The vast majority of patients with hereditary epilepsy are not born with mental retardation, but depending on the epilepsy condition, some patients will show abnormalities in intelligence as they grow and develop. Specifically, the type of epilepsy, the age of onset, the number of seizures and the duration of each seizure can affect the patient’s intellectual profile. Children with infantile spasms, Otawara syndrome, and Lennox syndrome are often associated with mental retardation, whereas febrile convulsions and benign epilepsy are not associated with intellectual abnormalities. The earlier the age of onset, the greater the impact on the patient’s intelligence. If epilepsy develops after the age of 10, most do not affect the patient’s intelligence. Patients with frequent seizures and frequent seizure durations >30 minutes are also likely to affect the patient’s intelligence.