Clinical relevance of interictal dysphoric disorder and its impact on quality of life in drug-resistant epilepsy

•The prevalence of IDD in DRE is high.•In DRE, subjects with IDD more likely present depressive or anxious symptoms.•In DRE, subjects with IDD more likely present certain personality disorders.•In DRE, subjects with IDD show lower QOL scores compared to subjects without IDD.•Adequate treatment requires early recognition of IDD and psychiatric comorbidities. This study aims to assess the prevalence of Interictal Dysphoric Disorder (IDD) in drug-resistant epilepsy (DRE) and to describe its clinical and psychopathological profile, including personality, as well as its impact on quality of life (QOL). A retrospective cross-sectional study from an Epilepsy Unit from January 2007 to December 2017. All patients were diagnosed with DRE. Patients underwent a battery of tests (HADS, SCL-90R, PDQ-4+, QOLIE-31) and a psychiatrist assessed the presence of Axis-I disorders and IDD. Statistical procedures were carried out using R-4.0.1 software. A total of 282 patients were included. A statistically significant association was found between IDD and mood and anxiety disorders (p