born May 3, 1877, Bremen, Ger.
died Dec. 25, 1925, Berlin
German psychoanalyst.
He helped establish the first branch of the International Psychoanalytic Institute in 1910 and pioneered the psychoanalytic treatment of manic-depressive psychosis (bipolar disorder). He suggested that the sexual drive develops in six stages and that if development is arrested at any of the earlier stages, mental disorders will likely result from fixation at that level. His most important work was A Short Study of the Development of the Libido (1924).