Stress, anxiety, depression, and epilepsy: Investigating the relationship between psychological factors and seizures
Introduction
Depression and epilepsy appear to be closely associated [1]. Depression is considerably more prevalent among people with epilepsy as compared with the general population [2], with people with poorly controlled epilepsy especially reporting higher rates of depression [3]. The nature of the association is, however, complex. There is some evidence that the relationship between seizure onset and depression onset is bidirectional [4], with diagnosis of epilepsy acting as a risk factor for the onset of depression and depression acting as a risk factor for the onset of epilepsy [5]. There is emerging evidence that this bidirectional relationship between depression and seizures is also evident for those with current epilepsy [6]. However other psychological problems such as anxiety [7], [8] and stress [9] are also reported to be more prevalent among people with epilepsy, but have been less studied [7]. How these psychological factors act together to influence seizures is not clear.
In those who do not have epilepsy it is well established that stress, anxiety, and depression are closely linked [10], although for these psychological factors, inter-relationships are likely to be complex [11]. In longitudinal studies of those without epilepsy, anxiety and stress appear to precede depression [12], [13]. The strong links between anxiety, stress, and depression are also supported by neurobiological research [14], [15], [16] and neuroimaging studies [17], [18], [19], [20].
Thus, for people with epilepsy, anxiety and stress may also contribute to the previously observed links between depression and seizures. People with epilepsy perceive that stress is the most common precipitant for seizures [9], and in community studies, anxiety is the most common psychological problem among people with epilepsy [7]. Anxiety may also be linked to poor seizure control and more recent seizures [8]. However, although associations between these individual factors have been observed, the nature of the overall relationship of depression, stress, and anxiety to seizures remains poorly understood [21], and previous studies have been cross-sectional. Longitudinal studies are important in establishing the directions of influence between different factors [22].
The aims of this analysis were to test how psychological factors (depression, anxiety, and stress) predict variation in (1) seizure recency and (2) seizure frequency over time.
Section snippets
Sample
A cohort of adults with active epilepsy were recruited to participate in a longitudinal observational study of the physical, social, and psychological health of people with epilepsy. Individuals identified through general practices who had taken part in previous studies in Cardiff [23] and Manchester [24] were contacted and invited to participate in the present study. Ethical approval was obtained from the relevant local research ethics committees (BroTaf and Salford & Trafford). A sample of
Results
Five hundred fifty-eight individuals initially consented to participate. Of these individuals, 341 were recruited from Cardiff, 108 from Manchester, and 115 via Epilepsy Action. Four hundred sixty-eight individuals responded to the first wave of questionnaires, and 443 individuals to the second wave of questionnaires.
Some individuals missed items on particular scales. A two-step approach was used to deal with missing values. First, for partially completed scales, regression-based imputation
Discussion
The aim of the study described here was to gain additional insights into the mechanisms underlying the relationship of anxiety, stress, and depression with seizures using the results from a longitudinal community-based observational study of people with epilepsy.
Findings suggest that depression, anxiety, and stress, when analyzed separately, predicted variation in seizure recency over time. However, depression mediated the relationship of anxiety and perceived stress with variation in seizure
Acknowledgments
The Health Foundation is acknowledged for the award of a Mid Career Fellowship, which allowed this research to be completed.
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