A fresh attempt to suggest that Hitler's behaviour might partly be influenced by advanced syphilis has been made by a US historian.
Hitler suffered poor health
The rumour that the Nazi leader might have contracted the sexual disease has surfaced before - along with a multitude of conflicting and occasionally outlandish theories about his health.
Syphilis is easily curable in its early stages by modern antibiotic treatments, but if left untreated for some years, secondary symptoms, including heart, nerve and mental problems may emerge.
The latest book, "Pox: Genius, Madness and the Mysteries of Syphilis" by Deborah Hayden, says that Hitler had many of the symptoms which might point to advanced syphilis.
These included encephalitis, dizziness, neck pustules, chest pain and an "accentuated heartbeat".
Ms Hayden also points to signals which suggests a mental decline in his last years, including "paranoid rages".
Mental disturbances and mania are also known symptoms of late-stage syphilis.
It is also suggested that Hitler received iodide salts - a well-known treatment for late-stage, or tertiary syphilis.
However, iodide salts were recommended for several other conditions, including angina, which might have been blamed for his chest pains.
The main evidence for Hitler's health problems comes from the accounts of his physician, Dr Theodor Morell.
Some historians have laid Hitler's health problems partly at Morell's door, claiming he may have even deliberately poisoned his patient.
I think that there is a preponderance of circumstantial evidence
Deborah Hayden, US historian
Ms Hayden told The Times: "This is not definitive proof, but I think that there is a preponderance of circumstantial evidence."
Other accounts suggest that Hitler certainly had a fixation on syphilis, which he considered a "Jewish disease".
A long passage in Hitler's book "Mein Kampf" is devoted to his thoughts on tackling the spread of the disease.
There have even been suggestions that Hitler believed, rightly or wrongly, that he had acquired syphilis congenitally.
However, other experts say that the range of Hitler's recorded symptoms could easily have been caused by something else.
Dr Fritz Redlich, a Yale University expert on neurology and psychiatry, found "no evidence" in medical records or from other sources that Hitler had syphilis.
Dr Redlich said that another condition, giant cell arteritis, an autoimmune disease which causes inflammation of the arteries, could account for Hitler's headaches, cardiac symptoms and vision problems.
Dr Tom Hutton, a researcher from the University of Texas, told a conference in 1999 that a condition with similar symptoms to Parkinson's disease might explain the Fuhrer's "mental inflexibility" - and perhaps even account for his delay in reacting to the Normandy landings in 1944.