Provide extra reassurance and physical attention. Try snuggling while watching TV or listening to music; give extra hugs or massage (back, shoulders, body, foot, hand); do a little dancing.
Provide cuddling alternatives. For some, a blanket or stuffed animal to pet discharges some of the need to touch.
Insist on firm boundaries. Don’t inadvertently encourage inappropriate fondling by allowing it even briefly one day and then reacting with indignity the next. Better to be consistently firm: “No, I don’t like that.” “That’s not right.”
Match your body language to your words. People with dementia are better at reading nonverbal cues. So frown and shake your head.
Realize that boredom can also be a root cause. Sexual activity can be almost an automatic response when there’s nothing better (more distracting) to do. Make sure the person spends time moving and engaged during the day.