Rush published one of the first descriptions and treatments for psychiatric disorders in American medicine, "Medical Inquiries and Observations, Upon the Diseases of the Mind" (1812). He undertook to classify different forms of mental illness and to theorize as to their causes and possible cures. Rush believed (incorrectly) that many mental illnesses were caused by disruptions of blood circulation, or by sensory overload, and treated them with devices meant to improve circulation to the brain such as a centrifugal spinning board, and inactivity/sensory deprivation via a restraining chair with a sensory-deprivation head enclosure ("Tranquilizer Chair"). After seeing mental patients in appalling conditions in Pennsylvania Hospital, Rush led a successful campaign in 1792 for the state to build a separate mental ward where the patients could be kept in more humane conditions.