Is Cognitive Reserve Applicable to Epilepsy? The Effect of Educational Level on the Cognitive Decline After Onset of Epilepsy

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Abstract
The aim of this study was to know the effect of education level (EL) on the cognitive change after onset of epilepsy. The rationale is that people with high EL may have more cognitive reserve and show resistance to damage brought about by epilepsy. Patients were from an outpatient epilepsy clinic of a national university hospital. All received initial and repeated neuropsychological tests and the Cognitive Ability Screening Instrument (CASI), at an interval of 12 months. CASI consists of nine items, with a total score of 100. We compared the differences between the two tests, in terms of z-scores. The EL was divided into high and low with a cut-off at 12 years, and age at entry was divided with a cut-off at 38 years. Epilepsy severity was divided into intractable and nonintractable. A total of 64 patients completed the study, including 31 with high EL and 33 with low EL, with no differences in gender and epilepsy severity between groups. In general, patients had cognitive impairment in multiple domains. At the baseline, the effect of EL was found for all items except remote memory and orientation, whereas the effect of age was observed for remote and recent memory. At the 12-month follow-up, subjects with high EL showed deterioration in mental manipulation, whereas subjects with low EL showed improvement in verbal fluency but deterioration in attention. Patients with high EL have better cognitive functioning than those with low EL after epilepsy has developed, which supports the cognitive reserve theory. However, 1-year follow-up might be too short to see significant changes between groups.