Abstracts

Patients undergoing temporal lobectomy are at risk of developing [italic]de novo[/italic] depression after surgery despite good seizure outcome. Neurobiological predictors of [italic]de novo[/italic] depression largely remain unknown. Previous research has indicated that patients with Major Depression have smaller hippocampi than controls. We explored whether this finding was also true for epilepsy surgery patients by examining the relationships between pre-operative hippocampal volumes, seizure outcome, and [italic]de novo[/italic] depression after epilepsy surgery., The sample comprised 42 patients undergoing epilepsy surgery in the Comprehensive Epilepsy Program, Austin Hospital (26 mesial temporal lobe resections and 16 non-mesial temporal resections). Patients were prospectively assessed pre-operatively, and at discharge, one, three, six, and 12 months post-operatively. Assessment included a semi-structured clinical interview (Austin CEP Interview) and the Beck Depression Inventory (BDI-II). Hippocampal volumetry was conducted on patients[apos] preoperative T(1)-weighted MRI scans and on 41 neurologically normal controls following stereotactic normalisation of the images., Post-operatively, 42% of mesial temporal patients and 19% of non-mesial patients were depressed within the first 12 months after surgery. The occurrence of depression was associated with significantly smaller hippocampi contralateral to the resection in the mesial temporal group ([italic]p[/italic]=0.003). This effect was also seen in mesial temporal patients who developed [italic]de novo[/italic] depression after surgery ([italic]p[/italic]=0.027). Contralateral hippocampi were particularly small in patients suffering from both depression and seizures post-operatively ([italic]p[/italic]=0.031). Furthermore, there were significant negative correlations between contralateral hippocampal volumes and BDI-II scores at one and three months post-operatively ([italic]r[/italic]=-0.46 and [italic]r[/italic]=-0.42 respectively, [italic]p[/italic][lt]0.05). There were no significant findings between depression, seizure outcome, and hippocampal volumes in the non-mesial group., Our findings suggest that the hippocampus is a structural marker of vulnerability to post-operative depression, particularly in the presence of post-operative seizures. They also indicate that a smaller hippocampus predates the onset of depression.,