Resting-state fMRI study of treatment-naïve temporal lobe epilepsy patients with depressive symptoms

Background: Patients with temporal lobe epilepsy are at high risk for comorbid depression, and it is hypothesized that these two diseases are share common pathogenic pathways. We aimed to characterize regional brain activation in treatment-naïve temporal lobe epilepsy patients with depressive symptoms and compare the results to epilepsy patients without depressive symptoms and to healthy controls.

Subjects and methods: We recruited 23 treatment-naïve patients (including anti-epilepsy drugs (AEDs) and antidepressants) and 17 matched healthy controls for this study. The patients were further divided into two groups: patients with depressive symptoms and patients without; the patients then used a self-rating depression scale (SDS) to assess their depression. All participants underwent resting functional magnetic resonance imaging (fMRI) scans using the Trio Tim magnetic resonance (MR) image system (3.0 T). The data were processed and analyzed using REST and SPSS11.5 software.

Results: The patients with depressive symptoms showed significantly higher activity in the bilateral thalamus, insula and caudate and right anterior cingulate compared with the two other groups (p<0.05, corrected). Brain network connectivity analysis revealed that connectivity decreased in the prefrontal-limbic system and increased within the limbic system and angular gyrus in patients with depressive symptoms (p<0.05, corrected).

Conclusion: The epilepsy patients with depressive symptoms showed regional brain activity alterations and disruption of the mood regulation network at the onset of seizures. The present study offers further insight into the underlying neuropathophysiology of epilepsy with depressive symptoms.