 With limited clinical experience, involving typically one or two patients, authors advanced different ideas, including brain lesions similar to those resulting from rheumatic chorea or encephalitis lethargica as a cause of tics, faulty mechanisms of normal habit formation, and treatment with Freudian psychoanalysis.The psychogenic view prevailed well into the 20th century.The possibility that movement disorders, including Tourette syndrome, might have an organic origin was raised when an encephalitis epidemic from 1918–1926 led to a subsequent epidemic of tic disorders.