Objective To examine cognitive responses to stress-related stimuli in patients with seizures and to explore whether the response patterns differ in patients with epilepsy, patients with psychogenic non-epileptic seizures (PNES) and healthy individuals. We also aimed to investigate self-perceived and physiological stress responses in patients with epilepsy and those with PNES, compared to healthy individuals, and to examine the relationships between the cognitive, self-perceived and physiological stress responses in patients with seizures.
Method A group of 54 patients with refractory seizures admitted for diagnostic video-telemetry assessment (epilepsy n=21, PNES n=26) and 21 healthy volunteers completed self-report questionnaires and performed an emotional Stroop test. Cognitive responses were investigated by exploring attentional biases in responses to neutral versus threatening stimuli comprising generally and socially threatening as well as somatic and seizure-related words. Heart rate variability (HRV) parameters were extracted from resting electrocardiogram recordings taken prior to the Stroop test and used as physiological stress markers.
Results Patients with seizures, particularly those with epilepsy, showed greater attentional biases towards threatening information than healthy individuals across all word categories (ps<.05). Both patient groups also reported greater levels of self-perceived stress than healthy individuals (ps<.01) and showed a different HRV pattern, characterised by reduced variability and a significantly lower parasympathetic nervous system (PNS) tone than controls (p=.002). In patients with epilepsy, the attentional bias towards somatic words was negatively correlated with the HRV measure of PNS tone (r=−0.59). Self-reported stress was not related to any of the cognitive or physiological stress measures in any of the patient groups.
Conclusion Many patients perceive stress as the commonest trigger of their seizures; however, the relationship between psychological and physiological processes relating stress and seizures has been poorly understood. Our findings show that patients with seizures are characterised by a pattern of abnormal attentional vigilance to threatening stimuli, high self-perceived stress and an altered autonomic nervous system responses. The relationships between attentional biases and HRV in patients with epilepsy suggest there may be a reciprocally causative relationship between cognitive responses, PNS tone and seizures. The long-term experience of stress and seizures could lead to a diminished PNS tone, which could exacerbate patients' attentional responses to stressors. In turn, the biased attentional responses could trigger more frequent physiological stress responses, causing further alterations of the autonomic nervous system and further increasing patients' vulnerability to stress and seizures.
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