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 toggle caption David Mack/Science Source Shots - Health News A New Look At An Old Epilepsy Drug Yields Treatment Clue November 6, 2013 Valproic acid has been a mainstay of epilepsy treatment for decades. But how the drug works has been a mystery. Researchers have now figured out the drug boosts a particular chemical in the brain. The finding may help scientists develop better treatments someday.