So Parkinson's is a popular armchair diagnosis, but simply put, we can't be certain. Hitler was a hypochondriac in the extreme, but what we can say is that there was a clear decline in his health beginning in the early '40s, with a known diagnosis of a heart condition in 1941, and while he rarely took a day off, his doctor was keeping him filled to the brim with various drugs - 28 different pills a day at one point. The tremblings and shuffling gait which some believe points to Parkinson's began to manifest themselves in 1942, and worsened through his remaining years. While he certainly exhibited the symptoms, as Kershaw notes, they must be taken long with the "lifestyle, diet, lack of exercise, and excessive stress, on top of likely congenital weaknesses" that defined his life during the period. But by early 1945, the symptoms had gotten very bad, and whether it was the correct diagnosis or a psychosomatic manifestation of his general state of being, his personal physician, Dr. Theo Morell, was treating him for the disease.

Ian Kershaw, "Hitler 1936-1945"

Richard Evans, "The Third Reich at War"