Features of cognitive dysfunction in late-onset temporal lobe epilepsy

A global increase in the aging population has resulted in more patients with late-onset epilepsy. Late-onset temporal lobe epilepsy (LOTLE) is one of the most common types of late-onset epilepsy and is frequently accompanied by memory impairments. Here, we investigated the relationships between memory function and clinical characteristics, including findings from long-term video-electroencephalograph (LVEEG) monitoring, in LOTLE.

We evaluated patients who had been diagnosed with LOTLE and Underwent LVEEG and neuropsychological tests (e.g., the Wechsler Memory Scale-Revised [WMS-R]) before the introduction of anti-seizure medications at our epilepsy center. We then performed multiple regression analyses using patients' clinical characteristics, including LVEEG data, as the independent variables, and cognitive scores as the dependent variables.

We included 17 patients with LOTLE. The mean age at onset was 65.18 ± 8.35 (47-78) years old. Among the WMS-R domains, verbal memory (β = -.79, p < .001), visual memory (β = -.645, p = .005), general memory (β = -.838, p < .001), and attention (β = -1.334, p < .001) showed negative relationships with the number of seizures of left temporal origin captured by LVEEG. Furthermore, patients who experienced transient amnestic episodes had relatively better delayed recall scores at 30 min (β = -.606, p = .005).

Our findings suggest that frequent seizures originating from the left temporal lobe impair various cognitive functions. They also indicate that the patterns of cognitive dysfunction in LOTLE may be divided into two types: one showing preserved delayed recall with transient epileptic amnesia, and one showing impaired delayed recall.