One of my laughers has dementia-related psychosis. April, not her real name, behaves quite aggressively, and does not really like anybody. She is what my dad would call a rabble-rouser, the equivalent of a raging teenager. April didn't like her first Laughter Yoga session. She exclaimed, "You're crazy!" She made raspberry noises and just really had a hard time. About 10 minutes into class, one of my trusty staff members removed her to another room.
The next week, I planned a theme of "Night." April started snoring. I declared, "Yes!" So we Laughter Snored. As I have said before, no one is wrong in Laughter Yoga. We acknowledge and redirect.
Class continued, and the staff and I moved among the laughers, shaking hands, howling at the moon, and breathing together. As I approached April to share a thumbs up, she returned a middle finger. I held my expression, nodded and moved on. I did not react. After all, she was giving me a kinesthetic boundary. She didn't want to play this time.
When I lead a class of people who have dementia, I consider every exercise fresh, each moment is entirely new. The next exercise, I approached her and she laughed with me in a loud, sarcastic way. Perfectly fine. As long as she is not making fun of anyone, any improvised laugh is great.
April would participate to a greater or lesser degree over the weeks. Then one day, I was in the hall saying goodbye. She pushed her walker up right next to me and laughed, "Ha Ha Ha." I laughed with her. We chanted "Very good, very good Yay!" Then she shouted, "Get out of my way." Woo Hoo!
I have a debrief with the staff after a Laughter Yoga session. I also try to find out everything I can about my residents. I discovered that April was verbally abused by her husband for many years. She is simply working that out. It has nothing to do with me, so I need not take it personal. I also don't have to let one person dominate or ruin class.
A few thoughts, don't assume that your dementia patients aren't getting it. Even those who don't remember my name see me and laugh or say, "Oh it's you!"
If Grandma flips you the bird, don't react, or change your expression, just nod and move on. She is telling you that she doesn't want to play right now. Don't give up. The next exercise might be the breakthrough. As long as you are in control of the class and she is not disruptive, let her stay. You'll know when she needs to leave. If you aren't sure, give your staff a non-verbal, is she okay, and let them make the call.