Association of apolipoprotein E ε4 allele with cognitive impairment in patients with epilepsy and interaction with phenytoin monotherapy.

Cognitive impairment implicates many factors beyond phenytoin monotherapy in patients with epilepsy. Apolipoprotein E ε4 allele has been reported to play a role in severe memory impairment that ultimately progresses to Alzheimer's disease (AD); however, knowledge about its role in cognitive impairment in patients with epilepsy is lacking. Our study proposes the possible involvement of the APOE ε4 allele in cognitive impairment in patients with epilepsy which is further worsened by phenytoin monotherapy. Assessment of the APOE ε4 allele in a population with epilepsy will help to identify the patients vulnerable to cognitive impairment and, therefore, the corrective therapy that needs to be addressed.