Description of a priest in a medieval Japanese essay, "Tsurezuregusa": is this the first report of frontotemporal dementia?

In Tsurezuregusa, a medieval Japanese essay written by Kenkō, a priest with the characteristics of behavioral variant frontotemporal dementia (bvFTD), has been described. He had characteristics such as early behavioral disinhibition; loss of sympathy and empathy; perseverative, stereotyped, and compulsive/ritualistic behavior; and hyperorality and dietary changes. Based on the diagnostic criteria for bvFTD, it is possible that he had probable bvFTD. According to the essay, despite his abnormal behavior, the priest had adapted to his surroundings, including the temple where he worked. His successful adaptation was likely due to the tolerance of people around him and/or the education he had acquired before the onset of the disease, which may have functioned as a "cognitive reserve."