Examining the association between depression and seizures amongst adults with epilepsy: A longitudinal analysis

This programme of work examined the links between psychopathology and seizures for adults with epilepsy using longitudinal data from two datasets and employing state-of the-art analytic approaches to tease apart inter-relationships. In the first study, using path analysis to examine direction of effects, a bi-directional relationship between seizure frequency and depression scores was confirmed. That is, not only did seizure frequency influence depression scores longitudinally and concurrently, but that depression scores also influenced seizure frequency equivalently. The second study employed a latent variable structural equation modelling approach to examine moderation and mediation and prediction of change in variable scores over time. In this study although anxiety, perceived stress and depression all separately influenced changes in seizures (frequency and recency), depression mediated the relationship between both anxiety and stress with seizures. The third study used a latent growth curve approach to focus on patterns of change within individuals. Trajectories of change in depression scores for individuals over time were examined as well as factors predicting this variation. This study found that seizure recency was a significant predictor of the individual differences in baseline depression scores as well as of the changes in depression scores over time for individuals with epilepsy. The implications of these results are that both effective management of seizures and depression are essential for people with epilepsy. Given that the current focus of clinical management strategies for people with epilepsy is on seizure management, this research suggests the importance of also identifying and managing depression amongst people with epilepsy. Strategies to implement this would include increased awareness of the importance of depression amongst clinical staff, improved screening for depression amongst people with epilepsy (for example by using depression screening questionnaires such as the Hospital Anxiety and Depression Scale), implementing effective treatment (such as by using antidepressants or cognitive behaviour therapy) if depression is identified. Future aims would include confirming these findings using alternative designs, for example a randomised trial to investigate whether these links between depression and seizures arise because of a common antecedent factor or shared risk factors and examine whether other factors (such as gender) influence the relationships observed between depression and seizure outcomes