The incipit of a piece in the Telegraph:
Clever children are almost four times more likely to suffer from the condition, which is also known as manic depression.
The latest finding, published in the British Journal of Psychiatry, supports a commonly held belief that exceptional intellectual ability is associated with the mental illness.
Famous sufferers include Sir Winston Churchill, Lord Nelson, Alexander The Great, Michelangelo, Picasso, Mozart, Rudyard Kipling, Charles Dickens, Albert Einstein, Sir Isaac Newton, Charles Darwin and Christopher Columbus.
While it seems that any list of maladies which looks for ‘historical’ sufferers is bound to include either Alexander or Caesar, this notion of a bipolar Alexander is new to me … where did this come from?
via Straight-A schoolchildren at higher risk of bipolar disorder, research claims | Telegraph.
rogueclassicism 
Murdering a loyal friend who dared to speak truth to power in a drunken rage is a pretty good clue. As were the numerous times Alexander withdrew into his tent, not speaking to anyone.
Interestingly, one of the virtues of Beowulf was that he never killed anyone when he was drunk.