What is the earliest reference to this speculation? Here's one theory:
"Bruce died in 1329 of a mysterious ailment called the " great malady." He was ill for only two years, and his physicians did not quarantine him. No one mentioned leprosy until a generation later."
"His skull was pitted and the upper jaw and nose eroded by disease. The people we talked to, claimed he died of syphilis instead of leprosy. Physicians often confused these diseases in the Middle Ages."
Leprosy Strikes Britain - Robert the BruceWhat do you think is the most likely answer to the question of his health?I think he had some kind of skin disease. Who knows which one. Syphilis disfigures, or...
Psoriasis?:
"A year later he died, supposedly of leprosy, more likely of a virulent form of psoriasis."
Strange Tales from ScotlandPorphyria? (of vampire fame due to sensitivity to sunlight):
"It's possible that even Robert the Bruce's "leprosy" may be down to [porphyria], as leprosy was a name attached to a great many skin complaints."
Talk at South BridgeOr...
Distemper??:
"He had for some time laboured under an inveterate distemper, in those days called a leprosy; a consequence of the fatigues, hardships, and sufferings which, to such an unparalleled degree, he had endured in the early part of his career."
Significant ScotsEpilepsy? (while not denying leprosy):
"Another feature was that his upper incisors and associated maxillary alveolar bone indicated that he might have suffered from epilepsy, a condition rare amongst medieval royalty."
History of Dentistry Research Page, NewsletterHope that helps.