Another theory about British King George III's illness

Modern medicine may help us to discover the real reasons behind King George III's erratic behaviour, writes historian Lucy Worsley. Using the evidence of thousands of George III's own handwritten letters, Dr. Peter Garrard and Dr. Vassiliki Rentoumi have been analysing his use of language. George III, when ill, often repeated himself, and at the same time his vocabulary became much more complex, creative and colorful. 

These are features that can be seen today in the writing and speech of patients experiencing the manic phase of psychiatric illnesses such as bipolar disorder. Mania, or harmful euphoria, is at one end of a spectrum of mood disorders, with sadness, or depression, at the other. George's being in a manic state would also match contemporary descriptions of his illness by witnesses. 

See this BBC article: What was the truth about the madness of George III?