title: Natural history studies: their critical role.
authors.forename: J A
authors.initials: JA
authors.lastname: Logemann
mesh_terms: D000978:Antiparkinson Agents / Q000627:therapeutic use*; D003680:Deglutition Disorders / Q000209:etiology; D006801:Humans; D007980:Levodopa / Q000627:therapeutic use*; D010300:Parkinson Disease / Q000150:complications / Q000188:drug therapy*; D010959:Tissue Plasminogen Activator / Q000627:therapeutic use*
chemical_list: D000978:Antiparkinson Agents; D007980:Levodopa; D010959:Tissue Plasminogen Activator