Good morning,
Just read your response "my husband can smile when he wants to" and must add
two cents from the PWP here.

You are right, the masking is a part of Parkinson's.
You error in " can smile when he wants to".

I recall the first time I saw a video of myself walking.  I had always
assumed that if I held my head up and smiled while I was struggling, no one
would notice that I walked a little different..........

Video showed not only a problem with gait........but I WAS NOT holding my
head up and smiling.........this came as quite a surprise to me!     My
husband will frequently comment re: my expression as being a bit
sullen.......when I thought I was smiling.

Smiles come from deep inside.......for some of us, they don't always show on
the surface.

Rita Weeks