Abstracts

Rationale: Recent research has shown the high rate of mental illness as a comorbidity in patients with epilepsy. In particular, anxiety in epilepsy has been overlooked irrespective of the high rate of prevalence, therefore we should pay attention to it. Relationship between epilepsy and anxiety has been explored in various ways. In the past, anxiety in epilepsy patients had been recognized as the reaction to having epilepsy and loss of control. In this context, a shorter duration of epilepsy was reported to be related with high trait anxiety in State and Trait Anxiety Inventory (STAI) because it was surmised that people with epilepsy had not been used to having epilepsy just after their diagnosis. However, in these days, a cohort study which examined the temporal relationship between epilepsy diagnosis and psychiatric illnesses including anxiety showed the bidirectional relationship. It means that psychiatric illnesses increase the risk of developing epilepsy, suggesting that psychiatric illnesses and epilepsy may share a common pathological background. Then, we explored the relationship between anxiety and epilepsy, focusing on refractory epilepsy which probably had severe pathological change.  Methods: This was a single-centered retrospective study. We reutilized a data set in which we analyzed the relationship among electrodermal activity (EDA), epilepsy-related factors and demographic features between epilepsy patients and normal controls. This study was approved by the institutional review board of Hokkaido University Hospital and written informed consent was obtained from all participants. In the original data set, participants were recruited from outpatients with epilepsy who visited our department from January 2016 to March 2018. Age- and sex-matched healthy controls were also recruited. Patients diagnosed with refractory epilepsy were included. Patients with concomitant mental disorders were excluded. Anxiety was assessed in both groups using state and trait anxiety scores with STAI (STAI-S and STAI-T, respectively). Additionally, information on the epilepsy syndrome, seizure number, epilepsy duration, and the number of prescribed anti-epileptic drugs (AED) was obtained from the epilepsy group. Correlations between STAI-S/T and the epilepsy-related factors was assessed. Results:   Eighteen patients with refractory epilepsy and twenty-four healthy individuals extracted in this study. The male-to-female ratio, age, or state anxiety did not significantly differ between the epilepsy group and the control group. All 18 participants in the epilepsy group were suffered from focal epilepsy. The seizure frequency varied greatly with an average frequency of 10.3 per month and a maximum frequency of 40 per month. The average disease duration (23.6 years) was relatively long. All participants in the epilepsy group used anti-epileptic drugs, and the average number of prescribed anti-epileptic drugs was 2.39.About the correlation between STAI-S/T and epilepsy-related factors, STAI-T and epilepsy duration was significantly correlated (P = 0.03; ρ = 0.52). STAI-T did not correlate with seizure number and AED number as well as STAI-S did not correlate with epilepsy duration, seizure number, and AED number. Conclusions: Patients with refractory epilepsy showed high trait anxiety. Furthermore, the long epilepsy duration might increase trait anxiety in patients with refractory epilepsy. Funding: This work was supported by JSPS KAKENHI (Grant Number, JP18K15505).