[Use of honorifics in all situations by a patient with semantic dementia]

We report the case of a 72-year-old man who had been given a diagnosis of semantic dementia (SD) at 64 years of age, and who began to use honorifics in all situations during the later clinical course. His initial clinical features were problems in word comprehension and naming, and some behavioural changes, including clockwatching and aberrant eating behaviours. The most prominent feature in this case was the use of honorifics in all situations, while other aspects of his language ability deteriorated. He even used honorifics with members of his family, including young grandchildren. Although it is difficult to explain the reason why the patient used honorifics in all situations, we considered 2 possibilities. The first is that although he remains able to use honorifics, he is unable to distinguish when the use of honorifics is not required. The second is that a change in emotional state, such as the "taming effect" or "placidity" that has been suggested to accompany frontotemporal lobar degeneration, might have affected his use of honorifics. The regular schedule of daycare services provides him with emotional stability because he does not have to constantly be aware of the time. Since no standard treatment has been established for SD, our experience with this case might be beneficial in caring for patients with SD.