Adolf Hitler had Parkinson symptoms in 1934, at age 45 years. He may have had transient symptoms in 1923, at age 34 years. Young-onset parkinsonism, during the 1920s, favored a diagnosis of post-encephalitic rather than idiopathic parkinsonism. Hitler had oculogyric crises, phenomena only associated with post-encephalitic parkinsonism. In addition, he had dystonic facial spasms, palilalia and a sleep disorder, phenomena more likely to be associated with post-encephalitic than idiopathic parkinsonism.

In November 1918, at age 29 years, Hitler may have had von Economo's encephalitis, while he was a patient in a hospital, recovering from poison gas. This paper looks at the possible relationship of von Economo's encephalitis to Hitler's asocial behavior; his obsessions and compulsions, his cruelty and rages. The influence of Hitler's parkinsonism on his conduct during World War II is discussed.