I hope this is the right place to mention this.

Sometimes if a previously upstanding older citizen starts talking dirty, or worse, it could be an early sign of dementia. Disinhibition, Inappropriate Sexual Behavior ISB, quite common in geriatric patients, and unfortunately might appear when someone still functions in a professional context. I’m throwing this in the mix in case you encounter it like I did. It’s still jarring and creepy no matter the cause.

Treatment of Inappropriate Sexual Behavior in Dementia | SpringerLink