In this review, we explore the relationship between epilepsy and cognition and between epilepsy and dementia. Chronic epilepsy, particularly mesial temporal lobe epilepsy (MTLE) with hippocampal sclerosis, may be associated with impaired cognition, which can be secondary to uncontrolled seizures, to adverse effects of antiepileptic drugs (AEDs) or to the underlying biological abnormality. The choice of an adequate AED with an appropriate dose regimen may lead to a favorable outcome. This feature is especially relevant in elderly patients with dementia and associated epilepsy, a vulnerable population in which the diagnosis of seizures can be difficult and for whom treatment guidelines are not yet available. Based on available information and on data derived from studies with other populations, recommendations for the management of these patients are presented.