What events caused Hitler to commit suicide?

As the war turned against the Nazis it became evident even to the arrogant Hitler that they were about to lose. He probably couldn't face the shame of what he had done and what would obviously have come out during the war trials.

Plus there seems to be some suggestion that Hitler had picked up syphilis from his girlfriend Eva Braun. Syphilis left untreated results in paresis which causes CNS problems, including paranoia and depression.