From the correspondence with his close friends of May 1931 it appears that Ehrenfest suffered from severe depression. By August 1932, Einstein was so worried that he wrote to the Board of the University of Leiden, expressing deep concern and suggesting ways in which Ehrenfest's workload could be reduced.

In Amsterdam, on September 25, 1933, he lost his battle with depression. Having made arrangements for the care of his other children, he first shot his younger son Wassik, who had Down syndrome, then killed himself.[1]