Structural brain changes in patients with temporal lobe epilepsy and comorbid depression

Abstract

To assess the morphological features of the brain structures in patients with temporal lobe epilepsy and comorbid depression. From 1 January 2017 to 31 December 2020, we studied 80 patients with temporal lobe epilepsy (aged 18-60 years, 38 of whom had comorbid depression) and 48 healthy subjects of comparable age. Magnetic resonance imaging (MRI) of the brain was performed using the epilepsy protocol in a scanner with a magnetic field strength of 1.5 T. Focal temporal lobe epilepsy was diagnosed by neurologists (epileptologists) specialising in epilepsy according to the International League Against Epilepsy (ILAE) classification of epilepsy. Psychiatrists assessed the presence and severity of depressive disorders by clinical interview and by participants' scores on the Beck Depression Inventory (BDI-II). MRI data were processed using FreeSurfer 6.0 software to determine volumes of subcortical structures and thicknesses of cortical structures. At the group level, analysis of covariance with Holm-Bonferroni correction was used as the statistical method. Morphometric analysis revealed a significant decrease in the volume of the thalamus bilaterally and the brain stem and an increase in the volume of the choroid plexus in the left hemisphere, as well as a significant decrease in the thickness of the entorhinal cortex, temporal pole and isthmus of the cingulate gyrus in the left hemisphere and middle temporal gyrus and inferior temporal gyrus in the right hemisphere in patients with epilepsy compared to healthy controls. No association was found between the presence of depression and significant structural changes on MRI. The data obtained suggest an effect of temporal lobe epilepsy, but not comorbid depression, on the morphology of brain structures.