Hippocampal subfields volumes and affective symptoms of patients with mesial temporal lobe epilepsy

Abstract

Background: Hippocampal sclerosis (HS) is the most frequent neuropathological finding in mesial temporal lobe epilepsy (MTLE-HS), leading to hippocampal atrophy due to neuronal loss and gliosis. Anxiety and depression are highly prevalent in drug-resistant MTLE-HS patients, but their neuroanatomical correlates remain unclear. This study investigates the independent association between affective symptoms and hippocampal subfield volumes in unilateral MTLE-HS.

Methods: We analyzed 46 consecutive patients with unilateral drug-resistant MTLE-HS using MRI-based volumetry of hippocampal subfields on both the sclerotic (HS) and contralateral (non-HS) sides. The Hospital Anxiety and Depression Scale (HADS) was used to assess affective symptoms. Subfields were segmented into anterior and posterior regions, and multiple linear regression models controlled for demographic and clinical variables.

Results: No significant associations were found between HS laterality and affective symptoms. Depressive symptoms (HADS-D) were not linked to hippocampal subfield volumes on either side. In contrast, anxiety symptoms (HADS-A) correlated with multiple non-HS subfields in univariate analyses, but only the posterior dentate gyrus (DG) remained significantly and negatively associated with HADS-A scores (β = -67.94, r² = 0.16, p < 0.01) in multivariate analysis.

Conclusions: In patients with unilateral MTLE-HS the levels of depressive symptoms were not independently associated with hippocampal subfield volumes. The posterior DG volume of the non-HS side presented a r² of 0.16 in our final model. These findings highlight the potential role of hippocampal morphology in anxiety pathophysiology among MTLE-HS patients and contribute to understanding neuroimaging markers of affective symptoms in epilepsy.

Keywords: Anxiety; Depression; Hippocampal Sclerosis; Hippocampal Subfields; MRI; Mesial Temporal Lobe Epilepsy.