Temporal lobe epilepsy and depression: a dysfunctional lobe overshadows a sclerotic hippocampus

Depression is one of the most frequent psychiatric comorbidities in drug-resistant patients with epilepsy, reaching up to 60% of them. Studies indicate that the pathophysiology of depression and epilepsy have a lot in common, especially the temporal lobe epilepsy (TLE). Since hippocampal sclerosis (HS) is a frequent histopathology finding in patients with TLE, the purpose of this study was to investigate if there is a frequency relation between depression and the different types of HS. 119 patients with TLE, with and without HS, were selected (HS1 = 40, HS2 = 40, NHS = 39) and their medical records were analyzed. Depression was seen in 44 of them, without difference between HS types nor NHS (HS1 = 20, HS2 = 12, NHS = 12, p = 0.1). However, women were 3 times more likely to have depression (p = 0.004). Patients without HS were younger at seizure onset than those with HS2 (p = 0.02). The HS2 group had more cases of initial precipitating injury than NHS (p < 0.001) but were similar to HS1 patients. Our study shows that presence of depression in drug-resistant patients with mesial temporal lobe epilepsy is linked to hippocampal disfunction rather than neuronal density in the hippocampus.