Rationale: The increase of the ageing population has resulted in a greater number of patients with late-onset epilepsy. Late-onset temporal lobe epilepsy is one of the most common types of late-onset epilepsy and is known to be frequently accompanied by cognitive dysfunctions such as memory impairment. This study investigated the relationship between memory functions in late-onset temporal lobe epilepsy and clinical characteristics including findings from long-term video-electroencephalograph (LVEEG) monitoring.
Methods: We evaluated patients diagnosed as late-onset TLE and underwent LVEEG and neuropsychological tests such as Wechsler Memory Scale-Revised (WMS-R) before introduction of anti-seizure medications at our epilepsy center. We performed multiple regression analyses using the patients' clinical characteristics, including data obtained from LVEEG, as independent variables and the WMS-R scores as the dependent variables. The study protocol was approved by the Nishiniigata Chuo Hospital Ethics Committee.
Results: We investigated 17 patients with late-onset TLE. 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 with left-beginning discharges captured by LVEEG. Regarding delayed recall, patients with transient amnestic episodes had relatively better scores (β= -.606, P= .005).
Conclusions: The results of this study suggest that frequent seizures originating from left temporal lobe impair various cognitive functions. However, further research is needed to clarify the causal relationship between seizures and cognitive dysfunctions, such as assessing whether reducing the number of seizures by epilepsy treatment improves cognitive functions. The results of this study also suggest that pattern of cognitive dysfunction in late-onset TLE may be divided into a type showing transient epileptic amnesia and a type showing decreased delayed recall.
Funding: There is no funding for this abstract.