Lifetime risk and cumulative incidence of epilepsy were examined among Rochester, MN, residents between 1960 and 1979, and are reported from Columbia University, New York; and Mayo Clinic. Rochester, MN. Among 412 individuals identified with incident epilepsy, lifetime risk was 1.6% to age 50 and 3.0% to age 80; cumulative incidence 0.9% to age 20, 1.7% to age 50 and 3.4% to age 80. Lifetime risk through 87 years of age increased over time from 3.5% in 1960-69 to 4.2% in 1970-79. One in 26 people will develop epilepsy during their lifetime. 
COMMENT. Lifetime risk forecasts the need for epilepsy services in a community. The greatest need for these services is in infants and the elderly. The incidence curve varies with age, with high rates in infants under 1 year of age, low rates from age 20 to 60, and an increase from 60 to age 80, a time period that is rapidly expanding in the general population. The authors estimate that 12 million individuals in the US will develop epilepsy in their lifetime.