Abstracts

Rationale: Rationale: Depression is highly prevalent in persons with epilepsy and a bidirectional relationship has been postulated. Prior cohort studies examining the relationship have not controlled for the effects of anti-epileptic medications (AEDs), nor the psychosocial stigma of epilepsy. We hypothesize that epileptic seizure patients differentially express depressive symptoms even after controlling for potential confounders. In this study, we compare depressive symptom severity in patients with epileptic seizures, non-epileptic loss of consciousness, and psychogenic seizures (PNES).Methods: Methods: Patients >=17 years old referred to a first seizure clinic with undifferentiated episodes of loss of consciousness were prospectively enrolled. Depressive symptoms and alcohol usage were assessed using the PHQ-9 and AUDIT-C questionnaires respectively. Exclusion criteria were patients taking anti-depressants and/or AEDs at the time of initial encounter, inability to complete the questionnaires (e.g. cognitive impairment), episodes that could not be delineated, and provoked seizures. Patients were classified as epileptic vs non-epileptic organic vs PNES based on clinical encounters and investigations (i.e. EEG, MRI brain). Mean PHQ-9 scores were compared using ANOVA and Student’s t tests. Additional variables included in the analysis were AUDIT-C scores, age, sex, anxiety and/or depression in the past, single vs multiple events, imaging (lesional vs non-lesional), EEG (normal vs abnormal), and time between last event and clinic visit.Results: Results: Among 218 patients, 100 were included in the study: 52 had epileptic events (20 single unprovoked seizure, 32 new diagnosis epilepsy), 41 non-epileptic organic events (40 syncopal, 1 concussion), and 7 with psychogenic seizures. Mean PHQ-9 scores were 6.62 for the seizure(s) group, 3.23 for the non-epileptic organic group, and 14.67 for the PNES group. PHQ-9 scores were statistically different between the three groups (F(2,97) = 18.443, p = 0.0001), between epileptic and non-epileptic organic groups (p = 0.012), and between epileptic and PNES groups (p = 0.006). Single unprovoked seizure patients (n = 20) also had statistically different PHQ-9 scores compared to single non-epileptic organic event patients (n = 30, p = 0.009). Group characteristics were not statistically different for other variables except for age.Conclusions: Discussion: We find that depressive symptoms differ among patient groups presenting to a First Seizure Clinic. At the time of their index event, patients with epileptic seizures already have greater depressive symptoms than others with similar transient organic impairment of consciousness. Depressive symptoms pre-date the initiation of AEDs and the accumulation of psychosocial stressors associated with the diagnosis of epilepsy. Following a transient impairment in consciousness, depressive symptoms may be a useful clinical variable helping differentiate between epileptic and non-epileptic patients.