Mechanisms of memory impairment in epilepsy depend on age at disease onset

Abstract

Objective: In this study, we aimed to uncover distinct antecedents of autobiographic memory dysfunction in patients with epilepsy with early (childhood/adolescence) vs late (adulthood) disease onset. Methods: One hundred sixty-six adults participated: 92 patients with focal epilepsy, whose cognitive and psychiatric functioning were compared to that of 74 healthy controls. Predictors of autobiographic memory deficit were contrasted between patients with early-onset (n = 47) vs late-onset (n = 45) epilepsy. Results: Overall, people with epilepsy performed significantly worse on measures of both semantic and episodic autobiographic memory and showed markedly high rates of depressive symptoms and disorders (p < 0.001). Reduced autobiographic memory in patients with early-onset epilepsy was associated with young age at onset, more frequent seizures, and reduced working memory. In contrast, the difficulty that patients with late-onset epilepsy had in recalling autobiographic information was linked to depression and the presence of an MRI-identified lesion. Conclusions: This study reveals that memory deficits in people with focal epilepsy have differing antecedents depending on the timing of the disease onset. While neurobiological factors strongly underpin reduced autobiographic function in patients with early-onset epilepsy, psychological maladjustment gives rise to the impairments seen in patients with late-onset epilepsy. More broadly, these findings support the practice of subtyping patients according to distinct clinical characteristics to find individualized predictors of cognitive dysfunction.