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. Spearman’s Correlation Coefficient was computed between each of the psychiatric and cognitive measures in each group. Fisher’s 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 Fisher’s 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.

KEY POINTS

People with non-lesional epilepsy or Functional/Dissociative Seizures (FDS) perform more poorly than healthy controls on neuropsychological measures.

It is often thought that psychopathological factors influence cognitive presentation in FDS, but this hypothesis has received little empirical support.

This study explores the relationship between cognition and psychopathology in FDS and epilepsy.

Correlation analyses reveal distinct associations in FDS compared to epilepsy, suggesting potential differences in underlying mechanisms.

Neurocognitive processes such as vocabulary abilities or attentional switching might contribute to FDS generation or presentation.

Allan H. Young: Employed by King s College London; Honorary Consultant SLaM (NHS UK) Deputy Editor, BJPsych Open. Received honoraria for attending advisory boards and presenting talks at meetings organised by LivaNova. Principal Investigator in the Restore-Life VNS registry study funded by LivaNova.

The remaining authors have no conflicts of interest.

This work was supported by the Bergqvist Charitable Trust through the Psychiatry Research Trust as a PhD scholarship to Irene Faiman. Professor Young s independent research is funded by the National Institute for Health Research (NIHR) Biomedical Research Centre at South London and Maudsley NHS Foundation Trust and King s College London.

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

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The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

The study was approved by the London Queen Square Research Ethics Committee (REC: 20/LO/ 0784, IRAS ID: 265164, 28/09/2021).

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