 18 years or older. Exclusion criteria included premorbid mental retardation or developmental disorder, comorbid neurodegenerative disease, and poor test effort as confirmed by formal symptom validity assessment. All subjects underwent comprehensive pre-surgical evaluation which included MRI/PET imaging, EEG monitoring, and neuropsychological testing. Cognition was assessed with the Wechsler Adult Intelligence Scale (WAIS-III or IV) or Wechsler Abbreviated Scale of Intelligence (WASI), and depressive symptoms were assessed with the Beck Depression Inventory (BDI-II). The BDI-II is a 21-item questionnaire with a total score range of 0 to 63. Scores of 14, 20, and 29 represent thresholds for mild, moderate, and severe depression, respectively. The following variables were evaluated: age, sex, education, lateralization of seizure focus, AED usage, age of onset of epilepsy, and duration of epilepsy. A multivariate linear regression analysis was performed to assess the relationship between BDI score and cognitive scores. Results: Thirty-one patients were included. Mean age was 38.6 (range 18-70), 61% were female, and 55% and 45% had left TLE and right TLE, respectively. Mean Full Scale IQ score was 86.1 (range 65-112), and mean BDI-II score was 14.7 (range 0-38). Seventeen patients were minimally depressed, 4 were mildly depressed, 6 were moderately depressed, and 4 were severely depressed. Regression analyses demonstrated a significant association between depression and cognition (p<0.01), especially in those with left-sided seizure foci. Conclusions: These results suggest that depression increases the cognitive burden experienced by patients with TLE, most profoundly left TLE. Therefore, it is imperative that depression be recognized and treated concurrently with the treatment of epilepsy.