Cognitive correlates of psychopathology in Functional/Dissociative Seizures and non-lesional epilepsy: an exploratory study

Objective: To explore the relationship between cognitive functioning and psychopathological features in Functional/Dissociative Seizures (FDS), and test whether this differs from that observed in epilepsy. Methods: We recruited a cross-sectional sample of adults (age > 18) with a diagnosis of non-lesional epilepsy or FDS between January 2021 and July 2022. Participants completed a series of psychiatric questionnaires and neuropsychological measures. Spearmans Correlation Coefficient was computed between each of the psychiatric and cognitive measures in each group. Fishers Z test of significance for independent correlation coefficients then tested the significance of the difference between correlation coefficients for the two groups. Results: There were no group differences in neuropsychological test scores. However, people with FDS reported higher seizure severity, depression levels, number of medically unexplained somatic symptoms, and exposure to traumatic events compared to epilepsy. Results of the Fishers Z-test revealed significant differences in correlation coefficients between groups in two instances. First, in the association between the number of traumatic experiences and cognitive switching (z = 2.77, p = 0.006); the number of traumatic experiences were positively associated with cognitive switching in epilepsy but showed a non-significant negative trend in FDS. Secondly, in the association between vocabulary abilities and the number of medically unexplained symptoms (z = -2.71; p = 0.007); higher vocabulary ability was associated with fewer somatic symptoms in epilepsy, while no such correlation was observed in FDS. Significance: This study provides preliminary evidence for the complex interplay between cognitive functioning and psychopathology in FDS and epilepsy. Neurocognitive functioning such as vocabulary abilities or attentional switching may play a role in the expression or maintenance of pathological features of FDS.