This from Cecil and Goldman's text book of medicine, Chapter on GCA and PMR:

"These disorders occur primarily in patients older than 50 years, in women more than in men; they are propagated by antigen-driven cell mediated (TH1) immune mechanisms that may be associated with specific genetic markers, and they are highly responsive to corticosteroids.
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Internationally, the frequency varies, with the highest rate occurring in Scandanavian countries."

My mother-in-law, British and French ancestry, had GCA. My maternal aunt, primarily Italian had it, and I, primarily Italian and Greek ancestry, also had it. A friend's mother, Portuguese ancestry, also had it.

It was first recorded in Baghdad in the 10th century by Ali Ibn Isa (Medical History Bayor Taylor Horton's headache era, Shelley 2013).