The ability to smile often disappears late in dementia. For some people, the mind-body disconnect means that the muscles forget how to manage even this seemingly reflexive movement. Others, lacking social awareness, fail to register the experiences that used to trigger a smile. This ability seems to vary by person.
What is helpful to know about this loss of the social smile?
You can't take it personally if your loved one no longer smiles. It's a developmental decline, not a deliberate move.
Don't assume that your loved one has no capacity for love or joy. Even though these emotions flow mainly in one direction, the person is still soaking up positive feelings from you.
You just might still see a wisp of a grin. Lucidity is known to come and go in severe dementia. So if a hint of smile happens, consider it a gift.