Abstract
The Neurological Disorders Depression Inventory for Epilepsy (NDDI-E) is commonly used to screen for major depressive disorder (MDD) in patients with epilepsy, yet little is known about longitudinal changes in NDDI-E scores in relation to seizure control and psychiatric care. This study evaluated temporal changes in NDDI-E total and Item 4 scores (ΔNDDI-E, ΔItem 4) over ≥6 months in 34 adults (≥18 years) with baseline NDDI-E scores >13. Patients were seen in a specialized outpatient psychiatry clinic within an epilepsy center. Data included Clinical Global Impression-Improvement (CGI-I) ratings by psychiatrists specialized in epilepsy care, seizure frequency, DSM-5-based psychiatric diagnoses, and treatment interventions (e.g., medication adjustments, psychotherapy, and psychosocial support). Patients also completed a self-report questionnaire. No significant difference in MDD diagnoses was found between those with baseline NDDI-E scores of 14-16 and ≥17 (6.7 % vs. 21.1 %, p = 0.36). Comorbidities included autism spectrum disorder, dissociative disorder, and other mental health conditions. Changes in seizure frequency did not correlate with ΔNDDI-E or CGI-I scores, while ΔNDDI-E and ΔItem 4 showed moderate correlations with CGI-I (ρ = 0.51 and 0.56). All patients with improved Item 4 scores had better CGI-I ratings (p < 0.001). Qualitative analysis indicated that emotional fluctuations and psychosocial stressors influenced NDDI-E scores. These results suggest that longitudinal improvement in NDDI-E Item 4 may serve as a marker for psychiatric benefit. Effective use of the NDDI-E requires considering the psychiatric and psychosocial dimensions beyond seizure control. To validate these findings, studies with larger sample sizes and longer follow-up are necessary.