Mutations in nicotinic receptor subunits have been identified in some families with autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE). Normal intelligence has currently been considered the rule, although anecdotal cases with intellectual disability have been reported. We aimed to evaluate the frequency and degree of neuropsychological disorders in ADNFLE associated with nicotinic receptor mutations by testing 11 subjects from four families with a comprehensive neuropsychological assessment. General intellectual function was below the normal range in 45% of the subjects. All were abnormal in one or more executive task. Memory was either more affected than executive functions or equally affected in two thirds of subjects, suggesting a frontotemporal pattern of cognitive impairment. Cognitive dysfunction appears to be an integral part of the broad phenotype of ADNFLE with nicotinic receptor mutations, a fact that has been underestimated until now. The cognitive disorder affects executive functions as well as memory in most subjects.