This retrospective study examined how vagus nerve stimulation (VNS) influences long-term mood, cognition, and seizure burden in patients diagnosed with both epileptic seizures (ES) and functional seizures (FS). Using 266 longitudinal survey responses, patients were stratified into three groups based on FS diagnosis and VNS status. Propensity-matched cohorts were comparable across demographics and seizure characteristics. Longitudinal analyses and violin plots demonstrated that FS⁺/VNS⁺ patients had higher depressive symptom scores (NDDI-E) and greater cognitive burden (QOLIE-C) than FS⁻/VNS⁺ counterparts, despite overall seizure reduction. Patients with FS but no VNS experienced persistently high symptom burden. These results suggest that while VNS may reduce seizure frequency in dual-diagnosis patients, mood and cognitive symptoms remain significant challenges requiring multidisciplinary management. Future work will compare outcomes with other neuromodulation modalities and expand analysis of psychiatric predictors of VNS response.