Marilyn Budzynski takes care of her 20-year-old son, Michael, in Eustis, Fla., in September. Michael suffers from Dravet syndrome, a severe form of epilepsy. Tom Benitez/MCT /Landov hide caption

itoggle caption Tom Benitez/MCT /Landov

In epilepsy, the normal behavior of brain neurons is disturbed. The drug valproic acid appears to help the brain replenish a key chemical, preventing seizures. David Mack/Science Source hide caption

itoggle caption David Mack/Science Source