Preoperative depressive symptoms predict postoperative seizure outcome in temporal and frontal lobe epilepsy.

Objective: Recent research has pointed to the possibility of a bidirectional relationship between seizure frequency in epilepsy and depressive symptoms. The study described here investigated the relationship between preoperative depressive symptomatology and postoperative seizure outcome in a sample of patients with temporal (TLE) and frontal (FLE) lobe epilepsy.
Methods: A retrospective analysis was conducted on the data from 115 eligible patients with TLE (N=97) and FLE (N=18) and resections limited to one cortical lobe who were evaluated preoperatively and 1year after epilepsy surgery with respect to depressive symptoms (Beck Depression Inventory, BDI) and seizure outcome. The latter was assessed in terms of actual total seizure frequency as well as a dichotomous variable (seizure free vs. not seizure free) for the 1-year outcome. Repeated-measures analyses of variance and regression analyses were applied.
Results: Seizure-free patients had significantly lower BDI scores preoperatively as well as postoperatively than patients who were not seizure free. In the regression analyses, the preoperative BDI score was a significant predictor of postoperative seizure frequency as well as seizure freedom. When only patients with TLE were analyzed, the results for the association between preoperative BDI and postoperative seizure frequency and seizure freedom remained consistent.
Conclusion: The present results provide evidence for a statistical bidirectionality of the relationship between depressive symptoms and postoperative seizure status in a mixed sample of patients with TLE and FLE. Possible reasons for this bidirectional association include an underlying common pathology in both depression and epilepsy, for example, structural changes or functional alterations in neurotransmitter systems.